What Is The Number-One Cause Of Spoiled Meat?

The way you handle game after it’s harvested can have a significant impact on the quality of the meat. Three factors contribute to spoiled meat: heat, dirt, and moisture. Heat is the number-one concern. Bacteria grows rapidly in a carcass, especially if it’s allowed to stay warm.

• Meat begins to spoil above 40° Fahrenheit.
• The higher the temperature—and the longer the meat is exposed—the greater the chance of spoilage.
• This is particularly true with large game.
• Basic field dressing techniques help cool game by removing entrails, which lowers body heat by allowing air into the body cavity.

As a rule, it’s best to field dress immediately. Field dressing a game animal isn’t a complicated process, but it’s a technique that’s best learned by observing someone with experience. The basic procedure involves cutting open the animal from the sternum to the anus, cutting the connective tissue that anchors the internal organs inside the body cavity next, and then removing the organs.

What are the three factors that can spoil meat?

How you care for game once it has been harvested will make a tremendous impact on how much you, your family and friends will culminate your hunt by enjoying a wonderful meal. Cut corners here and you will regret it later. Any complaints at the table about “gaminess” can be traced straight back to how you handled, or mishandled, your game after the harvest. Field Dressing, whether in the field or back at camp, it should be done soon after harvesting the animal. It involves removing all the internal organs from the body cavity. This first step begins the cooling down of the meat. An experienced hunter should guide the novice in the procedure. A good, sharp knife is needed in all phases of cleaning game animals. A sharp knife makes the work safer and easier since it is less likely to force the blade and lose control of the cut. Many experienced hunters have a sharpening device nearby to touch up the blade as needed. Watch a video on: Field Dressing. Skinning It helps to hang a deer after field dressing to facilitate draining any excess blood. Use a hose and water to help clean off excess blood but remember that moisture is one of the factors which contribute to bacteria growth, so dry the animal off well. Quartering is when you butcher the deer by removing the forequarters (shoulders), the hindquarters (hams) and the backstraps from the carcass. By Texas law, you may not process the deer beyond quartering until you reach your final destination. This means you may not ‘bone-out” the shoulders and hams. Keep your quartered deer meat cool and dry by placing your meat in plastic bags inside an ice chest. Add some ice and you’re ready for the trip home. You will need to retain the tags, along with proper “evidence of sex” (head of a doe or antlers of a buck) to your final destination.

• Consult the regulations in the Outdoor Annual for more information.
• Under no circumstances should you ever transport game animals on the hood or roof of cars.
• This is a sure way to spoil the meat.
• It is also very likely to offend many of the non-hunting public.
• Most non-hunters are not against hunting but witnessing this type of disregard for the animal could turn them against hunting.

Just don’t do it ! Now That You’ve Killed It (pdf) Transferring Game to Others It is possible to give game to other people when hunting. The hunter that harvests the game must fill out and sign a Wildlife Resource Document. Download the form, Field Care of Game Birds Many hunters clean and dress their birds right after the hunt.

It is important not to leave a pile of feathers and entrails at the hunting site or in town at a motel. Contain and dispose of feathers and entrails properly. Remember: One fully feathered wing or head must remain attached to dressed waterfowl while being transported between the place taken and the personal residence (personal abode) of the hunter, the personal residence of another person receiving the dressed birds or a migratory bird processing facility.

One fully feathered wing or head must remain attached to all migratory game birds imported from Mexico. Plastic gloves and a good pair of game shears are helpful for the task of cleaning birds. There are two basic styles of cleaning birds. First is picking the feathers and leaving the skin on. The other method is called “breasting” where the skin is removed with the feathers intact, along with the back and legs, leaving only the breast meat attached to the breastbone. This apparatus separates the breast and wings from the rest of the body. Place your birds in plastic bags and then into a cooler with ice for transportation. You can learn more about dove in our publication Field to Freezer (pdf). Watch a video on: How to Clean and Grill Dove.

What bacteria causes meat to spoil?

Infection – The organisms spoiling meat may infect the animal either while still alive (“endogenous disease”) or may contaminate the meat after its slaughter (“exogenous disease”). There are numerous diseases that humans may contract from endogenously infected meat, such as anthrax, bovine tuberculosis, brucellosis, salmonellosis, listeriosis, trichinosis or taeniasis,

Infected meat, however, should be eliminated through systematic meat inspection in production, and consequently, consumers will more often encounter meat exogenously spoiled by bacteria or fungi after the death of the animal. One source of infectious organisms is bacteraemia, the presence of bacteria in the blood of slaughtered animals.

The large intestine of animals contains some 3.3×10 13 viable bacteria, which may infect the flesh after death if the carcass is improperly dressed. Contamination can also occur at the slaughterhouse through the use of improperly cleaned slaughter or dressing implements, such as powered knives, on which bacteria persist.

• A captive bolt pistol ‘s bolt alone may carry about 400,000 bacteria per square centimeter.
• After slaughter, care must be taken not to infect the meat through contact with any of the various sources of infection in the abattoir, notably the hides and soil adhering to them, water used for washing and cleaning, the dressing implements and the slaughterhouse personnel.

Bacterial genera commonly infecting meat while it is being processed, cut, packaged, transported, sold and handled include Salmonella spp., Shigella spp., E. coli, B. proteus, S. epidermidis and Staph. aureus, Cl. welchii, B. cereus and faecal streptococci,

1. These bacteria are all commonly carried by humans; infectious bacteria from the soil include Cl.
2. Botulinum,
3. Among the molds commonly infecting meat are Penicillium, Mucor, Cladosporium, Alternaria, Sporotrichium and Thamnidium,
4. As these microorganisms colonize a piece of meat, they begin to break it down, leaving behind toxins that can cause enteritis or food poisoning, potentially lethal in the rare case of botulism,

The microorganisms do not survive a thorough cooking of the meat, but several of their toxins and microbial spores do. The microbes may also infect the person eating the meat, although against this the microflora of the human gut is normally an effective barrier.

What are the four important factors that are involved in meat spoilage?

Factors affecting meat spoilage – Factors affecting meat spoilage include Temperature, pH, bacterial activity, and water and storage space, During cooling, the surface temperature of the meat carcass changes. Meat is usually stored at about 2°C, except beef transported over long distances with a recommended temperature of -1.5°Ctwo.

• Slight temperature changes can significantly affect the shelf life.
• Therefore, increasing the temperature from -1.5 to 0, 2, or 5 °C decreases the decay time by approximately 70%, 50%, and 30%, respectively.
• The pH of muscle at slaughter is approximately 7.0, and the pH decreases from 3.5 to 8.5 within 18 to 40 hours in beef and 6 to 12 hours in pork.

In lamb carcasses, this usually occurs within 24 hours. Dark meat dry (DFD) can occur in all species but is more common in beef. DFD results from pre-slaughter stress and reduced glycogen stores below 0.6%, and DFD meat has a pH of 5.9 – 8.6. This higher pH causes the growth of spoilage bacteria.

What are 5 major causes of meat spoilage?

