Dr Morgan’s Arterial Injection: The Australian Connection
by Eben van Tonder
29 April 2017
Arterial pumping was one of the stepping stones to the use of multi-needle injectors universally used in meat curing plants. The initial motivation for the development of the arterial pumping system, on the one hand, was the need to preserve meat for the enormous British navy and on the other hand to supply food from the new world to booming British and European populations of the 1800’s. Arterial pumping, like the use of multi-needle injectors, solved the problem of rapid brine distribution through the meat in order to cut down on curing time.
The person who applied arterial injection to meat preservation and who patented it was Dr. John Morgan, professor of anatomy at the University of Dublin, son of Dr John Morgan, Surgeon to Guy’s Hospital. The original inventor of the system was the Dutch physician, Frederik Ruysch and the application was embalming. Morgan later sold his patent to a Mr Davies in Australia for the treatment of carcases to be transported between Australia and England before the advent of refrigeration.
Despite the fact that refrigeration was invented and successfully applied to the problem of the long-distance transport of meat at the end of the 1800’s, the development of the curing industry left the world with an enduring category of food in cured meat products and arterial pumping changed into multi-needle injector brine injection.
It was a certain Mr Morgan, in England, who invented the technique of injecting a liquid brine into the meat in the first place. The motivation was to increase the rate of curing in order to reduce the time required for processing. In temperatures above 20 deg C, pork spoils in three days.
It was important for farmers to cure the meat before a warm snap could allow spoilage organisms to work before the cure was properly diffused through the meat. Later, in industrial plants, the drive for a faster curing time would be cost factors. Increased output with limited and expensive equipment and people.
By injecting a liquid brine into the meat at evenly spaced intervals, the brine diffuse quicker through the meat. Morgan’s interest was the preserving of meat generally but included meat preservation for long sea voyages before the advent of refrigeration and not the curing of meat by farmers. The application of his method of injection, however, found its way into many homes and factories around the world.
Edward Smith writes in his book, Foods, in 1873 that “Mr. Morgan devised an ingenious process by which the preserving material, composed of water, saltpetre, and salt, with or without flavouring matter, was distributed throughout the animal, and the tissue permeated and charged. His method was exemplified by him at a meeting of the Society of Arts, on April 13, 1854, when I [Edward] presided.” (Smith, E, 1873: 35)
He describes how an animal is killed in the usual way, the chest opened and a metal pipe connected to the arterial system. Brine was pumped through gravity feed throughout the animal. Approximately 6 gallons were flushed through the system. Pressure was created to ensure that it was flushed into the small capillaries. Smith reported overall good results from the process with a few exceptions. He himself seemed unconvinced.
An article appeared in the Sydney Morning Herald that mentions Dr Morgan and his arterial injection method. An important observation from the article is the date of 1870. By this date, he is referred to as “Dr Morgan”, cluing us in about the timeline of Morgan’s life.
A second observation is a drawback of the system. The article states that “salting is the most common and best-known process of preservation (of meat), the principal modern novelty being Dr Morgan’s plan of injecting the saline solution into the arterial system – the principal objection to which has been that the meat so treated has been over-salted.” (Sydney Morning Herald, 1 March 1870, p 4)
The brine mix that Mr Morgan suggested was 1 gallon of brine, ¼ to ½ lb. of sugar, ½ oz. of monophosphoric acid, a little spice and sauce to each cwt of meat. (Smith, E, 1873: 36)
Seventeen years after Smith met Morgan at the Society of Arts meeting, in 1871, Yeats reports on a certain “Professor Morgan in Dublin, proposed a method of preservation by injecting into the animal as soon as it is killed, a fluid preparation, consisting, to every hundredweight of meat, of one gallon of brine, half a pound of saltpetre, two pounds of sugar, half an ounce of monophosphoric acid, and a small quantity of spice.” (Yeats, J, 1871: 225)
The plan was widely tested at several factories in South America and by the Admiralty, who had reported that they had good results from the technique. (Yeats, J, 1871: 225, 226)
It was in all likelihood the same Morgan that Smith reports on who, by 1871, became a professor in Dublin. One interpretation of the Yeats report is that Morgan, by this time, abandoned his arterial injection method for a more general injection into the muscle. It is more probable that Yeats simply is not concerned with a detailed process description.
