MICROSCOPIC STUDY OF STARCH GELATINIZATION UNDER HIGH HYDROSTATIC-PRESSURE

Starch gelatinization corresponds to a melting phase transition in aqu eous medium. Such a transition involves important mass transfer of wat er. Using a high-pressure bomb including optical ports, the volume var iation of starch granules in suspension was related to gelatinization during a high-pressure treatment up to 420 MPa. Microscopic observatio ns of wheat and potato starch granules were compared with macroscopic measurements of compressibility up to 600 MPa and gelatinization inten sity using differential scanning calorimetry on treated suspensions. W heat starch gelatinization started below 300 MPa and was completely ac hieved at 600 MPa. Potato starch was not altered under 600 MPa. The be havior of the volume variation of starch granules under pressure compa red with starch suspensions compressibility could be explained by simu ltaneous compression and hydration mechanisms.