Role of Microbes In Food Processing


Microbiology is the study of different microbes such as bacteria, viruses, slime molds, fungi, and protozoans. Microbes can be unicellular, multicellular, or acellular. The study of microorganisms that modify, colonize, contaminate or process food is known as food microbiology.

History of Food Microbiology

  • Food history varies with culture, environment, and social and economic impacts. The history of Food Microbiology is classified based on time and periods. In 7000 BC there was evidence of the manufacturing of beer.

  • The wine was found to be manufactured in about 3500 BC. For the first time, food spoilage was recorded in 6000 BC.

  • Around 3000 BC, Egyptians started manufacturing cheese and butter.

  • To prevent the spoilage of food, snow was used to preserve shrimp in 1000 BC.

Food Processing in Households


  • Lactobacillus is known as Lactic acid bacteria (LAB).

  • It grows in milk and converts it into curd.

  • LAB works by producing lactic acid that will coagulate the milk and will also partially digest milk proteins.

  • small quantity of curd will act as inoculum of LAB. When this inoculum is added to fresh milk and kept at a suitable temperature, it will multiply and convert milk into curd.

  • LAB increases the nutritional value of curd by increasing the Vitamin B12 in it.

  • Curd also acts as a probiotic for our stomach and checks the diseasecausing organism.


  • Cheese is one of the oldest items in which microbes were used.

  • Different varieties of cheese are available based on flavour, texture, and taste. These characteristics are dependent on the type of microbes used.

  • Swiss cheese contains large holes in it due to the bacterium Propionibacterium shermanii which produces a large amount of carbondioxide.

  • Cheese are classified into the following types −

Type of Cheese Microorganism Used


Camembert cheese

Penicillium camemberti


Roquefort cheese

Penicillium roqueforti


Swiss cheese

Propionibacterium shermanii

Other products used in Household

  • The dough, used for making dosa and idli are also fermented by bacteria. These foods get puffed up due to the release of carbon dioxide in the dough.

  • Dough used for making bread in bakeries is fermented with Saccharomyces cerevisiae, also known as baker’s yeast.

  • One of the most common traditional drinks. Today is obtained from the sap of palms and is also fermented by microbes.

Microbes in Industrial Products

Microbes are widely used in different parts of industries for the benefit of living organisms.

Alcoholic Beverages/Fermented Beverages

  • For years, yeast had been used for the production of wine, beer, brandy, whiskey, or rum.

  • Saccharomyces cerevisiae used for bread-making is the same yeast used for the preparation of fermented beverages. This yeast is also known as brewer’s yeast used for fermenting malted cereals and fruit juices, in order to produce ethanol.

  • Based on the type of raw material used for fermentation, and the type of processing used, different types of alcoholic beverages are obtained.

Other products obtained from yeast fermentation are as follows

  • Beer obtained from Barley (Hordeum vulgare) malt, in which alcohol content is just 3 to 6 percent.

  • Grapes are used to obtain wine and alcohol content is 10 to 20 percent.

  • Distillation of wine and alcohol is used to obtain Brandy and alcohol content is 60 to 70 percent.

  • European Rye cereal is sued to obtain Gin in which alcohol content is 40 percent.

  • Molasses of sugarcane is used to obtain Rum and the alcohol content is 40 percent.

Production of Antibiotics

The term antibiotic was given by Selman Walksman in 1942. They are considered remarkable discoveries for the welfare of human beings. The word antibiotic means something that fights against the living or against life in terms of disease causing organisms, and for humans, they prove to be beneficial.

  • The first antibiotic discovered was Penicillin. It was discovered by Alexander Fleming. It was a by-chance discovery. He was working on Staphylococcus bacteria growing on unwashed culture plates. These bacteria did not grow because there was a mould growing in culture plate which releases a chemical that inhibits the growth of bacteria. He named this mould Penicillin with a later name Penicillium notatum.

  • Antibiotics have greatly improved the ability to fight different deadly diseases such as Whooping cough, plague, diptheria, leprosy, etc., which earlier killed millions of people worldwide.

Organic Acid

Fermentation activities of certain bacteria and fungi are used to obtain organic acids.

  • Citric acid is obtained by anaerobic fermentation of sucrose. It is used as flavouring extract, malek medicines, dying, food, and candies ink. Fungus Aspergillus niger is used to obtain citric acid.

  • Acetic acid or vinegar is used is obtained by the two-step fermentation process. Firstly, carbohydrates are converted into alcohol by alcoholic fermentation and in the second step, alcohol is oxidized by Acetobacter aceti into acetic acid.

  • Butyric acid is obtained from Clostridium butylicum.


Enzymes are another milestone obtained through different microbial activity.

  • The bottle juices are clarified by the use of pectinase and protease.

  • Tissue plasminogen activator (TPA) or streptokinase is produced from the bacterium Streptococcus and is used as a clot buster for removing clots from the blood vessels for patients who have undergone myocardial infarction.


Microbiology is the study of different microbes such as bacteria, viruses, slime molds, fungi, and protozoans. Food history varies with culture, environment, social, and economic impacts. The history of food microbiology is classified based on time and periods. Curd, cheese, dough, and other drinks use different microbes for their processing. Microbes have industrial applications, that is, for obtaining antibiotics, enzymes, alcoholic beverages, and organic acids.


Q1. What is Cyclosporin A?

Ans. Cyclosporin is an immunosuppressant obtained from the fungus Trichoderma polysporum. It is used during organ transplants to prevent the rejection of grafts.

Q2. What are statins?

Ans. Statins are obtained from the yeast Monascus purpureus. It inhibits the synthesis of cholesterol and is thus used as a blood cholesterol-lowering agent.

Q3. Explain how microbes are used as biofertilizers?

Ans. Rhizobium bacteria is used to fix atmospheric nitrogen into organic forms. They are cheap, environment friendly, replenish the soil nutrients, and help in organic farming.

Q4. What is single-cell protein?

Ans. Single-cell protein is an alternate source of protein for plants and animals. So, microbes can be used as a good source of proteins.

Updated on: 18-Jan-2023


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