Meat Spoilage: A Critical Review of a Neglected Alteration Due to Ropy Slime Producing Bacteria The shelf-life of a product is the period of time during which the food retains its qualitative characteristics. Bacteria associated with meat spoilage produce unattractive odours and flavours, discolouration, gas and slime. There are several neglected alterations that deserve more attention from food business operators and competent authorities. Ropy slime is a typical alteration of the surface of vacuum and modified atmosphere packed cooked meat products, that causes major economic losses due to the increasingly sophisticated consumer requirements. This is a review article that aims at raising awareness of an old problem of new concern, in the light of new advances and trends for understanding the aetiology of the phenomenon, the origins of contamination and the prevention measures. Food is a complex, dynamic ecosystem, in which every component is continuously changing. It is essential to recognise these changes to minimize unwanted development, such as food spoilage, which is a naturally occurring process leading to undesirable modifications in sensory characteristics (appearance, texture, odour and flavour) and the absence of acceptable qualities. This phenomenon determines not only economic losses, but also the lack of consumable foods. In fact, an excessive amount of food is wasted due to spoilage, even with modern preservation techniques (Gram et al., ; Remenant et al., ). The Food and Agriculture Organization (FAO) of the United Nations (UN) and the World Health Organization (WHO) declare that one third of the food produced for human consumption is wasted each year (FAO, ). Food rejection is mainly associated with spoilage and is characterized by any change which determines unacceptable products for the consumer (Koutsoumanis, ). The causes of the loss of adequate qualities may be physical damage, chemical reactions, insect and rodent infestation and microbial growth (Gram et al., ; Ray and Bhunia, ). Despite refrigeration chains, chemical preservatives and the application of recent techniques, it has been estimated that 25% of all food produced globally is wasted post harvest or post slaughter due to microbial spoilage, so that this is actually the most common cause of alterations in food quality (Gram et al., ; Cenci-Goga et al., ). Compared to a multitude of foodstuffs, meat represents one of the most perishable (Doulgeraki et al., ): first, for the presence of chemical and enzymatic activities, and second, because it constitutes a perfect pabulum for the growth of a wide variety of microorganisms, especially as a result of its nutrient composition, high water content and moderate pH (Dave and Ghaly, ). Microbial growth, oxidation and enzymatic autolysis are the three basic mechanisms responsible for the spoilage of meat. In addition to lipid oxidation and enzyme reactions, meat spoilage is almost always caused by microbial growth. The breakdown of fat, protein and carbohydrates in meat results in the development of off-odours, off-flavours and slime formation, which determine disagreeable meat for human consumption (Ercolini et al., ; Nychas et al., ; Casaburi et al., ). The scientific community became interested in meat microbiology when meat products began to be shipped over long distances and when the spread of supermarkets in the 1950s changed consumers’ habits (Nychas et al., ). Nowadays, products have been directed from local markets to international trade and ready-to-eat meat products have unequivocally become part of modern diets. This new food culture requires high food quality and safety standards to be guaranteed for the entire commercial life of the product, with additional strict requisites to comply with in order to be accepted for international trade. The stability of meat characteristics becomes the first essential step for food producers to prevent undesirable modifications during the storage period. Many studies have been conducted so far. However, some alterations on meat, such as ropy slime-formation on the surface of cooked meat products, are still persistent (Iulietto et al., ). Ropy filaments were found in vacuum packs and reported in Finland at the end of ‘80s and the cause was identified as the growth of certain psychrotrophic strains of lactic acid bacteria (LAB) (Korkeala et al., ). Even though several decades have passed, slime is still occasionally evident before the sell-by date, and consumers reject the products, as they find the appearance of the food unacceptable (Aymerich et al., ). To confirm the topicality of the problem, Pothakos et al. (2014) underlined the current spread of psychrotrophic LAB in Belgian food processing environments, which led to unexpected spoilage in all kinds of packed and refrigerated foodstuffs in Northern Europe. Furthermore, as is easily understandable, ropy slime-forming bacteria determine huge financial losses for food producers in many countries (Korkeala et al., ; Aymerich et al., ). Starting from the description of the general aspects of meat spoilage, the aim of this paper is to focus specifically on the particular aspects of meat alterations due to ropy slime-producing bacteria, from contamination sources to prevention strategies, in order to raise awareness to provide an effective answer for preventing the formation of ropy filaments on cooked meat products. The shelf-life of meat and meat products is the period of time during which storage is possible and food retains its qualitative characteristics until the arrival of spoilage phenomena. The shelf-life of products is strongly linked to their deterioration, creating a borderline between an acceptable and an unacceptable bacterial concentration, which determines off-odours, off-flavours and an undesirable appearance. These sensorial modifications are related to the number and types of microorganisms initially present and their subsequent growth. For meat products, the starting total microbiota is approximately 10 2 -10 3 cfu gr -1, consisting of a huge variety of species (Ray and Bhunia, ). The environmental conditions of the meat during the different steps in its production and trade create a specific ecological niche, which favours some microbial strains initially present in the meat or introduced by cross-contamination, whereas other strains are disadvantaged (Castellano et al., ; Nychas et al., ). The prevalence of a particular microbial strain depends on factors which persist during processing, transportation and storage. Storage at refrigeration temperatures limits the growth of only 10% of the total microbiota and, when applicable, heat treatments remove the majority of vegetative cells. Therefore, shelf life may vary from days to several months and is strictly linked to post-processing recontamination. During storage, the dominant microbiota can cause the deterioration and release of volatile compounds or slime formation; as a consequence, the product becomes unacceptable for human consumption (Gram et al., ; Kreyenschmidt et al., ). The micro-organisms’ ability to grow in food is closely related to many factors, some of which are intrinsic in the substratum. Others are extrinsic, but all of them influence the development of the ecological environment (Cenci-Goga, ). The main factors, which affect the shelf-life of meat products and favour some bacterial strains rather than others, are: packaging (aerobically, vacuum or modified atmosphere), storage temperature, the composition of the products (presence of fat, NaCl content, nitrites, a w, pH) and other factors, such as antibacterial substances or biopreservatives (Nychas et al., ; Remenant et al., ) (). Meat represents a natural ecosystem in which the advantageous or disadvantageous conditions determine the survival and growth of some specific strains. Micro-organisms need energy for their metabolism, essential substances which they cannot synthesize and components for the constitution of cells; all these necessary elements are collected from the surrounding food environment and their presence allow the effective survival of food-borne strains during the lag phase (Cenci-Goga, ). In general, meat is rich in protein, lipids, minerals and vitamins, but poor in carbohydrates; this composition provides an opportunity for some species instead of others with different nutrient requirements. After microbial death, intracellular enzymes can catalyse some food nutrients to simpler forms, which can be exploited by other species. The presence of growth factors and natural or chemical inhibitors (additives such as nitrite) further select specific strains (Ray and Bhunia, ). All food substances which do not occur naturally or are environmental contaminants are generally regarded as added, There are several categories within the broad class of added food constituents. However, a practical definition considers all the substances deliberately put into foods as intentional substances and those which may get in by accident during processing as incidental. Among the first category of additives, antimicrobial agents are added to prevent bacterial contamination of food, thus avoiding spoilage and poisoning processes caused by pathogens or their toxins (Cenci-Goga et al., ). The relatively recent increase in the interest in green consumerism has actually encouraged a renewal of scientific interest in natural approaches, such as the addition of bioprotective cultures and natural antimicrobial compounds (essential oils, enzymes, bacteriocins) to meat products, in order to delay the growth of spoilage micro-organisms without interfering with the typical characteristics of the product (Burt, ). Plant-derived essential oils (EOs) are aromatic, oily liquids, obtained from plant material (flowers, buds, seeds, leaves, twigs, bark, herbs, wood, fruits and roots) which have shown remarkable antimicrobial activity against spoilage and pathogenic microorganisms in meat and meat products. Essential oils originating from oregano, thyme, basil, marjoram, lemongrass, ginger and clove were investigated in vitro (Barbosa et al., ) and on meat products (Burt, ; Fratianni et al., ) and found capable of affecting the growth and metabolic activity of foodborne microbiota (Skandamis and Nychas, ). Bacteriocins are microbial heat-stable peptides, active towards other bacteria (Gálvez et al., ); they are added as biopreservatives to improve the microbial stability and safety of chill-stored fresh and cooked meat (Samelis et al., ). In the EU, nisin (E234), a polypeptide produced by Lactococcus lactis, and natamycin (E235), produced by Streptomyces natalensis, are currently the only commercially available bacteriocins (Ercolini et al., ; Doulgeraki et al., ). Meat pH also affects the selection of bacteria; each species has an optimum and a range of pH for growth. During post slaughtering, muscle pH, normally decreases to 5.4-5.8, while pH is >6 in meat coming from stressed animals (defined as dark, firm, dry meat ) and in cooked meat products, such as sliced ham (Aymerich et al., ). The presence of adipose tissue and a high pH in meat determines a more rapid spoilage process due to a more rapid bacterial growth and consumption of nutrient (Ray and Bhunia, ). The oxidation-reduction potential is a function of the pH, gaseous atmosphere and presence of reductants. It measures the potential difference, in a system generated by a coupled reaction, in which one substance is oxidized and a second substance is reduced simultaneously, in electrical units of millvolts (mV). The redox potential of a food is related to its chemical