CBSE Class 8 Answered

(i) Souring of milk 

Due to fermentation process milk become sour if kept for a long time.

(ii) bread and cakes are fluffy

Baking soda is also called sodium carbonate which if added to the cake batter reacts with hydrogen ion from acid and releases CO₂ that makes the cake soft and fluffy.

(iii) food poisoning 

Food which is spoilt by microorganisms contains toxic substances released by the microbes. The spoilt food is bad in taste and emits a foul odour. If such food is eaten, it will lead to food poisoning. The major symptoms of food poisoning are vomiting, diarrhoea, pain in abdomen, fever and headache. Food poisoning can cause serious illness and even death.  

(iv) addition of oil and pickles

The oil is added to the pickle as a preservative. Preservation keeps the food fresh and prevents it from getting spoilt.

(v) black and green coating on bread

The Black and green coating on the bread occurs because of the formation of fungi, this happens when it is exposed to air and water.

(vi) drying of food before storage

Food must be dried thoroughly before storage otherwise there are chances of rotting.