PHYSICOCHEMICAL, FUNCTIONAL AND STRUCTURAL PROPERTIES OF NATIVE AND ACETYLATED POTATO (Solanum tuberosum) STARCHES ISOLATED FROM ‘ÚNICA’ VARIETY

Abstract

Acetylation is a chemical modification of the starch structure that consists of replacing a certain number of hydroxyl groups with acetyl groups using acetic anhydride. This process depends on certain factors, such as starch source, acetic anhydride concentration, reaction time and pH. The aim of this study was to characterize the native starch (isolated from a commercial potato ‘Única’ variety) and the acetylated starches by FT-IR spectroscopy, and evaluate their physicochemical (amylose content, color) and functional properties (swelling power, solubility, water retention capacity, thermal properties, and pasting profile). The evaluated samples were native starch (AN) and modified starches by acetylation with different concentrations of 5 %, 10 % and 15 % acetic anhydride (AAc5%, AAc10% and AAc15%). The apparent amylose contents for native starch and acetylated starch (AAc15%) were 17,3 and 31,4 %, respectively. The color parameters did not change after the acetylation. Both, the temperature and the enthalpy of gelatinization as well as the pasting profile decreased for the acetylated starches with respect to the AN starch. During pasting test, acetylated starch (AAc15%) showed a low value of the maximum viscosity (1599,4 mPa∙s) with respect to the value observed for native starch (3065,8 mPa∙s).