composition, processing treatments and storage. Raw meat has an E h (i.e., redox potential) of -200 mV, ground raw meat has an E h of +225 mV and cooked meat a range of +90mV to -50mV (Cenci-Goga, ). Water activity (a w ) is the measure of the amount of water in a food which is available for the growth of micro-organisms, including pathogens. It identifies the water available for carrying out enzymatic reactions, synthesizes cellular materials and takes part in other biochemical reactions. Raw meat has a w values of 0.98-0.99 and cooked meat approximately 0.94; those values allow the growth of most microorganisms (Aymerich et al., ). Dried products are usually considered shelf stable and are, therefore, often stored and distributed unrefrigerated. The characteristic of dried foods which makes them shelf stable is their low water activity. A water activity of 0.85 or below will prevent the growth and toxin production of pathogens, including Staphylococcus aureus and Clostridium botulinum,S. aureus grows at a lower water activity than other pathogens, and should, therefore, be considered the target pathogen for drying. Control of the drying process to prevent the growth and toxin production of pathogens, including S. aureus, in the finished product is critical to product safety if the product is distributed or stored unrefrigerated. Similarly, drying may not be critical for the safety of dried stored, refrigerated products, since refrigeration may be sufficient to prevent pathogen growth. Controlling pathogen growth and toxin formation by drying is best accomplished by: i) scientifically establishing a drying process that reduces the water activity to 0.85 or below; ii) designing and operating the drying equipment, so that every unit of product receives at least the established minimum process (Leonard, ). Packaging conditions and the gaseous composition of the atmosphere surrounding the meat greatly influence the composition of spoilage flora (Borch et al., ; Sechi et al., ; Rossaint et al., ). Aerobic storage conditions promote, above all, the growth of Pseudomonads (Rossaint et al., ). Pseudomonas spp., Acinetobacter spp., Moraxella spp. are considered the major source of meat deterioration in aerobically stored meat products at different temperatures from -1 to 25°C. Members of the P, fluorescens group, together with the psychrotrophic P, fragi, P, ludensis and P, putida, are the most commonly isolates in aerobically packed, spoiled meat (Ercolini et al., ; Ercolini et al., ). The population of Pseudomonads at the arbitrary level of 10 7 CFU g -1, has been attributed to the formation of slime and off-odours, especially when the metabolism of nitrogenous compounds prevails over the fermentation of carbohydrates. Shewanella spp. is a genus closely related to Pseudomonas spp. and contributes significantly to spoiling food: S. putrefaciens is one of the predominant spoilers in chill-stored, vacuum-packed (VP) meat and high pH VP meat (Doulgeraki et al., ). Packaging of meat under vacuum or CO 2 modified atmosphere has resulted in extended shelf-life compared to traditional packaging conditions (Yost and Nattress, ). The use of CO 2 and N 2 extends the lag phase of aerobic microorganisms and promotes the growth of facultative and strict anaerobic species. This change in packaging conditions determines a shift from aerobic bacteria, such as Pseudomonas spp., to facultative anaerobic species, such as Brochotrix thermosphacta (Nychas et al., ) and lactic acid bacteria (Doulgeraki et al., ) (). Lactic acid bacteria are the predominant microflora of vacuum or CO 2 -modified atmosphere packed products, representing dominant spoilage-causing bacteria (Yost and Nattress, ; Arvanitoyannis and Stratakos, ). In fact, the combination of micro-aerophilic conditions and a reduced a w inhibits gram-negative spoilage flora and favours the proliferation of LAB (Borch et al., ; Korkeala and Björkroth, ; Samelis et al., ; Audenaert et al., ). In addition, Modified Atmosphere Packaging (MAP) meats are affected by dynamics changes of headspace gases (headspace being the space in the package between the inside of the lid and the top of the food): CO 2 concentration changes during storage in relation with meat absorption or evolution of CO 2, depending on initial headspace CO 2, temperature, packaging configuration and meat characteristics. CO 2 would be adsorbed by the muscle and fat tissue until saturation and its absorption determines a decrease in headspace volume in MAP until packages collapse (Zhao et al., ; Ercolini et al., ). Among Enterobacteriaceae, Serratia spp. is the most common genus isolated from MAP meat (Doulgeraki et al., ). Storage temperature affects the duration of the lag phase, the maximum specific growth rate and the final cell number (Doulgeraki et al., ). Lower refrigeration temperatures decrease bacterial growth and modify the composition of the microbiota present on meat: psychrotrophic bacteria could grow, either Gram-positive, such as LAB, or Gram-negative, such as Pseudomonas spp. (Doulgeraki et al., ), at chill temperature. In MAP and vacuum packed meat products, the dominance of lactic acid bacteria is also maintained under refrigerated conditions. However, the growth rate is affected: Carnobacterium spp. prevails in a vacuum at -1.5°C, whereas homofermentative Lactobacillus spp. dominate at 4°C and 7°C (Ray and Bhunia, ). Among the Enterobacteriaceae, Hafnia alvei dominates at 4°C, and S. liquefaciens predominates at 1.5°C (Borch et al., ). Psychrophilic Clostridium spp. could be detected in vacuum-packed, chilled meat (Doulgeraki et al., ). Storage temperatures above 10°C are not unusual and a shift in microbial populations can be observed. Temperature abuse determines the growth of Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp (Koutsoumanis et al., ). From these considerations, it is evident how important an accurate management of time/temperature can be to control not only pathogen growth and toxin formation, but also spoilage micro-organisms. Unwanted bacteria growth and toxin formation as a result of the time/temperature abuse of food products can cause consumer illness. Temperature abuse occurs when the product is allowed to remain a sufficient length of time at temperatures favourable to pathogen growth resulting in unsafe levels of pathogens or their toxins in the product (Cenci-Goga et al., ; Leonard, ; Cenci-Goga et al., ). Since microbial survival follows different pathways depending on the many factors which occur, the detectable effects are multiple: visible growth (slime, colonies), textural changes (degradation of polymers) or off-odours and off-flavours (Borch et al., ; Gram et al., ; Nychas et al., ). The characteristics of meat deteriorations depend on the availability of variable substrates: glucose, lactic acid, nitrogenous compounds and free amino acids present in meat, as the principal precursors of microbial metabolites responsible for spoilage (Nychas et al., ). Depending on the microbial species and their oxygen affinity, these compounds will produce different catabolic byproducts (). The volatilome, the volatile fraction of the microbial catabolites, includes: sulphur compounds, ketones, aldehydes, organic acids, volatile fatty acids, ethyl esters, alcohols, ammonia and other metabolites. Depending on their olfactory thresholds and the interaction between the volatile and non-volatile compounds, these molecules will affect the sensory quality of both fresh and cooked meat (Casaburi et al., ). From aerobically stored meat, it is not infrequent to appreciate undesirable odours as putrid, cheesy, sulphuric, sweet and fruity (Borch et al., ). Off-odours are perceptible to consumers when the total bacterial count is between 10 7 CFU gr -1 and 10 7.5 CFU gr -1, Pseudomonas spp. and B. thermosphacta predominantly contribute to foul odours as a result of their metabolism (Nychas et al., ). When superficial contamination is nearly 10 8 CFU gr –1, the carbohydrates are depleted and Pseudomonaceae in association with psychrotrophic Gram-negatives, such as Moraxella spp., Alcaligenes spp, Aeromonas spp, Serratia spp., Pantoea spp., start using amino acids as sources of energy. Nauseating odours are associated with free amino acids and nitrogen compounds (NH 3, indole, tryptophan).B. thermosphacta aerobic metabolism of glucose produces a foul-smelling odour, such as acetoin and acetic acid (Koutsoumanis et al., ). Sulphur-containing compounds determine sulphuric odours, originating from hydrogen sulphide formed by Enterobacteriaceae and dimethyl sulphide by Pseudomonas spp. Cheesy odours are determined by acetoin/diacetyl and 3-methylbutanol formations produced by Enterobacteriaceae, B. thermosphacta and homofermentative Lactobacillus spp. (Casaburi et al., ). The off-odour from vacuum and MA-packed meat is less intense and is represented by a sour, acid aroma as a result of the spoilage caused by lactic acid bacteria, associated with the production of lactic- and acetic-acid during the logarithmic and stationary growth phase. The CO 2 and O 2 content affects the rate of consumption of glucose by B. thermosphacta. As a consequence, anaerobic metabolism produces less intense odours than aerobic metabolism, so the use of a low concentration of oxygen on modified atmosphere packaging is better for maintaining acceptable qualities (Pin et al., ). Shewanella spp. produces malodorant compounds, such as H 2 S in vacuum packaged meat (Gram et al., ; Doulgeraki et al., ). The presence of bacterial patina on the surface of meat products is appreciable when the microbiota are between 10 7.5 -10 8 CFU cm -2, Hydrogen sulphide, produced by L. sakei, H. alvei, S. putrefaciens, converts the muscle pigment to green sulphomyoglobin and its appearance is a consequence of glucose consumption. Sulphomyoglobin is not formed in anaerobic atmospheres (Borch et al., ). Leuconostoc spp. and Leuconostoc- like microorganisms, such as Weissella viridescens, may cause meat products to turn green, due to the formation of hydrogen peroxide, which oxidizes nitrosomyochromogen as the consequence of the exposure of meat to O 2 (Dušková et al., ).S. putrefaciens may determine green discolouration in vacuum-packed meat (Doulgeraki et al., ). In addiction, among the factors affecting light-induced oxidative discoloration of cooked meat during the storage, the headspace volume directly influences the total amount of O 2 available for the oxidation (Robertson, ). Clostridium spp. is responsible for the production of a large amount of gases (H 2 and CO 2 ): vacuum-packed meat could be affected by blown pack spoilage, characterized by deformation of the pack due to the accumulation of a large amount of gases, putrid odours, the presence of exudates, extensive proteolysis, changes in pH and colour. This type of deterioration can occur in chilled, vacuum-packed meat, caused by psychrophilic and psychrotrophic bacteria. Not only Clostridium spp. is responsible for blown pack (Yang et al., ), but LAB also play an important role in the production of the volatile, organic compounds found in the package headspace of spoiled meat (Hernandez-Macedo et al., ). CO 2 concentration during the storage of packages is attributed to metabolic by-products of the heterofermentative lactobacilli and leuconostocs. It usually determines off-odours as well. A high-incidence of ropy slime formation is found in vacuum-packed, cooked meat products, caused by the homofermentative Lactobacillus spp. and Leuconostoc spp. The stretchy, ropy slime are long, undesirable, polysaccharide ropes between