FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY

Authors

TERESA WITCZAK, ANNA STĘPIEŃ, KAROLINA PYCIA, MARIUSZ WITCZAK, AGATA BEDNARZ, MIROSŁAW GRZESIK

Title

Effect of chemical modification of starch and degree of hydrolisis on moisture sorption isotherms of hydrolysates

Abstract

In the research study, the moisture sorption isotherms were determined for the hydrolysates obtained by the enzymatic hydrolysis of native potato starch, acetylated potato starch, and distarch phosphate. Furthermore, the effect was determined of the dextrose equivalent values obtained (DE 6, 11, 16) on the hygroscopicity of products. The sorption isotherms were determined using a static method in the environment, where water activity ranged from 0 to 0.903 at a temperature of 25 ºC. Three mathematical models were applied to describe sorption isotherms. It was found that the four-parameters Peleg’s model made it possible to present the experimental data within the full range of water activity while the use of the BET and GAB models required to limit those data. All the plotted curves were characterized by a sigmoidal shape, typical for isotherms of type II according to the classification by Brunauer et al. [4]. In mono- and multilayer adsorption regions, all the hydrolysates analysed exhibited similar properties. The highest differences in the equilibrium moisture content were reported at a water activity higher than 0.7. It was found that the sorption properties of the products investigated were determined mainly by the dextrose equivalent values, while the chemical modification of starch significantly impacted the content of adsorbed moisture only in the high water activity environment.

Keywords

maltodextrins, dextrose equivalent, modified starch, sorption isotherm

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