Notice, as a matter of interest that he used the same basic brine mix of salt, water, saltpeter, sugar, monophosphoric acid and spices. This, together with the similarity in surname makes it quite certain that Mr Morgan and Prof. Morgan is the same person. In itself, this is an example of perseverance! In 1854 his arterial injection was met with scepticism where Yeats reports in 1871 that the Admiralty viewed his improved method.
WAS THIS MORGAN’S INVENTION?
The concept of arterial injection was not new. By the time Morgan demonstrated it to the Society of Arts, on April 13, 1854, it may have been as old as 150 years, used for embalming corpses for the purpose of medical studies. This invention is credited by some to the Dutch physician, Frederik Ruysch (1638 – 1730). He injected a preservative chemical solution, liquor balsamicum, into the blood vessels, but his technique was unknown for a long time. (Bremmer, E.; 2014)
British scientists who used arterial injection and from whom Morgan could have learned the system were the Hunter brothers William (1718–1783) and John (1728–1793) and their nephew, Matthew Baillie (1761–1823). The injection was into the femoral arteries. They all injected different oils, mainly oil of turpentine, to which they added Venice turpentine, oil of chamomile, and oil of lavender. Vermillion was used as a dye to create a more life-like skin colour, but would also have added preservation to the final solution. (Bremmer, E.; 2014)
There is a reference from 1837, on an essay delivered on the operation of poisonous agents upon the living body by Mr John Morgan (1797 – 1847), F.L.S Surgeon to Guy’s Hospital. (1837; Works on Medicine) The same publication contains an article by Dr. Baillie, M.D. on the morbid anatomy of some of the most important parts of the human body. John Morgan was definitely well familiar with arterial injection. Not only due to the fact that he was a contemporary of Baillie, but demonstrator of anatomy at the private school near Guy’s Hospital. (http://livesonline.rcseng.ac.uk/biogs/E000398b.htm)
Despite the fact that I can not locate a single reference, it is not unlikely that he was the father of Dr. John Morgan (Circa 1863), a professor of anatomy at the University of Dublin. A process of arterial injection is described that was used by Dr John Morgan from the University of Dublin. ” John Morgan, a professor of anatomy at the University of Dublin in Ireland, formally established two principles for producing the best embalming results: injection of the solution into the largest artery possible and use of pressure to push the solution through the blood vessels. He also was among the first to make use of a preinjection solution as well as a controlled drainage technique. Morgan’s method required that the body be opened so the heart was visible, then an 8-inch pipe was inserted into the left ventricle or aorta. The pipe was connected to yards of tubing ending in a fluid container hung above the corpse. The force of gravity acting on the liquid above the body would exert about 5 pounds of pressure, adequate to the purpose of permeating the body.” (Wohl, V.) This process described here is applied, not to the preservation of animal carcass, but for embalming a human body! It is, however, the exact same process that he demonstrated years earlier in London to Smith at the Society of the Arts meeting on 13 April related to carcass preservation.
From the process description, it is clear that we have finally identified the Morgan, father of the arterial injection method in meat curing as Dr. John Morgan, professor of anatomy at the University of Dublin, son of Dr John Morgan, Surgeon to Guy’s Hospital. The original inventor of the system was the Dutch physician, Frederik Ruysch and the application was embalming.
THE AUSTRALIAN/ NEW ZEALAND CONNECTION
In the week of 16 April 2017, two colleagues from New Zealand visited us in Cape Town. While getting a lesson in oyster eating in the picturesque town of Stellenbosch, they recalled the arterial injection method of Dr Morgan. I was intrigued by this since I tried to find German butchers who still practice it. The luke-warm reception of my questions in Germany leads me to wonder if it was ever widely practised there.
