The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting. Modern people interact with old historical figures with all the historical and cultural bias that goes with this.
Minette, the Cape Slaves, the Witels and Nitrogen
Copenhagen, May 1891
We pack as much work into a week as is possible, normally working into the weekend. Andreas told me that nothing is scheduled for next Saturday. Uncle Jeppe visits Liverpool once a year. He is returning to Copenhagen and Andreas and his dad asked me to welcome him at the harbour. I am always delighted to spend time with the old man! I was looking forward to the train ride into the city with him. I was bright and early at the harbour and when the English steamer docked, I eagerly looked through the crowd to see him.
The crowd was milling around with people greeting and porters busily hauling luggage to waiting for horse carts and some, off to board the train. I scanned the milling crowd and my eye caught sight of a beautiful young lady, a bit younger than me. She looked lost with no porter by her side, carrying two leather travel bags, too heavy for her. My glance passed over her, looking for Uncle Jeppe. My gaze almost immediately returned to her. There were two reasons for this. She was beautiful and there was something familiar about her! She looked up and right at me and instantaniously I recognized her. “Minette!!”
I could hardly believe my eyes! My heart jumped with excitement! At the same time as I recognised her, she saw me and a broad smile graced her beautiful face! “Minette!” I blurted out! The last person on earth I was expecting and the one person that I most dearly wanted to see! “Minette!” I said again, this time a lot softer as I riched her after a few quick strides to get to her. “Minette, what on earth!?” I said again. She dropped her bags and we embraced! “I almost did not recognise you with your hat and your nice dress!
“What are you doing here?” “Come,” I said and picked her bags up. “I’m here to visit you,” she said and started walking with me towards the train. I was still baffled. “Two months ago Andreas wrote to me. He invited me to visit and surprise you.” I realised that it must have been after Andreas and my long drinking session in Copenhagen that he hatched his plans. It appears that he took his lead from the many times I spoke about Minette and all our adventures.
Suddenly I remember that I was there to welcome Uncle Jeppe! Minette saw the panic in my eyes as I started looking around. “Uncle Jeppe is only arriving next week,” she helps me out of my misery. “He is still in Liverpool. The whole thing was a ruse to get you to the harbour!”
I have never been this excited to see anybody! The last time I saw her we were sitting in Pennys Cave on Table Mountain with our friends. Minette and my relationship is one big adventure. I realise it again with her here with me tonight! We always craved adventure.
It was on such an adventure when we discovered the cave on Kogel Bay, Dappa se Gat, where I think the slaves lived who took in the pigs from the Colenbrook which became known as the Kolbroek pigs. We discovered the Cave when we hiked from Hermanus to Cape Town, one year. We started in Hangklip at Pringle Bay close to Hermanus where my younger brother, Elmar, Juanita and their two kids live. We were looking for a different cave during that hike called Drosters Gat.
I started reading Alexander Von Humboldt’s work when I was still a small boy and was struck by the destruction brought about by European colonists. On the other hand, Von Humboldt’s energy with which he explored the natural world inspired me. It was through his eyes that I saw the world started to change and I developed an intense desire to see as much of it as I can before it’s gone! In my imagination, I would accompany him on his travels across South America and the Russian Steppe. This was when I started getting very interested in the physiology of the human and animal body as read about his work with Guthrie. One of my most memorable stores is how Gurthie and Von Humbolt went from home to home after a severe thunderstorm to buy up corpses of men, woman and children who died from the lightning to dissect to study human anatomy.
Across the decades that separate our lives, Von Humboldt mentored me. If I had enough money to buy a book I wanted, but not enough for food for the day, I would buy the book. Choices between using my savings from my Transport work to buy a house in Cape Town or to either travel to Europe to learn how to make bacon or go on an expedition to the Magaliesberg Mountains always ended up on whatever would teach me the most and be the greatest adventure. Buying a house never was a priority!
During my time as a transport rider across the vast open spaces of Southern Africa, I witnessed the destruction that people bring to nature and each other first-hand. I visited old Tswanruins at the Vaal River between Parys and Potchefstroom and at Hartebeespoort. I hiked through these massive Tswana and Sotho cities at the Suikerbosrand and in Johannesburg on the farm of Sarel Marais. The cities of the Tswana and the Sotho were decimated by Mzilikazi Khumalo, a Southern African king who founded the Mthwakazi Kingdom now known as Matabeleland. It was precisely because Minette and I shared these priorities and values that I was drawn to her. Well, apart from her good looks and inquisitive personality.
The existence of slavery and the wholesale destruction of our natural world went hand in hand. A period followed where I had a lively interest in slavery and the knowledge I gained allowed me to understand our land better. The Kolbroek pigs is an excellent example of a point where my interest in slaves and pigs intersected.
Minette and I heard stories in Cape Town of a cave where a community of runaway slaves lived. It was something we did. We would hear a legend and we then went looking for the site where the legend presumably played itself out. This is how we started looking for Drostersgat. Between Pringle Bay and Rooiels, much closer to the water’s edge, legend has it that a community of runaway slaves lived. The entrance is very narrow and like Dappa se Gat, one can enter it only during low tide. It is accessible from the sea. It became known as Drostres gat (cave).
We rode out to Pringle Bay at Cape Hangklip to go looking for the cave. It is always good to rely on local knowledge when looking for these things. Locals directed us to a restaurant and bar called Miems. The owners are Morris and Kerneels. Morris, a tall and well-built man, is a trained geologist who worked in Johannesburg mines for many years. Kerneels and Morris travelled to Ireland to earn extra money to buy the restaurant and bar. Where most Europeans are hoping for the new world to provide a living, Morris and Kirneels went to Ireland where they worked till they saved enough to start Miems at Cape Hangklip. Morris also heard the legend of Drostersgat and read about it in a story that Laurence Green, a journalist for the Cape Argus, wrote about it. According to legend, the cave is between Pringle Bay and Rooiels.
An old farmer told Green that the Gat (Cave) can only be accessed at low tide and one had to climb down with a precipice with a rope. The old farmer and a neighbour found the cave and went inside for about eighty yards. He remembers that it was dark and damp and one could see bones of large game animals and cattle still scattered across the cave floor. They also found trunks of melkhout trees, used to make fire to roast the meat. He wrote that there are graves of “strandlopers” (scavengers) around the general location of the cave. Morris found the cave or at least, what is reported to be the cave. It is marked on local Cape maps. He has been there more than once and says that he was not able to get into the cave. The opening is too small for a big man. He tried to access it from the sea without any success. It does not surprise me that the slaves managed to get into areas where he could not. By all accounts, they were gaunt and small.
Minette and I went looking for it, but despite a few attempts, we could not find it. Without even finding the cave, by simply looking at the area, it is immediately obvious that finding food would have been a massive challenge for the slaves. There are accounts of such slaves wandering around on Table Mountain only to eventually returned to Cape Town and hand themselves over to authorities to face the cruellest punishment rather than dying of starvation. It is this reality that made the feat of young Joshua Penny even more remarkable who stayed for an extended time period on Table Mountain.
The only place on the mountain that was regularly inhabited by these most unfortunate people was an overhang up Platteklip Gorge on Table Mountain. There are accounts of slaves who lived up this gorge taking live cattle up. Anyone who ever hiked up there will know that taking a cow or an ox up there must have been extremely arduous. The cave can still be seen to this day up the oldest recorded route up Table Mountain.
The many accounts of the struggle for food of the slaves and the fact that keeping livestock was a strategy they used to sustain themselves lend tremendous credence to the story of the Kolbroek pigs as Oupa Eben and Uncle Timo told it. In the Hangklip area, there are a number of other well-known legends of runaway slaves-communities hiding away in caves. The area is mysterious, rugged and to this day, sparsely populated. An old man once told me, there are many ghosts in these mountains!
We were not able to find Drosters gat, but it was on our hike from Rooi Els to Kogel Bay that we first came face to face with Dappa se Gat. We just passed Kogel bay and I got to the stretch of beach, strewn with round boulders, resembling cannon shot when I saw the cave. Dappa se gat! I could hardly believe my eyes. The legend from my youth now right in front of my own eyes. I immediately recognised it from Oupa Eben’s stories. The cave is a couple of hundred meters deep and during high tide it is inaccessible. That day I became convinced that Dappa se Gat is Drosterscave that Minette and I have been looking for for years. It is one and the same place. Morris, a trained geologist is adamant that at the location where the map indicates Drosterscave to be, there is in reality no cave. The slope of the land makes it impossible for there to be a cave and even if someone should enter by the very narrow tunnel which presumably is the cave entrance, you would find that it ends in nothing. So it happened that not even on Minette and my wildest adventures were we ever very far from bacon, hams, salamis, and pigs.
Another favourite adventure of ours is the Witels River. Between the Matroosberg and the Winterhoek Mountains is the town of Ceres that officially existed since 1854. A pass was constructed called, Michells Pass which follows the route to Ceres next to the Bree River. Where the Witels flows into the Bree River is an open “outspan” area which is clearly seen on the West bank of the river. I am sure that the trekkers spent a couple of nights here, feeding and resting their cattle before taking on the pass.
The first pass was built by Jan Mostert and was called Mostert’s Hoek Pass (1765). Jan was one of the first settlers to settle on Ceres’ side of Tulbagh. The pass was a very rugged 3kms. The road was so bad that wagons had to be dismantled and sections crossed on foot, the cargo and the wagons strapped to the backs of oxen.
Charles Michell surveyed Mostert’s Hoek Pass in 1830 to improve it. Andrew Geddes-Bain constructed the new pass in 1846, with the assistance of 240 convicts. The Bree River runs all the way into the Warm Bokkeveld. The pass effectively reduced the travel time from Cape Town to Beaufort West from 20 to 12 days. It was almost possible to do the route with a horse-drawn carriage.
On my way to Johannesburg through Kimberly, I stayed at the Winterberg Mountain Inn. It was the main road between the Cape and Kimberley. It was formerly known as Mill & Oaks Country Inn. The restaurant is built on the foundations of an olf wheat-mill dating from the 1800s. It was called the Ceres Meul (Mill). It is not known exactly when the Mill was built. Probably in the late-1700s by the first European settlers. The Inn is the kind of place that I prefer. Steeped in history, enough ghosts to chase, legends to unravel, exceptional food and great company!