the surface of the products and the casing or between the slices (). Slime production gives some bacteria an advantage, since it constitutes a protective layer to keep the bacteria moist (Bjorkroth and Korkeala, ).W. viridescens may be the cause of ropy slime formation or meat turning green. After the appearance of individual colonies on a wet surface, a continuous layer of greenish slime is formed (Dušková et al., ). Lactic acid bacteria are widespread in nature and in the environment of processing plants; they are unavoidably part of the contaminant flora of fresh meat after slaughter, and also of cooked meat. They are generally regarded as safe (GRAS) micro-organisms (Nychas et al., ; Ogier et al., ) with many applications in the food industry; in fact, under specific conditions, they compete efficiently with other micro-organisms for nutrients, and achieve substantial, viable counts (Krockel, ). In food production, LAB are frequently used for their desired effects, such as their application as a starter in meat to manufacture safe, high quality, fermented sausages or cooked meat products (Cenci-Goga et al.,, ; Zhao et al., ). Protective, bacteriocinogenic cultures establish a microbial ecosystem, typically associated with MAP and VP cooked meat, which prevents the multiplication of food-borne pathogens (Zhang and Holley, ). Apart from their beneficial effects, some strains of lactic acid bacteria are the major spoilage bacteria in vacuum- and modified atmosphere-packed cooked meat products. In fact, they are indicated as Specific Spoilage Organisms (SSO), determining evident meat spoilage of products stored under packaging conditions with an increased concentration of carbon dioxide (Nychas and Skandamis, ; Nychas et al., ; Koutsoumanis, ; Pothakos et al., ). The LAB most involved in meat spoilage consist of heterofermentative lactobacilli ( Lactobacillus spp., mainly L. curvatus and L. sakei ), heterofermentative leuconostocs ( Leuconostoc spp.), Carnobacterium spp. (Hu et al., ) and, to a lesser extent, the homofermentative Lactobacillus spp. and Pediococcus spp. As a result of their metabolism, homofermentative LAB produce almost exclusively lactic acid, which is mild and palatable, whereas heterofermentative LAB produce a significant amount of undesirable catabolites, such as CO 2 gas, ethanol, acetic-acid, butanoic-acid and acetoin with consequent off-odours and visual effects, such as ropy slime formation and meat discolouration (Krockel, ). As a consequence, LAB are responsible for some unusual alterations in meat: off-flavours, discolouration, gas production, a decrease in pH and slime formation, determining the spoilage of the products and reduction in shelf-life (Samelis et al., ). Organoleptic modifications produced by LAB become appreciable after they have reached the stationary growth phase (Korkeala and Alanko, ; Korkeala et al., ): sourness (LAB produce lactic and acetic acid during logarithmic and stationary phase of growth), gas formation (increase in CO 2 concentration in packages during storage, attributed to metabolic by-products of the heterofermentative lactobacilli and Leuconostoc spp.), slime and grey liquid (in some cases, the slime formation may be copious and unacceptable for selling; the amount increases with storage time and the appearance of the drip changes from transparent to white or grey) and ropy slime formation (Borch and Nerbrink, ; Bjorkroth and Korkeala, ). A clear dominance of LAB is evident in MAP products at their sell-by date, under different temperature and atmospheric conditions (Champomier-Verges et al., ; Yost and Nattress, ; Ercolini et al., ). Non-LAB counts in MAP commodities, e.g., cooked turkey breast, have been shown to be lower than 10 3 CFU g -1 (Samelis et al., ). Lactobacillus spp. and Leuconostoc spp. are almost the largest group which causes sensory changes, such as souring, the production of H 2 S, gas and slime. Furthermore, L. sakei and L. curvatus are the most frequent isolates, responsible for ropy slime-formation on the surface of meat products (Ray and Bhunia, ) (). Psychrotrophic strains are selected by the refrigerated conditions during meat processing; L. carnosum may be considered as the most typical psychrotrophic organism, also found frequently in artisan-type cooked MAP ham, determining defects of the products during a 3-week shelf-life (Bjorkroth et al., ; Vasilopoulos et al., ). Ropy slime-producing lactobacilli belong to the atypical streptobacteria i.e., heterofermentative psychrotrophic lactobacilli. Atypical streptobacteria are characterized by their ability to grow at a lower temperature (2-4°C) than other streptobacteria. Ropy slime producing bacteria strains can survive on de Man Rogosa Sharpe Agar at temperatures below 0°C: the minimum growth temperature is below -1°C for lactobacilli and 4° for Leuconostoc spp., the maximum growth temperature fluctuates between 36.6°C and 39.8°C. (Korkeala and Björkroth, ; Sade et al., ). This low, minimum growth temperature allows these bacteria to survive and compete with other bacteria in meat products and meat processing plants. Consequently, the use of low temperatures in the preparation and storage of meat products does not prevent the formation of ropy-slime, although refrigeration storage temperature determines a longer shelf-life of the product. The optimum temperature of growth is 30°C and such high temperatures are not usually reached during the storage of meat products, in spite of temperature abuses (Korkeala et al., ). Slime formation is due to the LAB secreting long-chain, high-molecular-mass, viscosifying or gelling exocellular polysaccharides into the environment. Extracellular polysaccharides or exopolysaccharides (EPS) are polysaccharides secreted outside the cell wall of the producing micro-organism. LAB synthesize a wide variety of EPS: synthesis may occur extracellularly from sucrose by glucansucrases or intracellularly by glucosyltransferases from sugar nucleotide precursors (Ullrich, ). Two forms of EPS are produced by lactic acid bacteria: capsular polysaccharide (CPS) if they remain attached to the cells, or unattached and released into the environment as exopolysaccharides (EPS) (Hassan et al., ). Some strains are able to produce both forms of EPS, others only produce the unattached type. However, strains producing only the capsular form have not yet been confirmed (Hassan et al., ; Ullrich, ). Ropiness is a term used to identify threads which can be drawn out from the surface of fermented milk by a needle. In addition, the term ropy has been used to describe strains producing EPS or ropiness. Therefore, LAB were distinguished as either ropy or non-ropy producers according to their ability to produce EPS (Hassan et al., ). Hassan et al. ( ) divided lactic acid bacteria into four categories, related to EPS production: group I, capsule-forming, ropy strains producing capsules and unattached ropy EPS; group II, capsule-forming, non-ropy strains which produce capsules and possibly unattached EPS; group III, non-capsule-forming, ropy strains; group IV, strains producing no or undetectable EPS. Depending on their composition, EPS are divided into two classes: heteropolysaccharides (HePS) composed of different monosaccharides, such as galactose, glucose and rhamnose and homopolysaccharide (HoPS), containing only one type of monosaccharide, either glucose (glucans) or fructose (fructans) (De Vuyst, 2011; Monsan et al., 2001). Leuconostoc spp. and some Lactobacillus spp. strains synthesize glucans and fructans from sucrose (Monsan, 2011; van Hijum, 2006). However, the formation of ropy slime is not inhibited by the absence of sucrose in the meat product. Many different heteropolysaccharides (HePS) are secreted by LAB, depending on the sugar composition and molecular size (Degeest et al., ). EPS production is associated with the protection of the cell against dessication, phage attacks, phagocytosis, antibiotics, toxic compounds, predation by protozoans and is involved in osmotic control, adhesion to surfaces and cellular recognition (Dudman, ; Ullrich, ). Slime production is influenced by the specific conditions of packaging and storage temperature and is linked to biofilm formation, stress resistance and sucrose utilization of responsible strains (Aymerich et al., ; Ullrich, ). In late 1980s a Finnish research group (Korkeala and Alanko, ; Korkeala et al., ) analysed the slime produced by two different, homofermentative lactobacilli and a Leuconostoc strain, isolated from different ropy, vacuum-packed meat products: the slime had a molecular weight in the range of 70000-30000, determined by gel permeation chromatography (GPC), and contained glucose and galactose in a ratio of 10:1-10:2. The identification of spoilage micro-organisms shows two different approaches: culture dependent and culture independent methods. The first procedure consists of the preliminary isolation and culture of micro-organisms isolated from a food sample and the subsequent identification of a single, colony-forming unit on nutrient and selective media (). Culture independent approaches, on the other hand, do not need a preliminary culture, however, strains can be detected directly on the food sample via a DNA and RNA analysis, which is also efficient for strains in a low concentration (Schirone and Visciano, ). From the 80s, ropy slime-producing bacteria were identified by means of selective media, and sugar fermentation was investigated with API 50 CHL and the sequencing of 16S ribosomal RNA (Korkeala et al., ). In industrial production plants, plate count methods are used in the microbial quality assessment of MAP meat products throughout the processing plant, in order to isolate meat-borne spoilage LAB strains on Plate Count Agar and de Man Rogosa Sharpe Agar media (Audenaert et al., ). For detailed information of the composition or the origin of the microbiota, phenotypic and/or molecular identification and typing of purified colonies is conducted (Audenaert et al., ). Molecular techniques in microbial ecology have changed the way of studying microbial diversity. In fact, they allow rapid, reliable identification and typing of microorganisms, usually by means of the detection of DNA polymorphisms between species or strains (Doulgeraki et al., ). PCR-based, molecular typing methods allow differentiation at the species and intra-species level; the specificity of this approach is based on primer selections and amplification conditions (Randomly Ampliphied Polymorphic DNA-PCR, Repetitive Extragenic Palindromic – PCR, Amplified Fragment Length Polymorphism) (Yost and Nattress, ; Casaburi et al., ). Yost and Natress ( ) defined a systematic approach to identify lactic acid bacteria associated with meat, to detect Carnobacterium spp., L. curvatus, L. sakei and Leuconostoc spp by means of specific primers for Carnobacterium spp. and Leuconostoc spp., created from 16S rRNA oligonucleotide probes and used in combination with species-specific primers for the 16S/23S rRNA spacer region of L. curvatus and L. sakei in multiplex PCR reactions. Among the culture-independent approaches, PCR-denaturating gradient gel electrophoresis (PCR-DGGE) is a method to assess the biodiversity and population dynamics of microbiota occurring in different ecosystems, used in food microbiology to investigate bacterial successions in fermented food or the composition of probiotic products (Temmerman et al., ; Masco et al., ). Among non PCR-based methods, the most promising is Restriction Enzyme Analysis coupled with pulsed-field gel electrophoresis (REA-PFGE), which is used