Sources Of Food Contamination And Poisoning In Home Economics

What Is Food poisoning?

Food poisoning is also known as food borne diseases, caused by food contaminated with pathogenic agents like viruses, bacteria, parasites or toxins.

This is caused by infectious organisms.

When one eats food infected with pathogens, it can lead to inflammation of the lining of the gut, particularly of the stomach and intestines.

What is a microorganism?

A microorganism is a microscopic organism that can be seen only through a microscope. They are often referred to as microbes or germs. The human body is full of microorganisms, and many of them are useful for our health

Sources of Food Contamination and Poisoning

There are major sources of food contamination. It can be from the air, water, dust, equipment, insects, sewage, employees and rodents.

Other sources of Contamination could be from the soil, live animals, external surface and the internal organs of infected animal meats.

Food poisoning can occur from chemical sources through accidental mixing of chemical supplies with foods.

Chemical contamination or microbial contamination can be contributed from ingredients.

There are 3 main sources of food contamination and poisoning

1. Contamination from the source:

E-coli or Salmonella contaminates meat like the ground beef, raw veggies, milk and eggs.

Contamination may begin with the machines that are designed to process and package the food in food industries.

These raw or processed foods are exposed while in or on the ground through contact with infected animal faeces, contaminated ground water or bacterial infections.

According to research, eggs are always infected before they are laid by the hen through Salmonella present in the hen’s ovaries.

2. Contamination during pre-processing of food

Meats from the slaughter houses are sources of contamination and food poisoning with pathogens can also occur during transit.

3. Contamination during processing of food

During food processing, Environmental contaminants like metal sharing and chemicals used to operate and maintain the machines may be contaminated.

Food industries should always apply safety measures to ensure food is safe during processing.

Contamination of food can occur due to lack of proper care, maintenance and use of machines and break through in the Ventilation system that leads to the processing area.

High heating can reduce contaminants during food processing.

Types of Food poisoning

Some food contaminants cause Vomiting, Stomach cramps and so on.

There are 250 different types of food poisoning documented but the most popular ones are Salmonella, Listeria, E-coli and Norovirus, also known as “Stomach Flu”.

Other food poisoning includes Botulism, Vibrio Vulniticus, Camplylobacter, Shigella, Staphylococcus aureus e.t.c


Food poisoning can be caused by a virus such as Sapovirus, Astrovirus, norovirus (norwalk virus) rotavirus and hepatitis A virus.


These are by far the most common cause of food poisoning which includes E-coli, Salmonella( which is the biggest cause), Listeria monocytogenes, Campylobacter, Clostridium, botulinum, Shigella, Staphylococcus Aureus and Vibrio.


These are type of food poisoning caused by parasites, tho not common as bacteria food poisoning. They Include; Taenia Solium or pork tape worm, toxoplasma gonoli, giardia lamblia, Diphyllobothrium latum, Cryptosporidium, flat worms, Trichinella and Ascaris Lumbricoides.

According to the Center Disease control, Toxoplasmosis is a leading cause of death relating to food poisoning in the USA.

Methods of Handling Left-over Food to Avoid Contamination

1. Use clean utensils to handle leftover food and use a clean container to store.

2. Refrigerate leftover food within two hours of preparation to reduce the chance of Bacteria growth.

3. Reduce hotness of a leftover food to discourage rapid bacteria growth.

4. Dispose leftover foods kept in the refrigerator for 3-4 days.

5. Reheat leftovers before eating.

6. Wash your hands with soup and clean water before handling any cooked food, most especially food you intend to store and eat later.

7. Store with clean containers.

8. Do not put food back into the same container used before preparing the food.

9. Never rely on your nose, eyes or taste buds to know how safe the food is. You cannot tell if the food is already contaminated by its smell, look or taste.

10. Discard food when in doubt.

11. Do not re-freeze foods that you have defrosted in the microwave.

12. Use only clean containers and plastic wrap designed for use in the microwave

What Is Food Spoilage?

The process where food product becomes unsafe to eat by consumer is known as FOOD SPOILAGE.

Food Spoilage means the taste, color, texture, flavour, look and nutritional value of a food is undesirable and unacceptable for consumption.

There are various factors that causes food spoilage and making them unsafe to ingest. They include; Oxygen, Air, Enzymes, Microbes, Light, Humidity, heat, bacteria that causes food spoilage and temperature.

All these factors affects the physical and chemical properties of food.

Sensory Signs of Food Spoilage

Know the signs of food spoilage when preserving food by drying, freezing or canning. It is very important in preventing a food borne infection.

1. Rising air bubbles or gas
2. Leaking
3. Foul odor
4. Change in color
5. Foamy
6. Sliminess
7. Dried food on top of containers
8. Cotton mold growth at the top or under the lid
9. Strange texture
10. Damaged package or frost
11. Canned food
12. Fish spoilage signs
13. Flavour deteriorates
14. Change in taste

Causes of Food Spoilage

There are various factors causing food spoilage such as:

1. Bacteria- which are most abundant on earth and they vary in shape and size.

2. Protozoa, which are single-celled microbes that causes illness like food poisoning

3. Fungi are mainly found in damp and warm places. They grow on the dead or rotten things.

4. Temperature is another factor causing food spoilage.

5. Improper Storage also lead to food spoilage.

6. Improper handling can also cause food spoilage.

7. Inadequate preparation and cooking of the food can cause food spoilage.

8. Careless packaging.

9. Invasion of harmful pathogens.

Microorganisms in Food Spoilage

Microbes found in spoiled or damaged food are Yeasts, mold, staphylococcus Aureus, Fungi, Aspergillus, Alternaria, Brochothrix, Aspergillus Versicolor, Alicyclobacillus acidoterrestris

Conditions that Favour the Growth of Microorganisms

1. Ideal temperature range for microorganisms:

Certain microorganisms can grow in any temperature. However, many of them thrive when the temperature is just right.

