Introduction to Bacon & the Art of Living

This is the definitive story of bacon and life. Our story.

The narrative spans the late 1800s and early 1900s, a time when many of the most pivotal advances in bacon curing took place, while blending seamlessly into the 2000s. Each character is based on a real historical figure and woven into events that actually occurred, both past and present. The world carries a steampunk flavour, with modern speech, behaviours, attire, and technology layered over a historical backdrop. The characters interact with one another through the cultural and historical biases of their time, creating a rich interplay between past and present.

The technological journey traced in this work is remarkable. It begins in prehistory and follows the evolution of curing methods across centuries, arriving in the modern day.

But it is also a personal journey. An our-story.

It may have started in Cape Town, but then again, perhaps somewhere else. Maybe on the dusty roads of Asia, in the Turfan Depression, or in cities like Samarkand and Batumi along the Silk Road. Perhaps it crossed the Alps into Hallstatt. Or maybe it began on the Wechsel in Austria, with a farm girl growing up on alpine meat and butter, raised by extraordinary parents and grandparents.

Maybe it began on the banks of the Vaal River and the wide grasslands of the Northern Free State. I’m not sure anymore. And perhaps it doesn’t matter.

Because wherever it began, it continues.

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Starter Cultures

January 1920

Dear Tristan and Lauren,

Allow me to update the reader on why this chapter appears here. My kids, Tristan, Shannon and Lauren are putting everything I’ve written about bacon curing in chronological order. They asked me to write short supplementary chapters where a strict chronology would be unfair to the story and about subjects I did not cover in my letters from Europe, the UK and New Zealand. I realise that writing about dry curing will be incomplete unless I follow it up with the history of the development of starter cultures which I will apply in this document more broadly than only dry curing.

A meat starter culture is a preparation of specific microorganisms, such as bacteria, used in the processing of meat products to enhance flavour, improve safety, and ensure consistent quality. Humans observed that long-term cured hams and bacon where only salt has been used develop the characteristic reddish/ pinkish colour associated with nitrate and nitrite curing. It has been understood in recent years that the curing takes place in these instances through microbial action that creates nitric oxide in the meat which in turn cure the meat. Apart from the cured colour, a distinct flavour profile develops which is also attributed to microorganisms. Instead of allowing the microorganisms naturally found in the environment such as curing caves and curing rooms where the meat is hung to act upon the meat, special starter cultures have been developed that start the process of curing and “ripening”.

Today, these starter cultures are carefully selected for their ability to perform desirable fermentative activities, such as acidifying the meat through lactic acid production, which helps to preserve the meat and prevent the growth of spoilage or pathogenic bacteria.

Starter cultures are typically used in the production of fermented meat products like salami, pepperoni, and chorizo. The specific strains used in a starter culture can vary depending on the desired end product characteristics, including the speed of acid production, flavour compounds, and colour development.

In this review, we will consider the most ancient “starter culture”, identified by Grace (2022) namely Bay salt. Then we will consider how these developed into a complete system in the 1950s through the work of Dr Fritz Niinivaara. Next, we will look at the close relationship between salt and starter cultures from a mechanical perspective. Lately, we will look at liquid protein and their value in the curing process and how a wet-cure can be developed using the same principles from starter-culture technology.

1. Bay Salt as an Ancient Carrier of Starter Cultures

Grace E. Tsai and her coworkers, Robin C. Anderson, Jackie Kotzur, Erika Davila, John McQuitty and Emelie Nelson, did the best work on record to identify the oldest starter culture. They set the stage in their investigation of Bay salt in seventeenth-century meat preservation: how ethnomicrobiology and experimental archaeology help us understand historical tastes by quoting Masosn (1775) in terms of the different salts that were produced by 1775. Their study was not aimed at identifying an ancient starter culture process, but in their research, they did just that. Salt turned out to be the best carrier for a starter culture and as you will see, the fact that it contained a starter culture was not known for many years until the work of Grace (2022) elucidated this fact with the aid of modern science. Mason wrote that ‘Sea salt is made by boiling and evaporating sea water over the fire.” This means that no starter culture could be present in this salt due to the boiling. The same applies to Basket salt which “is made by boiling away the water of salt springs over the fire. Rock salt is dug out of the ground.” Look at the difference with the production of Bay salt. He writes that Bay salt is made “by evaporating sea water, in pits clayed on the inside, by the heat of the sun.” (Charlotte Mason; The Lady’s Assistant; 1775.” This all from Mason (1775) as quoted by Grace (2022).

The curious fact from history as Grace (2022) elucidated was that despite the different salts available, bay salt remained a favourite for curing. They write, “Although there were at least four variations of salt before the pre-industrial era, several historical recipes specified the use of bay salt (solar salt) for meat preservation, elevating its cultural status and implying that early modern actors had a refined understanding of salts, their tastes and their applications.” (Grace, 2022)

Grace et al (2022) found that laboratory data suggest that bay salt contains microbes that produce nitrate and nitrite, which give the meat a more favourable taste and a pleasant aesthetic.” (Grace, 2022)

They give an excellent historical review which I am delighted to add for your enjoyment. They say that “seamen during the age of sail (AD 1571–1862) relied on such techniques on lengthy voyages to lessen the likelihood of food degradation, but the most salient of these methods is salting. Salt is given special attention in historical shipboard accounts because the sailors’ diet was heavily treated with it. Eugenio de Salazar expressed this sentiment when he wrote in The Landlubber’s Lament (1573) that ‘Lady Sea will not tolerate or conserve meat or fish that is not dressed in her salt. Everything else that is eaten is rotten and stinking’. John Collins, an English author, merchantman and accountant, wrote that it is a ‘great hazard of Mens[’] Lives … to salt the Provisions of a Ship or Garrison either with a bad salt, or ignorantly’.” (Grace, 2022)

“During the Ship Biscuit and Salted Beef Research Project, a project that aims to determine the effects of the maritime diet on the nutrition and health of sailors during the seventeenth century, we noted that recipes repeatedly referenced ‘bay salt’ for brining meat brought on voyages. We used one such recipe to re-create the salted beef and pork for the project. Upon retrieving some of the aged meats for laboratory analysis, we noted that their interiors had a pleasant pink colour, much like meats cured with nitrate, and became curious as to what may have caused this colouration in the meat. Thus began our research into bay salt and other historical salts to understand more about why recipes specified bay salt’s usage and whether the red colouration was typical of its use.” (Grace, 2022)

They give a concise but insightful overview of early salt production. “During the seventeenth century, various types of culinary salt were produced. Salts were described by colour (‘black’, ‘grey’ and ‘green’ salts), origin (similar to how Himalayan salt today indicates that it is salt from Pakistan) or, in the case of bay salt, its production method. Originally, bay salt referred to the provenience of the salt, as it was most famously produced in the Bay of Bourgneuf, France, which dominated the market during the seventeenth and eighteenth centuries. 

By at least the mid-seventeenth century, this term was applied to generic salt regardless of locale, made in salines (solar salt), shallow clay pans that were filled with salt water that was allowed to evaporate in the sun until the brine crystallized into salt. Various sources document this salt production method, including De Re Metallica (1556) by Georgius Agricola, Salt and Fishery (1682) by John Collins, The Surgeon’s Mate (1617) by John Woodall and Charlotte Mason’s The Lady’s Assistant (1775), among others.

