Koriyama Takako, Sato Yoko, Iijima Kumiko, Kasai Midori
Dept. of Nutrition and Food Science, Graduate School of Humanities and Science, Ochanomizu Univ., 2-1-1 Otska, Bunkyo-ku, Tokyo, 112-8610, Japan.
Faculty of Core Research, Natural Science Div., Ochanomizu Univ., 2-1-1 Otska, Bunkyo-ku, Tokyo, 112-8610, Japan.
J Food Sci. 2017 Jul;82(7):1546-1556. doi: 10.1111/1750-3841.13749. Epub 2017 Jun 6.
The influences of soaking treatment and storage conditions on the softening of cooked beans, namely, soybeans and red kidney beans, were investigated. It was revealed that the softening of fresh soybeans and fresh red kidney beans was suppressed during subsequent boiling after soaking treatment at 50 and 60 °C. Furthermore, in treated aged soybeans and red kidney beans that were subjected to storage at 30 °C/75% relative humidity for 6 mo and soaking treatment at 50 to 60 °C, the hardness during cooking was further amplified. This suggested that the mechanism of softening suppression differs depending on the influences of soaking and storage. Analysis of the pectin fraction in alcohol insoluble solid showed insolubilization of metal ions upon storage at high temperature and high humidity in both soybeans and red kidney beans, which suggests interaction between Ca ions and hemicellulose or cellulose as cell wall polysaccharides. The results of differential scanning calorimetry (DSC) showed that aged soybeans exhibited a shift in the thermal transition temperature of glycinin-based protein to a higher temperature compared with fresh soybeans. From the results of DSC and scanning electron microscopy for aged red kidney beans, damaged starch is not conspicuous in the raw state after storage but is abundant upon soaking treatment. As for the influence of soaking at 60 °C, it can be suggested that its influence on cell wall crosslinking was large in soybeans and red kidney beans in both a fresh state and an aged state.
研究了浸泡处理和储存条件对煮熟豆类（即大豆和红芸豆）软化的影响。结果表明，新鲜大豆和新鲜红芸豆在50℃和60℃浸泡处理后，后续煮沸过程中的软化受到抑制。此外，经过处理的老化大豆和红芸豆在30℃/75%相对湿度下储存6个月，并在50至60℃进行浸泡处理后，烹饪过程中的硬度进一步增大。这表明，浸泡和储存的影响不同，软化抑制机制也不同。对醇不溶性固体中的果胶部分进行分析表明，大豆和红芸豆在高温高湿储存时金属离子会发生不溶，这表明钙离子与作为细胞壁多糖的半纤维素或纤维素之间存在相互作用。差示扫描量热法（DSC）结果表明，与新鲜大豆相比，老化大豆中基于大豆球蛋白的蛋白质的热转变温度向更高温度偏移。从老化红芸豆的DSC和扫描电子显微镜结果来看，储存后的生豆状态下受损淀粉并不明显，但浸泡处理后则大量存在。至于60℃浸泡的影响，可以认为，无论新鲜状态还是老化状态，其对大豆和红芸豆细胞壁交联的影响都很大。
