0.4 Food safety: introduction to control of food hazards- general  (Page 4/6)

Staff members who show symptoms of viral infection should be identified and kept away from food processing areas. If a food handler has a viral infection, then it is very easy to spread that virus. It is good practice to have a return to work policy in place for staff who have been absent as a result of a viral infection, allowing you thus to identify any viral symptoms that may still be present.

Viruses can be transmitted in water; potable water must, therefore, be used for ice- making or as an ingredient in food.

Parasites

Parasites can be uni-cellular or multi-cellular microorganisms. They can colonize in the gastrointestinal tract of humans and other animals.

More often than not these parasites have really complex life cycles where they may be in a human’s intestinal tract for a long period of time and shed cysts. These cysts are a protected form of themselves and can infect other people or animals when they are consumed.

The most common food-borne parasites are protozoan parasites and parasitic worms.

Protozoan parasites

Protozoan parasites, which are uni-cellular organisms, are the most common food-borne (or water-borne) parasites. They are so common in some parts of the world that they are endemic. Examples of protozoan parasites include

• Giardia lamblia
• Cryptosporidium parvum
• Cyclospora cayetanesis
• Toxoplasma gondii

Parasitic worms

Parasitic worms are small, multi-cellular organisms which can colonize in the gastrointestinal tract or other tissues of humans or animals.

Some common parasitic worms include

• Anasakis simplex and related worms
• other seafood-associated parasitic worms
• Trichinella spiralis and related Trichinella species
• Ascaris lumbricoides and Trichuris trichiura .

Controlling parasites

Since parasites can be found in feces, there is a risk of contamination when using manure for fruit and vegetable crops. Consider using compost that does not contain manure to remove the risk of this parasitic contamination.

Since parasites can live in water, you must use potable water for the washing, packing, and processing food products.

Thermal processing can destroy parasites; so if appropriate, use this treatment to remove the parasite risk.

General control points for biological hazards

Product Specification

It is important to be aware of the presence and number of microorganisms in food. Many raw materials, therefore, have microbiological standards. It is common in the food industry to have specifications for the absence of microbiological contaminants.

Control Mechanisms

Physical and chemical control mechanisms significantly affect the survival and multiplication of microorganisms; for example, a reduction in pH in fruit juice by the addition of ascorbic acid can prevent microorganisms from multiplying.

Time and temperature are important control points since cooking or freezing rapidly can prevent the growth of biological contaminants. Freezing usually stops the multiplication of microorganisms; however it does not kill them. Thermal processing will kill most biological hazards.