meat contamination

8/6/2019 Meat Contamination

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ALTAF HUSAIN +923365167383

UAAR, RAWALPINDI, PUNJAB, PAKISTAN

MEAT CONTAMINATION

Meat

The edible flesh of animals, especially that of mammals as opposed to that of fish or poultry.

But in broader meanings it also includes the birds, fish and snails.

Contamination

The presence of extraneous, especially infectious, material that renders a substance or

preparation impure or harmful.

Meat contaminationAs meat constitutes a main portion of the diet of most people in Pakistan, millions of

animals are slaughtered and thousands of tons of meat are supplied daily to the market. Meat is a

highly nutritious edible portion of animals, and has a very high percentage of proteins (about 20%),

fats (about 10%) and has very low concentrations of carbohydrates. Meat also has a high

percentage of water content, about 75%.

All these factors make it very susceptible for microbial attack. It provides an ideal

environment for the growth of a wide range of microorganisms that include pathogenic bacteria


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such as Listeria monocytgenes, Clostridium perfrinenes, C. botulinum, E. coli and also Salmonella,

Yersinia, Campylobacter and Pseudomonas, etc. These organisms can cause listeriosis, botulism,

severe diarrhoea, vomiting, abdominal pain, fever, nausea and much more.

Infected animal meat may also be a potential source of infectious, tumour and haemorrhagic

viruses that may become active in non-permissive and common hosts. Cryptosporadium parasites

that cause diarrhoea and nausea, and prions may also be present in the meat of the infected

animals. Prions are small proteinaceous infectious particles that can transmit infectious diseases

such as Mad Cow disease. Although the risk of transmission of Mad Cow disease through the food

chain is considered to be low, it is not zero. The transmission of this disease by the ingestion of

contaminated meat has been documented.

Meat spoilage organisms include bacteria such as Acinetobacter, Moraxella, Alcaligenes,

Micrococci, and moulds and yeast, etc. Cooking of meat can destroy these spoilage and pathogenic

organisms but the occurrence of heat-resistant spores and the heat-resistant toxins of these

organisms cannot be ruled out. The chance of survival of these organisms are particularly high in

some partially cooked items, such as steaks and barbecue, in which the interior of the meat remains

uncooked.

Microbiological contamination in the meat processing chain

1. Carcasscontaminationduringslaughtering Unavoidable keep as low as possible.2. Meatcutting No reduction of contamination possible, but further contamination should be

prevented.


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3. Further processing No reduction of contamination possible, but prevent furthercontamination and create challenges / hurdles for microbial growth and survival (aw,

preservatives).

4. Heat treatmentof final product Pasteurization (approx. 80C): Substantial reduction ofcontamination, but products need refrigeration. Sterilization (above 100C): Total

elimination of contamination, products can be stored without refrigeration (in sealed food

containers).

Types of meat contamination

1. Fresh meat contamination2. Meat preparations contamination3. Poultry meat contamination

Fresh meat contamination

Quantitative contamination

Slaughter

In general meat of a carcass is sterile just after slaughter. If the animal became stressed just

before slaughter, the meat can be contaminated. Depending on the animal species, the number of

germs can amount 103/g in that case.

During bad evisceration, bacteria can enter the intestines of the muscles and cause bonetaint (discolouration of the meat in the neighbourhood of the bone). Via the blood stream

contaminated knives can also contaminate the meat. But with good manufacturing practices during

slaughter only 1 bacteria /10-100 g meat is present.

Deskinning


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During deskinning contamination takes place via the skin, knives, hands, cloths, water and

equipment. With GMP applied, the following counts are registrated:

Cattle: total germs : 103 105 /cm2

Enterobacteriaceae : 10 102/cm2

Sheep : total germs : 103 106/cm2

Enterobacteriaceae : 103/cm2

Pork: total germs : 103 106/cm2

Total Enterobacteriaceae is high as the skin is not removed.

Cooling

Due to rapid cooling at low temperature and high air velocity, total counts on the surface of

the carcass can decrease. When the cooling occurs badly, total counts can increase; with the

mesophilic count increasing more rapidly than the psychrophilic one. As pathogens are mesophilic,

the risk for food intoxication will then increase. GMP rquires rapid cooling under30 C

Cutting to pieces, deboning and packaging

During deboning and cutting to pieces, the relative surface will enlarge and the number of

germs a gram will increase. The count depends on the initial contamination of the carcass, thehygienic conditions and the temperature/time conditions of the treatment. Good results are

obtained at 10C and on the conditions of efficient cleaning and disinfecting of the equipment.

Qualitative contamination

Saprophytes

Gramnegative rods: Acinetobacter, Moraxella, Aeromonas, Alcaligenes, Flavobacterium,Pseudomonas, Enterobacteriaceae

Gram positive rods: Corynebacterium, lactic acid bacteria, Microbacteriumthermosphactum, Bacillus

Gram positivecocci: micrococci, staphylococci, faecal streptococci Yeastsand moulds

Pathogens


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Salmonella, Escherichia coli, Yersinia enterolytica, Staphylococcus aureus, Clostridium

perfringens, Clostridium botulinum

Organ meat contains higher counts than muscle meat. Its pH is higher and organs act as

physiological filter.

