Chapter 2 : Microbiological Hazards

Microbiological hazards refer to those microorganisms (microbes) which can contaminate food. Microorganisms can take various forms.

Bacteria are single-celled microscopic organisms which can be killed by heat and the treatment of food with some chemicals. Viruses, mould, parasites and certain strains of yeasts are other microbiological hazards.

Microbiological hazards include food poisoning bacteria such as Salmonella, E.coli andBacillus Cereus. Bacteria are very small, visible only when examined under a microscope.

If food poisoning bacteria are present in food, the food may look, smell and taste normal. If such food is eaten it may result in illness, such as sickness and diarrhoea, and even cause death in some situations.

These food poisoning bacteria are hazardous because they can :

Survive inadequate cooking, if already present in food, for example, Salmonella in chicken

Multiply to harmful levels in food given the right conditions, for example, poor temperature control during storage, handling or hot holding

Spread from raw foods such as meat, poultry and unwashed vegetables to cooked/ready-to-eat foods either directly or via food handlers, work surfaces and equipment - this is known as "cross contamination".

WHAT BACTERIA NEED TO GROWTH

A potentially hazardous food is a natural or synthetic food that needs to be held at 41°F or colder or 135°F or hotter because it is in a form capable of supporting:

1. The rapid and progressive growth of infectious or toxigenic bacteria

2.the growth and toxin production of Clostridium botulinum or

3.in raw shell eggs, the growth of Salmonella Enteritidis

Potentially Hazardous Food 

Potentially hazardous foods include foods of animal origin that

are raw or heat-treated, a food of plant origin that is heat-treated

or consists of raw seed sprouts, cut melons, and garlic-in-oil

mixtures that have not been properly acidified to prevent the

growth of pathogenic bacteria.

a potentially hazardous food does not include:

1. an air cooled hard -boiled egg with shell intact, or a shell egg that is not hard-boiled but has been treated to destroy all viable salmonella. Such as pasteurized shell in the eggs.
2.  A food with a water activity value of 0.85 or less, such as jams or jellies.

A food with a pH level of 4.6 or below when measured at 75°F, such as properly prepared sushi rice or pickles.

A food, in an unopened hermetically sealed container, that is commercially processed to achieve and maintain commercial sterility under conditions of non-refrigerated storage and distribution.