One of Minette’s banking clients told her about the Witsels river; that it runs down towards the Bree River from the southern Peaks of the Hex River mountains. The best approach is through the Waaihoek Kloof. The man who first identified the route will forever remain nameless in accordance with his own wishes. The next time I stayed at the Winterberg Mountain Inn, I asked the locals if they know the access route. They explained to me in great detail. When I got back to Cape Town a few months later, I immediately looked Minette up at the Bank and the plan was set out for a legendary hike.
One ascends a mountain and through a precarious route, access the river. Once you are in the river, there are very few ways out. The cliffs are for the most part right next to the river, forcing you to either swim or jump from boulder to boulder. At certain places, the cliffs fold over the river creating long stretches that you swim through caves, following the flow of the river. Next to the river, there are small stretches that resemble sea sand. It created the most amazing places to sleep. To go up the mountain, into the Witels River and out at the Bree River takes around 5 days. Some young people are able to cover the distance in a day provided that they don’t take anything heavy in their backpacks. The best Minette and I did was 2 days from start to finish, but the river was very full and progress painfully slow. The Witels river has become a spiritual pilgrimage for us and ranks as one of our most favourite routes on this bountiful earth!
One of the Witels hikes it started raining. Rain down the Witels can be life-threatening if it rains higher up in the catchment area and the river comes down. The force of the river carries large boulders from higher up, downstream and the force is such that if one would be in the water when this happens, chances for survival are slim to zero. We moved our backpacks higher up the sandbank and as close to the cliff as we could and still have a comfortable place to lay down. I was trying to get Minette’s mind off the raging river!
On one of my trips, I studied discoveries of the behaviour of gasses and how salts are formed on earth. This was the frontier of scientific thinking and I loved it. I would get my hands on as many good periodicals as I can find and study them on the long trek from the Cape to Johannesburg. As I was becoming disillusioned by our mental world to build a ladder to heaven to link us with the Devine and as I saw the other candidate of connecting me with what is permanent namely nature crumbling before my eyes before colonial forces, I became obsessed with science. On the one hand, I was eager to enlighten Minette of the latest discoveries and on the other hand, I wanted to see how much I remember. I use the opportunity to review it myself and write it down for you for study and meditation.
I was laying under my sleeping bag. Minette was getting her overnight spot comfortable for the night; painstakingly removing the rocks that would start irritating her once the initial tiredness has worn off. I asked her if she knew what air was made of. “Oxigen and of course. . . ” “Nitrogen!” she answered. “Correct! It was discovered separately in 1772, by the Scottsman, Daniel Rutherford and in the early 1770s by a Swiss, Carl Scheele. Rutherford called it “noxious air” and Scheele, “foul air.”” I replied.
I briefly explained for fear that I would bore her, “It exists as a gas and comprises of two nitrogen atoms, joined to form one gas molecule. They are split apart by something of high energy such as a lightning strike. This leaves the two atoms free to react with other matter floating around it.
“One of these elements floating around in the atmosphere is oxygen. Nitrogen reacts with oxygen and forms nitrogen monoxide (NO). Nitrogen monoxide, a colourless gas, is an extremely important compound. It is also called nitric oxide or nitrogen oxide. The nitric oxide is heated from the energy from the lightning flash that created it.”
The drizzle was coming down softly. Minette finished nesting and I got enough energy together to build a fire. I cleared a small sandy patch at my feet and with a twig I wrote the simple chemical reaction in the sand.
N2 (g) + O2 (g) lightning —> 2NO (g)
“There are different sources of Nitric Oxide. One very important one which I will tell you about later.”
“As it cools down, it reacts further with the oxygen molecules around it to form nitrogen dioxide. Nitric Oxide is one nitrogen atom attached to one oxygen atom. It now combines with another oxygen atom and forms nitrogen dioxide, a poisonous, brown, acidic, pungent gas. There is another important molecule that exists in our atmosphere as a gas namely ozone which is three oxygen atoms that combined into a molecule. Nitrogen mostly reacts with ozone to form nitrogen dioxide.”
“Like nitrogen, oxygen occurs as two oxygen atoms, bound in one molecule. Ultra-violet light and lightning cause the two tightly bound oxygen atoms to separate and react, either with other single-atom oxygen molecules or with more stable two-atom oxygen molecules. In the latter case, three oxygen atoms are bound into one molecule (O3). It is not very stable and quickly breaks down into one or two oxygen atom molecules or it reacts with nitric oxide to form nitrogen dioxide.”
I wipe my previous simple formulation from the sand to write another very simple one.
NO (g) + 1/2O2 (g) —> NO2 (g)
“Nitrogen Dioxide (NO2) reacts with more oxygen and raindrops. Water is H2O. The two oxygen atoms of nitrogen dioxide combine with the one from water to form 3 oxygen atoms bound together. There is still only one Nitrogen atom giving us NO3 or nitrate. There is now still one Hydrogen atom left and it combines with the nitrate to form nitric acid (HNO3). Nitric acid falls to earth and enters the soil and serves as nutrients for plants. Old writers called nitric acid (HNO3) aqua fortis or spirit of niter.”
I clear the sand at my feet for a third equation.
3NO2 (g) + H2O —> 2HNO3 (aq) + NO (g)
“Nitric acid is highly reactive and combines with salts in the soil. The Hydrogen atom is replaced by a calcium, potassium or sodium atom, converting it to a nitrate salt. This salt is called saltpetre. The extreme importance of this is that it is plant food. Saltpetre is used today for gunpowder, fertiliser and to cure meat.”
“Fascinating,” Minette said a bit sarcastic. I did not notice that she started cooking supper and I can help. She hands me an onion to peel. “Saltpeter!”, she said. I thought its the sweat from a horse. My dad always said that we ride the horses till the white saltpetre is running down his neck!
I smiled because she did not know how completely correct she was! The few raindrops that fell stopped. The sound of the rushing river and the peace of the mountains transcends everything. I looked at her in the glow of the fire and was struck by her beauty!
The Witels became one of those important cathedrals in our life! The first time I came down the Witels, it arrested my soul and I fell in love with it. Unspoiled! If you are thirsty, you drop into the water and drink directly from the river. The only company for almost the entire length of the river is the baboons on the cliffs. The place I gave my first lecture on nitrogen and the place where I first noticed how beautiful Minette is. It was the start of the two great loves of my life. Unravelling the technical reasons why saltpetre cures meat and Minette!
I would love to have you guys here with us. Today, as they say in the Bible, “my joy is complete” with Minette here with me. What I was feeling on the Witels and in Penny’s Cave is now undeniable. I have very strong feelings for this amazing woman who travelled halfway around the world to see me.
When we got home, Andreas and his family provided Minette with her own room. I was overjoyed that she is staying with us. That evening around the supper table we told our stories, including my nitrogen lecture on the Witels. Andreas slapped me on the shoulder when he walked past me. Let Minette join you tomorrow for Uncle Jeppes’ lunchtime lecture. He is going to start with “saltpetre” and since you and Minettes are clearly interested in it, you will both find it fascinating.”
We had the most amazing dinner!
Well, kids, its time to go to bed. A great week is waiting for me with Minette here. Next weekend I will write and tell you all about it!
The quest to understand how great bacon is made takes me around the world and through epic adventures. I tell the story by changing the setting from the 2000s to the late 1800s when much of the technology behind bacon curing was unraveled. I weave into the mix beautiful stories of Cape Town and use mostly my family as the other characters besides me and Oscar and Uncle Jeppe from Denmark, a good friend and someone to whom I owe much gratitude! A man who knows bacon! Most other characters have a real basis in history and I describe actual events and personal experiences set in a different historical context.
The cast I use to mould the story into is letters I wrote home during my travels.
From the Sea to Turpan
University Geology Museum (1), Copenhagen, June 1891
The day has finally arrived, our much-anticipated visit to the University of Copenhagen’s Geology Museum. It is located on Nørregade. The museum is part of the Natural History Museum of Denmark. It was truly exceptional. The exhibition of minerals is, from what I am told, one of the finest in Europe! There are exhibitions on meteorites, volcanoes, continental drift, the geology of Denmark, the geology of Greenland, fossils (including the largest bivalve including clams, mussels, oysters, and scallops in the World), and the origin of humans. The fact that we had to postpone the trip for a week worked out well. Despite Uncle Jeppe being unable to join us, the Curator of the Museum was there and what happened was exceptional! He proved to be just the man to bombard with my many questions!
Wondering About Meat Preservation
For as long as I can remember, I have been wondering about meat curing. As a child, I tried to imagine how people discovered that dry meat lasts longer. It seems self-evident to us now, but someone had to “discover” it! There is a difference between dry meat and cured meat. Cured meat is identified by three things. Its look, taste, and longevity. When an animal is killed, the meat blooms a beautiful red colour. If you do not rub it with saltpeter, it changes to a dull brown colour. If you, however, rub it with a mixture of salt and saltpeter, it retains the pinkish-reddish colour. If you rub it onto meat that already turned brown, after a few days the entire piece of meat will return to its pinkish-reddish colour, resembling fresh meat. This probably conjured up images of the power of immortality in the minds of the ancients endowing saltpeter with seemingly magical powers.
Is Curing possible without Saltpeter
Using saltpeter does not guarantee you of good bacon, but without it, curing does not happen. When you dry meat, this can be done without saltpeter and the meat will also last a long time but the meat will be dry and without juices. In South Africa, the old Dutch farmers fused their knowledge of drying meat in the chimnies in Holland and the North European practice of using vinegar in their hams with the indigenous practice of hanging meat out in the sun and wind to dry. They add coriander with salt to the vinegar to create what they call biltong. This is a good example where drying works well to preserve meat with or without saltpeter. Saltpeter can only be left out of the recipe if vinegar is used and lots of salt and provided that the temperature where the meat is hung is not too high.
It is possible to cure meat with salt only, but the process takes a very long time. Longer even than dry-curing with saltpeter. It is very difficult. Communities in Italy that does this often times have to carry the hams or bacons higher up the mountain to parts where it is still cold if the weather turns warmer. For our curing plant in Cape Town, similar to Uncle Jeppes’ plant, time is a luxury that we will not have and besides, we do not have the luxury of very high mountains. The process of curing it without saltpeter is such a specialty field that I will write to you about it separately.
The Friendly Curator and My Research Partner
The curator of the museum was on duty this weekend which was must fortuitous. He agreed to have coffee with us and answer our questions. This is the thing about the Danish that I notice wherever I go – they don’t have inflated egos. If this was in Cape Town, I can not imagine that someone with his position would have taken the time to have coffee with us and answer a novice to the area minerals and chemistry’s many questions.