As I reflected on the visit of my friends, I found it interesting that they both knew so much about it. That made me wonder if there was a special regional connection and if so, what could it be? I noticed that a newspaper article I referenced previously in a historical review of curing technology which refers to Dr Morgan was from an Australian newspaper.
An internet search, focusing on this region, revealed an interesting bit of information.
MR. DAVIS FROM ADELAIDE: THE AUSTRALIAN AGENT FOR DR. MORGAN
An 1866 article in the Launceston Examiner reports that Mr Davis, from Adelaide, bought the patent from Dr Morgan. Mr Davis took up “premises at Town Marie, on the Bremer River, about six miles from Ipswich” and the operation of curing commenced.
The process is described as follows. Dr Morgan’s patent consists of emptying and washing out all, even the minutest blood vessels of an animal, while the carcass is still warm, and afterwards, filling the same with brine. “This is done in a very simple and expeditious manner, and the meat thus cured is very different indeed in flavour, consistency, and general appearance, from that which has undergone the old and more tedious process of salting.” (Launceston Examiner, Sat 17 Mar 1866, Page 2, CURING MEAT BY DR. MORGANS’ PATENT PROCESS)
The journalist reports that he saw “five beasts killed and cured in about an hour at Mr Davis’s establishment. Having been despatched in an ordinary way, the animals are laid on their backs, sometimes before they are quite dead, and the flesh having been laid open with a knife on the breast bone, the bone is sawn in two, longitudinally, and forced open with an iron screw until the aperture assumes an oval shape, about twenty inches long by seven or eight wide.
The operator, who is Mr Davis’s manager, Mr Bennett (the only person, we believe, in the colony, besides the patentee, who is practically acquainted with the process) then commences his manipulations with the animal’s heart, to which he obtains access by means of the opening we have described. It isn’t impossible to see exactly what Mr Bennett is doing as his hands are inside the body of the beast and his face is close to the opening. It is understood, of course, that he is making an incision in the great artery of the heart, and fastening, in the hole thus made, the copper nozzle of a long gutta-percha tube (which descends from a bucket suspended from the ridge pole of the roof), containing the wash. Having secured this firmly in the aorta, trying it round the neck with twine so as to prevent any escape, he next makes another opening at a short distance from the first, and turning the stopcock at the end of the gutta-percha tube, the wash, which is a diluted brine, is forced by gravitation into the aorta, driving before it the blood which escapes from the other opening in a rushing stream, rising several feet into the air.
About a minute suffices to drive out all the blood, but the injection is continued some time longer, so as thoroughly to wash out the blood vessels until at last the wash comes away almost in a pure state. The beast is then rolled over so as to allow all the liquor to drain out, the carcass being afterwards restored to its previous position. When this has been done, the operator closes the aperture which he had made to enable the blood and wash to escape and having unscrewed the gutta-percha tube, screws on a second precisely similar to the first, but which is attached to the bottom of another bucket which contains the brine.
This brine is composed simply of salt, saltpetre, and sugar but Mr Davis proposes to add a little spice to the solution, as an experiment, to improve the flavour of the meat. The tube having been fixed, the tap is turned, and the brine is thus forced into the veins and arteries. In order to make quite sure that the liquor has thoroughly permeated every portion of the carcass, a small scratch is made near the end of the tail and a fountain of brine immediately jets out. A scratch on the thick leathery cuticle of the nose is attended with a similar result. (We may mention also that even the hides are thoroughly cured by the one process, and when taken off, the carcases are immediately stacked. One of the animals, too, that we saw cured was a cow heavy in calf and when the young one was taken out, it was found to be thoroughly impregnated with the brine.)
