How can the available water in food be decreased to inhibit bacterial growth?

Decreasing the available water in food to inhibit bacterial growth is effectively achieved by adding substances like salt or sugar. When salt or sugar is added to food, it creates a hypertonic environment. In this environment, water is drawn out of the bacterial cells through osmosis, leading to dehydration of the bacteria. This dehydration inhibits growth and reproduction, making it a common preservation technique used in many foods, such as cured meats and jams.

Other options may contribute to food preservation but do not specifically target the reduction of available water. While increasing acidity can create an unfavorable environment for some microorganisms, it primarily works through altering pH rather than directly affecting water availability. Adding preservatives can extend shelf-life and inhibit bacterial growth, but they often function through chemical means rather than physically reducing water levels. Heating food can kill bacteria but does not decrease the available water in a way that would prevent bacterial growth if the food is subsequently stored improperly. Therefore, using salt or sugar is the most direct method to decrease available water and inhibit bacterial growth in food.