to obtain a strain-specific band pattern for the monitoring of the succession of bacteria in meat during storage. Another method of choice, for taxonomy, is Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresi s (SDS-PAGE), which compares whole-cell protein patterns (Doulgeraki et al., ). Restriction Fragment Length Polymorphism (RFLP) technique consists of the digestion of genomic DNA by specific enzymes and separation of obtained fragments on agarose gel. RFLP could be associated with PCR of specific sequences in presence of high interspecific polymorphisms. A specific application of RFLP, the so-called Terminal restriction fragment length polymorphism (T-RFLP) is used to characterize psychrotrophic strains on MAP meat (Nieminen et al., ). The identification of causative agents of ropiness is carried out also through Ribotyping which is a method based on the analysis of ribosomal RNA where restriction enzymes provoke the formation of specific fragments of rRNA, determining a specific ribotypes for each strain (Bjorkroth and Korkeala, ). Pulse Field Gel Electrophoresis (PFGE), finally, is a technique that allows the identification of high molecular weight molecules thanks to the electric field periodically modifying. The final result is a specific pulsotype for each strain (Bjorkroth et al., ) Nowadays, the consumption of cooked, sliced and packaged meat products, such as cooked ham, chicken and turkey breast, emulsion-style sausages ( e.g., frankfurters, luncheon meat) is increasing as a result of consumers’ enhanced interest in low-calorie meat products (Hu et al., ). The majority of these products are sold under modified atmosphere (MAP) or vacuum-packed conditions and some of them are ready-to-eat’ products (Audenaert et al., ). Their storage is under refrigeration with shelf-lives varying from days to several weeks. Modified atmosphere and vacuum packaging conditions prolong the shelf-life of meat and favour the growth of psychrotrophic lactic acid bacteria (Borch et al., ; Korkeala and Björkroth, ). During slicing and packaging, contamination may occur and psychrotrophic LAB may grow exponentially in the meat product, determining an alteration in the quality of the meat (Krockel, ). The main categories of cooked meat products showing these contaminations are: grilled roast ham, cooked ham, classic cooked ham, roast turkey breast, roast loin of pork. Even though the raw materials have different origins (pork or turkey), they follow a similar production process. Briefly, the main steps are: a careful selection of the meat, trimming, syringing after the preparation of the saline (a mix of water, spices, natural flavourings and additives), churning, cooking in controlled temperature ovens, where the temperature of the product must reach 70°C in the centre, cooling, vacuum-packaging process and pasteurization for several minutes at a temperature of 115°C. Once cooled, they are ready for distribution. Since none of the commonly detected LAB species is highly heat-resistant and cooked meat products are heated to a core temperature of 68°-72°C, the majority of the vegetative cells are killed at the processing plant (Vermeiren et al., ). LAB contamination may occur after heat treatment (Makela et al., ; Makela et al., ; Aymerich et al., ). Post-cooking contamination takes place during chilling, handling, slicing and packaging, rather than via natural contaminants initially present on raw meat products determining MAP shelf-life (Borch et al., ). The potential contamination sources during the production process of MAP and VP cooked meat products are numerous: salt, spices and raw materials, but also the rooms, where products are stored before packaging. Not only materials collected from the surfaces of the processing rooms, but also air samples from the environment underlined the presence of lactic acid bacteria producing filaments (Makela et al.,, ). The origin of the contamination is also linked to the raw materials used, as confirmed by the isolation of lactic acid bacteria from cooked sausages (Korkeala et al., ) and from samples taken from carcasses and raw meat establishments (Makela et al., ). It highlights the fact that lactic acid bacteria can be transmitted through the air, by staff and via tools. Several authors have demonstrated re-contamination after the thermal processes following the handling of products (Mäkelä and Korkeala, ; Borch et al., ). The environment needs, therefore, to be thoroughly sanitized and a clear separation maintained between raw and cooked products (Mäkelä and Korkeala, ). In order to prevent the presence and growth of ropy slime-producers, there are various different approaches to consider. The rooms and equipment of meat processing plants act as sources of bacterial contamination and disinfection is a necessary procedure to minimize contamination of products with bacteria. Therefore, temporal and spatial separation between raw meat and cooked products decreases the risk of cross-contamination (Audenaert et al., ). Not all detergents and sanitizers are effective in eliminating environmental contamination: in particular the use of detergents and sanitizers with a low concentration of hypochlorite is not recommended due to their proved inefficacy towards ropy slime-producing bacteria (Mäkelä et al., ). Concerning the use of appropriate products for the in-depth hygiene of meat processing plants, cleaning and sanitizing have to be considered as fundamental procedures not only for avoiding pathogens contaminations but also for limiting the spoilage due to ropy slime producers. In food industry, detergent and sanitizer are used separately or in association. Detergents contain surfactants that reduce surface tensions between the soil and the surface while sanitizers are made of antimicrobial compounds able to reduce the microbiological contamination to an acceptable level, according to local health regulations. Mäkelä et al. ( ) demonstrated that detergent-sanitizer (DS) products with different antimicrobial compounds (Na-dichloroisocyanurate at 0.06%, Na-hypoclorite at 0.017%, cocobenzyldimethyl ammonium chloride at 0.027% and Dimethylcoco ammonium betaine at 0.27%) were less effective against ropy-slime producers than sanitizer (S) products used separately. In detail, applied sanitizer compounds were alkyldimethylbenzyl ammonium chloride (0.022% and 0.05%), alkyldimethyl ammonium chloride (0.014%), alkylmethylethylbenzyl ammonium chloride (0.022%), polyhexamethylene biguanide chloride (0.023%), Nahypochlorite (0.05%), paracetic acid (0.018%) and benzyldimethylalkyl ammonium chloride (0.1%). The lower effectiveness of detergent sanitizers was associated to the surface-active compounds which may modify the antimicrobial activity of the product. Consequently, in meat processing plants, it is better to use separately detergent and sanitizers than use combined detergents and sanitizers products. Quaternary ammonium products and acid sanitizer with hydrogen peroxide are reported to be more effective than products containing chlorine compounds and polyhexamethylene biguanide chloride (Makela et al.,, ). The prevention of unwanted meat processes must bear in mind the rising interest of food producers and consumers in healthier food production with fewer added substances. The new technologies of food preservation include non-thermal inactivation, such as ionization radiation, high hydrostatic pressure and pulsed electric fields, active packaging, bio-preservation and natural antimicrobial compounds. The bio-preservation of meat could be the answer to this demand: in fact, it consists of the control of pathogenic and spoilage microbiota by competitive microflora and natural molecules. Bacteriocins, for example, are ribosomally-synthesized, antimicrobial peptides or proteins, which are active towards other bacteria (Gálvez et al., ; Castellano et al., ). Bacteriocinogenic cultures and specific bacteriocins added to cooked meat are capable of preventing slime production (Aymerich et al., ). Nisin is a bacteriocin produced by L. lactis subsp. lactic and it inhibits the growth of Gram-positive organisms, including bacterial spores. However, it is not efficient against Gram-negative bacteria, fungi and yeast (Economou et al., ). It is not a toxic substance if it is ingested, it does not determine cross-resistance with medical antibiotic molecules and it is degraded by the intestinal tract (Kalschne et al., ). Nisin determines a significant inhibition of the growth of L. sakei on vacuum-packed sliced ham (Kalschne, ) with a shelf-life extension. Aymerich et al, ( ) demonstrated that Enterococcus faecium and L. sakei, bacteriocin producers, prevent ropiness due to L. sakei, whereas nisin inhibits the activity of L. carnosum in cooked pork loin (Kalschne et al., ). In addition, these bacteriocins are heat-stable and resist to pasteurization. It is, therefore, possible to add bacteriocins to the meat before the cooking process.P. lactis produces pediocin, a bacteriocin effective against Listeria spp. However, novel uses of this strain as a starter culture in some food fermentations also hypothesize the effect on strains of Gram-positive microorganisms (Kalschne et al., ). Bacteriocins are also involved in developing active packaging devices, creating an effective surface with antimicrobial effects. Bacteriocin-activated, plastic films for food packaging have been developed for the storage of hamburgers, hot dogs, frankfurters and cooked ham (Ercolini et al., ). An alternative preservation method for the prevention of filaments is High Pressure Processing (HPP) for processed meat and meat products. Most vegetative microorganisms in meat samples are inactivated at a pressure of 400-600 MPa and HPP improves food safety and prolongs the shelf-life of meat products. It could avoid the survival of bacterial strains responsible for ropiness on the surface of the product (Han et al., ). Finally, food preservation through application of Ozone (O 3 ) have been investigated, considering the bacterial inactivation determined by the attacks on cellular constituents, avoiding creation of mutants, and leaving no dangerous chemical residuals. The reduction of L. mesenteroides in clean water was 5 log count (PPM O 3 per 2 min of application) but direct application of ozone in food processing seems hardly feasible; the application on beef surface, in fact, resulted in low activity towards Leuconostoc spp., Lactobacillus spp. and P. fluoresces, associated with discoloration and odour development (Pirani, ). Meat spoilage and product shelf-life is an important challenge for all the experts gravitating around this area. The spoilage due to ropy slime-formation has influenced the marketing of vacuum-packed meat products and the use of this technology. The presence of ropy slime-producing bacteria and their associated sensory abnormalities lead to high direct financial losses (waste product) and indirect (such as product selection, disinfection of contaminated surfaces and non-delivery at destination). Although food security is likely to be guaranteed, the macroscopic appearance of the product at the time of packaging is particularly unpleasant, making it unsuitable for further processing or marketing. Food industries and productions must be supported by research, creating a strong link between discoveries and applications. Nowadays, ropy slime-formation on meat products represents a persistent problem, often ignored. It is, therefore, necessary to provide a basis as a starting point to find a beneficial solution. Table 1. Factors affecting the shelf-life of meat.

