Microbes in Household Products

i. Curd

• Curd is formed by adding a small amount of curd to milk, which acts as a starter.

• Lactobacillus and lactic acid bacteria (LAB) present in starter, multiply at suitable temperature and convert milk into curd.

• Acids released by LAB during the growth coagulates and partially digest milk protein, casein.

• Benefits of LAB:

a. Increases vitamin B₁₂ amount thus increasing nutrient quality of milk.

b. Checks disease-causing microbes in stomach.

ii. Dough

• Dough is formed by fermentation by bacteria.

• Bread is made by fermentation by Saccharomyces cerevisiae or commonly called baker’s yeast.

• CO₂ released during the process of fermentation gives the puffy appearance to dough.

• It is used to make foods like idli, dosa, bread, etc.

iii. Toddy

• It is a traditional drink of Southern India.

• It is made by fermentation of sap from palm trees by bacteria.

iv. Cheese

• Cheese is formed by partial degradation of milk by different microorganisms.

• Swiss cheese is formed by the bacterium Propionibacterium sharmanii. Its characteristic feature is formation of large holes due to production of large amount of CO₂.

• Roquefort cheese is formed by ripening with the fungi Penicillium roqueforti for a particular flavour.