Such sources, and the natural and practical knowledge they documented, also fed into the development of early modern scientific theories of salt, which played a crucial role in the evolution of matter theory from Aristotelian concepts of the elements to Newtonian chemistry. In addition to bay salt, other types of salt made using other techniques were present at the time. Sea salt was made by boiling seawater over fire, rock salt was mined out of the ground, and basket salt was made from boiling brine from salt springs.” (Grace, 2022)

“Even given the wide selection of salts available, the use of bay salt (generic solar salt, not specifically from France) in the English Navy during the seventeenth and eighteenth centuries is well documented in primary sources, and the consensus in existing historical studies is that bay salt was used because it was inexpensive to produce. However, when historical sources are studied in depth, bay salt’s persistent use throughout history, and people’s adherence to it, suggest that its popularity may not be solely explained by economics, and its cultural and historical significance is more complex than existing historiography insinuates.” (Grace, 2022)

In their study, Grace (2022) explored “potential reasons apart from economics that may explain bay salt’s continued popularity through time, combining analysis of historical sources and methods from experimental archaeology.” By using experimental archaeology they were able to fill gaps “in our knowledge about the past which cannot be filled through other archaeological and historical research methods. It does so typically through replicating a process that was believed to have been followed in the past to test an archaeological hypothesis. Historical archaeology is a subdiscipline of archaeology that studies material culture and supports its interpretation using written records or oral traditions.” (Grace, 2022)

• The meat and brine, with no addition of saltpetre (i.e. nitrate), increased in nitrate and ammonia in most samples.
• Common knowledge today indicates that curing meat with brine made from modern purified salt does not spontaneously generate nitrate or nitrite.
• Fresh meat by itself and the aquifer water have below detectable or trace amounts of nitrate and nitrite. The bay salt and sea salt (both of which come from the sea) have about twice as much nitrate as other forms of salt and several times more than in fresh meat.
• The increase in nitrate in the experimental meats and brines positively correlates to halophilic and/or halotolerant bacterial counts in the same experimental meats and brines.
• Bacterial counts of the experimental meats grown in other media that did not select for halophilic and/or halotolerant bacteria decreased over time.
• The bay salt, compared to the other salts, grows halophilic and/or halotolerant bacteria when plated. All other historical salts had low levels of bacterial counts.
• Although only a fraction of the bacteria have been isolated and sequenced, the few that have been identified appear to be nitrogen fixers or reducers.

-> Historical and contemporary sources on bittern in bay salt

Before we transition to bay salt as the definitive ancient carrier of what we call starter culture today, we must look at the reality that bay salt had a bitter taste.

“Sea salt exhibited the highest mineral concentrations in potassium, calcium, magnesium, sulphur and boron. Out of the three salts, the sea salt also had the lowest sodium content, whereas bay salt differed from the other salts by containing much higher amounts of iron. The rock salt had comparatively low mineral values except for sodium, of which it had the highest. Overall, no major trends or differences that would imply superior curing were found in the bay salt’s mineral content. This was somewhat expected, given that bay salt refers to a method of salt production rather than to a specific locale of production, which is what would produce mineral composition changes.” (Grace, 2022)

Grace (2022) deals with the matter masterfully and incorporates the age-old discussion of the size of the salt crystals. “Many historical sources indicate that bay salt had a pejorative reputation. An Irish resident in Nantes attempted to start a salt beef processing business but was unable to acquire appropriate salt, and as a result, his salt beef ‘held up badly on the long transatlantic crossing and was rejected on the basis that it spoiled because of the inferior, local sel de Guerande’. Collins rallied against bay salt in maritime provisions, writing that ‘Dutch Mariners returning from long Voyages, look fat, healthful, and fresh Coloured because their Flesh and Fish is saved with refined Salt. Whereas on the contrary our Mariners feeding on Provision cured with Bay Salt, are scorbutic and incombred with acrimonious Diseases’. Bay salt was outlawed in certain countries for its poor quality – during the mid-fifteenth century in Brielle, only purified salt was allowed to be sold in town. In 1471 in Bergen, a merchant in a legal dispute stated that his ship was loaded with salt on salt that had been purified in Bergen ‘from good green Bay salt’ as proof of its quality. Other sources concur that fish could not be cured with bay salt and that the Dutch, who controlled much of the fishing trade at the time, had to refine bay salt to create ‘salt on salt’ to cure their fish, which the English then copied. Creating salt on salt (salt upon salt) involved dissolving bay salt in water and reheating it by fire to purify the brine of calcium, a constituent of bitter. Bittern is the bitter remains from the crystallization of salt made of calcium and magnesium chlorides and sulphates, bromides, iodides and other chemicals originally present in seawater. Historical sources give several reasons for bay salt’s supposed inferiority: its inclusion of bittern, organic impurity and inconsistent quality.” (Grace, 2022)

“Because it was simply sun-evaporated from unfiltered saltwater, bay salt contained ‘dirt, sand, and bittern’, making it unsuitable for curing meat and fish. Bittern ‘renders the Meat dry, hard, dirty, rotten, and by reason of the Bittern in it, consumes the goodness or nutrimental part of the Meat’, which was said to cause ‘Scurvies, Consumptions, and other acrimonious Diseases, in the Bodies of Seamen, or Soldiers in a besieged Garrison, that are compelled to the frequent and long use of it’.” (Grace, 2022)

“Modern studies on the chemical composition of salts support the idea that magnesium and calcium salts, the main components of bittern, are unsuitable for curing and that seawater generally contains higher amounts of these chemicals, making salts derived from unpurified seawater detrimental for food preservation. In 1920, Dr. D.K. Tressler experimented with the effects of different types of curing salt on fish, and found that salt with proportions of magnesium and calcium seen in seawater inhibited salt from easily penetrating the fish, preventing the inner meat from being cured before it spoiled. The effects were evident less than a week after curing, and similar experiments agree with these results. 

Blesa et al. noted that water activity (a_w), an indicator of microbiological activity and spoilage, increases when meats are salted with potassium, calcium and magnesium salts, which meant that salts containing bittern had difficulty penetrating ham and would require a greater post-salting time compared to regular table salt, nearly pure sodium chloride without the minerals in bitter.

The effects of bittern on preservation were so evident that herring cured with ‘coarse French Bay salt should be limited to 17 lasts per hundredweight of salt, as opposed to 22 lasts with peat salt’, and ‘all curers should brand their barrels with the appropriate initial letter, either a B or S, so that buyers could immediately tell which salt had been used. Boiling, which was done for many types of salt, including peat salt, sea salt and basket salt, but not bay salt, was known to decrease bittern, as the boiling removed calcium salts.” (Grace, 2022)

“In addition to including bittern, bay salt has long been known to have inconsistent quality and to contain other impurities. In 1467, German merchants complained about the quality of bay salt which was ‘mixed with earth and caused herring cured with it to go bad’. Seawater that was entering the salines was not filtered or cleaned of debris, and, at least in the Bay of Bourgneuf, the water entered freely through bungholes in the seawall, meaning that its quality varied greatly depending on what detritus the tides brought in. French bay salt was impure and described as grey, black or sometimes green, but was said to still be used because it was ‘large-grained, inexpensive, and nearby’.” (Grace, 2022)

“However, even with such drawbacks, bay salt was consistently used for curing meats both for regular land use and for use at sea, as various primary sources show. Martin Frobisher, the sixteenth-century English privateer and seaman, had a suggested provision list dated to 26 March 1588 that included five tons of bay salt for his second voyage to the New World. In the same list, in a separate row under the subheading of salted beef, was written, ‘baye sawlte to preserve the same 55 bushels [of beef] at ijs [2.5] per bushel [of salt]’.  The fleet of the Mary Rose‘s last campaign was victualled with at least 2,134 quarters of bay salt. Collins, although he contradictorily wrote against the use of bay salt, included several recipes for curing with bay salt and noted ‘our [English] Mariners feeding on Provision cured with Bay Salt’. (32) Eliza Smith’s The Compleat Housewife (1727) includes a recipe for salt hams that uses a peck (two gallons) of bay salt, four ounces of saltpetre and three pounds of brown sugar.” (Grace, 2022)

“Yet the consensus among modern scholars is that bay salt was popular and frequently used because it was inexpensive. It was exported from France to England and other European nations from at least the medieval period, and exports reached a peak in the seventeenth century when it became such a large trade that it was a topic of concern in England as France was often an enemy. Bay salt’s popularity is attributed to its cost efficiency because it required little labour and equipment and no fuel to produce. It is estimated that bay salt from France during the fifteenth century was two-thirds to half the price of Lüneburg and other superior white salts (white salt being nearly pure sodium chloride), while English sources indicate that French bay salt was brought to London for less than fourpence per bushel, but salt from England saltworks cost sixpence. While economics appeared to play a major role in salt-purchasing decisions, primary sources also state that bay salt was good for curing because it was large-grained. Even as far back as the thirteenth century in The Account Book of Beaulieu, coarse-grained salt was used to cure fish, and fine-grained salt was kept for common use. In the eighteenth century, Hannah Glasse (1747) wrote that York hams were cured with Maldon salt brought from Essex that ‘is a large clear Salt, and gives the Meat a fine Flavour’. Some modern scholars claim that large, coarse grains of salt penetrate the flesh better and produce a better cure, whereas fine-grained salt allegedly sealed the surface, preventing the salt from entering further than the surface tissues.” (Grace, 2022)

