Meat and meat products

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* What is the flesh

* Fish

* Decontamination osmotic high bacterial loads with Honey

* Pollution, conservation, and alteration of meat and meat products

* Conclusion

* Bibliography


The study of the nutritional content of the meat, by high source of protein and high levels of consumption in the country or the world has motivated you to study different methods of food preservation.

Also how disintegrates and is degraded by pathogenic microorganisms, thus losing its nutritional value and protein, and becoming totally degraded material.

The meat products are also similarly contaminated by pathogenic microorganisms, which require techniques and methods for preservation.

Usually decrease microorganisms from meat protein, and causing totally deteriorndolas odors, microorganisms usually use three factors such as attack, humidity, temperature and pH.

For this reason it must properly implement conservation methods.

That is the meat

According to the food code, is the edible muscle of animals slaughtered under hygienic conditions, including (cow, sheep, pig, goat, horse and camel healthy, and also applies to farm animals, hunting, hair and feathers and mammals marine, declared fit for human consumption.

What nutrients provide us

All meats are encompassed within the protein foods and we provide between 15 and 20% of proteins, which are considered high quality because they provide all the essential amino acids needed. They are the best source of iron and vitamin B12. contribute between 10 and 20% fat (most of which is saturated), have low amount of carbohydrates and the water content ranges between 50 and 80%. We also provide B vitamins, zinc and phosphorus.

What factors influence the nutritional composition of meat

The age of the animal and the amount of exercise you perform. The food, especially if industrial type significantly affects the content and type of fat. Each race and muscle group in question will have different compositions.

What are the recommendations of consumption

The recommended serving is 150 – 200g, 3 times per week for adults and children rations would be about 15 g for each year of age who also ingest about 3 times a week.

The various categories (extra, 1st, 2nd, etc..) No major differences in the nutritional composition itself when choosing cooking mode. Slow cooking is indicated in lower grades, while grilling, frying or griddle recommended are extra, the 1st and most muscular area of the animal.

Consisting of meat

Especially muscle tissue, it is myoglobin which is a pigment that gives it its characteristic color in contact with air changes and this causes the outer court is darker than the interior. The varying intensity of the color red does not affect the nutritional value or not its digestibility.

They also contain fatty tissue which can be visible or invisible (interfascicular fat). The greater the amount of fat having a meat has lower water content. The amount of fat influences their nutritional value and digestibility.

Finally connective tissue, which is the separating or covering the large muscles and tendons. Its amount depends on the muscle group, increases with age and exercise you have performed the animal, making the meat tougher.

what kinds of meat consumption in response to fat

Lean meats are those with less than 10% fat, generically is considered the horse, beef, rabbit and chicken.

The fats are considered those containing more than 10%, we have: lamb, pork and duck. More specifically, should take into account the part of the animal, such as certain parts of pork tenderloin, ham and loin, or tongue and heart of all animals should be included in the first group.

what changes occur nutritional cooking of meat

The slow cooking destroys most of the vitamins, but improves the digestibility of the proteins, does not alter the fat content or minerals, although in part, as both a pass to the other broth. If cooking is performed in the pressure cooker is less destruction of vitamins. The microwave cooking produces the same losses as a normal oven. It is convenient to take it raw as well not exploited iron, decreases protein digestibility and loses.

The meat should be stored in the refrigerator and use once acquired should be within 48 to 72 hours, unless they stay frozen. No wash and upon purchase we require that the cuts are made whole pieces and then.

Nutrient composition of prepared meats per 100 g of food

The burgers and sausages, as well as many sausages are usually designed with waste from butchers (sometimes also with cats, dogs, etc.) And meat in a state of putrefaction, which makes trucks that provide the raw material leave many refrigerators suelan a nauseating scent in their wake and are enveloped in a cloud of hornets before dumping their contents into large pools with bleach and then to treat with sodium sulfates that could generate sulfuric acid residues. This set synthetically described, flooded with flavoring and coloring among other additives, then becomes what delights children and large houses known junk food and typical Sunday roasts.

