Effect of Heat-moisture treatment on quinoa, amaranth, taro, potato, and maize starch

Abstract

This research examined at how different starch particle sizes were physically altered by the same hot and humid treatment conditions (120°C, 30% moisture content, 1 hour treatment). The effects and differences of the HMT modification method on the morphological characteristics, pasting properties, thermal properties and gel rheological properties of different particle sizes of starch were also evaluated. In this study, the physicochemical properties of small granular starches extracted from seeds or roots of three plants were analyzed before and after treatment and compared with two New Zealand commercial large granular starches (potato starch and maize starch). Three small granule starches include quinoa starch, amaranth starch and taro starch. After HMT physical modification, the particle size of small starch particles increased significantly. It showed an apparent aggregation phenomenon on the scanning electron microscope photos, while this trend was very low for large starch particles. X ray diffraction showed that the change of crystal form was not related to particle size. The crystal form of potato starch changed after modification but not that of other starches. At the same time, the relative crystallinity of small grain starch decreased after modification, while that of large grain starch increased. All starch samples showed that HMT physical modification increased the thermal stability of native starch. At the same time, the gel, thermal and gelatinization properties showed that the effect of particle size on the modification of HMT might not be obvious, and it is more affected by amylose. At the same time, for the rheological properties of the gel, it can be observed that particle size will affect the results of oscillation. However, the effect of HMT on the flow properties and particle size is not a decisive factor. According to the different physical and chemical properties of starch with different particle sizes under the modification of HMT, it has excellent help and application to the food industry. It is helpful for industrial production. When starch with different particle sizes is modified by heat moisture treatment, it can be adjusted appropriately according to relevant purposes. Key words: Heat--moisture treatment, quinoa starch, amaranth starch, taro starch, structural properties, thermal properties, gelatinization properties, rheological properties.