Individually packaged saltine crackers are not considered time-temperature control for safety (TCS) food because of C) their reduced water activity.
What is water activity?
Water activity (aw) is a measure of the free water available in a food product. Free water is the water that is not bound to other molecules, such as proteins or carbohydrates. Microorganisms need free water to grow and reproduce. Therefore, foods with a low aw are less likely to support the growth of microorganisms.
Individually packaged saltine crackers have a low aw because they have been baked and dried. This process removes most of the free water from the crackers, making them less hospitable to microorganisms. As a result, individually packaged saltine crackers do not require time-temperature control for safety.