Effect of temperature on gelatinization and retrogradation in high hydrostatic pressure treatment of potato starch-water mixtures

The effect of temperature (20-70 °C) on the gelatinization and retrogradation of potato starch-water mixtures (10-70%, w/w) treated with high hydrostatic pressure (HHP) (400-1000 MPa) was investigated. Gelatinization enthalpy change (ΔH_gel) and re-gelatinization enthalpy change of retrograded crystalline part (ΔH_retro) of the HHP-treated starch were evaluated using differential scanning calorimetry. The value of ΔH_gel of 10-20% (w/w) mixtures decreased with increased pressure and temperature, while ΔH_gel of 30-50% (w/w) mixtures decreased to certain values with increased pressure and the values depended on treatment temperature. With higher temperature and pressure conditions, ΔH_gel of 10-40% (w/w) mixtures reached zero, but ΔH_gel of 50-70% (w/w) mixtures did not. Retrogradation was observed with HHP-treated 20-60% (w/w) mixtures and the value of ΔH_retro depended on the starch content, pressure, and temperature. The value of ΔH_retro trended to increase with increase in starch content. In addition, retrogradation was promoted by HHP treatment at low temperature. Gelatinizaiton and retrogradation behaviors of HHP-treated (400-1000 MPa) potato starch-water mixtures (10-70%, w/w) at 20-70 °C were summerized in a series of state diagrams.