A very important fact: the meat increases adrenaline and reduces brain serotonin, which puts aggressive, irritable, anxious, distressed and depressed the person who bases his diet on it, increasing their appetite and their desire to be addictive, according to each individual (cigarettes, alcohol, drugs, sweets, etc.).

That doctor or nutritionist that the thresholds of 2000 still defends meat, milk and its derivatives or deemed necessary, should not be attacked, but informed, and if you still keep saying the same thing, then remember the words of Leo Tolstoy:

Preservation techniques have allowed seasonal food consumption are permanent.

The two most important factors in food preservation are temperature and time.

Although there are several classifications, we can speak of two large storage systems from cold and heat.

In turn, the different types of maintenance are grouped into two main groups:

* Systems that destroys germs conservation (bactericidal)

* Conservation systems that prevent the development of bacteria (bacteriostatic)

The results obtained in ozonized atmosphere can be summarized as follows:

* Lack of molds in food and packaging.

* Longer storage of foods.

* Conservation of initial weight with high humidity.

* Better internal quality.

* Excellent appearance.

* Few impairment losses.

* Delays fruit ripening by acting breaking the ethylene molecule by oxidation. Ethylene is known to activate the metabolism of certain accelerated fruit ripening.


Fish is equally or more alterable than meat. In the refrigerated storage combat fish, as in the case of meat, the appearance of decomposition and undesirable odors.

Ozone amply achieved the solution to both problems. However if not been gutted fish, decomposition starts inside and ozone can be extended only a few days and complete the inevitable deterioration.

We also recommend the administration of ozone in the holds of fishing boats, transport of fish to sell centers in refrigerated display of seafood, restaurants and fishmongers.

Decontamination osmotic high bacterial loads with Honey:

In a survey to assess the bactericidal effects of molasses samples were contaminated honey 2 kg B with mean concentrations 1.2 x 106 cfu / g and 1.5 x 106 UFG / g for Salmonella typhimurium and Escherichia coli K – 88 respectively. We studied six variants in which the honey stored at controlled temperatures of 20 to 30 degrees Celsius as representative of the dry season and rain. Variants investigated were: I Honey B at 20 degrees E. Coli K – 88. investigated the total count of viable mesophilic aerobic bacteria, microorganism proteolytic microorganisms positive lactose, total count of molds and identifiers of genres; counting yeasts and pH determination.

Honey showed effective bactericidal action on Salmonella and E. Coli in seven days of exposure to 20 and 30 degrees Celsius. We also found that the honey has an effect of inhibiting bacterial growth for other health indicators analyzed.

The levels of bacterial and fungal contamination are very high in meat at 0 days of exposure to 20 and 30 degrees Celsius. We also found that the honey has an effect of inhibiting bacterial growth for other health indicators analyzed.

The levels of bacterial and fungal contamination are very high in meat at 0 days and even after 7 days are still much higher than those reported by Beno (1988), and Martinez and Ferrer (1989) and adequate levels in pig feed .

The evolution of the indicators investigated in honey has a tendency to decrease at 7 days in the proteolytic bacteria, lactose positive organisms and anaerobes. The total count of aerobic mesophilic fungi count and remain at levels of 105 cfu / g showing a slight incrmento, and aerobic spore-forming at levels of 103 cfu / g. The anaerobic microorganisms are reduced to 0 to 15 days, a situation that can be given by an oxidation process of these honeys during handling, breaking the state of anaerobiosis necessary condition for survival.

Although not detected the presence of Salmonella in honey investigated which coincides with that reported by Martinez and Ferrer (1992), if there are positive findings alos 0 and 7 days in the meat samples analyzed, indicating that this organism can remain viable gandes inside muscular portions (Piatkin and Krivosheim, 1981).

As the pH of honey used as a preservative, this ranged from 5.5 to 5.7 in the young, and from 5.5 to 6.0 in precenas. There were no significant changes. The pH is an important indicator because depending on your progress may indicate the presence or absence of a process of deterioration in food (and Krivosheim Piatkin, 1981).