Minette is a research partner second to none! She asks simple but powerful questions. She is never afraid to ask for clarification on points of seeming contradiction.
From Sea to Dry Deserts
The curator patiently listened to my questions before he started speaking. It was as if he did not really listen to my questions but decided to rather address the topic of the origins of curing more generally. Not one of s minded his approach. it was all fascinating and he had Minette, Andreas, his dad, his mom and me hanging on his every word.
First, the professor had to set me right in a wrong perception I had about how salts naturally occur on earth. I did not understand is that today our salts are very refined. Impurities are removed before it is sold. Different salts are neatly separated but in nature that is not how they occur. Salts occur in nature as a mixture of various minerals. When the ancients talk about saltpeter, for example, there were many different grades of purity. The nitrate salts may be mixed with what we refer to as table salt or sodium chloride along with many other chemical compounds. The opposite also occurs. If salt is mined from a salt pan, for example, there may be small amounts of nitrate salts mixed in with the table salt. There may even be some nitrite salts present in very small quantities from game urinating in the pan.
After setting me straight, the professor continued. “While people living in desert areas would have discovered that certain salts have the ability to change the colour of meat from brown, back to pinkish/ reddish, along with increased preservation power and a slightly distinct taste, it is certainly true that coastal dwellers would have observed the same. They would have noticed that seasalt or bay salt has the same ability.”
“It is possible that curing was first noticed by early seafarers: meat proteins contain nitrogen. When the meat is placed in seawater, the surface proteins start to break down and forms nitrites for a period of 4 to 6 weeks. Nitrite is then converted to nitrate over the next 4 weeks though bacteria. It is possible that they preserved meat in seawater barrels and that the whole process of curing was discovered accidentally.”
Our friendly curator ordered a second cup of strong coffee! We all remained spellbound. My note-keeping was put to the test and there was no time for me to even take a sip of coffee! I had to keep up and did not want to miss a single point.
“I suspect that people discovered this even long before barrels were invented. The use of seawater for meat storage and further preparation was so widespread that it would have been impossible not to have noticed meat curing taking place. If it is generally true that earliest humans first settled around coastal locations before migrating inland, it could push the discovery of curing many thousands of years earlier than we ever imagined, to a time when modern humans started spreading around the globe. When did it develop into an art or a trade is another question altogether, but I think we can safely push the time when it was noticed back to the earliest cognitive and cultured humans whom we would have recognized as thinking “like us” if we could travel back in time and meet them. I think the question of recognition in different regions we can safely put at the time when these areas were populated.”
“We know that dry-curing of pork takes around 5 to 6 weeks under the right conditions and if the meat is not cut too thick. It must be cool enough that the meat doesn’t spoil before it is cured. Even though I now suspect that curing was first noticed by communities living by the sea as I just explained, I suspect that curing salts in deserts were discovered since natural salts always appear as a mix of various salts and under certain conditions, these salt deposits contain small amounts of nitrate salts and ammonium chloride. The ancients would have noticed this.”
He then introduced me to something that I did not expect. Another curing salt! “The most important two curing salts that appear to us from antiquity are saltpeter (sodium nitrate) and sal ammoniac (ammonium chloride). Both salts were well known in Mesopotamia and references to them appear alongside references to salt curing of fish mentioned earlier and both salts were used in meat curing.”
I was riveted! “The ancients developed basic techniques of separating out the different salts. In particular, sal ammoniac was by far the more important salt of the bronze age (2000 BCE). It was produced in Egypt and mined in Asia. There are features of sal ammoniac that favours it as a salt for people who had a motivation to exploit new lands due to population pressure and climate changes. When the horse was domesticated around 5000 BCE, a food source was needed to sustain humans on long expeditions and I believe sal ammoniac fits the requirement perfectly.”
“Both salts cure the meat in a week which obviously had huge advantages compared to salting the meat with normal table salt. This, I speculate, was the first incentive to change to a dedicated curing salt. Secondly, sal ammoniac, as far as I can find, was globally traded from much earlier than saltpeter. Ancient Macedonian records indicate that even 2000 BCE saltpeter was preferred in food over sal ammoniac on account of the better taste of saltpeter.”
“Sal ammoniac was far more vigorously traded than saltpeter in the early Christian era and possibly for thousands of years before that. Fascinatingly enough, I realised that ammonium chloride will, like nitrates, undergo bacterial transformation into nitrites which will, then, in the meat matrix yield nitric oxide which will cure the meat. I further discovered that it is an excellent meat preservative.”
He then introduced us to a region of the word that I did not even know existed.
“Turpan is the name of an oasis in the far western regions of China. It is an extremely dry area. Turpan is also probably the only place on earth where sal ammoniac and nitrate salts in the form of sodium nitrate occur in massive quantities side by side.”
“Chinese authors of antiquity are unanimous that sal ammoniac came into China from Turpan, Tibet, and Samarkand and through Samarkand, it was traded into the Mediterranian along the silk road. It all makes for an appealing case for sal ammoniac as the actual curing salt from antiquity that was used in meat curing when the practice spread around the world. There is even a tantalizing link between Turfpan and the ancient city of Salzburg and the salt mines which leads me to speculate that the trade of sal ammoniac was done into the heart of Western Europe, into what became known as Austria. This leads me to believe that the actual technological progressions related to meat curing may have come from Austria. Whether it was Salzburg or Turfan is not clear.”
“Around Turpan (also called Turfan), Sal Ammoniac forms in volcanic vents and after volcanic eruptions before it has rained which dissolves it. It is highly soluble. It is unique in that the crystals are formed directly from the gas fumes and bypass the liquid phase, a process known as sublimation. The Turfan area, both the basin and the mountains are replete with different salts containing nitrogen (nitrate salts and ammonium) any one of which could be used effectively in meat curing.”
“The sal ammonia was mined from openings in the sides of volcanic mountains where steam from underground lava flows created the ammonium chloride crystals. These were traded across Asia, Europe and into India. Massive sodium nitrate deposits occur in the Tarim Basin, the second-lowest point on earth. I then speculate that traders used some of these deposits to forge ammonium chloride since the ammonium chloride crystals did not survive in crystal form on long voyages due to its affinity for water that breaks the crystal structure down. Once this happened, the sodium nitrate and the ammonium chloride look similar in appearance. Due to the fact that it is known that almost all the sal ammonia produced in Samarkand was exported, I deduce that demand outstripped supply and this provided the incentive for such forgery. I find support for the likelihood of such a forgery, not just in the limited supply of sal ammoniac compared to nitrate salts, but also in the fact that mining then sal ammoniac was a seasonal affair and extremely dangerous and a difficult undertaking.”
“It seems likely that sal ammonia wasthe forerunner of saltpeter as the curing agent of choice. It is composed of two ions, ammonium, and chloride. The ammonium would be oxidized by ammonia-oxidizing bacteria (AOB) into nitrites and the well-known reaction sequence would result.”
“Not only would it result in the reddish-pinkish cured colour, but it was an excellent preservative. An 1833 book on French cooking, The Cook and Housewife’s Manual by Christian Isobel Johnstone states that “crude sal ammonia is an article of which a little goes far in preserving meat, without making it salt.” (Johnstone, C. I.; 1833: 412) It is, of course, the sodium which tastes salty in sodium chloride and ammonium chloride will have an astringent, salty taste. I know exactly what ammonium chloride tastes like since it was added to my favourite Dutch candy “Zoute Drop” with licorice.”
More Information on Saltpeter
“Saltpeter is the curing salt that most of us are familiar with that preceded sodium nitrite as curing agent. By far the largest natural known natural deposits of saltpeter to the Western world of the 1600s were found in India and the East Indian Companies of England and Holland plaid pivotal roles in facilitating its acquisition and transport. The massive nitrate fields of the Atacama desert and those of the Tarim Bason were still largely unknown. In 1300, 1400 and 1500 saltpeter had, however, become the interest of all governments in India and there was a huge development in local saltpeter production.”
“In Europe, references to natron emerged from the middle of the 1500s and were used by scholars who traveled to the East where they encountered both the substance and the terminology. Natron was originally the word which referred to saltpeter. Later, the word natron was changed and nitron was used.”
“At first, the saltpeter fields of Bihar were the focus of the Dutch East Indian Company (VOC) and the British East Indian Company (EIC). The VOC dominated the saltpeter trade at this point. In the 1750s, the English East Indian Company (EIC) was militarised. Events soon took place that allowed for the monopolization of the saltpeter trade. In 1757 the British took over Subah of Bengal; a VOC expeditionary force was defeated in 1759 at Bedara; and finally, the British defeated the Mughals at Buxar in 1764 which secured the EIC’s control over Bihar. The British seized Bengal and took possession of 70% of the world’s saltpeter production during the latter part of the 1700s.”
“The application of nitrate in meat curing in Europe rose as it became more generally available. Later, massive deposits of sodium nitrite were discovered in the Atacama Desert of Chile and Peru and became known as Chilean Saltpeter. This was, as I have said before, only a re-introduction of technology that existed since 2000 BCE.”
“The pivotal area where I believe saltpeter technology spread from across Asia, India and into Europe, is the Turpan-Hami Basin in the Taklimakan Desert in China. Here, nitrate deposits are so substantial, that an estimated 2.5 billion tons exist, comparable in scale to the Atacama Desert super-scale nitrate deposit in Chile. Its strategic location on the silk road, the evidence of advanced medical uses of nitrates from very early on and the ethnic link with Europe of people who lived here, all support this hypothesis.”
“Large saltpeter industries sprang to the South in India and to the South East in western China. In India, a large saltpeter industry developed in the north on the border with Nepal – in the state of Bihar, in particular, around the capital, Patna; in West Bengal and in Uttar Pradesh (Salkind, N. J. (edit), 2006: 519). Here, it was probably the monsoon rains which drench arid ground and as the soil dries during the dry season, capillary action pulls nitrate salts from deep underground to the surface where they are collected and refined. It is speculated that the source of the nitrates may be human and animal urine. Technology to refine saltpeter probably only arrived on Indian soil in the 1300s. Both the technology to process it and a robust trade in sal ammoniac in China, particularly in western China, predates the development of the Indian industry. It is therefore unlikely that India was the birthplace of curing. Saltpeter technology probably came from China, however, India, through the Dutch East Indian Company and later, the English East Indian Company became the major source of saltpeter in the west.”