In general, microorganisms grow best at a temperature that is neither too low nor too high. When the surrounding temperature is too low, their metabolic activities are slowed down.

When it is too high, they may be killed or die out. The temperature range that favors the growth of microorganisms is from 20 to 38 °C. This is the ideal temperature range for the human body.

2. The presence of moisture:

The presence of moisture is important for a microorganism to grow. It helps these organisms to reproduce, grow and thrive. When the surrounding environment is humid, it increases the risk of infection.

Not all microorganisms are able to thrive in moist conditions and some thrive in dry conditions.

The presence of moisture within a particular environment can be measured using a hygrometer.

3. The availability of food:

The availability of food is essential for microorganisms to grow. If there is no food source for them to feed on, they will die out.

However, certain microorganisms can live off of your body even if there is no food source around.

These organisms are known as parasites. When you become infected with parasites, they feed off of your body and cause damage to your organs.

When you contract an infection, it can linger in your body for a long time before dying out. This is because your body has built up immunity to fight the infection, and the microorganisms can no longer feed on it.

4. The existence of an acidity level that aids growth:

Some microorganisms thrive in an acidic environment. The pH scale that measures the acidity of different substances is between 0 and 14.

When the pH level of a substance is below 7, it is acidic.

When the pH level of a substance is above 7, it is alkaline.

When the pH level of a particular environment is below 7, it can aid the growth of microorganisms.

5. The presence of oxygen:

The presence of oxygen is important for the growth of microorganisms. Different microorganisms can thrive in different levels of oxygen.

Sporules and Bacillus spores, for example, thrive in a low level of oxygen. This is because they are resistant to high temperatures and can remain dormant for extended periods.

The level of oxygen in an environment can be measured using an oxygen meter. This can also be done with a simple device called a bacteria plate.

6. The presence of light and its intensity

Light is essential for plants and microorganisms alike. Microorganisms can thrive in different types of light.

The presence of light is important for the growth of microorganisms. Without light, the organisms cannot grow and reproduce. Some microorganisms thrive in low light, others in high light, and still others in bright light. If the light is too bright, it can burn the organisms, causing them to die out.

7. The presence of space or room to grow and spread:

When microorganisms are left in a small environment, they are unable to grow and spread. But when they are in a large environment, they are able to grow and spread.

When the surrounding environment has limited room to grow and spread, it can halt the growth of microorganisms.

When the area is large enough to allow the organisms to grow, they can spread and infect other people. This is why it is important to disinfect surfaces that are at risk of being contaminated. This can help to control the spread of bacteria and viruses.

When you understand how the conditions that favour the growth of microorganisms, you can take precautions to reduce your risk of contracting an infection in future. You can also prevent others from becoming infected by making your environment clean and disinfected.

Causative; Microorganisms in Food Spoilage

Microorganisms are a natural part of the decomposition process. They help break down organic materials, such as plants and animals, and they play an important role in keeping our planet healthy. But, there are also microorganisms that can spoil your food if they’re not kept under control.

The most common types of bacteria found in foods include;

1. Salmonella Typhimurium (which causes typhoid fever)

2. Listeria monocytogenes (which causes food poisoning)

3. Campylobacter jejuni (which causes diarrhea)

5. EHEC O157:H7 (a strain of E-coli).

6. Fungi like Aspergillus flavus cause botulism from contaminated canned goods. These fungi also occur naturally on fruit trees during warmer months when temperatures aren’t too cold but still cool enough for mold spores to germinate without causing any damage to them yet.”

7. Enzymes may contribute to food spoilage. Enzymes are proteins that help break down food. They can be used for preservation, but they also contribute to spoilage by speeding up chemical reactions in the body of organisms that eat it.

For example, if you have an enzyme deficiency and eat a food containing enzymes (like fruits), your body will not be able to break them down so quickly. This causes more chemical changes within your digestive system than usual and these chemicals then start fermenting before they reach their intended destination (your stomach).

Low temperatures slows microbial growth, but will not completely prevent it. While low temperatures slow the growth of microbes, they will not completely prevent spoilage.

Microorganisms thrive in warm environments and can flourish when food is kept at room temperature or above. If you keep your food in a cool place for long periods of time, however, you can preserve it for longer periods of time. Cold storage methods are also used to prepare food for storage. When using these methods correctly and consistently it is possible to keep foods fresh for months or even years with little change at all due to microbial growth.

Keeping the pH at the right level can help slow the growth of microbes

The pH of a substance is the measure of its acidity or alkalinity. The range between 0 and 14 refers to its acidity, while 15-14 indicates a neutral (neither acidic nor basic) state.

A pH below 7 is acidic, while anything above 7 is considered basic and neither are good for foodstuffs.

Microbes can lead to chemical changes in food that cause it to spoil

The growth of certain types of microbes can cause the formation of harmful substances, such as ammonia and hydrogen sulfide. These substances are often responsible for the rotten smell associated with spoiled foods.

Certain types of bacteria produce enzymes that break down proteins into smaller components that bacteria use for energy production (protein hydrolysis).

This process may result in the release of amino acids into your food, which makes it unappetizing and even unpleasant to eat.

Too much exposure to oxygen makes food spoil faster

Oxygen is one of the main factors in food spoilage

This can happen when food is exposed to too much oxygen, which makes it more likely for harmful bacteria to grow and cause spoilage. The best way to prevent food spoilage is by keeping the level of oxygen in the air low.

The air is full of microbes that cause chemical changes in food, which can lead to its decay. You can do this by sealing off your home or car’s windows or by covering up any open containers with plastic wrap before placing them in storage areas like refrigerators or freezers.

Leave a Comment