8th Class Science Microorganisms : Friend and Foe Food Preservation

       Food Preservation

Certain food materials, for example milk, vegetables, meat, fish, fruits, etc get spoiled easily. Because they contain lots of water, which helps in the growth of microorganisms. We can prevent these foods from spoiling by using some techniques i.e. either by physical or by chemical treatment. The process, which is used for the preservation of food is called food preservation. Some of the common methods used for the food preservations are sun drying, heating, refrigeration, deep freezing, addition of common salt or sugar, addition of mustard oil and use of chemical etc. The preservative, such as, sodium metabisulphate or citric acid and pasteurization can also be used for such purpose.

Preservation usually involves the prevention of growth of microorganisms, which can oxidize fats and cause rancidity. It also includes inhibiting ageing and discoloration, that can occur during food preparation. Some of the methods used for preservation require the food to be sealed in air tight container after recontamination with microbes.

   Food Preservation    

       Food materials can be preserved for the longer time periods. There are different methods of food preservations, some are traditional and some are scientifically proved. The chemical which is used to preserved food articles are:

(a) Acetic acid

(b) Ethanol     

(c) Citric acid

(d) Ketone

(e) None of these

Answer: (c)

Explanation

Citric acid is one of the chemical, which is used to preserve the food articles.

       Antacids are the slow decomposition of fats and other oily products by the microorganisms. Which microorganism causes decomposition of fats in the food?

(a) Virus

(b) Algae      

(c) Bacteria

(d) Fungus

(e) None of these

Answer: (c)

Explanation

The microorganisms, which spoil the food by oxidizing the food is bacteria.  

• Wearing a headphone for just an hour or so can increases the bacteria in your ears by 700 times, as these headphone creates a warm, and moist environment in ear canal, which is ideal for breeding of bacteria.
• There are about more than 75 to 100 trillion bacteria in the human body, which is more than the number of cell in the body.
• There are certain bacteria, which cause food to rot and decay, but never cause diseases.
• The poisons released by bacteria are called toxins. The toxin release by staphylococcus aureus, clostridium botulinum and bacillus cereus is called exotoxins.
• The consumption of shellfish, such as, cockles, mussels, oysters and clams, is commonly associated with viral food-poisoning.

• Microorganisms are the very small life forms, which cannot be seen by the naked eyes.
• They are found in all types of climatic conditions.
• They are either unicellular or multicellular.
• The microorganism includes bacteria, fungus, algae, virus and protozoa.
• Virus is considered both as living and nonliving.
• Microorganisms are used for production of medicine.
• Microorganism cleans our environment by decomposing the waste material.
• A rizobium bacterium helps in fixing atmospheric nitrogen into the soil and increases the nitrogenous content of the soil.
• There are some harmful bacteria and other microorganism, which cause diseases.
• Some of the microorganism can manufacture their own food by the process of photosynthesis, such as, blue- green algae.