We have eaten the tongue of the beast cured in this manner, and nothing could have been nicer, or more thoroughly preserved; the beef, too, as we know by experience, will bear roasting – an operation which would not add to the succuleny of ordinary salt meat. The blend vessels having been thoroughly filled with brine, the carcass is left to soak for half an hour or more. It is then strung up and dealt with in the ordinary manner; the pieces are thrown into brine for a short time, turned over from time to time, and thoroughly examined, and, being found perfectly sweet, are placed in casks ready for shipment.
Mr Davis has commenced operations at a very unfavourable period of the year, and the only premises which he has been able to obtain are not the most suitable for the purpose. He has had to dress meat with the thermometer at 104° in the curing shed, and it is therefore not surprising that, in one or two exceptional cases, his success should not have been quite perfect. The test to which the meat is subjected, however, is so thorough that there is not the smallest chance of its being shipped in an unsound state. Mr Davis lately shipped nearly a hundred casks (3041b each) to, Sydney, for transmission to England by the Orwell.
It was stated by a Brisbane contemporary that 2c per pound was expected to be reached in the London market. This is absurd; anything over 6d will pay Mr Davis well, and 9d or 10d is the outside contemplated. We shall be glad to hear that something like this has been obtained and that this new and valuable industry is, therefore, likely to be established as a permanent addition to the resources and wealth of this town and district.” (Launceston Examiner, Sat 17 Mar 1866, Page 2, CURING MEAT BY DR. MORGANS’ PATENT PROCESS)
The fact that my friends from New Zealand are well familiar with the process is one clue as to the success of Mr Davis and his new process.
BENEFITS OF ARTERIAL INJECTION
A Linkedin friend from New Zealand made several useful comments to the above post. He suggested that he “did some trials (in the old Northern Transvaal) called pegging the jugular vein in and the jugular vein out. Once the liquid flows clear, peg the outgoing vein and stop the pump to the ingoing vein and tie it down. One should use about 30L of product to be successful.”
He mentioned that some butchers claim that this operation makes the meat more tender. I wondered what the benefits would be and why the meat will be more tender. A clue to understanding some of the chemistry at work is to remember that manipulation happens while the carcass is still hot. This changes the rules dramatically. Note the actual wording from the journalist, describing the Davis operation, “The animals are laid on their backs, sometimes before they are quite dead.”
Why would this make the meat more tender? The one reason would be if there is an absence or resolution of shortening.
There are several techniques to prevent shortening. One notable example presents itself, again from our evening of oyster eating in Stellenbosch. My one Kiwi friend is a keen hunter and in the same discussion as we had about the arterial injection, mentioned how he keeps a deer carcass at a chilled temperature and ages it for a set time which he measures by the age old method of pulling on the tail of the dead animal. If the tail comes loose, he knows it has been long enough. This turns out to be an ancient invention where conditioning and aging are used to prevent cold shortening in New Zealand lamb. “This method calls for holding the carcass in a conditioning-aging room until they have gone into rigor mortis. The temperature and time specifications were developed for the industry with the time varying with the temperature, that is, longer times were required at lower temperatures. The conditioning and aging will thus prevent cold shortening and the accompanying cold-induced toughness.” (Pearson, A. M.; 1989 : 415) This is however not what happens in arterial injection. It is nevertheless fascinating that the technique for preventing shortening in cold environments and arterial injection were discussed in sequence – both very typical for that part of the world.
Two factors would counteract the onset of shortening namely a higher pH and higher ATP levels. The table salt (NaCl) , saltpeter (KNO2) and sugar added by Davis will not have any effect on the pH and will therefore not impact the meat toughness or tenderness. The monophosphoric acid in Morgan’s brine formulation may, however, have the effect of lowering the pH.
