The Influence of Sugars on Pressure Induced Starch Gelatinization

Abstract

Besides the application of high pressure (HP) as a non-thermal preservation technology, HP could additionally have a deep impact on the material properties of the treated food. Especially the HP induced swelling and gelatinization of starch influences the processing properties of starch-based food systems and differs in comparison to thermal induced gelatinization. The aim of this study was to examine the impact of HP on starches under different conditions and to influence systematically the gelatinization and pasting properties of wheat starch by the addition of various types of sugar. Caused by limitation of conventional methods, this study also includes the development of an appreciate method based on the particle size measurements of the starch granules. Three methods of measuring particle sizes were examined for an application for pressure treated starches. Finally, an image analysis with microscope, camera and image processing software ImageJ was chosen to perform the analysis. Wheat, tapioca and potato starch with concentration of 5 (w/w) and 25 (w/w) were pressurized at 600MPa for ten minutes at 20°C as well as 60°C, to reach treatment conditions which are suitable for HP food pasteurization. The results showed that ultra HP significantly increased the particle size of the starch granules, whereas the degree of swelling was starch type and temperature dependent. High starch concentrations resulted in a limited swelling caused of the limited water content. This effect is enhanced with increasing swelling properties. Besides this, sugar caused a significant decrease of the granules size. A dependence of this effect with the type of sugar was not examined. This work should be a contribution to expand the understanding of the swelling mechanisms of starch granules under HP and should facilitate a future process and product development of HP pasteurized starch based products.