“To the South East, in China, the largest production base of saltpeter was discovered dating back to a thousand years ago. Here, a network of caves was discovered in 2003 in the Laojun Mountains in Sichuan Province. Meat curing, interestingly enough, is also centered around the west and southern part of China. Probably a similar development to the Indian progression.”
“In China, in particular, a very strong tradition of meat curing developed after it was possibly first introduced to the Chinese well before 2000 BCE. Its use in meat curing only became popular in Europe gain between 1600 and 1750 and it became universally used in these regions towards the end of 1700. Its usage most certainly coincided with its availability and price.”
“The Dutch and English arrived in India after 1600 with the first shipment of saltpeter from this region to Europe in 1618. Availability in Europe was, generally speaking, restricted to governments who, in this time, increasingly used it in warfare. This correlates well with the proposed time when it became generally available to the European population as the 1700s from Lauder. I believe that a strong case is emerging that the link between Western Europe and the desert regions of Western China was the place where nitrate curing developed into an art. The exact place, I believe, in Western China is the Tarim depression.”
Everyone sitting around the table was hanging to his every word. I did not notice but by this time a small crowd had gathered around us. The curator raised his voice slightly to allow everyone to hear.
“Meat curing, of course, there is another form of meat curing that I can tell you about.” As he started, Minette jabbed me in the ribs. “You see!” she said! “I told you!” Minette asked me before why the sweat of horses is also called saltpeter which is exactly the subject that he brought up.
“It may surprise you that one of the techniques used by ancient horseback riders to cure their meat was to hang strips over the neck of the horse or placing it under your saddle so that the sweat of the horse cure the meat. We now know that sweat contains nitrates and the same bacteria that reduce the nitrate to nitrite or that remove the one oxygen atom from the Salpeter to form nitrite is present no horses. This would result in the rapid curing of the meat. The fact that meat was placed under the saddles shows the importance of “softening the meat” in a time when people did not have many options in caring for their teeth.” It is the same mechanism, just in a less culturally acceptable way.”
“German and Austrian cookbooks pre-1600’s reveal that vegetable dyes were used to bolster colour and speak of curing with salt only. It is well known that the Germans and Austrians were familiar with nitrate curing and, I will argue, they would have been acquainted with sal ammoniac as a curing salt also, but no doubt due to the effect of sal ammoniac on taste, it fell out of common use. Hanging meat around the nacks of horses also had a limited lifespan in terms of popularity and as the availability of nitrate salts in Europe increased due to its use as a pharmaceutical and for military usage in gunpowder, the nations of Europe and China reverted to salt curing and today it is generally used globally. In fact, most people will say that it has always been the curing salt of choice.”
An Unforgettable Day
It was all over too soon. When the Curator of the Geology Museum was done, everybody applauded! I asked him how he knows so much about meat curing and not only geology and mineralogy. He told me that he grew up in a butcher’s family. His dad had a keen interest in mineralogy in particular since it deals with chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. The reason why he studied geology was because of his father’s inspiration.
That evening we did not read from Edward Smith’s book after supper. Instead, we went over the notes I took and where our host was too fast for me to catch everything he said, Minette, especially, helped me to get the facts straight. She has a very keen mind and a great memory.
We talked till very late into the night and all retired to bed, continuous that we all experienced something very special today. There were two groups of people that I wanted to share this with. Tristan, Lauren, I could not go to bed without writing this letter and I sat alone in my room writing this. It is now 2:00 a.m.. Tomorrow I will share this with the second group of people or as in this instance, a person. Jeppe could not attend on account of the birthday celebrations of a grandchild. I can hardly wait for Minette and me to share this with him.
Now I am off to bed! I am exhausted but insanely excited! My Danish experience had just gone to another level! I can hardly believe the privilege I have to be here!
Lots of love from Denmark and a very happy father!
Neither the University of Copenhagen, the Geology Museum or any other affiliated organisation had no input in any of the content in this chapter. All research and conclusions are that of Eben van Tonder and the interaction with the curator of the museum, as portrayed here, is fiction. Eben places it in this setting for literary and artistic reasons.
I have been approached by countless people from around the world with questions and insights which I did not address in my initial article. I continued to gather bits of information, stored in mails to myself, learn from production managers I got to know in every part of the world and great articles I discovered over the years as I worked on a daily basis to do first-hand experiments at Woody’s and I tried to answer these questions for myself and for others while, always, working on improving the system.
It is time for a completely new follow up article where I address these issues systematically. I look at heat treatment, colour development, moisture loss, protein denaturing, phosphates, salt, deboning, meat quality, pressure, freezing, chilling and gelation in relation to the use of TG. I continued to look at what an optimal TG blend will look like and the aspects that our production systems must incorporate. I also examine possible future developments in thermal processing and a few alternative ways to set up a production line where TG is incorporated into a grid system for the restructuring of large meat muscles, mainly for the production of bacon.
The number one question I was asked over the years is if TG affects meat colour. Some researchers reported slight colour changes on fresh meat, but as far as processed meats are concerned, it is an irrelevant question since there are much more important factors affecting colour than the small impact that TG may or may not have. Lets very briefly look at heating, colour development, and moisture loss to illustrate my point.
We begin with a review of the curing process and the effect of heat and smoke on colour development and moisture loss before we turn our full attention to a discussion of other factors affecting TG.
PROPER COLOUR DEVELOPMENT BEGINS WITH CURING: THE IMPORTANCE OF RESTING, AFTER INJECTION, BEFORE SMOKING
to to NO
When sodium nitrite is placed in solution in the brine preparation phase, the crystal structure breaks up and the ions separate into Na and . Nitrous acid is formed. This hydration of nitrous acid is an important time-consuming reaction (Krause, B. L.; 2009: 9).
After the formation of nitrous acid (), the next step “is the generation of either a nitrosating species or the neutral radical, nitric oxide (NO).” (Sebranek, J., and Fox, J. B. Jn.; 1985: 1170) A nitrosating species is a molecular entity that is responsible for the process of converting organic compounds into a nitroso (NO) derivatives, i.e. compounds containing the R-NO functionality. During resting, the most important one is the formation of Nitrosyl Chloride (NOCl). This is one of the good reasons why leaving out salt from bacon curing is not advisable. The time-consuming nature of these reactions is also the reason why a resting phase is vital.
In a large commercial high-throughput bacon curing plant we found that an optimal processing sequence has the following sequence. A few variations of this basic model will be proposed in this article, but this is the model that I used with great effect for many years and other models, if they survive critical theoretical scrutiny, needs to be tested.
injecting the meat,
resting it for between 12 and 24 hours (depending on the curing room temperature),
tumbling it again to pick up brine that leached out during the maturing or colour development stage and, This time, add TG blend.
slicing and packing
Lets now focus on colour development during smoking and thermal treatment to understand optimal smoker chamber temperatures.
PROPER COLOUR DEVELOPMENT: THE IMPORTANCE OF SMOKING
Cold smoking is normally seen as smoking where the core temperature will remain below 35 deg C. We use hot smoking where the core temperature riches > 35 deg C but < 45 deg C. Smoking and thermal treatment are therefore considered jointly. Temperature effects product taste, meat toughness, binding, coulour, and moisture loss.
During reddening, the temperature is increased, extraction flaps in the smokehouse closed to maintain humidity, and sulfhydryl groups are released which is a reducing substance in meat and important in proper cured colour formation. Fraczak and Padjdowski (1955) indicated that 80°C is the critical temperature for the decomposition of sulfhydryl groups in meat.” (Cole, 1961) (Reaction sequence)
During heating and smoking, there are several changes in the meat that has a direct effect on the colour development. The nitrosating species that is more dominant than NOCl is smoke due to the presence of phenolic compounds. In addition to the heat release of sulfhydryl groups, the pH is reduced in the meat. Randall and Bratzler (1970) noticed an increase in the myofibrillar protein nitrogen fraction, pH and free sulfhydryl groups of pork samples that were only heated, and a decrease of these values in the samples that were subjected to heat and smoke. “Results of this study indicated that smoke constituents react with the functional groups of meat proteins.” (Randall, 1970) These results seem to support a reddening step before smoke is applied due to the fact that heating would release the sulfhydryl groups and during the smoke steps, the pH will be reduced. (Reaction sequence)
DENATURING VS COAGULATION
With our consideration of smoking on meat, we have also entered the discussion of the effect of heat on meat. Before considering the effect of heat on the protein lets first see how the heat gets to it.
Mechanism of heat transfer
Heat is transferred during cooking through conduction, convection, and radiation. “Spakovszky and Greitzer (2002) defined conduction as ‘transfer of heat occurring through intervening matter without bulk motion of the matter,’ convection as heat transfer due to a flowing fluid, either a gas or a liquid, and radiation as ‘transmission of energy through space without the necessary presence of matter.’ Radiation can also be important in situations in which an intervening medium is present, such as heat transfer from a fire or from a glowing piece of metal (Spakovszky and Greitzer 2002).” (Yu, T.Y., et al, 2017)
“Meat cooking usually involves more than 1 mode of heat transfer (Bejerholm and others 2014).” During cooking in a smokehouse, heat treatment is achieved through dry heat surrounding the meat, but during reddening and smoking the air is or become moist and moist-heat (hydrothermal) thermal processing uses hot steam. Smoke House thermal treatment, including smoking, is, in reality, a combination of dry heat and moist heat. (Yu, T.Y., et al, 2017)
“Conventional cooking of meat results in heterogeneous heat treatment of the product on account of steep temperature gradients (Tornberg 2013). Emerging mild cooking techniques such as ohmic cooking can achieve a more homogeneous heating by heating the entire volume of meat at the same time (Tornberg 2013).” (Yu, T.Y., et al, 2017) THis is an important point for consideration in a continuous, fully automated system.
This is important in considering the effect of heat on the grid system with holes. The present role to steel ratio is 1:1,8. The exposed meat area is therefore approximately half (take the edging to be approximately 0.02 to give the total ratio of 1:2). This amplifies the effect of heating, but by what factor? This needs to be determined experimentally between different smokehouses. I have determined a variety of different options in smokehouse settings over the years.