In general, the normal pH of the muscle in an animal when alive is 7.0. After rigor, the pH drops to around 5.5. “The increased acidity of post-mortem muscle results from the accumulation of lactic acid, which is formed as glycogen is degraded (anaerobic glycolysis) to produce ATP. Animals that are not handled optimally ante-mortem will likely have faster running muscle biochemistry and a more rapid decline in muscle pH. This change in pH during the conversion of muscle to meat is perhaps the most important event because it affects so many chemical, physical, and sensory traits of meat products.” What you want to prevent is rapidly dropping pH while the meat is still warm. Muscle pH is critically important because both the rate and extent of pH decline greatly affect meat properties. If the pH decline is rapid and reaches 5.5 to 5.8 while the muscle temperature is still high (more than 36 °C), the meat may become PSE.
Using the arterial system, and assuming the water is between 20 and 25 deg C, the fact that water is administered while blood is in the carcass should aid in a cooling down of the carcass, but not to levels that are too low. This should have a positive effect on the meat quality.
Let us consider the relationship between the levels of ATP and rigor. Rigor does not occur until approximately one-half of the ATP is depleted. (Pearson, A. M.; 1989 : 410) The arterial injection of brine should have no impact on the formation or depletion rate of ATP. Dr Francois Melette explains that ATP consumption is at this point only and anaerobic release of energy. The muscle “does not know” that the blood is being drained and it enters an anaerobic metabolism as if the animal is being chased. The anaerobic regeneration of ATP is very ineffective and the glucose molecules are rapidly converted to lactic acid which accumulates in the absence of blood flow. (Private communication with Dr Melette)
He doubts if the lactic acid that is now being washed through the system will have a material effect on the meat fibers and will in all likelihood have no tenderising effect. The benefit is, according to him, more likely in the rapid decline of pH which will have an impact on micro and extend shelf life. (Private communication with Dr. Melette)
The claim for softer meat remains one that is hard to defend scientifically if one considers it from the vantage point of the action of lactic acid. There is, however, a benefit with ample scientific data to back it up and may result in more tender meat. The answer probably lays in what happens before rigor sets in, before ATP is depleted and before major lactic acid formation. It has to do with the salting of a carcass, immediately after death.
Prerigor salting results in a marked increase in water holding capacity (WHC) of the meat. If nothing else, this system achieves prerigor salting. “Hot salting” yields higher water holding capacity (WHC) and superior fat-binding characteristics in sausages despite the fact that salt increases the rate of ATP breakdown. As we have seen, the more rapid ATP depletion as a result of the salt should induce shortening. The high WHC of hot salted meat is, however, due to the “inhibition of rigor mortis in the fiber fragments resulting due to the combined effect of high pH and salt concentration before the ATP becomes depleted.” Studies have shown that the higher the salt concentration, the higher the WHC, up to a salt concentration of around 1.8%, but higher concentrations seems to have no material improved effect on the emulsion stability. Prerigor salting of meat results in increased solubilisation of the myofibrillar protein, but presulting does not appear to irreversibly protect the protein against loss of solubility. Although prerigor salted meat suffers from loss of myofibrillar protein solubility to the same extent as postrigor salted meat, its high WHC remains unchanged. Salted prerigor meat also maintains a high WHC during freezing and thawing. (Pearson, A. M.; 1989 : 424)
It is then indirect, through the improved WHC of the meat, that the meat is more tender. In the day of Morgan and Davis, the concern was primarily the preservation of the carcass and the meat was probably not immediately worked further.
One more note must be made about pH and micro control. The fact that a complicated relationship between pH and micro exist has emerged over the past few years and tremendous work has been done showing that different bacteria is able to live across different ranges of the pH spectrum. It seems that the main benefit of the system, improving shelf life is then related to the decline in carcass temperature and the action of saltpetre and salt and the normal course of and benefits of curing. Temperature, pH, sodium chloride, sodium nitrite, phosphates, however, all works together in terms of the efficacy and mechanics of curing and in this relationship, a reduction of meat pH is beneficial, even though in terms of specific microorganisms, the benefit may be questioned.
