Retrogradation kinetics of cross-linked and acetylated corn starches under high hydrostatic pressure

Abstract

Retrogradation kinetics of conventionally and high hydrostatic pressure (HHP)-assisted chemically modified (cross-linked with sodium trimetaphosphate/sodium tripolyphosphate (STMP/STPP) and acetylated with acetic anhydride) corn starches were investigated. During storage at 4°C, the glass transition temperature (Tg′) and the ice melting enthalpy were measured using differential scanning calorimetry (DSC), and relative crystallinity was measured using an X-ray diffractometer (XRD). In both conventionally and HHP-assisted modified corn starches, the Tg′ value and relative crystallinity increased during first 7–10 days of storage, then stabilized, whereas the ice melting enthalpy decreased until 10 days of storage, then remained constant. HHP-assisted modified starch showed different retrogradation kinetics from conventionally modified starch. However, the retrogradation rates of both samples were lower than for native corn starch. Although the Tg′ value, the ice melting enthalpy, and relative crystallinity represent different physicochemical properties, all can be used as indicators for evaluation of starch retrogradation.