“Heat may cause proteins to lose their native conformation (denature) by providing the polypeptides with kinetic energy, increasing their “thermal motion,” and thus rupturing the weak intramolecular forces (such as nonpolar interaction, various kinds of electrostatic interaction, and disulfide bonds) that hold the proteins together (Davis and Williams 1998). As the temperature increases, a protein starts to unfold. When almost all the tertiary and secondary structures are lost, the unfolded protein may aggregate, have its disulfide bonds scrambled, undergo side-chain modifications (Davis and Williams 1998), and cross-link with other polypeptides. Aggregation is the consequence of nonpolar interaction between heat-denatured proteins whose hydrophobic groups have turned outward into the surrounding water, in order to adopt a lower energy state (Davis and Williams 1998). A variety of side-chain modifications, such as those induced by oxidation or the Maillard reaction, have been characterized in proteins following heat treatment.” As heat increases, the 3-dimensional structure of meat proteins change. These changes manifest in a change in colour and gelation. (Yu, T.Y., et al, 2017)
DEVELOPMENT OF NITROSYLMYOCHROMOGEN
“Upon thermal processing, globin denatures and detaches itself from the iron atom, and surrounds the hem moiety. Nitrosylmyochromogen or nitrosylprotoheme is the pigment formed upon cooking and it confers the characteristic pink colour to cooked cured meats.” (Pegg, R. B. and Shahidi, F; 2000: 42)
We also need to review the main muscle proteins found in the body.
Skeletal muscles are bundles of muscle cells (also known as muscle fibers) embedded in connective tissue. (Yu, T.Y., et al, 2017) These muscle proteins “are grouped into three general classifications: (1) myofibrillar, (2) stromal, and (3) sarcoplasmic. Each class of proteins differs as to the functional properties it contributes.” (www.meatscience.org)
-> Myofibrillar Proteins
The first very important protein to take note off is the myofibrillar protein for the purpose of water binding and binding meat pieces together. These muscle fibers are muscle cells, grouped into muscle bundles. The structural backbone of the myofibrils is actin and myosin. (Toldra, 2002) They are the most abundant proteins in muscle and are directly involved in the ability of muscle to contract and to relax. (www.meatscience.org) Myofibrils also include tropomyosin and troponin, regulatory proteins associated with muscle contraction. Parallel to the long axis of the myofibril, are two very large proteins called titin and nebulin. (Toldra, 2002)
Myosin is a protein which is described as the motor, and the structural protein, actin’s filaments are the tracks along which myosin moves, and ATP is the fuel that powers movement. (Lodish, 2000) Myosin “converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.” (Cooper. 2000)
“Together, actin and myosin make up about 55-60% of the total muscle protein of vertebrate skeletal muscle, with the thicker myosin myofilaments yielding about twice as much protein as the thinner actin myofilaments. Actin alone does not have binding properties, but in the presence of myosin, acto-myosin is formed, which enhances the binding effect of myosin.” (Patterson, The Salt Cured Pig) In meat processing, it is important to note that it is the myofibrillar proteins which are soluble in high ionic strength buffers. (Toldra, 2002)
“Texture, moisture retention, and tenderness of processed muscle foods are influenced by the functionality of myofibrillar protein.” (Xiong, Y. L.;1994) The pork muscle that contains the most myosin is the longissimus dorsi or the eye-muscle or longissimus muscle on the loin. “The muscle fiber bundles of the longissimus dorsi are arranged at an acute angle to the vertebral column. The cross-sectional area of the longissimus dorsi increases towards the posterior part of the ribcage, but it has an approximately constant cross-sectional area through the loin.” (Animal Biosciences)
-> Sarcoplasmic Proteins
“The sarcoplasmic proteins include hemoglobin and myoglobin pigments and a wide variety of enzymes. Pigments from hemoglobin and myoglobin help to contribute the red colour to muscle.” (www.meatscience.org) These proteins are water soluble. Besides myoglobin and hemoglobin, this class of proteins also includes metabolic enzymes (mitochondrial, lysosomal, microsomal, nucleus or free in the cytosol). (Toldra, 2002)
Very important to remember for the purpose of meat processing is that myoglobin is the protein pigment responsible for the red colour in meat. The redness of meat is largely dependant on the concentration of myoglobin. Myoglobin is the storehouse for oxygen in the muscle. Because different muscles need different oxygen levels, the concentration of myoglobin will differ between muscles. The loin muscles in pigs are for example used for support and posture and therefore contains low levels of myoglobin. Myoglobin levels are further influenced by species, breed, sex, age (older animals generally have more myoglobin), training or exercise (this is why free-range pigs have more myoglobin than stall-fed animals), and nutrition. (Pegg and Shahidi, 2000)
-> Stromal Proteins
“Connective tissue is composed of a watery substance into which is dispersed, a matrix of stromal- protein fibrils; these stromal proteins are collagen, elastin, and reticulin.
Collagen is the single most abundant protein found in the intact body of mammalian species, being present in horns, hooves, bone, skin, tendons, ligaments, fascia, cartilage and muscle. Collagen is a unique and specialised protein which serves a variety of functions. The primary functions of collagen are to provide strength and support and to help form an impervious membrane (as in skin). In meat, collagen is a major factor influencing the tenderness of the muscle after cooking. Collagen is not broken down easily by cooking except with moist—heat cookery methods. Collagen is white, thin and transparent. Microscopically, it appears in a coiled formation which softens and contracts to a short, thick mass when it is heated and helping give cooked meat a plump appearance. Collagen itself is tough; however, heating (to the appropriate temperature) converts collagen to gelatin which is tender. In the consideration of a TG mix, collagen is one of our most important considerations.
Elastin (often yellow in colour) is found in the walls of the circulatory system as well as in connective tissues throughout the animal body and provide elasticity to those tissues. Reticulin is present in much smaller amounts than either collagen or elastin. It is speculated that reticulin may be a precursor to either collagen and/or elastin as it is more prevalent in younger animals.” (www.meatscience.org)
It is interesting that collagen has been used for centuries to create strings to bind things and for strings on musical instruments. Catstring or catgut is made by twisting together strands of purified collagen taken from the serosal or submucosal layer of the small intestine of healthy ruminants (cattle, sheep, goats) or from beef tendon and has been in use for a long time 900’s AD. (Wray, 2006) Gut strings were being used as medical sutures as early as the 3rd century AD as Galen, a prominent Greek physician from the Roman Empire, is known to have used them. (Nutton, 2012)
Abū al-Qāsim Khalaf ibn al-‘Abbās al-Zahrāwī al-Ansari (Hamarneh, et al., 1963)(Arabic: أبو القاسم خلف بن العباس الزهراوي; 936–1013), popularly known as Al-Zahrawi (الزهراوي), Latinised as Abulcasis (from Arabic Abū al-Qāsim), was an Arab Muslim physician, surgeon and chemist who lived in Al-Andalus in the early 900’s CE. He is considered as the greatest surgeon of the Middle Ages (Meri, 2005), and has been described as the father of surgery. (Krebs, 2004). He became the first person to have used Catgut to stitch up a wound. He discovered the natural dissolvability of the Catgut when his monkey ate the strings of his musical instrument called an Oud. (Rooney, 2009)
Later, in 1818, the modern founder of surgery, Joseph Lister, and his former student William Macewen independently and quite remarkably, almost at the exact same time, reported on the advantages of a biodegradable stitch using “catgut”, prepared from the small intestine of a sheep. Over the ensuing years, countless innovations have extended the reach of collagen in the engineering and repair of soft tissue in medicine and numerous other industrial applications. (Chattopadhyay, 2014) The interesting point should not escape our notice that collagen is included in our TG mixes ta facilitate meat protein – TG – connective tissue – TG – meat protein binding structure. Collagen is surface-active and is capable of penetrating a lipid-free interface. (Chattopadhyay, 2014)
The other major constituent of meat is, of course, lipids or fat but I deal with this separately below.
During thermal processing, moisture loss will take place. Let us predict the optimal temperature range that will give us the right moisture loss and colour development in the shortest possible time. Countries such as Australia sell their bacon cooked but in the UK, New Zealand, Canada, the USA and South Africa, bacon is sold par-cooked. I, therefore, consider temperatures which will be considered par-cooked and fully cooked.
DIFFERENCES IN MOISTURE LOSS
“Bendall and Restall (1983) systematically studied the physical changes occurring during heating of intact beef-derived single muscle cells, and also the very small myofiber bundles of 0.19 mm in diameter (containing 40 to 50 cells) at final temperatures between 40 and 90 °C. In addition, the authors also studied heating of larger bundles of 2 mm in diameter.” (Yu, T.Y., et al, 2017)
According to their work, the stewing process progresses as follows:
From 40 to 52.5 °C
Denaturation of sarcoplasmic (include hemoglobin and myoglobin) and myofibrillar proteins occurs. Related to colour development the denaturation will effect sarcoplasmic protein even though its denaturation probably occurs from at least 25 °C. Related to moisture and the range of 40 to 52.5 °C, a slow loss of fluid from the myofibers into the extra-myofiber spaces occurs without shortening. (Yu, T.Y., et al, 2017) The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity. (Ceresinoa, 2018)
Between 52.5 and 60 °C
At this temperature, there is “an increasingly rapid loss of fluid from the myofibers, reaching a maximum rate and extent at about 59 °C.” There is no overall shortening at this temperature mainly due to heat shrinkage of the basement membrane collagen (type IV and perhaps type V as well) at about 58 °C. (Yu, T.Y., et al, 2017)
Between 64 to 94 °C
“Considerable overall shortening and a decrease in cross-sectional area are noted, accompanied by increased cooking loss with heat shrinkage of the endomysial, perimysial, and epimysial collagen.” (Yu, T.Y., et al, 2017)
“Long periods of stewing causes partial or complete gelatinization of the epimysial collagen, followed by the peri- and endomysial collagen, resulting in the soft and tender feature of stews (Bendall and Restall 1983). It is worth mentioning that meat with a high pH (Zhang and others 2005) or fat content (Wood and others 1986; Jung and others 2016) has been shown to exhibit higher water-holding capacity.” (Yu, T.Y., et al, 2017)
The important aspect for us is the key temperature of < 52.5 where moisture loss becomes “rapid”. This gives us an important upper “meat temperature” limit above which rapid moisture loss occurs.
The following section confirms the conclusion of par-cooked bacon’s optimal thermal processing range of between 40 and 52 deg C. Due to inconsistencies in the smoke chamber, it is suggested that a maximum internal core temperature of 40 deg C is set.