“Only one source, Collins’s, in his argument that bay salt is unfit for use, attributed its inferiority to the salt’s large size. He stated the exact opposite of other authors – that the coarse grains’ slow dissolution rate prevented it from preserving the meat, specifically noting that a third of the salt does not dissolve in time, therefore requiring more salt to be used overall. However, nearly all sources disagree with Collins, and his discourse has a political agenda to preserve the English salt industry. For example, a section labelled ‘Arguments for the Encouragement of English Salt, and hindering the Expence of Foreign’ argues against the importation of French salt. Even the name of today’s salted beef (corned beef) is derived from the term ‘corns’, which was the seventeenth-century word for small bits of material, in this case, coarse salt crystals.” (Grace, 2022)

“Salt grain size is determined by the speed of evaporation. A fast boil agitates the crystals of salt and prevents them from accumulating into large grains. Evaporation by the sun or other methods of slowly drying allows large crystals to form, as seen in bay salt. As bay salt did not require fuel to evaporate the seawater, it was more economical, but there is evidence that coarse-grained salts were so much more preferable that salt producers were careful to produce the large grains even when expenses had already been made to clarify the salt. In 1678, Thomas Rastel, in a salt-clarifying recipe, specified not to stir the brine and egg white mixture too much in order to produce large-grained salt similar to that of bay salt. While most historical sources indicated coarse salt was beneficial for curing, modern experiments by Arvill Bitting have indicated that the salt size did not affect the rate of penetration of salt into fish. Furthermore, most shipboard meats were wet-cured and stored in brine, thus making grain size irrelevant.” (Grace, 2022)

“In short, historical sources show that bay salt was inferior in quality but still utilized because it was inexpensive and served its purpose satisfactorily, but low costs cannot explain everything. Curiously, although Collins repeatedly criticized bay salt and wrote that it ruined food, he specifies its use in several salted meat and fish recipes. In The Art of Making Common Salt (1748), William Brownrigg, a London physician, wrote, ‘For certain uses such as curing fish English white salt and rock salt are not as good as Bay salt which is imported from France.’ Historical studies have demonstrated that affluent households used bay salt for curing but more costly white salt for the table even when they had the means to use white salt for curing if desired, implying that regardless of financial means, different types of salt were still purchased for set purposes. The English Navy relied heavily on bay salt and, interestingly, ‘only reluctantly gave up using French [bay] salt’ during the end of the seventeenth century, even though by then it had become more expensive than local salts produced from Portsea. Furthermore, even after bay salt became less expensive than white salt in England during the mid-seventeenth and the eighteenth centuries, it became common to mix bay and white salt for curing. Thomas Wilkins was said to have leased Hampshire saltworks in England in 1701 and experimented with the production of solar salt, paving some of the evaporation pans with brick, which produced large-grained white salt. He also made other salts on unpaved ground, which produced salt the colour of French bay salt. He wrote, ‘And [the gray salt] pleasing those best, who fancied the Bay salt to have some particular virtue in it; I gave myself no further trouble to pave the pans.’ While bay salt contained organic debris and bittern, sources suggest that it also had some quality to it that was extremely desirable so that it was used even when inexpensive and supposedly higher-quality white salts were available. Even today, unrefined solar salt, such as salt from Guérande and Salinas de Añana, is used by five-star chefs who boast of its quality in gourmet cuisine.” (Grace, 2022)

-> Mineral analysis results

“Sea salt exhibited the highest mineral concentrations in potassium, calcium, magnesium, sulphur and boron. Out of the three salts, the sea salt also had the lowest sodium content, whereas bay salt differed from the other salts by containing much higher amounts of iron. The rock salt had comparatively low mineral values except for sodium, of which it had the highest. Overall, no major trends or differences that would imply superior curing were found in the bay salt’s mineral content. This was somewhat expected, given that bay salt refers to a method of salt production rather than to a specific locale of production, which is what would produce mineral composition changes.” (Grace, 2022)

->Nitrate, nitrite and ammonia assay results

From Richard Bosman’s Quality Cured Meats. I include the post by Pasch du Plooy who submitted the picture to show how alive this discipline is. He writes, “My Dad built this beautiful stand for me a few weeks ago. We asked Richard Bosman Quality Cured Meats for one of his finest Prosciutto’s. He blew us away with this 18-month-old aged ham! Sliced in front of guests. We kept it simple and served it with fresh, seasonal melon and a spritz of citrus oil. Such a hit at our last wedding.”

“None of the salts had detectable ammonia (minimum observable level being 0.0469 mM at the lowest standard concentration), but nitrate was present in all salt samples, particularly in the bay salt and sea salt. Nitrite was only detected in the sea salt.” (Grace, 2022)

-> Microbiological analysis results

“Bay salt exhibits much higher microbiological activity compared to the other salts, and is the only one to grow exponentially in the mannitol salt agar. The select microbes that were selected from 16s rRNA analysis were obtained from the salted beef. Most are commonly found in the soil and water environments, but three are uncharacterized species, or species that have not yet been classified and are largely ‘new’ or ‘unknown’. Of the previously characterized species, all are able to assimilate nitrogen via the nitrogen fixation process through the conversion of atmospheric or free nitrogen in the environment into nitrogen salts such as nitrate. The uncharacterized species discovered here also belong to genera known to be capable of nitrogen fixation, but are also able to reduce oxidized nitrogen compounds such as nitrate to nitrite through the removal of an oxygen molecule. Among the most efficient nitrate-reducing organisms are micrococci, and at least one of the isolated species falls under the genus Micrococcus.” (Grace, 2022)

“Bay salt may have been chosen out of the other available historical salts for its superior curing properties, specifically because it provided nitrate and the starter culture needed for nitrate reduction compared to the other salts.”(Grace, 2022)

-> Nitrate, salt and historical ideas on salt

“The data point to a few key conclusions that suggest that the bacteria in the bay salt increased nitrate and nitrite.

• The meat and brine, with no addition of saltpetre (i.e. nitrate), increased in nitrate and ammonia in most samples.
• Common knowledge today indicates that curing meat with brine made from modern purified salt does not spontaneously generate nitrate or nitrite.
• Fresh meat by itself and the aquifer water have below detectable or trace amounts of nitrate and nitrite. The bay salt and sea salt (both of which come from the sea) have about twice as much nitrate as other forms of salt and several times more than in fresh meat.
• The increase in nitrate in the experimental meats and brines positively correlates to halophilic and/or halotolerant bacterial counts in the same experimental meats and brines.
• Bacterial counts of the experimental meats grown in other media that did not select for halophilic and/or halotolerant bacteria decreased over time.
• The bay salt, compared to the other salts, grows halophilic and/or halotolerant bacteria when plated. All other historical salts had low levels of bacterial counts.
• Although only a fraction of the bacteria have been isolated and sequenced, the few that have been identified appear to be nitrogen fixers or reducers.

The results make a strong case that bacteria in the bay salt are the primary responsible agent in producing the nitrate and nitrite in the meats.” (Grace, 2022)

2. The Development of Modern Starter Cultures

In later years, in the 1800s, this concept of a starter culture would be the basis for tank curing and later the Wiltshire process. These developments have been reported on in the greatest detail in this work. Let’s skip over these for the time being and pick up the development of modern starter cultures.

The modern use of starter culture in meat processing seems to be as established as fermentation itself. How many know that this art which seems to have been with us forever was only commercialised in the 1950s by the work of Dr Fritz Niinivaara? He is the father of the meat fermentation industry and the use of starter cultures we have today.