Intrinsic factors	Extrinsic factors
Species, breed, age and feeding of the animal of origin	Quality management system
Initial microbiota	Packaging system
Chemical properties (pH, a w, redox potential, peroxide value)	Temperature control
Product composition	Processing conditions and hygiene
Antimicrobial components	Storage types
Biopreservation systems (bacteriocinogenic LAB cultures and/or their bacteriocin)	Relative humidity
	Atmospheric gas composition and ratio

Table 2. Expected shelf-life of cooked meat products under refrigerated storage and dominant microbiota.

Storage conditions	Gas composition	Expected shelf-life	Dominant microbiota
Aerobic	Air	Days	Pseudomonas spp.
Modified atmosphere packaging	50% CO 2 with O 2	Weeks	B. thermosphacta
50% CO 2	Weeks	Enterobacteriaceae
<50% CO 2 with O 2	Weeks	B. thermosphacta
100% CO 2	Weeks	Lactic acid bacteria
Vacuum packaging	no gas	Months	B. thermosphacta, S. putrefaciens, lactic acid bacteria

Table 3. Meat spoilage: prevalent alterations detectable.

Alteration	Product	Aetiology
H 2 S production	Cured meat	Vibrio, Enterobacteriaceae
Sulfide odour	Vacuum packaged meat	Clostridium spp., Hafnia spp.
H 2 O 2 greening	Meats	Weisella spp., Leuconostoc spp., Enterococcus spp., Lactobacillus spp.
H 2 S greening	Vacuum packaged meat	Shewanella spp.
Slime production	Meats	Pseudomonas spp., Lactobacillus spp., Leuconostoc spp., Enterococcus spp.,
Weissella spp., Brochothrix s pp.
Blown Pack	Vacuum packaged meat	Clostridium spp., lactic acid bacteria
Putrefaction	Ham	Enterobacteriaceae, Proteus spp.
Bone taint	Meats	Clostridium spp., Enterococcus spp.
Souring	Ham	Lactic acid bacteria, Enterococcus spp.

Table 4. Ropy slime producing bacteria.

Origin	Packaging	Strains isolated	References
Cooked meat products	Vacuum	L. mesenteroides	(Korkeala et al., ; Bjorkroth and Korkeala, ;
	Packaged	L. mesenteroides subsp. dextranicum	Samelis et al., ; Yost and Nattress, ; Ercolini et al., ;
		Homofermentative lactobacilli	Hu et al., ; Pothakos et al., )
		L. sakei	(Korkeala and Alanko, ; Makela et al., ; Bjorkroth et al.,
		L. gelidum,	; Bjorkroth and Korkeala, ; Samelis et al., ;
		L. amelibiosum	Aymerich et al., ; Hu et al., )
		L. gelidum subsp. gasicomitatum	(Korkeala and Björkroth, )
(Borch et al., ; Aymerich et al., ; Jaaskelainen et al., )
Sliced cooked ham	Vacuum	L. carnosum	(Bjorkroth et al., ; Samelis et al., ; Nychas et al., ;
	Packaged	Vasilopoulos et al., ; Krockel, )
Herring	Preserve	L. gelidum subsp. gasicomitatum	(Lyhs et al., )
Boiled eggs	In brine	L. gelidum	(Pothakos et al., )
Processing rooms at meat plants		L. sakei	(Makela et al., )
		L. amelibiosum

The authors express their sincere appreciation to members of Polyglot, Perugia, for their careful reading and comments on the article. The findings and the conclusions in this paper are those of the authors and do not necessarily represent the views of the University of Perugia.

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Permission is granted subject to the terms of the License under which the work was published. Permission will be required if your reuse is not covered by the terms of the License. To request a reprint or commercial or derivative permissions for this article, please click on the relevant link below. : Meat Spoilage: A Critical Review of a Neglected Alteration Due to Ropy Slime Producing Bacteria

What is the most common bacteria in meat?

– Thoroughly cooking chicken, poultry products, and meat destroys germs. Raw and undercooked meat and poultry can make you sick. Most raw poultry contains, It also may contain,, and other bacteria. Raw meat may contain Salmonella,,, and other bacteria.

You should not wash raw poultry or meat before cooking it, even though some older recipes may call for this step. Washing raw poultry or meat can spread bacteria to other foods, utensils, and surfaces, and does not prevent illness. Thoroughly cook poultry and meat. You can kill bacteria by, Use a cooking thermometer to check the temperature. You can’t tell if meat is properly cooked by looking at its color or juices. Leftovers should be refrigerated at 40°F or colder within 2 hours after preparation. Large cuts of meat, such as roasts or a whole turkey, should be divided into small quantities for refrigeration so they’ll cool quickly enough to prevent bacteria from growing.

What enzymes cause spoilage in meat?

The main enzymes involved in meat lipid hydrolysis are phospholipase A1 and phospholipase A2 (Toldra, 2006). The non-enzymatic hydrolysis is caused by heme proteins such as hemoglobin, myoglobin and cytochrome which are susceptible to oxidation and produce hydroperoxides (Kanner, 1994.

What toxin is in spoiled meat?

Putrescine is the toxin responsible for the odor of rotting meat ; its consumption can cause headaches, vomiting, diarrhea, and heart palpitations, and has been linked to an elevated risk of colorectal cancer.

What are 3 common causes of food spoilage?

Protecting Your Family from Food Spoilage Posted by Argyris Magoulas, Food Safety Education Staff, Food Safety and Inspection Service in A woman holding her nose at spoiled food in the pot in front of the refrigerator. March is National Nutrition Month. Throughout the month, USDA will be highlighting results of our efforts to improve access to safe, healthy food for all Americans and supporting the health of our next generation.

What happens to foods when they spoil and are they dangerous to eat? What causes foods to spoil and how? These are questions we often get on USDA’s Meat and Poultry Hotline. Read on to learn the science behind food spoilage. Spoiler Alert! Signs of food spoilage may include an appearance different from the food in its fresh form, such as a change in color, a change in texture, an unpleasant odor, or an undesirable taste.

Various factors cause food spoilage, making items unsuitable for consumption. Light, oxygen, heat, humidity, temperature and spoilage bacteria can all affect both safety and quality of perishable foods. When subject to these factors, foods will gradually deteriorate.

1. Microorganisms occur everywhere in the environment, and there is always a risk of spoilage when foods are exposed to unsuitable conditions.
2. Microbial spoilage results from bacteria, molds, and yeast.
3. While microorganisms may or may not be harmful, the waste products they produce when growing on or in food may be unpleasant to taste.

Pathogenic Spoilage In addition to causing food to deteriorate and taste unpleasant, some types of spoilage can be caused by pathogenic bacteria, which can have serious health consequences. For example Clostridium perfringens (common cause of spoilage in meat and poultry) and Bacillus cereus (common cause of spoilage of milk and cream) are also pathogenic.

• When exposed to unsuitable storage conditions, such as the Danger Zone (between 40 and 140° F), these organisms can multiply rapidly and they can release dangerous toxins that will make you sick if you consume the item, even if it’s cooked to a safe internal temperature.
• To keep food out of the Danger Zone, keep cold food cold, at or below 40 °F (4.4 °C), and hot food hot, at or above 140 °F (60 °C).

