Meat Production Contamination

Contamination in Meat Production

• The deep muscle tissues of healthy, slaughtered livestock contain few, if any, microorganisms.
• Exterior surfaces (hide, hair, skin, feathers) of healthy animals and birds are naturally contaminated with a variety of microorganisms.
• Each processing step subjects the carcass to opportunities for contamination with microorganisms from the exterior surfaces, utensils, equipment, and the gastro-intestinal tract.
• Cutting of carcasses involves the use of utensils and equipment, which transfers microorganisms to the cut surfaces.
• Theoretically, removal of the skin should expose the sterile surface of the muscle, but in practice, the extra handling contributes significantly to the bacterial load on the surfaces.

Sources of Contamination

• Exterior surface of the animal
• Contents of the gastro-intestinal tract
• Equipment and utensils
• Workers' garments and hands
• The abattoir itself (e.g., air, floor drains)
• Water (and if used, ice)

Control of Contamination

• Use properly cleaned equipment
• Ensure that the abattoir is properly cleaned/sanitised
• Use hygienic methods of dressing that control contamination
• Clean utensils at appropriate intervals during the process
• Apply a high standard of personal hygiene

Microbial Load on Meat

• Meat with a good shelf-life has 10^2-10^4 organisms per cm^2
• Exterior surfaces of healthy, live animals and birds are naturally contaminated with large numbers of a variety of microorganisms (10^7 organisms per cm^2)
• The soil (ground) is also a major source of microorganisms (10^7 bacteria per gram of soil)
• Faeces are about 100 times more contaminated (10^9 and 10^8 per gram of faeces, respectively)

Importance of Clean Animals

• It is extremely difficult to obtain clean meat from dirty animals or birds
• Only relatively clean animals should be presented for slaughtering
• Cleanliness of livestock depends on husbandry, weather, climate, methods of transport, and holding conditions at the abattoir

Foodborne Diseases

Definition

• A foodborne disease is an illness in humans in which the food is or contains the causative agent

Agents of Foodborne Diseases

• Bacteria: Salmonella spp., Staphylococcus aureus, Clostridium perfringens, Campylobacter jejuni/coli, Clostridium botulinum, Bacillus cereus, certain strains of Escherichia coli, and Listeria monocytogenes
• Chemical substances: ciguatera, scrombroid, paralytic shellfish poisoning
• Parasites: Giardia, Trichinella
• Viruses: hepatitis A, Norwalk

Foodborne Disease Mechanisms

• Infection: The food acts as a vehicle to transport the infectious agent into the gastrointestinal tract where the microorganisms colonise and produce illness
• Intoxication: Microbial growth in the food causes the production of toxin(s) in the food prior to ingestion
• In Vivo Intoxication: The food acts as a vehicle for organisms that form toxin in vivo

Events Necessary for Foodborne Illness to Occur

• The causative agent must be present in the food
• The causative agent must be present in sufficient numbers (e.g., bacteria) or high enough concentration (toxin) to survive normal handling of the food
• A sufficient quantity of food containing enough of the agent to exceed a person's resistance must be ingested
• The resistance of individuals in a population varies greatly

This quiz covers contamination in meat production from slaughtered livestock, processing, and handling. It discusses the sources of microorganisms and the risk of contamination during each step.