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 2θ＝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.