The sources of microorganisms can be broadly classified as:

Microbial Contamination

• Microbial contamination refers to the non-intended or accidental introduction of microbes such as bacteria, yeast,mould, fungi, virus, prions, protozoa or their toxins and by-products
• Mould often occurs if food is stored at the wrong temperature, at high humidity or beyond its recommended shelf-life.
• Viruses may be brought into food premises on raw foods such as shellfish which have been bought from an unapproved       
• Bacteria also rely on other things to transfer them to food. These things are known as vehicles. Examples of vehicles  include: hands, knives, cloths, equipment, food-contact surfaces.  Bacterial cross contamination may be defined as:   “the transfer of harmful / pathogenic bacteria from one item /        food / surface / person to food”.

Direct cross contamination

This occurs in food when there is direct contact between the source of the bacteria and food. For eg: Raw meat stored above or in contact with cooked meat, Raw chicken stored above or in contact with Coles law, Food handler sneezing/coughing onto food

Indirect cross contamination

This occurs when harmful bacteria are transferred from the source to the food via a vehicle. For eg: Using the same knife/chopping board to slice raw meat and then cooked meat without washing it and disinfecting it between tasks, Using the same cloth to wash down the raw food preparation area and then the cooked food preparation area, Touching food after blowing your nose, without first washing your hands

Physical Contamination

• Food can be contaminated physically by foreign objects.
• Foreign objects can be brought into the premises with raw materials or introduced during storage, preparation, service or
• Improper sanitary habits and unhygienic behavior becomes a link between pathogen and meat contamination
• Foreign objects which are commonly associated with food complaints include: Nuts, bolts, wire, metal, Transportation        Vehicles, Operatives (involved in butchering operations),     Cardboard, plastic, string , Rodent droppings, hairs, Cigarette butts, glass, flaking paint , Plasters, earrings, fingernails

Chemical Contamination

• Chemical contamination occurs when various chemicals enters the environment of raw meat.
• Chemically contaminated meat degrades the quality and makes it undesirable for consumption.
• Undesirable chemicals can enter foodstuffs during:
• Growth – e.g. veterinary drugs, fertilizers, pesticides and environmental contaminants. For e.g. lead
• Processing – e.g. oils and lubricants, cleaning chemicals, Use of Disinfectants
• Transport – e.g. as a result of spillage or leaks
• Sale – e.g. cleaning chemicals Washing and Sterilization

Various Points of Contamination in an Abattoir

• Lairage/Holding
• Stunning Area
• Sticking/Bleeding Area
• Carcass Dressing Area
• Area of Evisceration
• Area of Making Wholesale Cut
• Condemned meat room
• Detained Meat Room
• Hide and skin store
• Gut and tripe room
• Red offal room
• The edible fat rooms
• Cutting rooms
• Equipment washes
• Fresh meat dispatch area