It is recognized that the inner mass of the meat do not contain microorganisms or are scarce, having, however, bacteria found in lymph nodes, bone marrow, even in the same muscle. In the lymph nodes of the animals have been isolated meat staphylococci, streptococci, Clostridium and Salmonella. Common practices in slaughterhouses remove lymph nodes in the edible parts. However, the most important pollution source is external and occurs during bleeding, skinning and quartered, microorganisms are mainly from the external parts of the animal (skin, hoof and hair) and intestinal tract. Methods “humane” slaughter recently approved, whether mechanical, chemical or electrical lead, by itself, a little contamination, but the incision and bleeding that can then be performed to determine significant pollution. When pigs and birds are slaughtered by the classical method with the knife, the bacteria that contaminate this soon can be found in meat from different parts of the channel, conveyed by the blood and lymph. On the external surface of the animal, in addition to its natural flora a large number of species of microorganisms from soil, water, feed and manure, while the gut microorganisms contain typical of this part of the digestive tract. Knives, cloths, air, hands and clothing of personnel can act as intermediaries of contamination. During the subsequent handling of the meat may have further pollution, from transport trucks, boxes or other containers, and other meats contaminated air and staff. It is especially dangerous psychrophilic bacteria contamination from any source, eg other meats chilled. Certain machines and grinders, stuffers and others, can provide significant amounts harmful microorganisms and so can produce some special ingredients such as fillers and spices. Growth of microorganisms on surfaces in contact with the meat and meat therein can do much to increase their number.

Due to the variety of sources of pollution, the types of organisms commonly found in meat are many. Molds of different genres, reach the surface of the meat and developed thereon. Particularly interesting species of the genera Cladosporium, Sporotrichum, Geotrichum, Thamnidium, Mucor, Penicillium, Alternaria and Monilia. Yeasts are often found, especially nonsporulating. Among the many bacteria that can be found, the most important are the genus Pseudomonas, Alcaligenes, Micrococcus, Sttreptococcus, Sarcina, Leuconostoc, Lactobacillus, Proteus, Flavobacterium, Bacillus, Clostridium, Escherichia, Salmonella and Streptomyces. Many of these bacteria grow at refrigeration temperature .. also possible contamination of meat and its products by human pathogens, particularly enteric origin.


The preservation of the meat, as well as nearly all perishables, is performed by a combination of methods. The fact that most of the meat constitute excellent culture media with abundant moisture, pH near neutral and plenty of nutrients, coupled with the fact that some organisms may be found in the lymph nodes, bones and muscles as contamination by organisms spoilage is almost inevitable. Preservation makes it more difficult for most foods.

Using the heat:

in accordance with the heat treatment employed, industrially canned meats are divided into two groups: (1) heat-treated meat in order to convert the content of tin in the sterile, at least “commercially sterile”. And are cans that do not require special storage, and (2) meat receiving sufficient heat treatment to kill the germs that cause disruption, but must be kept refrigerated to prevent spoilage. Canned hams and deli meats are the last treatment.

Las meats of group 1 are canned and are self preservable, whereas those of the group two are not and are conserved in refrigeration. Cured meats and canned owe their stability microbial to heat treatment already adding various salts of cured. The heat treatment of these is 98 C, typically the size of the package is less than 1 pound (453.59 g) – cured meats and keeping self are packaged in containers of more than 22 pounds (9.97 kg) and are treated at temperatures of 65 C.


The sooner you do, faster cooling of the meat less likely to least likely to reproduce mesophilic germs. The principles underlying the refrigerated storage, applies equally to meat and other foods. Las storage temperatures vary of -1.4 to 2.2 C, being the first the most frequent used. The maximum time of conservation of beef greater refrigerated is about 30 days, depending on number of germs present, of temperature and of relative humidity, for pork, lamb and ewe of 1-2 weeks and for veal still less. Los sausages that not are baked, sausages and chorizos not cured or the picadillo to prepare them, must kept chilled. By increasing the temperature generally decreases the humidity of the storage.

Al increase the carbon dioxide of the atmosphere, inhibition of microbial growth is greater, but also accelerates the formation of metamioglobina by what is lost great part of the “freshness” or natural color of the flesh.