Meat preparations contamination

Minced meat preparations have a high microbial load due to:

the meat originating from different parts of the carcass that are treated intensively andmicrobiological highly loaded

Mincing enlarging the relative surface and the number of germs a gram The equipment is contaminated

Some of the spices used are microbiological highly loaded

The intestinesQuantitative contamination

Transport and stunning

During transport of poultry, cages, feathers and legs are contaminated with Acinetobacter-

Moraxella, Pseudomonas, corynebacterium, Micrococcus, Staphylococcus, flavobacterium and

yeasts. Typical is the faecal contamination during electrical stunning (contraction of the cloaca with

faeces contaminating the carcass).

Scalding

During scalding the poultry is submersed in hot water during 2-3 minutes at 60-63C.

Scalding is needed to defeather the poultry. The hot water contains 50000 germs/ml. During the

heating process the mesophilic count on the carcass decreases from 107/cm2 to 104/cm2, and the

psychrotrophic count decreases from 104/cm2 to 102/cm2.

Defeathering

During defeathering the total count increases. Especially in the feather follicles there is anaccumulation of micro-organisms. The mesophilic number increases from 104 to 105/cm2. The

psychrophilic count remains constant. During defeathering, contamination with Salmonella is

critical.

Evisceration


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During good evisceration, no quantitative increase of the microbial load may occur.

Qualitatively, contamination with Enterobacteriaceae may occur. There is risk for cross

contamination between man and equipment.

Rinsing

Rinsing occurs by spraying with water that contains 40-60 ppm chlorine. Water

contaminated with Pseudomonas is a disadvantage for the microbiological quality of the poultry. By

rinsing, 50 to 90% of the germs is mechanical removed.

Cooling

Cooling of the poultry carcass can in several ways:

in static tanks (1/3 ice, 1/3water, 1/3 carcasses) during 4-24 hours : the psychrophiliccount increases and there is cross contamination with salmonella

by continuous immersion in cooled water (with or counter stream, during < 1 h at 4C : totalcount remains constant, but there is cross contamination with salmonella

by air cooling : light drying of the skin : total number remains constant

Weighing and packaging

Total count is determined by GMP. Cross contamination with Salmonella remains risky.

Qualitative contaminationAt the end of the slaughter process, the microbiological contamination is as follows:

The meat is sterile when slaughtered On the skin there are 104 105 total germs per cm2, with the following species:

Pseudomonas, Acinetobacter-Moraxella, corynebacteria, micrococci and

enterobacteriaceae.

Pathogenic germs: Salmonella, Campylobacter, Yersinia enterolytica, Staphylococcusaureus, Clostridium perfringens and Escherichia coli.


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Fish, crustaceans and molluscs

Quantitative contaminationFreshfish

Fish meat is sterile. Skin, gills and intestines are contaminated:Environment Skin Gills Intestines

Pure cold water 102/cm2 103/g 103/g

Polluted tropical and subtropical water 107/cm2 109/g 109/g

Additional contamination on board and land is determined by the GMP. Contamination

occurs mainly via boat room, equipment, ice and man.

Treatments aboard increasing the contamination: gutting, rinsing (with sea water), storage

in ice. On land, contamination occurs as follow: unloading, deboning, gutting, cutting into pieces,

packaging and transport.

Crustaceans

Crustaceans in cold water contain 105 germs/g. In warn water, they contain 105-106

germs/g.

Molluscs

Oysters and molluscs contain 104 to 106 germs/g.

Qualitative contamination

Freshfish

Fresh fish from cold water is mainly contaminated with psychrophilic Gram negative germs

like Pseudomonas, Acinetobacter-Moraxella, Flavobacterium and Alcaligenes. Fish from warm

water is contaminated with Gram-positive germs like Corynebacterium, Bacillus, and Micrococcus.

Storage in ice gives more than 90% Pseudomonas spp.

Fish from polluted zones or treated unhygienically can be contaminated with Salmonella,

Enterococci, Staphylococcus aureus, Clostridium botulinum type E. In living fish, 2 pathogens can

survive: Clostridium botulinum type E and Vibrio paraheamolyticus (in warm water).

Crustaceans

Crustaceans from cold water are contaminated with Pseudomonas, Acinetobacter-

Moraxella and Flavobacterium (Gram-negative psychrophilic bacteria). Crustaceans from warm


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water are contaminated with Gram-positive corynebacteria and micrococci. The pathogens

observed in Crustaceans are the same like those observed in fish.

Molluscs

In Molluscs, no to little Gram-negative germs are present. The following Gram-negative

germs are found: Vibrio, Pseudomonas, Acinetobacter-Moraxella, Flavobacterium and Cytophaga.

Molluscs cultivated in estuaries that are highly contaminated, can be contaminated with

enteropathogens originating from manure. Typical are Salmonella, Shigella, Vibrio cholerae,

Escherichia coli, Clostridium botulinum, Clostridium perfringens, Staphylococcus aureus and some

viruses.

