The impact of pressure, temperature and treatment time on starches: pressure-induced starch gelatinisation as pressure time temperature indicator for high hydrostatic pressure processing

The applicability of pressure-induced starch gelatinisation as a pressure time temperature indicator (PTTI) was investigated by examining the impact of pressure, temperature and treatment time on starches of A-type, 13-type and C-type crystallinity. Pressureinduced starch gelatinisation was highly sensitive to changes of temperature, pressure and treatment time. At constant temperature and treatment time, the degree of gelatinisation increased with increasing pressure. The higher the temperature, the lower was the pressure of complete gelatinisation at the temperatures investigated. At constant temperature and pressure, the degree of gelatinisation increased with increasing treatment time. However, the degree of gelatinisation of potato starch suspensions remained unchanged after treatments above 60 min. The velocity rate of gelatinisation increased, the higher the constant pressure, indicating that pressure-induced gelatinisation is a time-dependant process. Hence, an application of starches as PTTIs seems possible. However, the starches have to be carefully selected regarding maximum gelatinisation at the temperature and treatment time applied in the high hydrostatic pressure process that reflects the pressure range desirable for processing. (C) 2004 Elsevier Ltd. All rights reserved.