Microorganisms cause problems in the storage of chilled meat are mainly psychrotrophic bacteria of the genus Pseudomonas, while those of the genera Alcaligenes, Micrococcus, Lactobacillus, Streptococcus, Leuconostoc, Pediococcus, Flavobacterium and Proteus and certain yeasts and molds may grow at temperatures casualties.


La Freezing destroys approximately half of the bacteria present, whose number decreases slowly during storage: species of Pseudomonas, Alcaligenes, Mocrococcus, Lactobacillus, Flavobacterium and Proteus, continue their growth during thawing, if this is practice slowly. If are followed recommended standards for meats packaged, frozen by the rapid procedure, defrosting is so short that not allows a bacterial growth appreciable.

Using conservative:

Already is has tried to the use, in storage rooms for conservation of meats in refrigerating, atmospheres containing carbon dioxide or ozone. Conservation in concentrated brines is a very old method usually results in a poor quality product. To that the salazonado proves more cash brew combined with the cured and the smoked.


El curing from meats is limited to those of veal and pork, both chopped as cuts in pieces (as hams, ancas, head, ribs, loins and bacon of pork and leg and chest of the veal). Originally, curing was practiced to conserve salted meats without refrigeration, more currently most canes cured carry addition other ingredients and are conserved chilled, and many are smoked, for what they are also, to some extent desiccated. The agents of cured permitted are: sodium chloride, sugar, sodium nitrate, nitrate sodium and vinegar, but often used in general the cuatros former. The functions such products meet are: sodium chloride or sodium chloride is preferably used as a preservative and which contributes to the flavor agent. La brine in that is introduced the meat during curing usually has a sodium chloride concentration of 15%, in contrast with the that is injected, which have higher concentration, approximately to 24%. Its main object is lower the aw.

Sugar, besides flavor, served also as energetic material for bacteria that reduce nitrates in cured solution. Used primarily sucrose, but may be replaced by glucose if carried out curing shorter, and can even be deleted sugar.

The sodium nitrate acts indirectly as color fixative and is slightly bacteriostatic in acid solution, especially against anaerobes. Serves also as reserve material from which reducing bacteria can originate nitrites during one cured long.

Sodium nitrite serves as a source of nitric oxide, which is the true color fixative, also possess some bacteriostatic power in acid solution.


In the old methods of smoking, when high concentrations of salt used during curing and drying and when joining the meat smoke conservative principles was greater, the obtained products (hams, jerky, etc..) Could be stored without refrigeration . However many of modern methods originate a product alterable that must kept refrigerated. The hams precooked and sausages of high moisture content are examples of this type.


Spices and seasonings are added to meat products, such as cold cuts, not in concentrations high enough to act conservative, but its effect can be added to other factors conservatives. Certain products as mortadela of Bologna, Polish sausages, of Frankfurt and other sausages, owe their power conservative to a combination of spices, curing, smoking (desiccation), cooking and cooling.


Los antibiotics most recommended in this regard have been clortetracina, oxytetracycline and chloramphenicol. Antibiotics can be added to meat in different ways:

* Administering to the animal feed for a longer period

* Equally to administering larger doses over a short period of time before slaughter

* Injection into the channel or portions thereof.

* Applying to the surface of the meat or mixed with the minced meat.

The use of antibiotics in animal feed takes out a selection of organisms present in the intestinal tract and probably reduces the number of bacteria that cause deterioration, thus, they are unlikely to contaminate meat during slaughter and dressing later. It has been suggested that the injection of antibiotics before slaughter could be used to prolong the shelf life of the atmospheric temperatures channels before reaching the refrigerator or for a short time to keep at temperatures favoring softening special portions and to prolong the period of storage of meat that remain refrigerated.

