Food Poisoning - Introduction, Symptoms & Food Preservation

Food is an integral part of existence for living organisms. It provides us with energy to carry out every day activities. It helps build our immunity system to be fit to fight against diseases. This is the reason why it becomes all the more necessary to eat the right food at the right time. Sometimes, microorganisms grow on the food which we consume. Food gets contaminated when these microorganisms multiply and release toxic substances, resulting in food poisoning.

Let us have a detailed look at the causes, symptoms and treatment of food poisoning.

Causes of Food Poisoning

Food poisoning can be caused by the following three factors:


Bacteria is the major cause of food poisoning. Salmonella is the major cause of food poisoning in the US. Campylobacter and Clostridium botulinum are the other two lethal causes of food poisoning.


The viruses responsible for food poisoning include norovirus, sapovirus, rotavirus, and astrovirus. Food poisoning through viruses is less common, but proves to be fatal. Hepatitis A virus is a serious condition transmitted through food.


Food poisoning through parasites is very rare. Toxoplasma, a common cause of food poisoning, can be found in cat litter boxes.

Food can also be contaminated during the growing, harvesting and storage steps. The harmful organisms transfer from one surface to the other and result in food contamination. The raw, ready-to-cook food products are more at risk. Since these food items are not cooked, therefore the pathogens are not destroyed resulting in food poisoning.

Symptoms Of Food Poisoning

Following are a few of the symptoms to help you check if you are diagnosed with food poisoning

  • Weakness
  • Headache
  • Nausea
  • Diarrhoea
  • Vomiting
  • Irritable abdominal cramps
  • Mild fever
  • Loss of appetite

Also Read: Food Poisoning Symptoms

Treatment of Food Poisoning

The following treatment should be given to a person suffering from food poisoning:

  • Drink plenty of liquids to replace the lost electrolytes
  • Allow ice cubes to melt in the mouth or sip small amounts of water even if vomiting persists.
  • Gradually start eating blander food items such as cereals, toast, rice, banana, etc.

Prevention of Food from Contamination

To prevent food from contamination, it is very important to adopt proper methods for food preservation. We can preserve food by inhibiting the growth of microorganisms on food and slowing oxidation of fats.

Storage and preservation of whole food grains and cooked food are different. Microbes act on cooked food since it needs moisture to breed and whole food is usually devoid of moisture. This is the reason why bread left unused under moist conditions sees the action of microbes on it.

One of the characteristics of contaminated food apart from visible changes is that it emits a foul smell and tastes different than usual.

Listed below are a few methods of food preservation using which food can be prevented from contamination.

Chemical Method

Preservatives are used to check microbial activity in this method of preservation of food. Acid preservatives are also added to prevent food from spoilage in pickles, squashes, jams, canned food, etc. Some common preservatives:

  • Salt
  • Edible Oils
  • Sodium benzoate
  • Sodium metabisulphite

Preservation by common salt

Salt removes water from any food material as it is water absorbent. In the absence of water, microbes do not multiply. Hence salt is added to fish and meat to extract moisture content so that microbial activity is inhibited. It is also added to tamarind, raw mangoes etc. A salt solution, called brine is used in the process of pickling.

Preservation by sugar

Sugar, salt, absorbs moisture from food, making it too dry for microbes to exist. In food items like jams and jellies, sugar is added as a preservative. The process of desiccating food by dehydrating it first and then packing it with pure sugar is known as sugaring. Sugaring is used to preserve food, some fruits are preserved this way. In some cases, meat and fish are also preserved using the sugaring process.

Preservation by Oil and Vinegar

One of the most commonly used methods to preserve food is the use of edible oil. Oil and vinegar checks on spoilage in pickles. Fruits and vegetables are also oiled to preserve them from getting rotten. Vinegar has properties to stop and slow down the spoilage of food over a long period of time, it does so because acidity level or pH of vinegar does not allow any microbial activity to occur.

Heat and Cold Treatments

Boiling milk and food before storing them is one of the methods of food preservation. Pasteurization is the process of heating packaged and unpackaged foods to about 70 degrees Celsius for 15-30 seconds and stored after suddenly chilling. This way, milk can be consumed without boiling as it is free from microbes. We preserve meat and other food items under cold temperatures in the freezer to prevent attack by microbes.

Storage and Packing

Fruits, vegetables, and cooked food are stored in airtight containers, aluminium foils, cans, paper bags, and Ziploc bags to prevent them from getting contaminated.

Also Read: Food Adulteration

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Related Links

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Food Preservation Methods


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