A certain Dr Acton asked him to give a lecture about his life’s research in the area of meat preservation by fermentation and dehydration and about the importance of bacteria in this process. At the time of delivering the lecture, Dr Fritz Niinivaara had spent half his life doing research on starter cultures and was Professor Emeritus, Department of Meat Technology, University of Helsinki, Finland.

I present much of his lecture as it is a unique experience to hear a man with his stature tell the story in the first person. The importance of this lecture goes beyond the starter culture industry. Dr Niinivaara’s recollections go back to the foundation of meat science as we know it today and are therefore of extreme importance, not just to the fermentation industry, but to meat science overall. It harkens back to a time when researchers were proud of their field of study and when much work was done to correct misconceptions about meat. We strangely find ourselves in similar times which makes the lecture not just foundational to our trade, but also relevant for today.

-> The History of Food Fermentation

Niinivaara writes that “the preservation of food by fermentation is as old a custom as is the history of man. It was, surely, learned by chance. The purpose of fermentation is not only to preserve the food but also to improve its flavour, consistency, texture, and nutritive value. So, fermentation creates new and unique products from a given raw material: wine from grapes; cheese from milk; beer from malt; and salami or dried ham from meat. Dried, fermented meat products have a shelf-life of months and a delicious flavour, quite different than the flavour of meat.”

“Fermentations were carried out during centuries without any scientific knowledge about the nature of the processes involved. Up until recently, sausage-makers would transfer old curing brine to the newly prepared one. Thus new brine would become inoculated with beneficial microorganisms, causing the desired changes in the cured meat during ripening. This traditional method was based on empirical observations, with almost no knowledge of bacteriology. Therefore, the results were not always satisfactory. Failure was not uncommon.”

“In the 19th century, Pasteur showed that fermentations are caused by specific types of organisms. The first defined bacterial starters, intended for the fermentation of milk, were introduced about 100 years ago. It was not until the 195O’s, however, that a pure starter culture became available for the fermentation of meat (Liicke et al., 1989). Shortly thereafter, pure cultures were mixed for even better results. The scientific basis of the use of starter cultures in the meat industry was for the first time presented in my doctoral dissertation in 1955. This study will be described later.”

People often ask me: How did I become interested in the use of bacteria for the production of dried fermented sausage?

As a student and later as an assistant of Finnish Nobel Laureate (Biochemistry, 1945) Professor Artturi I. Virtanen, I became quite well acquainted with the importance of the bacterial cultures used in the processing of dairy products: cheese, butter, sour milk products (yoghurt), among others. Professor Virtanen had spent a great part of his life in the field of Dairy Science, having made many important discoveries. The results of his research significantly improved the quality of dairy products by ensuring the success of the delicate biological processes utilized then.

In 1947, Professor Virtanen asked me to initiate and to organize a new field of endeavour: meat research in Finland. Consequently, I left my work in biochemistry and started a brand new career without having the slightest idea about this new discipline, unaware of the nature of the problems to be solved.

I found my experience in Dairy Science to be quite useful. The fermentative changes in cheese were quite well known at that time, thanks to Professor Virtanen’s previous research work. The formation of the typical flavour, aroma and consistency depended on the activity of the appropriate microbial flora in the cheese. Cultured microbes were used in these processes.

The ripening of dry sausage, I supposed, might have been by a similar process, but the information on the kind or kinds of bacteria which played a role therein was non-existent. Some microbes could have been useful and desirable but also harmful if found to cause discolouration, unpleasant odour or putrefaction within the system,

Therefore, I concluded that it might be an interesting and economically important task to clarify the relationship between different microbes, the changes produced during the process and the quality of the final product.

Decisive for my future work was the discussions with Dr Niven and Dr Deibel in Chicago in 1953. Both of these scientists were interested in the role of microbes in meat fermentation, e.g., in the ripening of dry sausage. This was my first study trip to the U.S.A..

-> The First Successful Achievement with Pure Cultures for Meat Processing

In spite of the many unsuccessful experiments in the U.S.A., I decided to start the research in order to isolate bacteria and test the influence of these organisms in the manufacture of dry sausage. The main purpose of the studies was to isolate bacteria from good quality dry sausage and to determine their influence on the ripening process. The ultimate purpose of the study was to inoculate sausage batter with cultures of the isolated bacteria in order to improve the process by shortening the fermentation time, improving colour and flavour and eliminating the risk of spoilage and discolouration inherent in the traditional process.

In addition to the organoleptic evaluation, microbiological, chemical and physical determinations were carried out. Variations in moisture content, drying loss, fat content, pH value, redox potential, photometric color determinations, and the content of glucose, lactic acid, nitrate, nitrite ammonia and hydroxylamine in the sausage, were carried out.

Microbiological analyses included differences in total bacterial count, aerobic and anaerobic microorganisms and micrococci were determined. The technological trials were carried out in the pilot plant of the Research Institute for the Meat Industry, in Hämeenlinna, Finland.

In the preliminary tests, the best results were achieved with a bacterial strain which we called “M-53.” In accordance with Bergey’s Manual, this organism was classified to be closest to Micrococcus aurantiacus. The “M-53” organism was then used as the starter organism in the original and subsequent research work. The results of this research work became the author’s Doctoral Dissertation in 1955 (Niinivaara, 1955).

In my dissertation, the following important observations were made and published. Using starter cultures:

• Colour formation was speeded up.
• The pH value of the system was lowered more rapidly.
• The desired consistency was achieved more rapidly.
• Total processing time could be shortened considerably, a great economic advantage.
• The process became fail-safe in view of the antagonistic nature of the starter culture which inhibited many spoilage or pathogenic organisms.

-> “It is a Long Way From Idea to Success.’’

There were many factors which led through many difficulties to the success of utilizing starter cultures industrially. The first of these, a very important one, was the industrial propagation of suitable strains. Fortunately, I was able to start a good cooperation with an enthusiastic person from Germany, Herr Rudolf Müller, who agreed to develop the cultivation of microbes, i.e., “starter cultures”, on an industrial scale. At that time, there was no model to follow for this kind of product and, therefore, we had to overcome numerous difficulties. The greatest one of these was the preconceived opinion of many people in industry as well as in research institutes.

The bacterial culture methodology I had used at pilot plant scale was not directly applicable at the industrial scale. A new method had to be developed. Lyophilizing technology was still in quite a primitive stage: it was not cost-effective, and it significantly decreased the activity of the microorganisms. If that were not enough, later on we had problems with bacteriophage, which destroyed the cultures towards the final stages of cultivation. Therefore, we were forced to isolate new phage-resistant strains exhibiting the characteristics we had determined to be desirable in starter cultures for sausage: nitrate reduction capacity, acid production capacity and an antagonistic effect towards harmful/ undesirable bacteria.

Finally, when after much toil lyophilized starter cultures became available, we met the skeptical attitude and preconceived opinion of the meat industry.

Fortunately, at that time I was working in the Research Institute for the Meat Industry in Hämeenlinna and therefore had the opportunity to organize experiments in order to demonstrate the advantageous influence of the starter cultures. Through Herr Müller, the positive, encouraging results obtained by the Finnish meat industry were transmitted to the German meat industry, where initially the attitude was very sceptical, as well. In fact, many leading European Meat Research Institutes would stubbornly not accept this innovative methodology and, therefore, discouraged further research on the subject.

Thus, the Finnish meat industry was the first test laboratory in the development of starter cultures for industrial use. The Finns (filled with “Suomalainen Sisu,” a mixture of courage, determination, inspiration and stubbornness), went from pilot-plant scale to the industrial level of applications. But slowly, through continued experimental work in Finnish industrial plants, and later on in the German meat industry, the beneficial influence of starter cultures on the production, quality and economics of dry fermented sausage was finally recognized. The use of starter cultures was accepted and became a reality. This was a key accomplishment!

In 1972, at my initiative, the International Starter Culture Symposium was organized in Helsinki. This event strongly influenced the opinion and effectively removed the prejudice from many meat scientists. Afterwards, cooperation with many countries developed and collaborative studies were carried out and published (Proceedings, Starter Culture Symposium, Helsinki, 1972).