Microbial invasion of tissues:

As soon as the animal dies, the tissues are invaded by contaminating microorganisms. Contamination is affected by:

microbial load of the animal’s gut. The higher this, the greater the invasion. This is why we recommend fasting for 24 hours before sacrifice.

physiological condition of the animal prior to slaughter. When it is excited febrile or fatigued, bacteria penetrate more easily into the tissue, the indentation may be incomplete, which favors the growth of bacteria and chemical changes can be performed more easily in tissues (for example, due bacterial growth, which is faster due to the higher pH), it is also more rapid the loss of juices of muscle fibers and the denaturation of proteins. During fatigue glycogen is consumed, so that there takes place lowering of the pH, which normally falls by 7.2 to 5.7.

method of slaughter and bleeding. The better made is bleeding and more hygienic this is done, the better the quality of meat preservation. No research has been done on the influence of humane methods of slaughter capacity of preserving meat, although it is said that pork and bacon from animals killed by electric shock becomes easier than greenish the of animals were killed by carbon dioxide.

cooling rate. Rapid cooling of the meat slows tissue invasion by microorganisms.

Growth of microorganisms in meat:

type and number of contaminating microorganisms and dispersion thereof in the meat. For example, if the flora contamination of meat has a high percentage of psicotrfos, alteration, at refrigeration temperatures, will be faster than in the meat with a low level of these microorganisms.

physical properties of the meat. The proportion of muscle surface exposed to the outside have great influence on the speed of alteration, because there are usually found most microorganisms and aerobic may Sufficient air. The fat that is able to protect some surfaces, is itself susceptible of alterations, mainly of chemical and enzymatic nature. The minced meat greatly increased the surface exposed to air, which promotes microbial growth and also to chop it is clear juice, which facilitates the distribution of organisms on the meat. The skin is a protective agent, but also on its own surface to develop microorganisms.

Chemical properties of the meat. Already indicated that meat in general is a good culture medium for microorganisms. The water content is important in determining the possibility that microorganisms grow and the type thereof to grow, especially in the area where there may be more desiccation. The surface may be so dry that does not allow microbial growth; may have a slight humidity allow the growth of mold, a damp somewhat greater to allow for yeast, and if too wet grow bacteria. Of great importance in this respect is the relative humidity of the atmosphere in which it is stored. microorganisms are offered a generous amount of nutrients, but the high proportion of protein and low content in carbohydrates fermentable favors the development of the types fermentative able to use protein and its degradation products as sources of carbon, nitrogen and energy. The raw meat pH varies between 5.7 and 7.2, depending on the amount of glycogen present at the time of slaughter and later suffered changes. A higher pH favors the development of microorganisms. A lower pH slows it down and sometimes acts selectively, allowing, for example, only the growth of yeasts.

Availability of oxygen. Anaerobiosis conditions present on the surfaces of the meat favor the development of molds and yeasts and the aerobic bacteria. Among the pieces of meat prevailing anaerobic conditions that tend to stay because the potential oxidation – reduction is offset to a very low level in minced meat oxygen diffuses slowly into and raises the potential for oxidation – reduction, unless the packaging is impervious to it. The anaerobiosis favors putrefaction.

Temperature. The meat should be stored at temperatures only slightly above the freezing, only allowing the development of germs psicotrofos. Molds, yeasts and bacteria psicotrofas develop slowly and produce certain defects that mention later. In these conditions it is very difficult putrefaction, which is very easy to change the temperature. As in most foods, the temperature has a decisive importance in the selection of the type of microorganisms which grow and consequently the type of alterations produced. A freezing temperatures, for example, is led to the development of germs is likely psychrophiles and proteolysis occurs by a dominant bacterial spices, followed by the use of peptides and amino acids secondary species. At atmospheric temperature ordinary develop, however, germs mesophilic as coliform bacteria, and species of the genera Bacillus and Clostridium, which produce acid from the limited amount of carbohydrates present.

Alterations suffered under aerobic conditions:

Bacteria can produce aerobically:

Surface mucus caused by certain species belonging to the genera Pseudomonas, Alcaligenes, Streptococcus, Leuconostoc, Bacillus and Micrococcus. Sometimes it is because certain species of lactobacillus. The temperature and the amount of water available influence the type of organism causing this alteration. A refrigeration temperatures, abundant moisture will promote the growth of bacteria belonging to the Pseudomonas group – Alcalifenes, with less humidity like frankfurters, will be most favored micrococci and yeasts, and even less if they can grow mold.