Spoilage of food is not just an issue of quality; it is also a matter of food safety. USDA recommends following the to Food Safety (Clean, Separate, Cook, and Chill) to prevent food spoilage and reduce your risk of foodborne illness. Learn appropriate storage methods with the FoodKeeper app Learn about proper food and beverages storage with the,

1. It will help you maximize the freshness and quality of items by showing you the appropriate storage methods for more than 400 items.
2. By doing so you will be able to keep items fresh longer than if they were not stored properly.
3. It was developed by the USDA’s Food Safety and Inspection Service, with Cornell University and the Food Marketing Institute.

It is also available and as a mobile application for and devices. : Protecting Your Family from Food Spoilage

What is the biological cause of meat spoilage?

i. Bacterial spoilage of meat: –

Surface spoilage:

It is caused by Pseudomonas, Acenatobacter, Streptococcus, Leuconostoc, Bacillus and Micrococcus. Temperature and available moisture influence type of microorganisms causing slime.

Change in color of meat:

Red color of meat may be changed into green brown or grey due to production of oxidising agent, H 2 S, etc. by microorganisms. For example, Lactobacillus and Leuconostoc cause greening of sausage.

Change in fat:

Fat of meat may become rancid due to lipase producing microorganisms such as Pseudomonas and Achromobacter.

Surface color due to pigmented bacteria:

Serratia marcescens give red spots. Pseudomonas syncyanea give blue color, Chromobacterium lividum gives greenish blue to brownish black color, Flavobacterium give yellow color.

Phosphorescence:

It is caused by luminous bacteria e.g. Photobacterium growing on surface of meat.

Off odors and off taste:

Undesirable odor and taste called taint are caused by many bacteria due to production of volatile acids such as formic acid, acetic acid, butyric acid etc.Actinomycetes give musty or earthy flavor.

Can you cook off spoiled meat?

Unpleasant taste – ITisha/Shutterstock No one should willingly taste meat when there’s potential for it to be spoiled. However, sometimes it’s too late and you get a mouthful of cooked, but atrocious meat. Oven Via clarifies that although cooking spoiled meat can kill germs, mold, and other kinds of bacteria, it’s still not safe to eat as it will not get rid of harmful toxins.

1. Spoiled meat can also contain spores, notes the National Library of Medicine, that are made from a mold and are capable of creating and spreading more bacteria.
2. Cooking can make spores more of a threat as they are heat-resistant and heat is needed for them to reproduce germs.
3. Although temperatures above 140 and under 160 degrees Fahrenheit are recommended for destroying spores, they can still survive, especially when spoiled meat has access to oxygen.

As a result, spoiled meat will taste exactly as it smells — sour or tangy. This is a reminder that if you consumed spoiled meat and feel sick, please go to a hospital right away.

How long until meat is spoiled?

Salad Egg, chicken, ham, tuna, and macaroni salads 3 to 4 days Does not freeze well Hot dogs Opened package 1 week 1 to 2 months Unopened package 2 weeks 1 to 2 months Luncheon meat Opened package or deli sliced 3 to 5 days 1 to 2 months Unopened package 2 weeks 1 to 2 months Bacon and sausage Bacon 1 week 1 month Sausage, raw, from chicken, turkey, pork, or beef 1 to 2 days 1 to 2 months Sausage, fully cooked, from chicken, turkey, pork, or beef 1 week 1 to 2 months Sausage, purchased frozen After cooking, 3-4 days 1-2 months from date of purchase Hamburger, ground meats and ground poultry Hamburger, ground beef, turkey, chicken, other poultry, veal, pork, lamb, and mixtures of them 1 to 2 days 3 to 4 months Fresh beef, veal, lamb, and pork Steaks 3 to 5 days 4 to 12 months Chops 3 to 5 days 4 to 12 months Roasts 3 to 5 days 4 to 12 months Ham Fresh, uncured, uncooked 3 to 5 days 6 months Fresh, uncured, cooked 3 to 4 days 3 to 4 months Cured, cook-before-eating, uncooked 5 to 7 days or “use by” date 3 to 4 months Fully-cooked, vacuum-sealed at plant, unopened 2 weeks or “use by” date 1 to 2 months Cooked, store-wrapped, whole 1 week 1 to 2 months Cooked, store-wrapped, slices, half, or spiral cut 3 to 5 days 1 to 2 months Country ham, cooked 1 week 1 month Canned, labeled “Keep Refrigerated,” unopened 6 to 9 months Do not freeze Canned, shelf-stable, opened Note : An unopened, shelf-stable, canned ham can be stored at room temperature for 2 years.

3 to 4 days 1 to 2 months Prosciutto, Parma or Serrano ham, dry Italian or Spanish type, cut 2 to 3 months 1 month Fresh poultry Chicken or turkey, whole 1 to 2 days 1 year Chicken or turkey, pieces 1 to 2 days 9 months Fin Fish Fatty Fish (bluefish, catfish, mackerel, mullet, salmon, tuna, etc.) 1 – 3 Days 2 – 3 Months Lean Fish (cod, flounder, haddock, halibut, sole, etc.) 6 – 8 Months Lean Fish (pollock, ocean perch, rockfish, sea trout.) 4 – 8 Months Shellfish Fresh Crab Meat 2 – 4 Days 2 – 4 Months Fresh Lobster 2 – 4 Days 2 – 4 Months Live Crab, Lobster 1 day,

Not recommended Live Clams, Mussels, Oysters, and Scallops 5 – 10 Days Not recommended Shrimp, Crayfish 3 – 5 Days 6 – 18 Months Shucked Clams, Mussels, Oysters, and Scallops 3 – 10 Days 3 – 4 Months Squid 1 – 3 Days 6 – 18 Months Eggs Raw eggs in shell 3 to 5 weeks Do not freeze in shell.

How long can meat sit out before spoiling?

Will Reheating Food Make It Safe If You Forget to Refrigerate It? If you reheat food that was forgotten on the counter overnight or was left out all day, will it be safe to eat? TWO HOURS is the MAXIMUM time perishable foods should be at room temperature (ONE HOUR at temperatures 90 degrees F and higher). This INCLUDES the time they’re on the table during your meal.

Meat, poultry, seafood and tofu Dairy products Cooked pasta, rice and vegetables Fresh, peeled and/or cut fruits and vegetables.

Reheating food may not make it safe. If food is left out too long, some bacteria, such as staphylococcus aureus (staph), can form a heat-resistant toxin that cooking can’t destroy. One of the most common sources of staph bacteria is the human body. Even healthy people carry staph — according to the U.S.

• Food and Drug Administration’s, staph bacteria are present in the nasal passages and throats and on the hair and skin of 50 percent or more of healthy individuals.
• Staph bacteria is found in facial blemishes, cuts and lesions.
• Most likely, the only way you’ll know if a food contained staph bacteria is when someone gets sick.

: Will Reheating Food Make It Safe If You Forget to Refrigerate It?

What bacteria Cannot be killed by cooking?

Myth : If you let food sit out more than 2 hours, you can make it safe by reheating it really hot. – Fact: Some bacteria, such as staphylococcus (staph) and Bacillus cereus, produce toxins not destroyed by high cooking temperatures. Refrigerate perishable foods within 2 hours in a refrigerator temperature of 40 degrees or below.

What is the safest meat to eat?

Tyler Olson /Shutterstock Fight disinformation: Sign up for the free Mother Jones Daily newsletter and follow the news that matters. Every time you eat, you’re rolling the germ dice. According to the Centers for Disease Control and Prevention, 1 in 6 Americans contracts a foodborne illness annually; 128,000 are hospitalized, and 3,000 die.

Pathogens from meat kill more people than those from any other food group. A CDC study found that between 1998 and 2008, contaminated meat was responsible for 29 percent of all deaths from foodborne illness (23 percent of deaths were from produce, 15 percent from dairy and eggs, and 6.4 percent from fish and shellfish).

Most carnivores don’t let the risk of sickness stop them from eating meat—and a lot of it. The average American eats nearly 271 pounds of meat a year. But here’s the good news: When it comes to foodborne illness, not all meats are equally risky. So which kinds are safest? A few tips for choosing the least germ-ridden cuts: 1.

• There is no such thing as risk-free meat.
• Or risk-free food in general, notes Donald Schaffner, a professor of food microbiology at Rutgers University.
• If the food isn’t cooked sufficiently, or if the preparation area isn’t clean, “it doesn’t matter whether you’re eating chicken, steak, or pork,” he says.

“Food prepared in an unclean environment is always going to be high risk.” 2. But some cuts are more likely to make you sick. In 2013, researchers from the Center for Science in the Public Interest (CSPI) analyzed data about outbreaks, illnesses, and hospitalizations from foodborne pathogens in particular kinds of meat between 1998 and 2010.

The meat risk pyramid to the right illustrates their findings.3. Contaminated chicken sickens more people than any other meat. That’s partially because we eat so much of it—more than 50 pounds a year per person. But it’s also because of the way that chicken is prepared and cooked, says Caroline Smith DeWaal, CSPI’s director of food safety.

