Microbes in Household Products - Practice Questions & MCQ

Dairy Products:
1. Curd

• Micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it to curd. 
• During growth, the LAB produces acids that coagulate and partially digest the milk proteins. 
• A small amount of curd added to the fresh milk as inoculum or starter contains millions of LAB, which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin B12. 
• In our stomach too, the LAB plays a very beneficial role in checking disease-causing microbes.

2. Cheese

• The curd is separated from the liquid part to form the cheese. 
• Cheese is one of the oldest food items in which microbes were used. 
• Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.
• The large holes in ‘Swiss cheese’ are due to production of a large amount of CO2 by a bacterium named Propionibacterium shermanii.
• The ‘Roquefort cheese’ are ripened by growing a specific fungi, Penicillium roqueforti on them, which gives them a particular flavour.

3. Bread, Dosa, Upma &  Idli

• The dough, which is used for making foods such as dosa and idli is also fermented by bacteria. 
• The puffed-up appearance of dough is due to the production of CO2 gas. 
• Similarly the dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae). 

4. Toddy

• Toddy’, a traditional drink of some parts of southern India is made by fermenting sap from palms.