Modifying the color of meat pigments. The typical red color of the flesh can be changed to various colors, green, brown or gray, as a consequence of the production of certain bacteria oxidising compounds, such as peroxides or hydrogen sulfide. The green color of the sausages is due, apparently, to Lactobacillus species (particularly heterofermentative)) and Leuconostoc.

Modifications undergone by fats. Lipolytic bacteria are capable of producing accelerate lipolysis and oxidation of these substances. The fat rancidity can be produced by liplticas species belonging to the genera Achromobacter or Pseudomonas and yeast.

Phosphorescence. A defect rare caused by bacteria luminous or phosphorescent develop in the surfaces of the meat, as some species of Photobacterium.

Different surface colors produced by bacteria pigmented. May occur red spots caused by Serratia marcescens or other bacteria with red pigments. Pseudomonas syncyaneas can give a blue coloring to the surface. Bacteria with yellow pigments produce coloration of the pitch, due, in general, species belonging to the genera Micrococcus or Flavobacterium. Chromobacterium lividum and other bacteria produce patches of blue-green coloration or blackish brown in meat stored in stored meat. The color purple “ink stamp” is produced in the superficial fat cocci and rods fitted with yellow pigments. when fat becomes rancid and are peroxides, yellow becomes green, and finally acquires a color between blue and purple.

Taints. The so-called “husmo” smell or unpleasant taste that appears in the flesh as a result of bacterial growth on the surface, is often the first sign of deterioration is evident. Almost all the alterations that produce a sour smell called general “soured”. This odor may be due to volatile acids, for example formic, acetic, butyric and propionic acids, and even yeast growth. The flavor “refrigerator” is an undefined term that identifies any old or last taste. Actinomycetes may be responsible may be responsible for some taste musty or earthy.

Yeasts are able to grow under aerobic conditions on the surfaces of the meat, producing a surface film viscous, lipolysis, taints and abnormal coloring: white, cream, pink or brown, due to pigments of yeasts.

Growth aerobic molds can produce:

Adhesiveness. The initial development of the mold makes the surface of the meat tacky.

“Whiskers”. The meat stored at temperatures close to freezing is capable of supporting a limited development of mycelia without formation of spores. Molds involved in the process are very numerous, and among them is Thamnidium chaetocladioides or T. Elegans, Mucor, M. Lusitanicus or M. Racemosus, Rhizopus and others. It has been recommended growth from a special strain of Thamnidium to improve taste during aging beef.

Black spots. They are usually caused by Cladosporium herbarum and sometimes by other molds with dark pigments.

White spots. It should, in general, Sporotrichum carnis, but can also be produced by any mold with wet colonies resembling yeasts such as the genus Geotrichum.

Greenish spots. They are mostly produced by green spores of the genus Penicillium species such as P. Expansum and P. P.asperulum Oxalicum.

Fat breakdown. Many molds has lipases, which was responsible for the hydrolysis of fats. Molds also contribute to its oxidation.

Taints. Molds provide meat around their colonies a moldy taste, sometimes given a name that refers to the causal agent, eg “Thamnidium alteration”.

Alterations produced by anaerobic microorganisms:

Soured. Means smell (and sometimes taste) sour. This may be due to ascetic acid, formic, butyric, propionic, higher fatty acid or other organic acids such as lactic or succinic acid. It may be due to:

the own enzymes of the meat during the aging or maturation;

anaerobic production of fatty acids or lactic acid by bacterial action, or

proteolysis without putrefaction caused by anaerobic or facultative bacteria and which is sometimes called “sour fermentation malodorous”.

The species of the genus Clostridiums butterfat and coliform bacteria produce acid and gas acting on carbohydrates. In vacuum packaged meats, especially if the wrapping material is impermeable to gases, usually grow lactic acid bacteria.

Putrefaction. putrefaction is authentic anaerobic decomposition of proteins with the production of malodorous substances: hydrogen sulfide, mercaptans, indole, skatole, ammonia, amines, etc.. It should, in general, a species of the genus Clostridium. Sometimes, however, is produced by facultative bacteria, acting on its own or collaborating in the production, as evidenced by checking the long list of species called “putrefaciens”, “putrificum”, “putida”, etc., is generally due to Proteus spp. The confusion that lends the term “putrefaction” is because it is usually applied to any type of change that is accompanied by unpleasant odors either anaerobic decomposition of proteins or other compounds degradation inclusos no nitrogen. The smell of fish or trimethylamine dela isovaleric acid in butter, for example often described as putrid smells. The putrefaction caused by clostridia is accompanied by the formation of gas (hydrogen and carbon dioxide).

