Preparation of amylosucrase treated potato starch complexed with butyric acid and its structural characteristics

Abstract

Potato starch was modified by using amylosucrase (AS) from Neisseria polysaccharea for 3 and 24 h and complexed with butyric acid. Branch-chain length distribution, thermal properties, crystallinity, and digestibility were changed by the AS-treatment. The proportion of A chains (DP ≤ 12) decreased, while those for both B2 chains (DP 25-36) and B3 chains (DP 25-36) increased with increasing reaction time. Thermal properties of AS-treated starch such as the onset, peak and conclusion temperatures of gelatinization, and melting enthalpy increased with enzyme reaction time. However the complex of AS treated starch had the lower melting temperature than that of their control due to the bulky carboxylic group of butyric acid. The carboxylic group induced disruption of amylopectin double helices, resulting in the decrease of the level of crystalline order. Therefore, the X-ray pattern of AS-BAs complex displayed V type pattern with a peak of gentle slope, and the R value of 1022/995 cm-1 in FTIR showed that AS-Bs were less ordered that ASctrs. In previous studies, there were many reports that amylose could form a complex with a fatty acid, which is with a longer chain length than caprylic acid. To date, there has been minimal research regarding amylopectin-fatty acid inclusion complex. Butyric acid has a very low ability of forming a complex with raw starch. Thus, this study hypothesize the possibility that amylopectin-short chain fatty acid inclusion complex could be formed by controlling of the branch chain length of amylopectin. The starch-butyric acid could support the prevention and therapy for inflammatory bowel disease like Crohns disease. Therefore starches complexed with butyric acid could provide functional food ingredients that could enhance the health.