STD-5, CHAPTER-6, EXTRA QUESTION QUESTIONS

1.      Give any three reasons for spoilage of food.

Ans: Three reasons for spoilage of food are, micro-organisms, enzymes, insects, worms and rats.

2.      What are micro-organisms?

Ans: Micro-organisms are the organisms which are too small to be seen by unaided eye.

3.      Name two micro-organisms.

Ans: Bacteria and fungi

4.      State two factors that contribute to the fast growth of micro-organisms.

Ans: Two factors that contribute to the fast growth of micro-organisms are, moisture and temperature.

5.      How can we check the growth of micro-organisms in our food?

Ans: For checking the growth of micro-organisms in our food, we need to:

i)   Remove moisture from food i.e. dry it.

ii) Keep the food at low temperature (in the refrigerator)

6.      What are enzymes?

Ans: Enzymes are chemicals that are present in all fruits and vegetables which speed up chemical changes in them.

7.      How do enzymes help fruits?

Ans: i) Enzymes are useful because they cause ripening of fruits.

ii) When green fruits ripen, they change their colour and become sweet.

8.      How enzymes contribute to the spoiling of food products?

Ans: i) Enzymes speed up chemical changes that result in the loss of flavour, colour and appearance.

ii) They, thus, contribute to the spoiling of the food products.

9.      How can we protect our food items from insects, worms and rats?

Ans: i) We should keep the cupboards, shelves and containers clean and dry.

ii) This will prevent them from making a home at places where our food items are kept.

10.  Suggest any three ways to prevent spoilage of food.

Ans: i) Perishable food stuffs, like milk, meat, fruits and vegetables, must be stored in the refrigerator.

ii) Foods, like spices, cereals, biscuits and other snacks, should be kept in airtight jars.

iii) By preserving food.

11.  What do you understand by food preservation?

Ans: Food preservation is the process of treating and handling of food to stop, or slow down, the spoilage caused by micro-organisms.

12.  Describe the methods that are used for preservation of food.

Ans: i) Dehydration: In this process, water content of the food stuff is removed.

ii) Food can be preserved by adding salt and sugar.

iii) Food can be preserved by adding acetic acid, in the form of vinegar.

iv) Canning and Bottling: Food is cooked and sealed in sterile cans or jars and these containers are boiled to kill any remaining bacteria.

v) Pasteurisation: In this process, food product is subjected to pressurised heating, for a short time, followed by immediate cooling.

vi) Refrigeration: This procedure uses low temperature to prevent growth of micro-organisms.

vii) Vacuum packing:  In this method air is removed from the package prior to sealing.

13.  How the process of dehydration help to preserve food?

Ans: i) In dehydration process, water content is removed from the food stuff.

ii) Since, micro-organisms need water to grow, they cannot multiply, or grow, on dried foods.

14.  Name some food items which are preserved by the process of dehydration.

Ans: Many vegetables like onions, cauliflower, are preserved by the process of dehydration.

15.  How adding sugar and salts help in preserving food?

Ans: Sugar and salt tend to take out moisture from the food so that it is not available for growth of micro-organisms.

16.  Name some food items which are preserved by adding sugar and salt.

Ans: Pickles and jams can be preserved by adding salt and sugar in them.

17.  Name the food items where vinegar is used as a food preservative.

Ans: Vinegar is used as a food preservative in pickles.

18.  Name the food items which are canned to preserve them.

Ans: Many fruits, vegetables and meat products are canned to preserve them.

19.  What is pasteurisation? What is the maximum temperature used in this process?

Ans: i) Pasteurisation is the process of heating food followed by immediate cooling, to limit the growth of micro-organisms.

ii) The temperature used during pasteurisation is below 212⁰ F (100⁰ C).

20.  Why we should not drink unpasteurised milk?

Ans: Drinking unpasteurised milk is not safe as we can get diseases due to the presence of disease causing micro-organisms.

21.  Who discovered the process of pasteurisation?

Ans: Louis Pasteur discovered the process of pasteurisation.

22.  Why is it advised to keep the pasteurised milk under refrigeration?

Ans: i) Milk is pasteurised to kill micro-organisms.

ii) However, many more heat-resistant organisms only get reduced in number and do not get completely removed.

iii) Hence the pasteurised milk must generally be stored under refrigeration to keep bacterial growth in it under control.

23.  How pasteurisation increases the shelf life of milk?

Ans: Pasteurisation destroys the micro-organisms. It also deactivates some enzymes and increases the shelf life of milk.

24.  Why does food stay fresh for a longer time when stored in a refrigerator?

Ans: i) The temperature is low inside a refrigerator.

ii) Micro-organisms and enzymes get deactivated at low temperatures and hence, the spoilage of food gets prevented.

25.  How the process of vacuum packing preserves food?

Ans: i) In this method, air is removed from the package prior to sealing.

ii) The vacuum, thus created, reduces oxygen in the package. This limits the growth of bacteria or fungi in the package.

26.  Which food items are preserved by vacuum packing?

Ans: Dry foods like cereals, nuts, coffee, cheese and potato chips are preserved by the process of vacuum packing.

27.  Foods, containing fats and oils, become rancid in the presence of _______.

Ans: Oxygen

28.  Packets of potato chips and other namkeens are filled with ______ gas.

Ans: Nitrogen

29.  How is food preservation useful to us?

Ans: Food preservation is helpful in many ways:

i)                    It helps to maintain nutritive value of food.

ii)                  It increases the shelf life of food, thus, increasing its supply. Many perishable foods can be preserved for a long time.

iii)                It makes seasonal foods available throughout the year.

iv)                It decreases wastage of food by preventing decay or spoilage of food.

It helps in adding variety to the diet.