Question

Explain the use of microbes in household products.

Answer 1

Answer:

Microbes in household products :  

(i) Curd - Micro-organisms such as Lactobacillus and others commonly called Lactic acid bacteria (LAB)  grow in milk and convert it into curd.

• During growth, the LAB produce acids that coagulate and partially digest the milk proteins.

• The starter or inoculum contains millions of LAB, which at suitable temperature multiply, thus  converting milk to curd.

• Curd is more nutritious than milk as it contains a number of vitamins especially $\sf vit \:B_{12}$.

(ii) Cheese - One of the oldest food items in which microbes were used is cheese. It is degraded concentrate  of milk fat and casein.

• Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity  determined by the microbes used.

• For example - Large holed Swiss cheese is ripened with the help of bacterium called  Propionibacterium sharmanii. Roquefort cheese is ripened by fungus Penicillium roquefortii.

(iii) Bread - Bread is prepared from dough, which is fermented using Baker’s yeast - Saccharomyces  cerevisiae. Puffed - up appearance of dough is due to production of $\sf CO_{2}$ during fermentation. $\sf CO_{2}$ gas  along with ethyl alcohol evaporates during baking, making bread porous and soft.

(iv) Dosa and Idli - The fermented preparation of rice and black gram, prepared by using bacteria.

(v) Toddy - A traditional drink in some parts of south India is made by fermenting sap from palm - Caryota  urens. It contains 6% alcohol.

(vi) Other food microbes are used to ferment is soyabean and bamboo shoots to make foods.