Sources Of Food Contamination And Poisoning

Food Poisoning

This is the general term for health problems arising from eating contaminated food. Food may be contaminated by bacteria, viruses, environmental toxins or toxins present within the food itself, such as the poisons in some mushrooms or certain sea foods.

Symptoms of food poisoning usually involve nausea, vomiting, and diarrhea. Some food borne toxins can affect the nervous system.

Sources Of Food Contamination And Poisoning

Food contamination most often occur when;

1. Foods or drinks come in contact with organisms in fecal matter.

2. Eating foods raw without proper washing.

3. Meat, egg and diary products are frequently contaminated resulting from the crowded conditions in many animal processing facilities.

4. Water may be contaminated with organisms that cause illness, especially in areas where water treatment is uncommon or not well managed.

Types Of Food Poisoning

1. Norovirus: This is a contagious virus responsible for more than half of food poisoning cases. It is usually spread by unsanitary food preparation. Cooks or servers who do not wash their hand before touching food can spread the norovirus.

2. Botulism: This is a rare illness caused by bacteria that grow in foods that have been improperly canned or preserved.

3. Escherichia Coli: E. Coli is a type of bacteria found in the intestines of all humans and animal. The bacteria may contaminate meat during processing. It can also seep into foods that are not properly prepared safely.

4. Salmonella: It is a type of bacteria in the intestines of animals. It can live in animal products such as meat and eggs. It is important to cook foods long enough or at high temperature to kill salmonella present.

Methods Of Handling Left-over Food To Avoid Contamination

Most people hate to throw out food that has not been eaten at the end of a meal. At the same time, improper handling and storage of leftovers is one of the most common causes of food poisoning in the home. However, with care, it is possible to avoid both waste and illness. To avoid contamination;

1. Refrigerate or freeze left over food within 2 hours after preparation.

2.Refrigerate in small portions in separate containers different from those used during the cooking, shallow containers are better.

3. Reheat leftover and refrigerate food to proper temperature before consumption. Always reheat leftover refrigerated foods rapidly to 165 of before serving.

Sensory Signs Of Spoilage And Causative Micro Organisms

Food Spoilage

Food spoilage refers to undesirable changes taking place in the food which eventually leads to the rejection and therefore to wastage. This does not include food which is unfit for consumption for sanitary reasons.

Sensory Signs Of Food Spoilage

The appearance of food will change due to spoilage. These include:

1. Change in colour.

2. Change in texture.

3. Unpleasant odour​.

4. Undesirable taste.

5. Softer to the touch.

6. Mould may be visible externally.

Causes Of Food Spoilage

Food spoilage can be caused by the following;

1. Action of Micro-organisms e.g. Bacteria, yeast and moulds.

2. Insects.

3. Food enzymes.

4. Chemical reactions in the food.

5. Physical changes due to freezing, burning, drying, pressure, etc.

Micro-Organisms In Food Spoilage

The air around us contains micro-organisms which are simple forms of plant life that are clearly seen through a microscope. There are many types of microorganisms, the ones that concern us most, as far as food poisoning is concerned are three main types: bacteria, yeast and mould.

Conditions That Favour The Growth Of Microorganisms

The conditions that favour the growth of micro-organisms are:

1. The nature of the food.

2. Air.

3. Moisture (Water).

4. Warm temperature

5. Darkness.

1. The Nature Of The Food: Micro-Organisms need food to grow and multiply. They thrive better on foods that contain large amounts of water such as meat, fresh fish, soups and sauces. They also prefer cold cooked foods and cold processed foods like miced meat and fish.

2. Air: Air is required by aerobic bacteria to grow and multiply, but some anaerobic micro-organism like yeast and clostridia botulinum do not require it.

3. Moisture: Moist condition and water encourage the growth of microorganism especially fungi. Foods are best stored in dry airy cool stores.

4. Warm Temperature: Warm temperature, about 37 oc, encourages the growth and multiplication of micro-organisms. Some are destroyed at temperature above 70 oc. All micro-organisms are killed if the temperature is raised to 105oc, for one hour duration. Low temperature slows down the rate of growth of micro-organisms but do not kill them.

5. Darkness: Darkness encourages the growth of microbes but sunlight destroys most of them.

Causative: Micro-Organisms In Food Spoilage

1. Bacteria: Bacteria are the most dangerous pathogenic living organisms that cause food poisoning. In the presence of moisture and warmth bacteria will grow and multiply very quickly and spoil the infected food. As it breaks down the food, acids and other waste products are created. Among the dangerous bacteria are salmonella, clostridia and staphylococcus.

2. Yeast: Yeast can be responsible for the decomposition of food with a high sugar content e.g. Bread, yoghurt and beverages. Yeast consume the sugar in the food and convert it to alcohol and carbon dioxide which is given off. Yeast growth is restarted by low temperature but stopped in a concentrated sugar solution up to 65 oc or more.

3. Mould: Moulds grow on foods that have been stored for a long time under a humid atmosphere or a low temperature of about 20oc-40oc. Moulds grow from tiny cells called spores which are carried in the atmosphere. When mould spores settle on food, they infect it and grow on the food which eventually becomes mouldy. Mouldy foods are unfit for human consumption and should be thrown away.

The presence of mould on food also indicates that the food could be infected by bacteria. Foods that are easily attacked by moulds are bread, biscuits, left-over boiled foods, etc.