KINETICS OF THERMAL DENATURATION
Kajitani, et al, (2011) studied the kinetics of thermal denaturation of protein in cured pork meat related to each of the three protein classes of meat proteins namely myosin (from myofibrillar proteins), sarcoplasmic proteins and collagen (from stromal proteins). Of great interest to us is the sarcoplasmic proteins which include the pigment containing myoglobin.
The first important consideration is that the “thermal denaturation of muscle proteins such as myosin, sarcoplasmic proteins and collagen, and actin, occurs at different temperatures. To describe those reactions during thermal processing, temperature dependency of the reaction rate constant is necessary.” As the level of NaCl in the meat increased, “the thermal-denaturation rate constant of each protein increased.” (Kajitani, et al, 2011)
Adding salt to the sarcoplasmic proteins means that it starts to denature at a temperature of around 50 deg C, reaching a peak at around 68 deg C. Adding Sodium Chloride moves the graph to the left.
Graph source: (Kajitani, et al, 2011)
Having now considered thermal treatment and smoke in some detail, we can move to a consideration of TG in particular, but we will broadly keep looking at colour development, binding strength, and water loss.
TG is mixed into solution before added to the meat. The TG mix contains connective proteins and the first important matter to take into account is the solubility of these proteins.
The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity. Optimal pH for commercial TG was found to be between pH 5.5 and 6.0. (Ceresinoa, 2018)
DIFFERENCES IN SOLUBILITY
In terms of the use of Transglutaminase, different proteins are used in the TG mix as added connective protein to enhance the overall binding action. When TG is mixed in a solvent before application, different solvents will provide different solubility which may concern operators.
For example, TG containing stromal proteins such as collagen which shows low solubility in a neutral aqueous solvent such as water but high solubility in a curing brine solution with phosphates and salts on account of the high ionic charge of this solution.
From Yu, T.Y., et al, 2017.
The solubility of different proteins under various ionic strengths further informs us of the importance of salt and phosphates in solubilizing myofibril protein. Mixing the TG into a small brine solution has in my experience the best results.
MIXING AND TUMBLING – COLOUR LOSS AND BINDING
The system I developed over the years and used with great effect is to mix a batch of “stuffing meat” which I use in conjunction with whole muscles. Whether such a mix is made or comminuted muscle meat prepared for sausages, researchers have found that mixing time has an effect on the color and will increase the deterioration of the desired color if conducted in excess of 12 min” (Sun, 2009). Over the years I noticed a similar colour change if whole meat muscles have been over-tumbles, but if the meat is smoked, the colour change is immaterial.
The greatest benefit of the system relates to binding. The reason why I use “stuffing meat” is that this combines modern binding systems such as transglutaminase with old-school meat processing techniques, such as chunking, flaking and tearing. Bhaskar Reddy, et al. describes chunking and its benefits as “passing the meat through a coarse grinder plate leading to decrease in the particle size not greater than one and a half inch cubes. This technique increases the surface for the extraction of myosin and aids in better binding during mixing.” (Bhaskar Reddy, et al.; 2015) This describes the system I currently use to produce the stuffing meat. Bhaskar and his colleagues refer to flaking and say that “high-speed dicing or slicing machine is being used for flaking and reforming of restructured meat products. Fine flakes produce more acceptable appearance, increase tenderness and decrease shear force value”, referencing Mandal et al., 2011; Reddy et al., 2015. They add another category which they refer to as “sectioned and formed meats” which are “primarily composed of intact muscle or section of muscle that are bound together to form a single piece”, quoting Pearson and Gillet, 1996; Mandal et al., 2011; Sharma et al., 2013. This is the process then of taking the whole muscle meat and joining them together in the grid system. My method combines then chunking with sectioned and formed meats.
The “old school” method relies on the combined effects of salt, phosphate and mechanical action. Bhaskar Reddy, et al. (2015) references Boles and Shand, 1998 who found that “by using this technology, the product must be sold either precooked or frozen because the product binding is not very high in the raw state but high yields (25% above meat weight) are possible.
One of the benefits of the “old school” methods is the effect of meat particle size. “An increase in meat surface area and an increase in the availability of myofibrillar proteins for binding is the net consequence of comminution.” (Sun, 2009).
“In a study to evaluate mixing time on the binding effect of restructured meat, Booren, Mandigo, Olson, and Jones (1982) found that there was a significant linear increase in binding strengths up to 12 min of mixing at 28C.” (Sun, 2009)
The excellent review article of Sun (2009) makes reference to a study by Ghavimi,
Rogers, Althen, and Ammerman (1986) where they assessed vacuum, non-vacuum, and nitrogen back flush processing conditions at 1–38C during tumbling of restructured cured beef. Fascinatingly, they concluded that meat had higher cooked yields in a non-vacuum atmosphere. This, in the context of the application of Transglutaminase, is a very interesting observation.
I have long proposed a re-examination of the viability of vacuum tumbling, but I recognise the entrenched nature of this technology in modern meat processing plants and propose a new line set-up for investigation.
This eliminates the re-routing of meat back to the tumblers which are expensive assets while it achieves the application of the TG, final pick-up of any brine that purged out of the meat during resting as well as the balancing brine added after injection. In order to facilitate a proper pick up of this “loose brine”, some processors choose to add between 1 and 2% pork protein at this stage which will mean that the brine added during this step consists of the pork protein and the TG blend in a small amount of brine.
Lets first look at why a tumbler works. The interaction of the meat, rubbing against the meat and the pressure created as the mass of meat falls to the bottom of the tumbler during the drum rotation causes pressure which then “activates” the protein by causing the highly swollen muscular protein cells to burst. Bhaskar Reddy, et al., (2015) quotes Feiner, 2006 who stated that it is the “kinetic energy released during falling of meat pieces at bottom of the tumbler which serves to disrupt cellular membranes, which in turn causes protein extraction. It is the baffles inside the tumbler which “move the injected pieces of meat up the wall of the tumbler and once the pieces of meat reach a certain height, gravity causes them to fall.” (Bhaskar Reddy, et al., 2015)
This is, in my opinion far more aggressively and successfully achieved through a paddle mixer or a ribbon mixer than only the falling of the meat inside the tumbler. Mixing in a paddle or ribbon mixer will, in my estimation, better develop the myosin protein to become “sticky.” Remember that the aim of this step is to “solubilize the protein, creating a layer of activated protein on the surface of meat which is responsible for slice coherency in the cooked product. The sarcolemma surrounding the tightly swollen muscle cells is, in my opinion, more likely to be destroyed by the impact of energy from paddles than only tumbling and myofibrillar proteins will be released and solubilized (which is the object of tumbling). There is considerable academic and anecdotal support for this. Dikeman and Devine state in their Encyclopedia of Meat science, second edition (2014), commenting on the fact that paddle mixers run at reduced revolutions per minute (rpm), that they “can be useful for applying mecahnical action to whole muscle pieces. . . to produce a surface protein exudate without damaging muscle integrity.” (Dikeman and Devine, 2014: 126, 127)
Meat must be mixed until they become tacky – almost furry. “Rust and Olson (1973) found that the extraction of myofibrillar proteins on the surface of meat has two functions. One is to act as a bonding agent holding the meat surfaces together and the other is to act as a sealer when thermally processed and therefore, aid in the retention of water in the muscle tissue.” “In addition, cellular disruption of the meat tissue occurs during tumbling which together with the curing additives allows the meat to improve the yield (Chow et al., 1986). Constraining connective tissue sheaths around muscle fibres are disrupted, allowing further myofibrillar swelling introduced by salt (Katsaras and Budras, 1993). (Bhaskar Reddy, et al., 2015)
It is, of course, possible to mix the TG mix into the stuffing meat by hand, but one loses all the benefits listed above. For the exact reason, I believe a more aggressive treatment of the whole muscle meat just prior to filling into the grids should yield far better reshaping and binding results. Too little mixing will result in meat being “loose” and a failure to bind together. Too much mixing, on the other hand, will result in a loss of tenderness and the product being “rubbery”. (Pearson and Gillett, 1999)
The reason why mixing is essentially done in a tumbler under vacuum is mainly that, removing the oxygen, prevents oxidation. This prevention of oxidation will, however, also be accomplished by maintaining a low temperature during mixing which is obviously also very good to control negative mirco-growth. (Pearson and Gillett, 1999)
Bhaskar Reddy and colleagues state that tumbling or massaging (physical action upon the meat, in whatever form) “improves the speed of curing by increasing salt absorption.” (Bhaskar Reddy, et al., 2015) It is this reason why I still prefer the two-step tumbling. The solubilization of the proteins by the fat and the phosphates are greatly enhanced if the meat is left to rest for 12 or 24 hours and re-tumbled/ mixed which of course will increase the protein bind.
Having made this statement, we get to a long-standing debate related to tumbling namely if one must tumble continually (uninterrupted) or if one must have intervals of rest periods. For every study that intermitted tumbling is superior, there seems to be a study that shows continues tumbling is superior. Why is the one preferred over the other? Exactly because brine needs time to diffuse into the muscle. (Krause et al., 1978) One needs the drum to stop turning so that the meat can be immersed in the brine in order to absorb into it. This is not achieved, as many believe, by the vacuum which presumably opens up the meat fibers and somehow pulls the brine into the meat. The reason why this is done intermittently (tumble, rest, tumble, rest) and not in a two-step process of tumbling, unloading, resting in the chiller, loading into the tumbler and tumbled again, is presumably to eliminate the need to load and unload the tumbler twice. In a high throughput factory, this should, in any event, be done with loading equipment and should not be a consideration. I also doubt if the total time of resting in a tumbling program will be sufficient for the brine to be absorbed if one takes absorption rates into meat into account.
Whichever way I look at it, a two tumbling system is preferred over injection, resting, tumble, adding TG 15 minutes before the end of the program and grid filling (only one tumbling step). There are simply too many advantages which are ignored which one will get in a system of injection, tumbling, resting, TG tumble, grid filling.
My only concern of using paddle mixers for the second step and not tumblers relates to the formation of foam. If foam is created, this may lead to protein denaturation and the binding strength will be compromised (Kerry et al., 2002) This will have to be evaluated. In my own experience, when using a blender to do the stuffing meat, this has never in 2 years of using the technique created foam. Whole muscles will have to be tested for foam formation which I know happens in a tumbler if only a partial vacuum is pulled. I suspect the paddle mixer will work very well.
