Textural and morphological changes of heat soaked raw Amaranthus caudatus

In recent years, the interest in alternative cereals as pseudocereals has increased. The pseudocereal amaranth should be heated thermally before consumption. The purpose of this study was to investigate the textural and morphological change of Amaranthus caudatus during heat soaking below boiling temperature. Therefore, the effects of heat soaking at different temperatures (20, 50, 60, 70, 80 ?C) and times (1, 5, 24 h) of Amaranthus caudatus were researched. A significant textural and morphological change of amaranth grains was found for samples soaked at temperatures ?60 ?C, due to gelatinization of starch. Overall, with an increase in temperature moisture content and water absorption increased, while the firmness of grains decreased. A similar trend was observed for color changes: higher temperatures lead to a darker grain color. SEM images of hydrothermally treated amaranth samples displayed microstructural changes of the embryo and perisperm, which explain the firmness decrease. The temperature had a higher influence on morphological and textural changes than soaking time. Especially higher temperatures significantly altered the texture and external appearance of the grains while soaking time had negligible effect.

Automated summary

The study found that heat soaking at temperatures below 60℃ can cause significant textural and morphological changes to amaranth grains, mainly due to starch gelatinization. With an increase in temperature, moisture content and water absorption increased, while the firmness of grains decreased. It was also observed that temperature had a greater influence on morphological and textural changes, significantly altering the texture and external appearance of the grains, while soaking time had negligible effect.