THE GRIFFITHS PROGRESSION
The Griffith Laboratory (established in 1919), who popularised the direct use of nitrite in curing brines around the world. They took an already existing process, the direct use of sodium nitrite in curing brines which the imported into the USA as Prague Salt, a crude mix of salt and sodium nitrite, prone to separation during transport and improved on it. They created Prague Powder where the sodium nitrite and salt crystals are fused together in the right ratio to prevent separation. They did exactly the same with the invention of Morgan and improved on it. (Prague Powder, page 7, 8) Butchers probably started using arterial injection on primals as opposed to the entire carcass, long before Griffith came around, but they “formalised” this. So, when we talk about the Griffith progression, we are no longer talking about carcass preservation, but the working of deboned meat.
In a 1963 publication from Griffith, they claim that they are credited, not with the discovery of arterial injection, but with the “experimentation (the educational pioneering) and the demonstration of its practical application to meat curing.” (Prague Powder, page 7, 8) Griffith had agencies around the world, including South Africa and Brazil and it is likely that the system of arterial injection was popularised by them in these regions, along with its practice in the UK. By the mid-1900’s, Griffith sales representatives demonstrated to butchers around the world, how legs, already boned from the carcass, can still be injected in this way.
There is another matter of interest here. Davis mentions that he experimented with spice which he added to the cure. Morgan, of course, already suggested this in 1854. Interestingly enough, what he did by adding spices was to introduce bacteria, yeast, and molds into the brine system which was intended to preserve. This fact was later noted by the chief chemist of the Griffith Laboratory, Lloyd Hall. Hall used ethylene oxide within a vacuumed environment to sterilise spices while maintaining appearances, taste, and aroma. (www.reunionblackfamily.com/) Griffith became one of the first companies to introduce the use of “batch packs” for the butcher’s trade.
Few factories around the world are set up to work with a carcass while it is hot. (1) I am aware of some of these in Germany. The overall risks of hot boning are enormous and few have the experience and equipment to do so. You have far better water holding capacity in the meat, but the risk of bacterial spoilage for companies who are not fully set up and skilled to manage this, far outways any potential benefit.
The system of arterial injection was initially used only to prepare the carcass for transportation. It preserved the meat by getting nitrates and salts as early as possible into the carcass. Lowering the pH and reducing the temperature in combination with salt and nitrites will have strong preserving ability, but if it is enough when they used nitrates and not nitrites (as they did post 1945), is doubtful. The voyage between Australia and England, in all likelihood, would have been undertaken in the southern hemisphere winter, but I still can not imagine that this was ever successful in a long term, sustained manner. (2)
The article about the Davis operation mentions that the temperature in the curing shed in March reached 40 deg C. It is interesting that at the time of writing, no successful shipment to England has not been achieved and mention is only made that product was shipped to Sydney for shipment to England. It will be interesting if any record of this being done successfully can be found.
Griffith played a key role in spreading the practice around the world in the early and mid-1900’s, but in Australia and New Zealand it was done by Morgan, the inventor of the system who is credited with its introduction and the man who did the ground work was Mr Davis. Its greatest value was probably the fact that it was one of the progressions that resulted in the current system of multi-needle injection. As such it will always be a process that is close to my heart.
The entire experience with my New Zealand friends in Stellenboch gave me much greater insight into this old method of curing, introduced me to a fascinating technique to prevent shortening in cold climates and, more importantly, taught me how to eat oysters. Take chopped red onions and soak it in red wine vinegar, preferably for a few hours. Take a teaspoon and spread it over the oyster. Add a liberal helping of salt and pepper and enjoy one of the most amazing tastes on earth! At all cost, avoid Tabasco!
Great food, amazing company and talking meat and curing! Life is good!
On 1 May 2017, I did a tough hike across Table Mountain. During this hike, I give a short synopsis of the article.
The system of arterial injection as progressed by Griffith is a form of hot-boning with the benefits being the same. One of the reasons why hot boning is practised is that it removes the need to add additional phosphates (additional to what is in the meat already). For bacon, extended around 15%, the need for additional phosphates is in any case probably non-existent, whether the boning is done hot or cold, but generally, hot boning removes the need for phosphates which is, in certain countries, a huge benefit due to consumers demanding it.
