Question

please fast

20. Read the following and answer any four questions from 19 (i) to 19 (v). (1×4)

Rancidity: Rancidity can be defined as the chemical decomposition of fats and oils

due to hydrolysis or auto-oxidation or microbial activity, producing aldehydes,

hydroxyl acids, keta acids, and other compounds. This causes a considerable damage to the natural structure of fats and oils, producing undesirable odors, flavors and

discoloration in the food containing them; making them unfit for consumption.

For Example: When butter is kept open for a long time, then its smell and taste gets

changed (due to the presence of butyric acid (a four-carbon acid)).

Factors responsible for causing rancidity are light, oxygen, trace elements such as

iron and zinc, salt, water, bacteria, and molds etc.

Types of chemical reactions responsible for causing rancidity:

(i) Oxidation Reaction: Oxidation is said to have occurred when a substance reacts

with oxygen in the air forming oxides. It causes the formation of peroxide at the

double bonds (C=C) of fat molecules with subsequent breakdown of these

peroxides to form aldehydes, ketones and acids of lower molecular weight. This

results in off-flavor, off-odour and sometimes change in colour.

(ii) Hydrolysis: Hydrolysis can be defined as the breaking down of a chemical

compound into two or more simpler compounds by reacting with water. It

decomposes a lipid into its component fatty acids and glycerol.

Following are the methods for preventing rancidity of food: (write any three)

1. In order to prevent rancidity due to oxygen or water vapours present in a

container, vacuum packing should be used or the packing should be filled with

inert gases. For Example: Potato Chips are usually packed in thick foil packets

filled with Nitrogen.

2. Refrigeration of foods also reduces the rate of most of the reactions that cause

rancidity.

3. Reducing the water content in foods by drying or smoking and then storing them

in a moisture free environment helps to reduce the chances of rancidity.

4. By adding anti-oxidants (butylated hydroxyanisole (BHA), butylated

hydroxytoluene (BHT) to the food containing fats and oils.

5. Keeping food in air tight containers also helps to reduce oxidation.

i) All the methods mentioned below can be used to prevent the food from getting

rancid except:

(i) Storing the food in the air-tight containers

(ii) Storing the food in refrigerator

(iii) Keeping the food in clean and covered containers

(iv) Always touching the food with clean hands

(a) (i) and (ii)

(b)(i) and (iii)

(c) (i), (iii) and (iv)

(d)(iii) and (iv)

ii) Which of the following gases is used in the storage of fat and oil containing foods

for a long time?

(a) Carbon dioxide gas

(b) Nitrogen gas

(c) Oxygen gas

(d) Neon gas
iii) Rancidity of lipids of lipid-rich foodstuff is because of

(a) Reduction of fatty acids

(b) Hydrogenation of unsaturated fatty acids

(c) Dehydrogenation of saturated fatty acids

(d) Oxidation of fatty acids

iv) Which of the following chemical reactions responsible for causing rancidity?

(a) Reduction

(b) Oxidation

(c) Hydration

(d) Redox reaction

v) Which of the following is a food antioxidant?

(a) butylated hydroxyanisole (BHA)

(b) butylated hydroxytoluene (BHT)

(c) Saccharine

(d) Both (a) and (b)​

Answer 1

Answer:

HEY MATE !!

HERE IS UR ANS ⤵️⤵️

i) option d ( iii and iv )

ii) option b ( nitrogen gas )

iii) option a ( reduction of fatty acids )

iv) option c ( Hydration )

v) option a { butylated hydroxyanisole (BHA) }

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