Relationship between electrical conductivity and water activity of starch-water composites

Abstract

When electrical conductivity (EC) is studied in food hydrocolloids, such as starch, molecular structure is important because conductivity depends on the interaction of water with charged carboxyl group or hydroxyl groups (Marcotte et al. 1998). Several authors have found that EC of starch-water composites increases with temperature and decreases during starch gelatinization (Wang and Sastry 1997; Karapantsios et al. 2000; Li et al. 2004). This behavior is explained considering granule swelling, increase of viscosity, and reduction of the area for starch particle movement. Decreasing water content in the material decreases EC (Lewicki Piotr 2004).