Changes in the Molecular Structure of Potato Starch Conferred Digestion Resistance by Fatty Acid Addition and Heat Treatment

Abstract

X-ray diffraction (XRD) was used to analyse potato starch with a 20% moisture content that was made digestion-resistant by the addition of palmitic acid and heat treatment at temperatures in the range of 120-160 ℃ . This starch was also analysed for the quantity of fatty acids able to form starch complexes and in vitro digestion test. Changes in molecular structure that accompany starch-fatty acid complex formation were then investigated based on the results from these analyses. XRD analysis confirmed that fatty acid addition caused emergence of new peaks in the region of 2 θ＝ 13, 19°. There was a strong positive correlation between the 2 new peaks and the internal free fatty acid content, which also increased at higher heat treatment temperatures. This positive correlation suggested these peaks are attributable to structures from the starch-fatty acid complex.