Bacteria in Cooked Meat

As mentioned above, thorough cooking can generally destroy most bacteria on raw meat, including
pathogenic ones. Nevertheless, if there are subsequent lapses in food safety practices, food
poisoning may still occur. To start with, raw meat may be contaminated with spores of certain
pathogenic bacteria (e.g. Clostridium perfringens) and its spores are not readily destroyed by normal
cooking temperature. Heat of cooking can rather activate the spores to germinate and develop into
vegetative cells which can multiply rapidly in foods that are placed at ambient temperature for a
long period. Consuming foods that contain high levels of Clostridium perfringens vegetative cells
may lead to foodborne illness.

Beef

The most common pathogenic bacteria found in beef is Escherichia coli. The E. coli strain O157: H7 is
a rare, dangerous bacterium that can cause severe damage to the intestinal lining. Salmonella,
Staphylococcus aureus, and Listeria monocytogenes are also common contaminants in beef. All of
these organisms can be destroyed by cooking.

Pork

In pork, E. coli, Salmonella, S. aureus, and Yersinia enterocolitica are the most common bacterial
contaminants. Chitterlings (intestine) can be contaminated with Y. enterocolitica, leading to a
diarrheal illness known as yersiniosis. Microbial contaminants in pork can be destroyed by cooking to
an internal temperature of 145 °F.

Chicken

Chicken is often contaminated with Salmonella enteritidis. S. aureus, Campylobacter jejuni, L.

monocytogenes, and E. coli can also be found in chicken. Chicken should be cooked to an internal
temperature of 165 ° F to kill the microbes.

Spoilage under aerobic condition

1.) Surface slime, caused by Pseudomonas acinetobacter, Moraxella alcaligenes Streptococcus,

Leuconostuoc, Bacillus and Micrococcus.

2.) Change in colour of meat pigment. The red colour of meat may be changed to shades of green,
brown or grey by Lactobacillus and Leconostocs spp.

3.) Changes in fat. The unsaturated fat in meat gets oxidized by lypolitic bacteria which produce off
odours due to hydrolysis of fats and production of aldehydes and acids. This type of spoilage is
caused by lypolitic Pseudomonas, Achromobacter and yeast.

4.) Surface colour change. The red pigment producing bacteria, Serratia marcescens, caused red
spots on meat. Blue color surface is caused by Pseudomonas syncyanea and yellow color is caused
by Micrococcus species.
5.) Off odor and off taste. Volatile acid like formic, acetic, butyric and propionic acid produce sour
odor and Actinomycetes produce musty or earthy flavor. Yeast also cause sliminess discoloration and
off odor and taste defects.

6.) Aerobic mold also cause spoilage in meat. These are stickiness, whiskers, black-spot, white-spot,
green patches off odor and off taste.

Spoilage under anerobic condition.

i) Souring is caused by production of formic, acetic, butyric, lactic, succinic and propionic acid.

ii) Putrefaction. It is caused by decomposition of proteins under anaerobic condition by Clostridium

species. The foul smell is due to production of hydrogen sulphide, mercaptans, indol, scatol,
ammonia and amines.

10.4 Poultry Meat

Poultry meat like meat of other animals is also susceptible to contamination by various sources.
Contamination of skin and lining of the body cavity take place during various processing operations.
The organisms of great importance in poultry are Salmonella spp. and Campylobacter jejuni. Several
Gram negative psychrotropic bacteria viz., Pseudomonas, Acenitobacter and Flavobacterium have
also been isolated from poultry carasses. Ground turkey also may carry fecal streptococci. It is
important to freeze the poultry fast in order to keep it in good condition for several months.
Freezing further reduces the number of microorganisms in the poultry meat provided the
temperature is maintained quite low (-18 ° C or below).

Control of meat borne pathogens

Effective control of meat borne pathogens and enhancement of meat safety can be achieved by
control of latent infections among livestock, animal welfare and humane treatment, application of
antimicrobial interventions at the farm, during harvesting, dressing and product processing,
improvement in process food hygiene and potential application of new or novel processing and
preservation technologies. Animal stress can damage meat quality and lead to more contamination
and increased pathogen shedding. Antimicrobial intervention technologies can be used effectively to
improve the microbiological quality of meats. These technologies include reduction of contamination
on the raw product, minimization of microbial access to the products, reduction of contamination
that has gained access to the product, inactivation of the microbes on the product without cross
contamination and prevention and control of the growth of non-inactivated microbes, which have
gained access to the meat. An effective pathogen control at pre-harvest, postharvest, processing,
storage, distribution, merchandizing, preparation, food-service and consumption of meat include
activities employed during pre-harvest or in the field, during post harvest or processing in the plant,
at retail and food service and at home. Pre-harvest pathogen control interventions include diet
manipulation, use of food additives, antibiotic, bacteriophage therapy, and immunization of the
animals, complete exclusion, probiotics and proper animal management practices like pen
management, clean feed, clean and chlorinated water, and clean and unstressful transportation.
Antimicrobial intervention activities during harvest and post harvesting should be designed to
minimize introduction of microbial contaminants and reduce existing contaminant levels through
implementation of decontamination and sanitization interventions, processing treatments for partial
or complete destruction of contaminants and antimicrobial procedures for inhibition or retardation
of microbial growth. Certain inspection regulations should be followed in meat and poultry plants,
such as establishment of sanitation standard operating system, operations under the HACCP system
and performing HACCP verifications to meet microbiological standards, establishment of good
manufacturing practices (GMP) and good hygiene practices (GHP). Antimicrobial interventions used
to control pathogens in further processed meat products include physical hurdles (low and high
temperature, non thermal process like irradiation and high pressure and packaging treatments),
physiochemical interventions (low pH, reduced water activity, modification of oxidation reduction
potential through packaging and application of antimicrobial additives), and biological interventions
(microbial competitors, such as lactic acid bacteria and antimicrobial products, such as bacteriocins).
Events of the most food borne illness happen due to mishandling of foods in various ways. So, there
should be provisions to educate the food handlers and consumers particularly on culinary tips.

Preventing Contamination in Different Kinds of Meat

Food poisoning due to microbial contamination of meat can be prevented by cooking the meat
thoroughly before consumption and observing good hygiene practices when cooking and handling
meat. This includes the use of clean utensils, cutting boards, knives, and prevention of cross-
contamination between raw meat and ready-to-eat foods. If there is a lapse in safe handling
practices, cooked meat may still become tainted through cross-contamination. The ready-to-eat
cooked meat should be discarded if it has been held at room temperature for more than 4 hours. If
the cooked meat is held at room temperature for less than 2 hours, it can be refrigerated for final
use later or used before the 4 hours limit is up.