-> Mixed Starter Cultures

After having gathered a great deal of information about the importance and role of the micrococci in the ripening process of dry sausage, we started to clarify the role of lactobacilli in the process. These investigations led to Esko Nurmi’s Doctoral Dissertation in 1966. As a result, we were the first to develop the combined inoculation with mixed starters containing a pure culture of Micrococci and a pure culture of Lactobacillus plantarurn. The Micrococcus ensured colour formation whilst the Lactobacilli was responsible for the decrease in pH value and for the formation of the desired texture and consistency. This was another key accomplishment!

Before Nurrni’s findings, it was commonly believed that Lactobacilli were the main spoilage organism in European dry sausage (Coretti, 1958). These studies showed that lactobacilli are also useful and, in many cases, necessary organisms in the ripening process.

-> Some Aspects of the Properties of the Starter Cultures

–>> Antagonistic Properties

Research carried out during recent years has proved that the antagonistic properties of starter cultures is a very important conservation factor. In addition to their role in fermentations, the suppression of spoilage and pathogenic bacteria offers new applications for the use of starter cultures in food manufacturing. Just in the last years, the use of microorganisms as protective flora has expanded, for example, in the packages of cooked sausages

In my first publication on starter cultures (Niinivaara, 1955), the inhibitory effect of starter cultures was already mentioned. This was shown in laboratory trials, but also in technological experiments at pilot plant scale. We were able to show that the microbial formation of hydroxylamine is possible only when nitrate was present in the growth milieu. Hydroxylamine had an inhibitory effect on the growth of spoilage bacteria.

In the work by Pohja (a dear, inspiring co-worker of mine) and Niinivaara (1 957), we showed how the starter organisms inhibited the growth of many undesired organisms. Later, the antagonistic influence of starter cultures on the growth of Salmonella senftenberg in the dry sausage (Niinivaara et al., 1977) was shown. Pohja’s doctoral dissertation pointed out the first selection system of useful Micrococci. Later on, his work has been used as the model for other microbes. Thus, the starter cultures improve the hygienic conditions during processing and minimize the potential health risks caused by the pathogenic organisms.

–>> The Gram-Negative Bacteria in the Fermentation

There are many indications that gram-negative bacteria play an advantageous role in the fermentation process. For instance, the proteolytic activity of the bacteria in this group can degrade proteins to form the desired aroma. On the other hand, we usually try to avoid the growth of gram-negative bacteria because many pathogenic organisms belong to this group.

Esko Petäjä (1977) started an investigation to clarify the role of gram-negative bacteria in sausage ripening. He isolated a Vibrio strain (Vibrio costicolus) that he used in the drying and fermentation of dried ham with limited success. Although it had a positive influence on the flavour of ham, Vibrio costicolus was found to be very sensitive, difficult to cultivate and apt to lose its fermentative capacity after freezing. Therefore, it never came into commercial use.

Petäjä also isolated several strains of Aeromonas. Two strains of his collection, Aeromonas X and Aeromonas 19, had the most favourable effect on the quality of sausage. The best results he achieved were when Aeromonas was inoculated together with Lactobacilli.

These strains are not available commercially despite the fact that 12 years ago we achieved very interesting results in production trials carried out under the direction of Dr. Abraham Saloma in Argal S.A., a commercial operation in the city of Lumbier (Navarra), in Spain. This factory has for several years successfully used these starter cultures in the commercial production of Spanish dry sausages, Salchichon and Chorizo.

–>> Starter Cultures and the Nitrite Problem

During the last decades, investigations have been carried out on the fate of nitrate/nitrite in cured meat products. Evidence exists that under certain circumstances the formation of carcinogenic nitrosamine is possible. This is one reason why many laboratories are trying to find out how to minimize the concentration of nitrite in meat products to a level where bacterial spoilage could be avoided without jeopardizing color formation.

My co-worker Eero Puolanne has worked on this problem. In 1977, he published his Doctoral Dissertation “The effect of lowered addition of nitrite and nitrate on the properties of dry sausage.” He was able to show that by using starter cultures it is possible to lower the nitrite and nitrate addition by one third from the normal level.

–>> Investigation by Niven

By an astonishing coincidence, at the same time my work on the use of Micrococci was published, Charles Niven published his study on the use of Pediococcus cerevisiae (P acidilactici) as starter culture in the American type of dry sausage known as “summer sausage” (Niven 8, Wilson, 1955). We had worked independently of each other. After the discussion in Chicago in 1953, we did not have any contact with each other, but our studies were published exactly at the same time (April 1955). Niven’s Pediococci also became commercially available and was sold under the name ACCEL (E. Merck, Rahway, N.J.).

–>> Future Research

The future opens many new perspectives to create new starter cultures and utilization of microorganisms in new fields.

Leistner, et al. (1 990) have mentioned the genetic possibilities of improving certain properties of bacteria. In the future we could, through gene technology, improve the production and activity of microbial protease, lipase, catalase, nitrate reductase, to name a few. In that way we could give new properties, or strengthen the desirable ones already existing in the microbe.

It seems also possible to transfer new genes into a given microorganism so that it may produce aroma components, vitamins, specific desirable metabolites, and so on. In addition to the research oriented towards the solution of old, traditional problems of meat fermentation, there are new elegant methods to create better cultures with stronger activity in those desirable reactions that favor a good fermentation process.

Much research has been carried out in the field of meat fermentations. Yet, we are far away from understanding the complete interrelations between the microbiology, the technology and external factors influencing the fermentation and ripening process (Buckenhuskes, 1990).

–>> International Cooperation

The year after my studies on starter cultures were published, we started the international cooperation with Germany. The objective was to create starter culture technology and a distribution organization to deliver the cultures to the meat processors. This cooperation continued for about 20 years.

Many other international contacts came into being later on, which proved to be very beneficial for the research and development work. In that fashion, we were able to exchange thoughts and ideas, bacterial strains and even research work personnel between countries. Mutual cooperation was carried out with Yugoslavia, Hungary, Bulgaria and later with Spain. In all these countries, fermented sausages have for centuries constituted a very important gastronomical tradition. In addition, they play a significant role in the meat industry.

I would especially like to allude again to a very interesting and sympathetic cooperation with a meat processing firm in Spain. This cooperation started in 1976 by the initiative of Dr Abraham Saloma, who was then the technology director of this company, Argal, S.A., then a subsidiary of the Antonio Porta Labata Group. Under Dr Saloma’s direction, important improvements were achieved in the production of fermented salchichon and chorizo at commercial scale.

One significant accomplishment at Argal was the establishment of one of the most complete starter culture programs anywhere in the meat industry. More than 12 different strains of microbes (bacteria, yeasts and fungi) were daily propagated and incorporated into fermented products. Each particular sausage was inoculated with a tailored mixed starter culture that ensured distinctive characteristics and high quality in the final product. I would like to thank Dr Saloma for these pleasant years of fruitful cooperation, friendship and international understanding

The year 1955 was the birth year not only of starter cultures for meat, but also the birth year of the international cooperation called the European Meeting of Meat Research Workers (EMMRW), renamed the International Congress of Meat Science and Technology (ICoMST) in 1987. The birthplace of this Congress was the same small Finnish town, Hameenlinna, where much of the starter culture work originated and was carried out.

This Congress has gathered annually, without interruption, during 35 years, having become an international forum for lectures concerning not only starter culture research but meat science and technology across many international borders. More than 30 countries participate each year in this congress. It has been a wonderful feeling that the idea of scientific collaboration, originally expressed in a small circle amongst good friends and colleagues, was the seed for a great intercontinental cooperation

–>> Some Remarks About My Life’s Other Activities

As I mentioned at the beginning of this lecture, I started meat research in Finland in 1947. There was no model in Europe to learn what meat science was all about and which problems had to be solved. Even in countries where meat research had been started, like in Germany, everything was destroyed by the war. Meat science laid in primitive stages in ruined Europe. The only way was to identify the problems and to produce solutions alone, and through research build the knowledge, to improve the quality of the products, to improve the economy of the production, to improve the utilization of the byproducts. We started our independent research work from zero in meat science and technology.

