Final answer:
Jams and dried meats use high concentrations of sugar and salt to create osmotic pressure that dehydrates and inhibits bacterial growth, allowing these foods to be preserved without refrigeration.
Step-by-step explanation:
Jams and dried meats often do not require refrigeration to prevent spoilage because of the high osmotic pressure created by the addition of solutes like sugar and salt. These solutes draw water out of microbial cells, causing dehydration and inhibiting their growth. The high concentrations of sugar in jams, for example, act as a preservative by dehydrating any bacteria that were not killed during the cooking process, preventing them from multiplying. Similarly, salt used in dried meats like ham and bacon prevents bacterial growth, preserving the food without the need for refrigeration.
Desiccation is a traditional method of food preservation that reduces the water activity in foods, which is crucial because microorganisms depend on available water to grow. By lowering the available moisture through drying or the addition of solutes, microbial growth is slowed down or halted, which is essential for preserving food safely over extended periods.