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) (400-1000MPa) was investigated. Gelatinization enthalpy change (ΔH) and re-gelatinization enthalpy change of retrograded crystalline part (ΔH) of the HHP-treated starch were evaluated using differential scanning calorimetry. The value of ΔH of 10-20% (w/w) mixtures decreased with increased pressure and temperature, while ΔH 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 of 10-40% (w/w) mixtures reached zero, but ΔH of 50-70% (w/w) mixtures did not. Retrogradation was observed with HHP-treated 20-60% (w/w) mixtures and the value of ΔH depended on the starch content, pressure, and temperature. The value of ΔH 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 (400-1000MPa) potato starch-water mixtures (10-70%, w/w) at 20-70°C were summerized in a series of state diagrams.