The most important question in the production of cooked sausages was the water-binding capacity of meat. This was the theme with which we worked during the first years, since 1952 in co-operation with German meat scientists Grau and Hamm.

The next step was to concentrate on the problems of the fermented meat products. As I described at the beginning of this lecture, the role of the beneficial microbes should be cleared up. The final goal was to find and cultivate microbes, add them as the pure cultures in the meat mass and by that way speed and ensure safety in the processing. Both things mean better economy in the production. Of decisive importance for this work was the encouraging discussion in the American Meat Institute Foundation with Dr. Niven (in 1953) and later the financial aid by USDA in the form of two grants of considerable amount. In many scholarly papers. New information about the basic problems in meat science was published in the international scientific journals and congresses. This research activity created a new field of food science. This made it possible to establish a professorship at the University of Helsinki for Meat Science and Technology. Through this research work, meat technology gained “saloon competence,” as people say in Europe. It became working knowledge.

Through financial aids by the meat producers, the chair and professorship of Meat Technology were founded. My duty was to start this academic activity in 1961 again from zero, like the industrial meat research 14 years earlier.

Besides the scientific research-partly continuing the old themes-the education of new generations of young students for leading technical positions in the meat industry was my duty with high challenge.

This professorship in Meat Technology was the first one in Europe. No models existed for the content of the instruction. No academic text books existed. The lectures, the exercise works had to be created from zero, again.

Now, more than 100 meat technologists are in leading positions in the Finnish meat industry. Eero Puolanne, one of my students, is continuing my academic career as professor of Meat Technology and Director of “my” Meat Research Institute.

Just before retiring and leaving my duties as university professor, I started a new activity in the field of meat.

It was generally known that consumers had lots of wrong information about the nutritive value of meat. Housewives, who in most homes are responsible for the preparation of meals, were confused when buying meat: which meat or which part of the carcass for which purpose. The strong propagation from the side of Die Grunen, the “greens,” vegetarians and raw food eaters, made the housewives still more confused. They often ask: “Is meat healthy for my family or is it not?” To improve the knowledge of the consumers about the quality and nutritive value of meat, to facilitate the choice of meat, to give new ideas in food preparation, we
founded a society that we called “Meat Information Center,” of which I was the first chairman and charter member

During the last years, we have been able to build a useful cooperation with many corresponding organizations abroad. The international cooperation helps us to get new ideas and to evaluate experiences about different activities

Last, but not least, I should like to mention the constructive cooperation with students in Finland: The Society of Food Science (“Lipidi”). I have made numerous studying excursions with my excellent students in many countries in the world, sharing ideas, promoting knowledge of food science, creating strong bonds with fellow professionals and fostering goodwill amongst many people internationally. This Society has selected a few honorary members, one of them being Abraham Saloma (since 1978). Other (“Lipidi”) honorary members are Professor Robert s. Harris (U.S.A.), Doctor Peter Zeuthen (Denmark), Professor Lothar Leistner (Germany), Professor Ferenc Lorincz (Hungary), Professor Torsten Storgards (Sweden), Professor Rainer Hamm (Germany), Professor Velimir Oluski (Yugoslavia), Doctor Sandor Balogh (Hungary), and Professor Ralston Lawrie (U.K.).

During the 22 years I was active in the University of Helsinki, I performed the duties of the chairman of this Society for 20 years. Like my job as University Professor, my position in this society was inherited by my successor in the office, my dear student, Professor Eero Puolanne.

–>> In Conclusion

I am very happy to be able to review today, before this wonderful audience, many of the magnificent developments which have taken place during the past 35 years. Time has quickly flown from the first experiments when we inoculated sausages experimentally to the present when starter cultures are indeed an integral, indispensable part of fermented meat and other food products. The reason why I was invited to participate in this very interesting meeting is that I was there when this beautiful story began.

3. How Microbes Migrtate Into Meat

With two excellent dissertations behind us in the discussion on bay salt and the birth of the modern starter culture industry told by the man who pioneered the technology in the meat industry, we can now consider the important question of how bacteria penetrate meat.

The relevance is that Richard Bosman and I are working tirelessly to create a curing system that uses bacterial fermentation. In order for meat to be cured, either an oxidation reaction of ammonium/ ammonia or L-Arginine is required or the reduction of nitrite is. (See my chapter in Bacon & the Art of Living, The Curing Molecule) The focus of our work is on creating the former.

I posed a few initial questions about the relationship between the penetration of meat by bacteria and the percentage of salt used in a curing brine (with no nitrates and nitrites) to the inventor, scientist, entrepreneur and author, Greg Blonder. (For more on Greg visit Genuineideas) Greg set me on the path to the solution.

The pioneering work on the subject of the general penetration of bacteria in meat was done by the New Zealand researcher, C. O. Gill who was associated with the Meat Industry Research Institute of New Zealand in Hamilton. It is an area of meat science where remarkably little has been done since and I suspect, in light of the emerging new curing methods of meat fermentation which allows for an oxidation step to nitric oxide, will become a focus area over the next couple of years for researchers.

Preliminary Thoughts

-> Is Meat Intrinsically Sterile?

Meat is sterile if we exclude any bacteria contamination due to disease or injury. Gill (1979) writes that “it has been shown that muscle tissue from commercial carcasses is sterile if care is taken during sampling, the outer contaminated layers being first removed either by surgical techniques or by deep searing of the tissue with a hot template (Buckley et al. 1976; Gill et al. 1978).” He makes it clear this is the case across all species when he writes that “in addition to . . . work on mammals, there is also evidence that the flesh of fish and birds is usually sterile (Herbert el nl. 1971; Mead et al. 1973).” (Gill, 1979) Not only is the meat sterile, but “carcasses from normal healthy animals would appear to have considerable residual ability to maintain tissue sterility.” (Gill, 1979)

The clear fact is that meat is sterile on the inside and contamination with bacteria from the gut, post-slaughter is unlikely since “bacteria cannot pass across the intestinal wall nor penetrate muscle tissue until there is considerable breakdown of the tissue structure. Similarly, there is no movement of bacteria longitudinally within the intestinal wall until tissue breakdown is well advanced (Kellerman et al. 1976; Gill et al. 1976; Gill & Penney 1977). There is therefore no mechanism by which bacteria can pass from the intestine of dead animals to other tissues until at least several hours after death, the time involved being largely dependent on the temperature at which the carcass is stored.” (Gill, 1979)

-> Important Characteristics of Bacteria to Consider

We must be aware of the phases of bacterial growth.

In an “ideal environment”, the following phases of bacterial growth are observed a lag phase, an exponential or log phase, a stationary phase and as nutrients decline in the environment, a death phase.

The bacterial growth curve represents the number of living cells in a population over time. Michal Komorniczak/Wikimedia Commons/CC BY-SA 3.0

We must also be aware of the fact that bacteria can be either proteolytic or non-proteolytic. Proteolytic bacteria is a type of bacteria that can produce protease enzymes, which are enzymes that can break down peptide bonds in protein molecules. The result of proteolysis is therefore the breakdown of proteins into smaller molecules catalyzed by cellular enzymes called proteases. (Shirai, 2017)

Proteolysis in dry-cured meat products has been attributed mainly to endogenous enzymes (Toldráet al. 1992a). On the other hand, Rodríguez (1998) found that “proteolysis on hams may be due not only to endogenous but also to microbial, enzymes.” Gill (1977) came to the same conclusion years earlier when they found that bacteria are confined to the surface of meat during the logarithmic phase of growth but when proteolytic bacteria approach their maximum cell density, extracellular proteases secreted by the bacteria apparently break down the connective tissue between muscle fibers, allowing the bacteria to penetrate the meat. Further, non-proteolytic bacteria do not penetrate meat, even when grown in association with proteolytic species. (Gill,1977)

In terms of the penetration of bacteria into fresh meat, Gill (1977) found that the “penetration of meat by nonmotile bacteria (i.e. not mobile) and the rapid rate of advance of invading microorganisms indicate that physical forces are involved in the movement of bacteria through meat. Non-proteolytic species do not invade in company with proteolytic species probably because, with mixed cultures, penetration originates in the area of growth of a microcolony of the proteolytic species so that the non-proteolytic bacteria are excluded. Protease production by bacteria does not occur until the end of logarithmic growth when the meat is in an advanced stage of spoilage. Therefore, unless the meat has been treated with a protease preparation to cause breakdown of the muscle structure, there should be no penetration of bacteria into organoleptically sound meat.” Gill (1977)

Also, “the proteolytic species were present between the muscle fibres throughout the meat, and some degradation of muscle fibres occurred. . . . Penetration of meat by bacteria apparently results from the breakdown of the connective tissue between muscle fibres by proteolytic enzymes secreted by the bacteria.” Gill (1977) Shirai (2017) quotes Gill (1984) when he stated that bacteria migrate into meat via gaps between muscle fibres and endomysia. Gill did not salt the meat as part of their experiments.