For the sausage producer, it puts the question of temperature in the cutter on the table. If the temperature remains between 12 and 18 deg C, there is no need for additional phosphate in the cutter bowl. This, however, massively impacts on shelf life of the sausages which leads to most producers opting a temperature below 4 deg C for meat going into the cutter and remaining cold during cutting.
The solubility of protein at different temperatures, WHC, micro management through temperature, the denaturing of different proteins at different cooking temperatures are critically important subjects and we will deal with them separately in a different article.
The matter of exactly how curing prevents spoilage is not always easy to understand. One must also understand the different sources of microbial contamination. All these matters must be taken into account when evaluating the efficacy of arterial carcass injection for preserving spoilage.
In order to get a sense of some of the many issues involved in such a consideration, let us look at one of the most prevalent spoiling organisms for cooked-cured bacon namely Lactic Acid Bacteria (LAB). Why bacon curing is effective in terms of preventing spoilage through Lactic Acid Bateria (LAB), has not fully been explained yet. The hurdles are salt, sodium nitrite, phosphates, reduced water activity, smoking, drying, par-cooking, cooling and freezing and post processing, the bacon is packed in vacuum packaging. The action of each of the different barriers against spoilage has been well described in isolation, but when considered together, the total efficacy seems to exceed the sum of the parts. (Blackburn, Clive de W.; 2006: 233, 234)
The rate of spoilage is not only retarded through curing, but it is heavily dependent on factors such as the initial contamination level, the specific primal, the age of the animal and the slaughtering conditions. There external factors such as the state of the processing factory, the ambient temperature, the air, the microbial load on surfaces, equipment and equipment used, the individual cleaning regimes in place and practised by the processing staff, seal contamination in vacuum packaging and oxygen permeability of vacuum packaging material. Any bridge of hurdles or contribution by contaminants in bacon will be severe due to the addition of carbohydrates (glucose, sucrose, maltodextrins, potato starch, skim milk, etc.) to bacon brines and other growth enhancing ingredients such as spices. (Blackburn, Clive de W.; 2006: 233)
When Lactic Acid Bacteria (LAB) cause spoilage in bacon, it manifests as “sour” off-flavours and off-odours, milky exudate, and frequently, slimy, swelling of the pack, and/or greening. (Blackburn, Clive de W.; 2006: 233)
It is a well-researched fact that chilled temperatures do not destroy LAB’s, but merely retard its growth rate and their rate of spoiling. Increasing the storage temperature of bacon accelerates these. (Blackburn, Clive de W.; 2006: 233)
It is important to remember that the ability of LAB to spoil is not only dependent on their growth rate but also on their specific metabolic activity of the particular LAB specify, growing under a particular storage condition in cured meats. In fact, particular species have been identified that dominate in cured meat where pH, smoking, salt brine, moisture, MAP and a particular storage temperature is used. Whole meat products seem to favour one species for emulsion-type products, another, from the same processing environment for whole muscle products. Similarly, different pH and storage conditions, favour different species. One species dominates in pork during production (trimming, injection, tumbling and smoking) and another dominates in slicing and packaging. (Blackburn, Clive de W.; 2006: 234)
A general observation is that most LAB contamination for cured meat occurs post-processing, but this general observation should not be assumed and should be proven in any particular plant. The production line should be checked for processing errors and results should be measured through micro testing.
This short overview of LAB’s shows that the matter of preventing meat spoilage is not simply a matter of applying a brine to the meat, but a host of intrinsic and external factors play a huge role in preventing spoilage.
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Blackburn, Clive de W., 2006, Food Spoilage Microorganisms, CRC Press and Woodhead Publishing, Ltd..
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Pearson, A. M.. 1989. Muscle and Meat Biochemistry. Academic Press, Inc.
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Smith, Edwards. 1873. Foods. Henry S King and Co.
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