What is the primary factor that influences bacterial growth related to moisture?

The primary factor that influences bacterial growth related to moisture is water activity, which is commonly expressed as "aw." Bacteria generally require a certain level of water activity to survive and reproduce. A water activity level above 0.85 is generally recognized as the point where bacteria can thrive. This is because water activity levels above this threshold provide sufficient moisture for bacteria to carry out their metabolic processes, leading to growth and potential food spoilage.

When the water activity is below 0.80, bacterial growth is significantly inhibited. Foods with lower moisture content, like dried fruits or cured meats, typically have lower water activity levels and are less prone to bacterial growth. Understanding these levels helps food managers ensure food safety by controlling moisture content in food products. Thus, a water activity level above 0.85 is critical in determining the risk of bacterial growth.