Husmo. This is even more inaccurate a term that applies to any abnormal odor or taste. The term “bone husmo” refers to any souring or putrefaction which is close to the bone, especially in hams. It is usually equivalent to putrefaction.

Fresh meat

In most fresh or cured meats are present lactic acid bacteria, mainly those belonging to the genera Lactobacillus, Leuconostoc, Streptococcus, Brevibacterium, Pediococcus, which develops even at refrigeration temperatures. A limited development of these usually does not impair the quality of the meat. In certain types of sausages, salami, Lebanon and Thuringer, is encouraged, however their growth and produced lactic fermentation. The lactic bacteria may be, however, responsible for three types of alterations: (1) superficial or deep viscosity, especially in the presence of sucrose, (2) green production, (3) soured because excessive production of acid mainly lactic acid.


The burgers maintained at ambient temperature ordinarily undergo putrefaction; at temperatures near freezing acquire the sour odor. The soured at low temperatures is produced mainly by Pseudomonas, collaborating with some lactic bacteria. In some samples multiply Alcaligenes, Micrococcus and Flavobacterium. When the burgers are stored at higher temperatures found in it numerous species of microorganisms, although there is no research to differentiate between mere presence and multiplication in them. Among the genres that have been found include Bacillus, Clostridium, Escherichia, Enterobacter, Proteus, Pseudomonas, Alcaligenes, Lactobacillus, Leuconostoc, Streptococcus, Micrococcus and Sarcina, and molds of the genus Penicillium and Mucor. Also have found some yeasts.

Pork sausages:

The fresh sausages are prepared primarily with minced pork which is added to salt and spices. It sells well or stuffed into natural or artificial casings. The pork sausage is a food susceptible to alterations; must therefore kept under refrigeration and even in these circumstances of limited duration. At refrigeration temperatures between 0 and 11 C, most likely altered the soured, which has been attributed to the propagation and production of acid by Lactobacilli and Leuconostocs, although sometimes multiply at temperatures slightly above Microbacterium and Micrococcus. Pork sausages stuffed, and especially those of limited size, are subject to long term storage mucilage formation on the outer surface of the casing and the appearance of different colored spots produced by molds. The genus Alternaria produces small blackish spots on the strings refrigerated.

Sausages and other dried meats:

The cesina suffers swelling caused by species belonging to the genus Bacillus, soured produced by many bacteria, redness caused by Halobacterium salinarium, or a species of the genus Bacillus red, and blue, due to Pseudomonas Sincynea, Penicillium spinulosum (purple) and yeast species belonging to the genus Rhodotorula.

In the jars “chipped dried beef” (dehydrated meat slices) sometimes occurs gas, which has been attributed to aerobic denitrifying organisms like Pseudomonas fluorescens. The gases are nitrogen oxide. Some Bacillus species also produce similar conditions carbon dioxide.


Sausage packs may swell due to the production of CO2, usually by heterofermentative lactic acid bacteria. This occurs when the cover is elastic and impermeable to gases.

In the liver sausage and bologna bolognese can develop the type micrococci acidogenic Micrococcus candidus, in liver sausage Bacillus also found under multiplication. They can also develop Leuconostoc and Lactobacillus, which grow at low temperatures, producing a sour not looking at most of the sausages, but well suited to certain types, such as Lebanon, Thuringer and Essex. The red color of the sausages can fade and become chalky gray that has been attributed to oxygen and light and can be accelerated by bacteria. The “cold staining ringed” have been attributed to oxidation, bacterial production of organic acids or reducing substances, an excessive amount of water and an insufficient heat treatment.

The nitrate-reducing bacteria results in the formation of gas (nitric oxide). Carbon dioxide produced as a consequence of the development of the heterofermentative lactic bacteria fan builds and sausages, unless the material in which they are embedded is permeable to said gas.