-> Is Bone-Taint Evidence of Intrinsic Bacteria?

Bone taint is often given as evidence for the existence of intrinsic bacteria in the deep tissue regions of fresh meat. When discussing this, Gill (1979) says that “in hams which have been injected (pumped) with brine, any deep spoilage is likely to result from the injection of extrinsic bacteria.” (Gill, 1979) He rules out that bone-taint is evidence of intrinsic bacteria when he writes “‘bone-taint’ of hams is not unequivocal evidence for the occurrence of intrinsic bacteria.”

For all the possible causes for bone-taint considered by researchers by the 1970s, I give the complete paper by Gill (1979) below where he concludes that “it is clear that more than one condition is encompassed by this term (bone-taint), and it is possible that with beef carcasses a considerable proportion of the conditions so described are not the result of bacterial growth in deep tissues.” (Gill, 1979)

How Would Starter Culture Bacteria Enter Salt-only Dry-cured Meat

The question is relevant because I suggested in my comments on salt-only curing methods that bacteria play a role in oxidising nitrogen-containing elements to nitric oxide and that it is possible to have a curing system where no nitrite is used.

How Bacteria Can Enter Dry-Cured Meat

Gill did not dispute the fact that bacteria from the surface are able to penetrate meat. More recent studies have, however, shown this to be the case even for non-proteolytic bacteria also. Bosse (2015) studied the kinetics of migration of colloidal particles in meat muscles in the absence and presence of a proteolytic enzyme to simulate non-motile bacteria penetration. They concluded that “particles are able to diffuse into the densely packed fiber structure of meat muscles, which is contrary to the long-held belief that such penetration may not occur in the absence of extensive proteolysis or mechanical damage of tissue.” (Bosse, 2015)

Water and Salt: Changes to Microstructure of Meat

To develop a possible model of vectors facilitating the migration of bacteria to the deep tissue parts of meat, we consider the combined effect of water and salting.

Thorarinsdottir (2011) investigated the effects of salting and different pre-salting procedures (injection and brining versus brining only) on the microstructure and water retention of heavy salted cod products. They found that “salting resulted in shrinkage of fibre diameter and enlargement of inter-cellular space. Water was expelled from the muscle and a higher fraction became located in the extra-cellular matrix. These changes were suggested to originate from myofibrillar protein aggregation and enzymatic degradation of the connective tissue. During rehydration, the muscle absorbed water again and the fibres swelled up to a similar cross-sectional area as in the raw muscle. However, the inter-cellular space remained larger, resulting in a higher water content of the muscle in the rehydrated stage.” (Thorarinsdottir, 2011) Such water would undoubtedly contribute to the migration of bacteria during a starter culture containing brining of meat. Their observation is that when salt is rubbed on the meat surface and migrates into the meat, water is expelled from the muscle and a higher fraction which becomes located in the extra-cellular matrix will undoubtedly aid the migration of bacteria into meat in a salt-only curing system. The inter-cellular space is also enlarged during dry salting, believed to result from enzymatic degradation of structural components in the muscle during the first days of dry salting.

They state that the microstructural changes in dry-cured ham and these “have been related to proteolysis (as we developed above) and have been described as degradation of the proteins in the costamere and in the cell membrane. After curing, the Z-disks are no longer in line. It has also been observed that the myofibrillar bundle becomes more compact with a large number of empty spaces or gaps in between neighbouring myofibrils.” (Larrea et al., 2007).

White Spots

In 2023 I did a study on possible reasons for white spots on bacon that were cover-brined and then heat-treated. In the process, I looked at exudate from fresh meat that is in reality peptone (liquid protein) and is an extremely effective bacterial food. The relevance of microbial migration into meat comes in that surface bacteria are the major problem before injection because the injector needles push bacteria which are found on the meat surface into the meat. The drain tray is a brilliant way of preventing microbial contamination during processing. More about these drain trays later in this article.

Changes to the microstructure of dry-cured meat which results in water being expelled from the muscle to become located in the extra-cellular matrix is one of the likely routes for the migration of bacteria during salt only curing from the surface into the deeper tissue regions. Further, there is an increase in the inter-cellular space that was believed to result from enzymatic degradation of structural components in the muscle during the first days of dry salting. Besides this Staphylococcus xylosus, known for its ability to oxidise nitrogen and form Nitric Oxide is a proteolytic bacterium.

4. The Answer is Before Us

Liquid Protein and Starter Cultures

The reason why I include the discussion on liquid proteins in consideration of starter cultures is because I believe its application in liquid brines and wet curing processes offers the most exciting future trajectory for starter cultures. It was in Nigeria where I learned about a comprehensive meat safety system based on good bacteria and seeing its wholesale application worlds opened to me.

The Lagos Question

Thawing frozen chicken in Lagos brought renewed perspectives on muscle proteins in light of the discussion on starter culture and meat penetration. In Lagos, in my apartment kitchen, I was able to isolate 60% protein from 1L of purge that came out of chicken that was injected by the supplier before he delivered it to us in a frozen state and we thawed it to portion it.

It was instructive to review muscle protein which contains a variety of proteins that contribute to the structure, function, and biochemical properties of the meat, including their interaction with various solvents. I review key muscle proteins, their solubility, presence in different meats and participation in curing processes.

Key Muscle Proteins

1. Myoglobin

Water-soluble and responsible for the red colour of meat. It can undergo colour changes and participate in curing by reacting with nitric oxide (NO) to form nitroso myoglobin, giving cured meats like ham their pink colour. It is the most abundant protein we see every day in the factory that leaches out as the meat thaws.

2. Actin and Myosin (Myofibrillar Proteins)

Salt-soluble. These proteins are primarily involved in muscle contraction and structure. They’re found in all meat types and can undergo slight colour changes but are less involved in curing reactions compared to myoglobin.

3. Collagen

Insoluble in water but can transform into gelatin in the presence of water when cooked for long periods. This transformation makes it soluble in water. Collagen is more abundant in beef and pork than in chicken and participates minimally in curing processes. However, its conversion to gelatin can affect the texture of processed meats.

4. Elastin

Similar to collagen, elastin is insoluble in water and does not play a significant role in curing. It’s found in connective tissues and contributes to the meat’s toughness.

5. Tropomyosin

Salt-soluble, found in muscle tissues, and plays a role in muscle contraction by regulating the access of myosin to actin filaments. It has a minor role in meat curing processes.

6. Albumins and Globulins (Sarcoplasmic Proteins)

Water-soluble, these proteins are involved in various biochemical processes within muscle cells. They have limited participation in curing and colour change processes. Albumins are mainly found in blood, but they also appear in the cells’ sarcoplasm with proteins like myoglobin.

Presence in Beef, Chicken, and Pork

When thawing the chicken, albumin and globulin with some myoglobin with enzymes and nutrients. Without directly analyzing it, I sense that there is more myoglobin in chicken than one would expect. Still, the following general rules apply:

– Myoglobin: High in beef, moderate in pork, low in chicken.

– Actin and Myosin: Abundant in all three meat types, with slight variations.

– Collagen: High in beef and pork, especially in tougher cuts; lower in chicken.

– Elastin: Presence varies with the cut and age of the animal but generally follows collagen trends.

– Tropomyosin, Albumins, Globulins: Present in all meats but vary less between types compared to myoglobin and collagen.

