The ratio of the water vapor pressure of a product to the saturation pressure of water at the same temperature. Water activity of foodstuffs is important in determining their physical structure, handling characteristics, palatibility, digestibility, and shelf life.

Starch containing approximately 100% amylopectin which is obtained from certain plant sources such as corn, rice. According to the starch source the terms waxy maize starch, waxy rice starch may be used. Waxy starches ar egenrally chemically modified to improve heat-, acid-, shear-, and freeze/thaw stability for use in food applications.