Effect of the milling process on the thermal behavior and crystallinity of buckwheat starch

Abstract

Buckwheat starch is an alternative source to supply the high global demand for starch. The properties of starch can be modified through chemical and physical methods; one of them is the milling process, which can be considered as green method according with the green chemistry principles. Thus, this work aims to use the milling process and study its effects on thermal and crystalline properties of starch extracted from common buckwheat (Fagopyrum esculentum). It was observed in differential scanning calorimetry and X-ray powder diffraction that after the milling process, the starch losted its crystallinity and was pre-gelatinized. Nevertheless, the samples showed similar decomposition, dehydration and oxidation profiles, as observed by thermogravimetry and differential thermal analysis curves. The thermal stability did not show considerable difference (less than 5 °C) after the milling process. Moreover, the medium infrared spectroscopy showed that the milling process did not change the functional groups of starch. The morphology of the starch granules, as observed by scanning electron microscope presented surface roughness, and also the decrease of the average diameter of the modified starch was observed.