Commercial chicken plants typically dip the meat in several baths before packaging, giving bacteria plenty of opportunity to spread. What’s more, says Smith DeWaal, it’s harder to cook away bacteria in chicken. “Chicken has creases and folds in the skin,” she says.

• Pathogens can hide in those folds.
• A lot of other meat doesn’t even come with skin on.” 4.
• Ground beef is the second riskiest kind of meat.
• One reason for this, says Smith DeWaal, is that during grinding, “the pathogens on the surface of the meat get pushed into the center.” If that ground meat isn’t properly cooked—say, in the middle of a rare burger—the germs get a free ride into your digestive tract.5.

Steaks, pork chops, and other whole-muscle meats are the safest bet. That’s because the cooking process can easily kill off bacteria on the cut’s surface, while the inside of the meat is essentially sterile, protected from any potential pathogens—in theory.6.

But steak isn’t as safe as it should be. According to the US Food Safety and Inspection Service, about 10.5 percent of steaks are subjected to a process called mechanical or needle tenderization, where metal blades or pins repeatedly puncture the meat before packaging. While this technique improves the meat’s texture, it also moves bacteria from the surface into the center of the cut, where the germs may survive cooking.

The scary part: Processors are not required to label cuts that have been mechanically tenderized—so there’s no way to know whether your steak might have extra interior bacteria. Mechanically tenderized beef has caused several recent outbreaks, including one in Canada in 2012, which sickened 18 people and led to the biggest beef recall in Canadian history.

1. In 2013, the US Department of Agriculture promised to require labeling on mechanically tenderized beef, but the agency is stalling on finalizing that rule.7.
2. Pork isn’t as dangerous as you thought.
3. One interesting takeaway: Pork, which has a reputation as a veritable petri dish, is actually relatively safe.

One reason is that we now cook the hell out of it. “Our grandmothers told us we really needed to cook pork really well,” says James Dickson, a professor of microbiology at Iowa State University. Another reason is that rules for feeding pigs have changed.

Until around World War II, domestic pigs used to be fed garbage containing animal feces, which are full of the parasite Trichinella, source of the serious disease trichinosis. Laws passed in the 1950s and ’60s ended that, and the incidence of trichinosis dropped dramatically, Between 2008 and 2012 there were just 84 cases of trichinosis, only 10 of which were associated with commercial pork products.

(Interestingly, 41 of the cases were associated with bear meat.) 8. Cold cuts of all kinds are also less dangerous than you thought. The CSPI report classifies them as medium risk, unless you’re pregnant, elderly, or have a weakened immune system. Deli meats are at particularly high risk for the pathogen Listeria monocytogenes, which causes listeria, one of the most dangerous of all foodborne illnesses.

Most of us can eat cold cuts contaminated without getting sick, but for senior citizens and immune-compromised people who contract listeria, the hospitalization rate is 90 percent. While pregnant women might not show symptoms, the bacteria can attack the fetus, causing miscarriage or stillbirth.9. Processed foods like sausage, hot dogs, and chicken nuggets, while terrible for you nutritionally, are actually relatively low-risk when it comes to bacteria.

“That’s because the processing—whether it’s cooking or chemicals or whatever—kills the pathogens,” explains Smith DeWaal. “We’re not saying they are great for you, but they are low risk when it comes to acute foodborne pathogens.” 10. Organic meat is just as germ-laden as conventional.

Several studies have shown that organic meat isn’t any less likely to transmit dangerous pathogens than nonorganic meat. Some studies have suggested that organic meats might carry fewer antibiotic-resistant bugs; this one from 2011 found that organic poultry contained less antibiotic-resistant Enterococci than conventional.

But a 2012 study, on the other hand, found similar rates of antibiotic resistant bacteria in organic and conventional pork samples.11. Cooking your meat correctly won’t necessarily prevent you from getting a bug. Even if you heat your meat to the proper temperature, the germs it carries can still get onto surfaces in your kitchen, where they can contaminate other food.

In order to cut down on cross-contamination risk, clean your cooking surfaces and utensils thoroughly, and never wash meat before cooking “because that will just splatter the germs,” says Smith DeWaal.12. Requesting your meat “well done” or “medium” won’t save you from illness, either. Those terms are vague and subjective, says Doug Powell, a former professor of food safety and current publisher of the foodborne illness site Barfblog,

“When I go to a restaurant and they ask me how I want my steak, I say, ‘140 degrees,'” he says. “If they give me a funny look I get up and leave.”

Can Salmonella be killed by cooking?

Does Cooking Kill Salmonella? – The short answer: Yes, cooking can kill Salmonella, Depending on the type of food, the Centers for Disease Control and Prevention recommend cooking food to a temperature between 145 degrees F and 165 degrees F to kill Salmonella,

What are 3 factors affecting food spoilage?

Protecting Your Family from Food Spoilage Posted by Argyris Magoulas, Food Safety Education Staff, Food Safety and Inspection Service in A woman holding her nose at spoiled food in the pot in front of the refrigerator. March is National Nutrition Month. Throughout the month, USDA will be highlighting results of our efforts to improve access to safe, healthy food for all Americans and supporting the health of our next generation.

What happens to foods when they spoil and are they dangerous to eat? What causes foods to spoil and how? These are questions we often get on USDA’s Meat and Poultry Hotline. Read on to learn the science behind food spoilage. Spoiler Alert! Signs of food spoilage may include an appearance different from the food in its fresh form, such as a change in color, a change in texture, an unpleasant odor, or an undesirable taste.

Various factors cause food spoilage, making items unsuitable for consumption. Light, oxygen, heat, humidity, temperature and spoilage bacteria can all affect both safety and quality of perishable foods. When subject to these factors, foods will gradually deteriorate.

Microorganisms occur everywhere in the environment, and there is always a risk of spoilage when foods are exposed to unsuitable conditions. Microbial spoilage results from bacteria, molds, and yeast. While microorganisms may or may not be harmful, the waste products they produce when growing on or in food may be unpleasant to taste.

Pathogenic Spoilage In addition to causing food to deteriorate and taste unpleasant, some types of spoilage can be caused by pathogenic bacteria, which can have serious health consequences. For example Clostridium perfringens (common cause of spoilage in meat and poultry) and Bacillus cereus (common cause of spoilage of milk and cream) are also pathogenic.

When exposed to unsuitable storage conditions, such as the Danger Zone (between 40 and 140° F), these organisms can multiply rapidly and they can release dangerous toxins that will make you sick if you consume the item, even if it’s cooked to a safe internal temperature. To keep food out of the Danger Zone, keep cold food cold, at or below 40 °F (4.4 °C), and hot food hot, at or above 140 °F (60 °C).

Spoilage of food is not just an issue of quality; it is also a matter of food safety. USDA recommends following the to Food Safety (Clean, Separate, Cook, and Chill) to prevent food spoilage and reduce your risk of foodborne illness. Learn appropriate storage methods with the FoodKeeper app Learn about proper food and beverages storage with the,

1. It will help you maximize the freshness and quality of items by showing you the appropriate storage methods for more than 400 items.
2. By doing so you will be able to keep items fresh longer than if they were not stored properly.
3. It was developed by the USDA’s Food Safety and Inspection Service, with Cornell University and the Food Marketing Institute.

It is also available and as a mobile application for and devices. : Protecting Your Family from Food Spoilage

What are 3 factors that cause spoilage of poultry meat?

The primary causes of poultry products spoilage are as follows: Prolonged distribution or storage time. Inappropriate storage temperature. High initial bacterial counts.

What are three main causes of food spoilage?

There are mainly three types of causes of food spoilage viz. biological, chemical and physical causes. Biological causes comprise of growth and activity of microorganisms such as bacteria, yeast and moulds ; activity of food enzymes and damage due to pests, insects and rodents etc.

Chemical causes include reaction with oxygen and light and chemical reactions within food constituents. Physical causes consist of temperature and physical abuse. All of these factors can act together. For example, bacteria, insects, and light, all can be operating concurrently to spoil food in a field or in a warehouse.

Similarly, heat, moisture, and air at the same time affect the multiplication and activities of bacteria and chemical activities of food enzymes. The major types of spoilage that occur in foods are due to microbiological, biochemical, physical and chemical changes.

Growth and activity of microorganisms such as bacteria, yeast and moulds Activities of food enzymes, present in all raw foods, promote chemical reactions within the food affecting especially the food colour, texture and flavour Inappropriate holding temperatures (heat and cold) for a given food Gain or loss of moisture Reaction with oxygen and light causing rancidity and colour changes due to oxidative reactions Physical stress or abuse Damage due to pests, insects and rodents etc. Non-enzymatic reactions in food such as oxidation and mechanical damage

Spoilage due to growth and activity of microorganisms: Most significant deteriorative changes occur in foods due to microorganisms present in air, soil, water and on foods. They use our food supply as a source of nutrients for their own growth, which results in deterioration of food and render our food supply unfit for consumption.

Bacteria Yeasts Moulds Factors affecting growth of microorganisms Spoilage due to enzymatic activity Factors affecting enzymatic activity Spoilage due to insects, pests and rodents Spoilage due to chemical reactions Spoilage due to physical factors