Effects of high pressures treatment on starches

The effects of ultra-high pressure (UHF) on 25 starches were characterized via microscopy and DSC. Furthermore, the swelling behaviour, digestibility, paste viscosity and gel formation was determined. With few exceptions B-starches were shown to be more pressure resistant than A- and C-type starches. The pressure range in which the gelatinization occurs is typical for the corresponding starch. Only some starches (e.g. waxy corn starch) show the extensive swelling and almost complete desintegration of the granules, which usually is observed after a heat gelatinization. Typical for a UHF-gelatinization is, that most starches show very little swelling and maintain their granular character. These starches develope very little viscosity at normal paste concentrations and form pastes of smooth texture, resp. rigid gels at concentrations above 15%. Due to the limited swelling without any resp. very little solubilization of the amylose obviously the retrogradation occurs within the granules, which probably is a further reason for the quite different paste and gel properties of UHF-gelatinized starches in comparison to heat gelatinized ones.