DIFFERENT GELLING ABILITY OF DIFFERENT PORK MUSCLES
A matter of interest is the different gelling strengths of different proteins. Between poultry, beef, fish, milk, and pork, but also between different pork muscle groups. This is of interest to me for choosing the best muscle to produce the stuffing meat. Robe and Xiong (1993) reports that pork longissimus dorsi muscles (predominantly white) formed stronger gels when compared to pork serratus ventralis muscles (predominantly red).
One would not use the longissimus dorsi muscles to produce stuffing meat, but there may be muscle groups in the leg with similar visual characteristics. Is there an advantage in using some of these muscle groups for the stuffing meat? It is an interesting question that must be investigated. Robe and Xiong (1993) concluded that their work indicates that “red and white muscle types (in pork) should undergo different processing treatments for optimum quality meat products.”
PRESSURE – COLOUR AND BINDING
Contrary to popular belief, pressing of the meat does not facilitate the binding or the effect of TG in any way. (Pearson, and Gillett, 1999) Pressing into moulds have a few important functions. In the first place, it ensures the meat, particularly large meat pieces, are forced into a regular shape which is the key behind improved slicing yields.
The second reason for pressing relates to surface area and meat contact. If there are cavities in the meat log, binding at those locations will obviously be compromised and the appearance of the meat slices, especially when bacon is sliced, will be undesirable.
SALT – COLOUR AND BINDING
Sun (2009) points out that “discoloration of restructured steaks can be caused by salt. A decrease in color desirability with increased salt levels has been observed by some researchers (Huffman & Cordray, 1979; Schwartz & Mandigo, 1976). The raw color could be improved by sodium tripolyphosphate (STP), which helps to compensate for the effect of salt (Schwartz & Mandigo, 1976). As a matter of interest, Huffman, Ly, and Cordray (1981b) as cited by Sun, “showed that addition of salt at all levels increased thiobarbituric acid (TBA) values and decreased color levels.” No such effect has however been noticed with heat treated, smoked and cured meat.
Salt and phosphates during the mixing/ tumbling step are essential in that it aids the extraction of myofibrillar proteins which in turn aids in the overall binding. (Pearson and Gillett, 1999)
The interaction of salt and TG is a key consideration. Sun reports that “in cooked restructured meat products, gel firmness and water-holding capacity (WHC) have been reported to increase by the addition of TG in high-salt (2%) products but not in low-salt products (Pietrasik & Li-Chan, 2002b). TG was able to improve consistency (firmness) but not cooking loss of the product in a low salt (1%) system (Dimitrakopoulou, Ambrosiadis, Zetou, & Bloukas, 2005).” (Sun, 2009)
“Kuraishi et al. (1997) investigated the effect of salt on binding strength and indicated that provided there was addition of salt (NaCl), TG treatment caused effective binding of meat pieces. Their result showed that an increase in binding strength caused by adding salt (1.0–3.0%) with TG when compared to TG alone.” (Sun, 2009)
PHOSPHATES – BINDING
Phosphate generally enhances the effect of salt. Sun (2009) reports that “a variety of phosphates in different combinations, concentrations, and with concomitant salt concentrations were evaluated by Trout and Schmidt (1984). They found that tetrasodium pyrophosphate had the greatest binding effectiveness, which was followed by sodium tetrapolyphosphate, and then sodium hexametaphosphate.
They concluded that most of the changes in binding could be explained by the ionic concentration of the phosphates. STP also delays development of rancidity and is added at a level of about 0.25% for adequate protein extraction and flavor development (Pearson & Gillett, 1996). Nielsen, Peterson, and Møller (1995) observed optimum effects of STP on the texture at a concentration of 0.2%. (Sun, 2009)
COMBINATION OF STROMAL PROTEINS WITH ALGIN/ CALCIUM OR TG
I include this in a separate heading, due to the low-cost stromal proteins of collagen, elastin, and reticulin and muscles with a high percentage of it. The protein is of huge interest in TG formulations. How will the inclusion of pork gelatin aid the binding system with TG?
In considering connective tissues, it is astounding to recognise the monumental presence of K. B. Lehmann. In terms of the curing reaction in meat, it was this German hygienist and bacteriologist from the Hygienic Institute at Würzburg, Germany who confirmed Polenski’s suspicions (Saltpeter) that nitrite is the key in the cured colour formation and not nitrate as was believed. He further importantly identified its colour spectrum when diluted in alcohol. (Fathers of Meat Curing) It was probably based on his work and that of his student, Karl Kißkalt, that the German government allowed the use of nitrite in curing brines during the first world war.
It was Lehmann and his coworkers who showed that “the toughness of different cuts of meat, measured mechanically, was closely related to their content of connective tissue, and that the decrease in toughness resulting from cooking was related to the collagen of connective tissue rather than to the elastin.” (Mitchell, et al.; 1926)
They found that “under the influence of moist heat the collagen is readily changed to gelatin, thus losing its toughness. In the raw condition, white fibrous connective tissue (mainly collagen) is almost twice as tough as yellow elastic connective tissue (mainly elastin), but when cooked, the former loses most of its toughness while the latter remains practically unchanged in this respect.” (Mitchell, et al.; 1926)
“Ensor, Sofos, and Schmidt (1990) concluded that the use of high-connective-tissue meat or addition of concentrated forms of connective tissue in algin/calcium gel restructured meats could improve product texture and reduce formulation costs.” (Sun, 2009) Gelatin is the ideal thickening agent to accompany transglutaminase since it contains a variety of different amino acids, including our old friends Glutamine and Lysine which are now cross-linked by the action of transglutaminase. (Aguilar, M. R. and Román, J. S.; 2014: 186) It is important to use the right kind of gelatin. Fish and pork gelatin will be objectionable for either religious or allergen concerns by various processors in various parts of the world and it is an important consideration.
I am aware of tests underway in Chili where pork protein is tested in conjunction with TG to replace MDM. The viability of this must be tested.
WHAT ABOUT FAT?
We skipped over fat when we looked at the constituents of muscles and now returns to it. Many people refer to fat as lipids, but fats are only a subgroup of lipids called triglycerides. Lets set some basic concepts up, to begin with. Human body fat, animal, and vegetable fats have triglycerides as its main constituent. Their function in blood is to facilitate bidirectional transference of adipose fat which is the fat layer under our skin, around internal organs), in bone marrow, intermuscular and in the breast tissue.
Let’s look closer at the adipose tissue. It is “composed of a loose collection of specialized cells, called adipocytes, embedded in a mesh of collagen fibers. We looked briefly at collagen when we reviewed the stromal proteins. The main role of adipose tissue in the body is its role as a fuel tank for the storage of lipids and triglycerides.
One gets white and brown adipose tissue with white tissue being the most numerous. “The main role, or function, of white adipose tissue is to collect, store and then release lipids. However, because of the properties of the lipids being stored, the adipose tissue also acts as a protective cushion (resists knocks) and also as a layer of insulation against excessive heat loss.
Lipids conduct heat very poorly (only about a third of the rate of other materials) so even a small layer of adipose cells (about 2 mm) will keep a person warm at 15 degrees centigrade, whereas a person with only a 1 mm layer of protection will be feeling quite uncomfortable.
About 80% of average white adipose tissue is lipid, and of that, about 90% is made up of the six triglycerides: stearic, oleic, linoleic, palmitic, palmitoleic and myristic acid. Also stored are free fatty acids, cholesterol, mono- and di-glycerides.” (brooklyn.cuny.edu)
“Each adipocyte cell has a large, central, uniform, lipid packed central vacuole which, as it enlarges, pushes all the cytoplasm, the nucleus, and all the other organelles to the edge of the cell, making it look a bit like a band or ring under the microscope.
These cells can vary in size from about 30 microns to over 230 microns, and, despite their distorted appearance, contain all the necessary biochemical machinery of other cells.
Every adipose cell must touch at least one capillary or blood vessel (an artery or vein). From this the cells draw all their needed supplies, including lipids.
Fatty foods, with high lipid content, often provide more lipids than can be digested and used right away. The excess is stored in the adipose tissue. Excess carbohydrate and protein taken in with meals can also be converted to fat (usually in the liver) and then moved to the adipose tissue for longer-term storage.
Lipids are the major fuel reserve for humans and most mammals. These molecules are very efficient at storing needed energy. One gram of fat stores about 9 kcal per gram, compared to carbohydrate or protein (4 kcal per gram). For mobile animals, this means that less bulk has to be carried around and a normal sized body that is about 20% fat has enough stored energy to last about 20 – 30 days without eating!” (brooklyn.cuny.edu)
Let’s look more closely at triglyceride. There are many types of triglycerides. We are all familiar with the two main groups of triglycerides, namely saturated and unsaturated types. Saturated fats are “saturated” with hydrogen — all available places where hydrogen atoms could be bonded to carbon atoms are occupied. the importance to us for meat processing is its melting point which is higher and are more likely to be solid at room temperature. It is this saturated fats that, when ingested,raises the level of cholesterol in your blood. (daa.asn.au)
On the other hand are the unsaturated fats which have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. For our purposes, the net result is that they have a lower melting point and are more likely to be liquid at room temperature. These fats help reduce the risk of high blood cholesterol levels and have other health benefits when they replace saturated fats in the diet. (daa.asn.au)
When one works with pork fat, it is important to keep an eye on the temperature. During processing, highly unsaturated fats will start to melt and form a fat coating on the product which is visually unappealing. (Toldra, 2010) Beef fat is firmer with a more intense flavour in comparison with pork or chicken. Beef fat’s melting point is comparable to pork kidney fat due to the low content of collagen and saturated fats. The reason why pork fat is popular is that it is largely tasteless and flavourless. The rules for making meat emulsions are based on fat choice and temperature. “Pork backfat gives the best suitable product for slicing. Jowl and belly fat can also be used. The endpoint chopping temperature should remain below 18 deg C, 12 deg C, and 8 deg C for beef, pork, and poultry fat respectively to avoid fat melting.” (Toldra, 2010)
“To make spreadable products fat must be dispersed in the liquid state at “hot” temperatures. The endpoint chopping temperatures should be above the fat melting point (i.e., 35 deg C). To achieve this final temperature, fat is usually pouched in water at temperatures above 80 deg C before being mixed with protein (liver or lean meat). The object is to reach a final internal temperature between 50 and 60 deg C for ham fat and between 70 and 75 deg C for jowl fat. Fat poaching also causes contraction of the connective tissue which will facilitate the grinding; it eliminates low melting fats, which can cause weight losses during cooking and it lowers the microbial content. Thus, for hot emulsions, low melting fat is preferred such as ham and jowl fat remain firm during cooking at high temperatures.” (Toldra, 2010)
Triglycerides are composed of three fatty acids. The fatty acid content in animals depends on age, type of feed and the environment. Diet plays an important role, especially in pork which is one of the reasons why pork, raised in informal settlement environments are very poor substitutes for commercially farmed animals where feed are strictly controlled. The properties of the fat will generally be determined by the composition of the fatty acids. “It will be soft (oily appearance) and prone to oxidation when there is a high percentage of polyunsaturated fatty acid linoleic (typical of feed rich in corn, for instance) and linolenic acids.” (Toldra, 2002)
There are two main groups of lipids in the body. The one is triglycerides which we just had a look at. The other is phospholipids. They are present in very small amounts but have a strong key role in flavour development and the oxidation of postmortem meat. They also have a relatively high proportion of polyunsaturated fatty acids in comparison to neutral lipids. Some of the major constituents are phosphatidylcholine (lecithin) and phosphatidylethanolamine. Phospholipids vary depending on the genetic type of the animal and anatomical location of the muscle. Therefore, the amount of phospholipids tends to be higher in red oxidative muscles than in white glycolytic muscles. (Toldra, 2002)
The interaction of fat and protein is a very important consideration in restructuring meat. “The fat level clearly influenced the structure of the gel/ emulsion network, as reflected by the differences in the type of protein molecular interactions involved in its formation, and this, in turn, affected the fat binding properties and the texture of the end product.” (Sun, 2009)
It is difficult to bind fat effectively to meat. De NG, Toledo, and Lillard (1981) found that water and fat binding by meat batters diminish when temperatures exceed 16°C during comminution. This speaks directly to the preparation of stuffing meat and it requires for the meat temperature to be kept as low as possible, but not so low that it makes it impossible for workers to use it in the restructuring process.
