Question

A common preservative used in jam and pickles is
a. Sodium benzoate
b. Nitric acid
c. Sodium chloride
d. Copper sulphate

Answer 1

Hint: Food additives are the chemicals that are added to food to preserve it or enhance its taste or color. These also prevent fats and oils from turning rancid. Salt, sugar and vinegar are some common examples of food additives.
Generally, these food additives do not have any nutritive value. There are more than 3000 substances that are used as food additives for providing flavor, color or preservation.

Complete answer:
Preservatives are added to food to prevent the growth of microbes and enable food to be stored for a longer time. For example, nitrates and nitrites are used to preserve meat and meat products. Sulphur dioxides are used in the dried fruit juices. Sodium metabisulphite is also used as a preservative in juices.

Many other chemicals are used as food preservatives like sodium benzoate is used in ketchups, fruit juices, syrups, jellies, jams and pickles. It is commonly used in acidified food items and it inhibits the growth of yeasts, molds and bacteria in the food item. Benzoic acid decreases the intracellular pH after it is absorbed into the cell which decreases the anaerobic fermentation of glucose through phosphofructokinase. It thus inhibits the survival of microorganisms that cause food spoilage.

Hence, the correct answer is option (A).

Note: When food is exposed to air it undergoes a chemical change known as oxidation that changes the color, flavor and nutritional value of the food. It also makes food more susceptible to spoilage with microorganisms like bacteria and fungi. Thus antioxidants and preservatives are added to prevent it from spoilage.