Pig parts used for the production of bacon and treating it varies in different countries, so also differ alteration types and germs that produce it. The bacon used in the American procedure is altered and barely out of the smoker apparently almost free of molds and yeasts and with a low content of bacteria. Ordinarily Streptococcus faecalis appears in them, under the salt tolerance and development capacity at low temperatures. The most important microorganisms in the deterioration of bacon are molds, especially if the product is sliced, packaged and stored in domestic refrigerators. In late summer and early autumn are dangerous Aspergillus, Alternaria, Monilia, Oidium, Fusarium, Mucor, Rhizopus, Botrytis and Penicillium. The dry salty bacon and Oxford style microbial problems occur. Any rancidity suffered is generally due to chemical causes.

The sliced bacon, when standing in unopened envelopes, is altered mainly due to lactobacilli, but can also grow micrococci and fecal streptococci, especially if the wrapper is somewhat permeable to oxygen. After opening the package I submitted alteration due to molds.


The most common change in the hams is the “sour”, a term that refers to several types of alteration ranging from proteolysis authentic odorless and putrefaction, with its nasty smell mercaptans, amines, indole, hydrogen sulfide, etc.. , which may be caused by numerous psicrohalficos germs. The species may have for belonging, according Jersen (1954) to the following genera: Alcaligenes, Bacillus, Pseudomonas, Lactobacillus, Proteus, Serratia, Bacterium, Micrococcus and Clostridium, to which must be added some producers estreptobacilus sulfide. soured types are classified according to their location as the tibial bone, the lean, the rump of the femur bone and buttock.

When the hams are cured for a long time was more common putrefaction by Clostridium putrefaciens. Grows at temperatures close to the cooling and develops even ideal storage temperature. Most soured causing germs can not initiate its development at these temperatures, but continue it once initiated at higher temperatures. Altered cured hams home procedures, especially the lean soured, is of type proteolytic putrefactive or gas as a result of local development of various species of Clostridium. Probably multiply before or after curing and development is not affected by the concentration of the brine used.

Tenderized hams that have been precooked and have suffered a medium cure, are perishable and must be protected from contamination and must be kept refrigerated to prevent spoilage by microorganisms. The hams softened, improperly handled, may be altered under the action of either bacterial altering meats, including Proteus species, Escherichia coli, etc. And the food poisoning producing staphylococci (Staphylococcus aureus).


The meat to be a high protein food and most consumed in the country is necessary to know how good and how can contaminate and deteriorate, and likewise also is frequently the causative organisms be warned of impairment.

For good preservation of meat, you need to work hygienically from the time of killing, governed by the rules of hygiene of meat processing.

A good indented will guarantee a lower growth of microorganisms like proper disinfection of working groups, also avoiding contact with dirt.

The factors that most affect bacterial growth are temperature, humidity and pH; pathogens from meat, fail to develop and deteriorate the product only taking the above factors into the optimal conditions for their development. The meat has microorganism, which at low temperatures – 0 C, can not develop, the lack of moisture prevents their development. It is for this reason that there must be good cooling or freezing for storage thereof; when discussing the extraction of moisture from old traditional method (drying), which consists of increasing the pH and the salt removed by moisture by the sun and air. Completely inactivating microorganisms.

Microorganisms attack deteriorndolas fiber meats completely, reducing protein and converting them into toxins and waste.


FRAZIER, W. C. Food Microbiology. 3rd Spanish edition, Editorial Acribia, Inc. Zaragoza (Spain)

Microbiology, Pelczar / REID / CHAN, 4th edition, McGraw-Hill Publishing printed in Mexico.

Microbiology; PHILIP L. Carpenter, 2nd edition, Editorial Inter. American Printed in Mexico.

Treaty of Microbiology: BURROWS William, 12th edition, editorial Inter. American, Printed in Mexico.

COLLINS Fimlt MI Biol. 1964. Editorial Acribia Zaragoza (Spain) Microbiological Methods


Paper given by:


Experimental National University

From the Western Llano

Ezequiel Zamora