Background : In food science, research on miscellaneous grain crops has focused primarily on their components, with limited studies conducted on their germination. In this study, we isolated and purified amylases from germinating seeds of various miscellaneous grain crops, including barnyard, foxtail, and common millets, and examined their properties. Methods : Amylase was extracted from germinated seeds from barnyard, foxtail, and common millets and purified using ion exchange chromatography, chromatofocusing, and gel filtration chromatography with Sephadex G-100. The enzyme properties, including pH and temperature effects, molecular weight,isoelectric point, Km value, metal ion effects, and substrate specificity, were then determined. Results : Two types of amylase enzymes, amylases I and II, were purified from each germinated seed. The purified amylases were identified as (sulfhydryl) SH enzymes because their activities were inhibited by Hg2+, monoiodoacetic acid（MIA）, and p-chloromercuribenzoic acid (PCMB). Based on the breakdown products, amylase I was classified as a β-amylase, effectively hydrolyzing starch, amylopectin, and low-molecular-weight amylose. Amylase II, characterized by the appearance of its breakdown products, was identified as an α-amylase, catalyzing the breakdown of starch, amylopectin, and both low- and high-molecular-weight amyloses. Conclusions : Clarifying the properties of amylases in the germinating seeds of miscellaneous grain crops is important for understanding their potential applications and studying their germination physiology.

View full abstract

[in Japanese]

View full abstract

Sweet potato tempura was deep fried at 160°C, 180°C, and 200°C to visually understand the water behavior of food ingredients during the deep frying and determine whether the quality of the finished product could be evaluated using visual indicators. The change in the contrast values of the oil surface images during the deep frying was consistent with the water evaporation rate, indicating that the alteration in water evaporation from tempura over time can be estimated using such values. The water behavior of the batter and sweet potatoes was examined by substituting the water in the batter with heavy water. Immediate water evaporation post-deep frying originated from the batter, with the subsequent one from the sweet potatoes. The tempura quality was optimal when the potatoes were deep fried at 160°C, wherein minimal water evaporation occurred, the sweet potatoes retained water, and the batter maintained an adequate water content. These results suggest that evaluating the quality of sweet potato tempura using contrast values as visual indicators is feasible, given that water behavior during the deep frying can be estimated based on the alterations in water evaporation rates.

View full abstract