Question

Food can be kept for long periods of time by adding salt or sugar because these substances-
A. Make the food too acidic for spoilage to occur
B. Bind to water, thereby making it unavailable to the microorganisms
C. Effectively kills the microorganisms
D. Dissolve the cell walls in plant foods

Answer 1

Most of the food items are perishable and are easy targets to the microbes. Food spoilage is an undesirable phenomenon that can be prevented using food preservation techniques. One of the techniques is dehydration. Bacteria grow in moist environments. Salt or sugar is a dehydrating agent.

Complete answer: Food preservation is a technique that ensures longer food shelf life and protection from harmful spoilage-causing microorganisms. Food preservation can be done by various methods. These methods aim at preventing contamination by microbes by keeping them away from the food items. The general principle of food preservation is inhibiting the cellular activity of food or devoiding moisture from food.
Dehydration is a common preservation method. Salt and sugar are used as dehydrating agents. The sugar or salt molecules bind to the water present in food items. This dehydrates the food items and makes it inappropriate for microbes to flourish over them. Microorganisms find it difficult to grow over dehydrated food. They die due to water scarcity and drying. Dry food makes nutrients unavailable to microbes hence preventing food from spoilage. Dehydrated food items can be kept for longer periods. The taste and texture of food stay preserved by this method.

So, option B is correct.

Note: Fish is a perishable food item. It is mostly preserved by applying salt to it. Pickles are also a preservative technique. Oils and salts added in pickles ensure the longer shelf life of the preserved food items. Freezing and drying are other common methods of food preservation.