Curing and Color Change Potential

1. Myoglobin: High potential for colour change and curing.

2. Actin and Myosin: Moderate ease of participation in curing, minor colour changes.

3. Collagen, Elastin, Tropomyosin, Albumin, Globulins: Low to negligible direct participation in curing and colour changes.

It is a strange thing how thawing chicken can make one review meat proteins and how this review can possibly lead to a breakthrough that eluded me for a few years now. Remarkable!

From these considerations, the following practical application follows:

Any person who works with fresh meat is familiar with the reddish exudate that comes from any fresh meat cut. I have recently been confronted with white exudate from bacon post-heat treatment. I have been in the meat industry for 15 years, most of this time spent on bacon. I am too familiar with the white exudate that forms in the pan upon frying. Towards the end of shelf life, sometimes this white exudate appears in the vacuum packets.

In an amazing week, these different forms of exudate came into focus in their relationship to microgrowth and weight loss. The different exudates were evaluated by Sheard (2001) in their work “Factors affecting the composition and amount of ‘white exudate’ from cooked bacon.

Micro and Liquid Fresh-Meat-Protein

In my work with Richard Bosman on nitrite-free curing, we have learned the importance of peptones which are liquid proteins as bacteria food for starter cultures. As we just indicated, the liquid terminating from defrosting meat is mainly due to water and soluble proteins released from the meat during the thawing process, resulting from damage to the cells due to ice crystals.

While I was contemplating how to “harvest” the albumen, I made contact with an exceptional entrepreneur and butcher who invented a tray to fit into meat crates to separate the meat from the albumen as early as possible. The invention was based on many years of personal experience where he carefully noted the effect of albumen on microbial activity and managed to infer a direct linear relationship.

E. Mostert had a micro analysis done on this simple method where they analyzed fresh beef, ostrich, pork and chicken (whole and pieces) along with a variety of spices (unspecified) in the validation of the method.

E Mostert analyzed meat in its albumen after 24 hours at ambient temperature. The meat was placed on a drain tray and samples were sent for analysis 24 hours later and held at ambient temperatures. The results are reported as “after drain.”

These astounding results indicated the power of mayoglobin (liquid protein) as a bacteria food. It was supported by Richard Bosman and my own work on cultivating bacteria which we rely on to convert L-Argenine in the meat protein into nitric oxide to cure meat. In our case we did not want to remove the micro from the meat – we wanted to enhance their metabolism by feeding them.

As far as pathogens are concerned, the Western Concept of limiting TVCs on meat provides us with a simple method for extending the shelf life of meat products by simply separating the meat from any exudate at every step of processing. The relationship between micro and albumen/myoglobin has been confirmed by Sheard (2001) both for fresh meat and processed meat.

An interesting case was recently brought to my attention where white spots were reported on high-injected bacon logs, post-curing and heat treatment. I suspected it was a sarcoplasmic protein. Richard Bosman was interested in identifying at what temperature albumen would change to white.

He harvested albumen from fresh pork and at 40 deg C it changed to white in colour.

A food science professional who asked me to remain anonymous tested such white spots on meat for micro and found the TVC count on the white spots to be many times higher compared to the surface of the meat that did not have white spots. It was this report from private conversations, along with the results from the drain tray and Richard and my experience with peptones (liquid protein) as the primary food for bacteria that completed the picture for me of the linear relationship between fresh meat exudate and par-cooked exudate as in the case of high injected and tumbled pork and surface micro activity. The implications to shelf life and hurdles against microcontamination are vast!

When thinking about the basics of the Wiltshire system, the albumen is a key feature in the overall system. It is the liquid protein exudates from freshly injected meat that provides the basis for bacteria food.

Sheard (2001) confirmed the protein to be a sarcoplasmic protein and by comparing albumen (pork drip) with other forms of exudate, the high protein content is confirmed.

Exudate from Fresh Meat vs Bacon

Shread (2001) discuss the nature of the exudate. “One might anticipate that the exudate from bacon would differ from that of pork since the addition of salt, either dry or as a brine, is often used to solubilise meat proteins (for example Jolley & Purslow, 1988). Actin and myosin are the major protein components of the myofibril, comprising about 70% of the protein in muscle (Jolley & Purslow, 1988). However, only trace amounts of actin and myosin were evident at the positions where one would expect to find these two proteins. The exudate from cooked bacon, thus, contains less actin and myosin than the ‘sticky exudate’ that is produced during the manufacture of reformed hams (Jolley & Purslow, 1988).” (Shread, 2001)

“Previous work has shown that myosin is irreversibly denatured when meat blocks were exposed to high concentrations of sodium chloride (5M or about 29% NaCl) (Dilber-Van Griethuysen & Knight, 1991), resulting in minimal protein extraction (Callow, 1931). Dilber-Van Griethuysen & Knight (1991) argued that such salt concentrations could pertain during curing, immediately following injection, when there would be localised areas of high salt concentration, followed by a slower equilibration. This could account for the alternate light and dark bands (tiger-striping) sometimes seen in sliced bacon (Voyle, Jolley, & Offer, 1986) and provides a reasonable explanation for the virtual absence of myosin and actin in the bacon exudate examined” by them. (Shread, 2001)

The discussion, interestingly leads to a discussion of the phenomenon which some observe of white spots forming on bacon. It may be the result of exudate from the bacon during the cooking process and I retain this discussion as far as starter cultures are concerned. Shead (2001) offers the following suggestion: “Having identified the composition of the exudate, it is of interest to consider how the exudate is formed during cooking. Elevated temperatures result in the denaturation of myofibrillar and connective tissue proteins (Bendall & Restall, 1983) and shrinkage of the myofibrils, the main water compartment in muscle (Offer & Knight, 1988a). This results in the expulsion of water from the myofibrils, with weight losses of about 20–30% depending on the cooking method and type of bacon, and a consequent shrinkage in the dimensions of the product. In bacon, a large proportion of the water (65–90%) is lost by evaporation because of its large surface area; the rest is manifest as fluid, containing a small quantity of protein together with any liquefied fat. In the case of bacon, the fluid also contains salt. The proteins, derived from the sarcoplasm, are mainly low molecular weight and readily soluble. Heat denaturation of these proteins causes them initially to coagulate, entrapping some water and salt, conferring the typical appearance of the white exudate associated with cooked bacon. Further cooking results in evaporation of water from the exudate and a concentration of the solid material, which eventually darkens and burns onto the surface of the pan or grill.” (Shread, 2001)

Tempering and Exudate

A surprising result from Shread (2001) is the increased exudate associated with tempering. They concluded that their “results suggest that the partial freezing of meat, necessary for the high-speed slicing of bacon, increases the amount of exudate produced. It is well known that freezing increases the amount of drip in pork — typically double that of unfrozen pork (Offer & Knight, 1988b) — and since approximately 60% of the water would be frozen at -7 Deg C, even in bacon with 2–3% salt (Sheard, Jolley, Katib, Robinson, & Morley, 1990), this result is not surprising. The precise mechanism is unclear but it is known that freezing has marked effects on the structure of muscle. Freezing results in the formation of large columns of ice crystals outside the muscle cells and a consequent dehydration and shrinkage of the muscle fibres; these re-swell on thawing in a time-dependent fashion (Offer & Knight, 1988b). Thus, freezing has marked effects on the structure of the main water holding compartment in meat (the myofibrils) and the state and location of the water.” (Shread, 2001)

Conclusion

Where are we after all this? The concept of a starter culture delivered by salt has been firmly entrenched. We heard first-hand accounts of how the modern starter culture industry formed along  with the key considerations and aims. I then stepped off the beaten path and explored liquid proteins and alluded to the incorporation of modern processing systems building on West African food safety systems that rely on cultivating large colonies of good bacteria. I showed how drain trays can be used effectively in harvesting peptones for inclusion in new wet cure starter culture systems. What a journey!

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Further Reading

The relevance of microbial migration into meat comes in that surface bacteria are the major problem before injection because the injector needles push bacteria which are found on the meat surface into the meat. The drain tray is a brilliant way of preventing microbial contamination during processing. See Bacterial Migration Into Meat

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Reference

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