Effects of added seed-coat powder from adzuki beans on the physical properties, sensory characteristics and preservation of steamed sponge cake

In order to utilize the seed-coat powder of adzuki beans as a food material, three materials were examined by adding them to steamed sponge cake. Powder A: untreated seed-coat powder from adzuki beans. Powder B: Powder A was soaked in distilled water and then ultrasonicated for 15 minutes. Powder C: Powder A soaked in distilled water for 15 hours. The effects of the addition of konnyaku gel to the steamed sponge cake mixture on the physical properties, sensory characteristics, and preservation of the cooked sponge cake were also examined. The soft wheat flour in steamed sponge cake was substituted by Powders A, B and C up to 20%. Compared with the control without the seed-coat powder, the steamed sponge cake, in which up to 20% of the wheat flour was replaced by the seed-coat powder, resulted in a hue of adzuki beans, a high specific volume and higher moisture content, harder and more brittle texture, and more preferable flavor, taste and overall rating. The addition of Powder B and konnyaku gel (2.2%) significantly suppressed the aging of starch and the number of bacteria in the steamed sponge cakes during storage. In conclusion, the addition of the seed-coat powder from adzuki beans and konnyaku gel to the steamed sponge cake improved its quality.