Final answer:
Jams and dried meats do not require refrigeration because the high sugar concentration in jams reduces free water, and the low moisture content in dried meats prevents bacterial growth.
Step-by-step explanation:
The reason jams and dried meats often do not require refrigeration to prevent spoilage is primarily due to the reduction of water activity in these foods. When jams are made, they undergo a cooking process that involves a high concentration of sugar.
Sugar is a hygroscopic substance, meaning it attracts water. This property allows sugar to bind with water molecules, reducing the amount of free water available for microbial growth which could cause spoilage.
Dried meats, similarly, have had most of their moisture removed through processes such as curing, smoking, or dehydration. With the reduction of water, the ability for bacteria to grow is inhibited.
The lack of moisture and the presence of other preservatives in dried meats such as salt make these products stable at room temperature, negating the need for refrigeration.