Secondly, when one talks about fat and stuffing meat, one must consider the interaction between a TG blend containing pork gelatin and fat in the meat mix which is less than optimal. TG by itself is not a good binder for fat. The easiest way of handling fat in stuffing meat is to avoid it. I have found pork fillet to be particularly suited due to its lean nature.
Remember that gelatin “works by creating a very fine mesh of proteins, between which the (hydrophilic) liquid gets trapped. A mixture of fat and water isn’t a liquid. It can be either a rough two-phase mixture, with visible fat droplets swimming around in the water, or it can be an emulsion, with invisibly small fat droplets dispersed through the water. Emulsions appear smooth, e.g. milk.” (cooking.stackexchange.com) Fat in the stuffing meat will interfere with the binding.
As far as the whole meat muscles are concerned, it is important to lay the meat pieces fat down in the mold to minimize contact between added meat and fat.
After thermal treatment, the meat must be frozen as soon as possible.
Sun (2009) reports that “although most of the studies using TG for restructuring meat conducted by incubation meat at optimum temperature (37–508C) of MTG or by cooking to obtain sufficient binding strength, some researchers obtained good binding effect by using cold binding (2–58C), with the combination of TG and sodium caseinate, without addition of salt or cooking (Kuraishi et al., 1997; Serrano, Cofrades & Jimenez Colmenero, 2004). Kuraishi et al. (1997) indicated that the TG reaction condition of 58C for 2 h would not enable any bacteria present to increase much and discoloration of the meat was not observed in the raw, refrigerated state. In my experience, IT binds very well at lower temperatures.
The maximum activity observed for TG was at 40 °C for the commercial TG. At temperatures above 45 °C, TG suffered a rapid drop in its activity. Optimal pH for commercial TG was found to be between pH 5.5 and 6.0. (Ceresinoa, 2018)
DIFFERENT BACTERIA PRODUCE TG WITH DIFFERENT PROPERTIES
It has been found that different strains of bacteria that produce the enzyme TG, produce it with different yield and properties. Different TG producing bacteria strains are still being identified from different environments. “The isolation of a strain of Streptomyces mobaraense was the first step towards the extensive commercial exploitation of this enzyme. Thereafter, a number of various microbial strains, such as Streptomyces lydicus, Streptomyces cinnamoneum CBS 683.68, Streptomyces sp. CBMAI 837, have been found being able to biosynthesize TG extracellularly. How the TG is produced definitely impacts its application. TG’s of various origins and in different concentrations have different functionality. (Ceresinoa, 2018)
Generally, increased TG concentration produces a better binding of meat. The optimum pH for the commercial TG was found to be between pH 5.5 and 6.0, but TG from different strains have a different optimal pH. TG from Bacillus circulans BL32, for example, has been reported to have an optimal pH of 7.2. (Ceresinoa, 2018)
“As to temperature influence on TG activity, minor differences were seen between the enzymes, with a maximum activity observed at 40 °C for the commercial TG and at 35–40 °C for SB6. At temperatures above 45 °C, both enzymes suffered a rapid drop in their activities. These findings are consistent with studies of TG derived from other streptomycetes such as Streptomyces hygroscopicus and Streptomyces sp. CBMAI 837. (Ceresinoa, 2018)
Sinew and excess fat must be removed in the trimming stage to maintain product quality and consistency. The use of a grid system allows the deboning department to trim to exact product specifications. In regular bacon production, leaving the silverskin and membrane on the meat is advisable since it will prevent excess moisture loss during thermal processing. In a restructuring scenario, it will have to be removed during trimming because it will interfere with the binding.
It is possible to address PSE. The first option will be so source meat during the summer from non-Western Cape sources, but this presents difficulty for the farmers who are the backbone of the industry and may go against strategic alliances. A second strategy will be to work closely with farmers and the local abattoirs because much can be done pre and immediate post slaughtering. These are, however matters that are notoriously difficult to implement.
What can be done from a processing perspective? Motzer, Carpenter, Reynolds, and Lyon (1998) successfully used pale, soft and exudative pork to manufacture restructured hams. The problem with producing bacon from PSE meat is that “due to the rapid pH drop while muscle temperature remains high, the proteins in the myofibrillar fraction become partially denatured and lose their functionality. Denaturation of myosin in PSE muscle ultimately affects the water holding capabilities of the meat system. As a consequence, products manufactured with PSE may be expected to lose higher amounts of water.” (Motzer, et al., 2006) The unfortunate reality is that 100% PSE meat cannot be utilized in high quality processed products (Marriott, et al. 2006).
Motzer and coworkers (2006) report on Shand et al. (1994) who evaluated the effects of various levels of salt, temperature and kappa carrageenan on the bind of structured beef rolls and reported that as salt or levels of kappa carrageenan increased, the bind increased. They found that kappa carrageenan was the only binder different that when adequately solubilized improved adhesion of PSE meat.
As far as water holding capacity, they found that adding modified food starch (MFS) and isolated soy protein (ISP), enhanced the water holding capacity of hams produced from PSE pork meat. They noted that isolated soy protein (ISP) “resulted in a thicker adhesion than normal for the meat pieces. Manual stuffing became difficult and often resulted in air pockets within the meat log.” (Motzer, et al., 2006) This will, however, be overcome by a proper press system.
Even though there were improvements in the ham, the fact remained that “due to loss of structural integrity, PSE meat will lose considerable water “, especially after thermal processing. Most of the water is released due to the partially denatured myofibrillar proteins.” (Motzer, et al., 2006)
The complete article can be found at PSE Meat Treatment. Without reformulating a brine for the summer in Cape Town, incorporating kappa carrageenan, MFS, and ISP, losses in bacon production will remain material for pork procured locally. It will manifest in excessive purge in the final product stage, excessive moisture loss during and after thermal processing and poor binding of restructured parts of the bacon logs.
Of course, a strategy will be to produce ham with the badly affected meat. “Motzer et al. (1998) revealed that utilizing 50% PSE pork in a restructured product with either modified food starch or carrageenan yielded better quality pork than 100% PSE treatments. Schilling et al. (2002) later demonstrated that combining 25% PSE and 75% RFN (red, firm, and non-exudative) pork in a chunked and formed ham was similar in quality to a 100% RFN pork sample when soy protein concentrate and modified food starch were incorporated together at 2 and 1.5%, respectively. Similarly, Torley et al., (2000) reported that increasing the ionic strength and utilization of polyphosphates resulted in increased cooking yield similar to that of a product manufactured from RFN pork.” (Marriott, et al. 2006)
It is my suggestion that all these be tested in a summer mix of products to compensate for the extraordinary level of PSE prevalent in regions like the Western Cape during the summer. “This research makes it clear that PSE pork can be incorporated into processed products, but it can be unsatisfactory to use formulations with more than 25% PSE. Samples formulated with 25% PSE pork exhibit acceptable texture, but those formulated with 75 or 100% PSE often sustain cracking.” (Marriott, et al. 2006) This relates to cooked hams. Bacon is a different matter and mixing PSE and non-PSE meat cannot be part of the solution. Producing hams instead of bacon with such meat is an option.
The bottom line is that solutions exist and an effective strategy is possible but will require focus and cooperation.
INCLUSION OF OTHER PRODUCTS
I have for some time considered the inclusion of a blood-based binding system with TG which “can be used for binding comminuted and large pieces of meat (Boles & Shand, 1998, 1999). The binding mechanism of restructured meats is based on the blood clotting action between fibrinogen, thrombin, and TG. Cross-linking and gelation between fibrin itself and between meat collagen and the fibrin are induced by TG (Sheard, 2002).” (Sun, 2009).
Other products to consider for inclusion are crude myosin, extract, surimi (Chen, Huffman, & Egbert, 1992), egg white powder, raw egg white, egg powder, bovine, porcine, lamb, broiler plasma powders, broiler breast meat powder, gelatine (Lu & Chen, 1999), dried apples, corn crumbs, mushrooms (Marriott, Graham, Schaffer, & Boling, 1986c), rice bran oil and fiber (Kim, Godber, & Prinaywiwatkul, 2000), and walnut (Jime´nez Colmenero et al., 2003; Serrano et al., 2006).
TG represents one of the most exciting developments in meat processing from the perspective of the large-throughput meat factories. The optimal utilization of the technology is still in its infancy, despite the many decades that passed since it was first made available from the shores of Japan.
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