Conditions of Slaughter houses in Pakistan

Before reaching the consumers, meat is exposed to several undesirable conditions. In

Pakistan, the condition of the slaughter houses of the big cities is deplorable, whereas villages and

small cities have no slaughterhouses available. It is commonly seen that the carcasses are placed on

the floor in blood, dirt and dung for several hours before being transported. The time of the

transportation of meat is also very long due to mismanagement and old means of transportation.

The meat is transported in open vehicles in which it is exposed to dust, dirt, smoke and personally

acquired infectious agents. Therefore, meat can be a potential source of food infection and food

poisoning.

Slaughterhouse hygiene problems and solutions

Main problems in bovine and large ruminant slaughtering

Severe hygienic problems in the slaughtering of cattle and buffaloes in many places stem

from the difficulty in handling these heavy carcasses where there is inadequate or no slaughter

equipment available. Proper equipment for handling bovines includes manual or electric hoists for

lifting up the carcass getting it off the floor for flaying, eviscerating and splitting.


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In traditional slaughtering, bovine carcasses are placed with the back on the ground. In this

position the hide is loosened from the carcass, starting from the hind leg, belly and forelegs. The

hide serves as protection of the meat surfaces from direct contact to the ground. Evisceration also

takes place in this position. This procedure is the only possible method in rural slaughtering and

may work reasonably well, if only one or two animals are slaughtered carefully and without time

pressure. As soon as more animals are brought to be slaughtered in the same location, such as at a

commercial slaughter slab in which workers are usually under time pressure, heavy bacterial loads

on the meat through cross contamination cannot be avoided.

Often, in the case of using hoists for relatively hygienic flaying, eviscerating and carcass

splitting, the forequarters or even both fore and hindquarters are dropped to the floor afterseparating them from the suspended carcass sides. All efforts at having slaughtered and dressed the

carcass hygienically are thus spoiled.

Main problems in small ruminant slaughtering

Slaughtering of sheep and goats is technically easy. Even with simple equipment it can be

done in a clean and hygienic manner. The exception are sheep breeds with large amounts of wool,

in which a great deal of cross contamination from hair to skin can occur if no proper equipment toassist the skinning process is available, such as a skinning line that suspends the carcass in a

horizontal position using the four legs.

Meat contamination of short-haired species during skinning and eviscerating usually can be

kept minimal if simple equipment for carcass suspension is available, such as wall hooks or racks

with hooks (in small operations) or hooks or gambrels attached to an overhead rail in larger

operations.


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Hygienic problems in slaughterhouses for small ruminants are mainly caused by the absence of

a carcass suspension system or handling negligence, such as:

Slaughtering on the floor without the possibility of hanging the carcass; Hanging too closely together both un-skinned and skinned carcasses in the slaughter line,

resulting in contact of hair or skin to already-skinned carcass parts;

Carcass suspension too low, with forelegs and shoulders touching the floor; Careless evisceration that spreads intestinal content onto the meat surface.

Solutions

At the occasion of Eid-ul-Azha, almost every Muslim family follows the religious ritual of

offering the sacrifice of animals. By the time the animal is sacrificed, it has gone through immense

amount of stress. It is necessary for animals to be stress- and injury-free during operations prior to


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slaughter so as not to exhaust muscle glycogen reserves. If the glycogen in the tissues is exhausted

and rigor mortise sets in, the whole carcass becomes stiff due to the contraction of the musclefibres. If the meat is cooked when the muscles are still in rigor, it is extremely tough and tasteless.

This condition is prevented by aging or ripening the meat after slaughtering it, which is achievedby storing the meat at room temperature until the muscles gradually recover their extensibility and

become more tender through partial enzymatic breakdown of muscle fibres. At this stage, rigormortis is said to be resolved. Rigor is completed in cattle after 12-24 hours and is resolved by the

time periods that depend on the temperature 10-11 hours at 30 C. Aging also leads to

improvement of flavour. If lamb and, to a lesser extent, beef are chilled too rapidly after slaughter of

the animal, the muscles may undergo extreme contraction or cold shortening which results in the

meat being very tough when cooked.

Cold shortening does not take place when the carcass is cooled more slowly, and the

temperature must not fall rapidly below 10 C. To achieve this, the carcass is placed at room

temperature for some hours to accelerate rigor and then it is rapidly chilled or frozen. This process

is called conditioning.

The long distance that the animals are transported to, poor transport facilities, poorhygiene, high surrounding temperature and lack of refrigeration after slaughter, lead to heavy

contamination, growth of microorganism, considerable losses from spoilage and chances of food-

borne illnesses. All this can be aggravated by inadequate care of the meat during transportation and

in the market. Particularly in case of shipment of the meat to great distances, it is essential to adoptsophisticated techniques and methods of refrigeration. The meat should be transported in closed

containers and vehicles, properly wrapped in polythene and hanged instead of being placed on the

floor of the vehicle with people sitting on it.

Beside these, a board having highly qualified professionals and microbiologists should be

established to look after equality control, conditions and health of animals and the conditions of the

slaughterhouses.

meat contamination

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