Nakamura Sumiko, Ohtsubo Ken'ichi
Faculty of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1, Higashijima, Akiha-ku, Niigata 956-8603, Japan.
Foods. 2023 Jun 28;12(13):2510. doi: 10.3390/foods12132510.
In the present paper, we investigated the characteristics of chalky rice grains generated by ripening under high temperature and compared them with whole grains. We evaluated 14 unpolished rice grains harvested in Japan in 2021, and these samples (original grains) were divided into two groups (a whole grain group and a chalky grain one). We found that not only activities of endogenous amylase and proteinase, but also cell wall-degrading enzymes, such as xylanase and cellulase, changed markedly between chalky grains and whole grains. Using rice grains blended with 30% of chalky grains as the material, we compared the sugar and mineral contents and textural properties of the rice grains soaked and boiled in either ordinary water or hard water, such as Evian or Contrex. It was shown that xylanase, in addition to amylase and proteinase, may play an important role in changing the texture of the boiled chalky rice grains. For the sake of preventing the above-mentioned deterioration in the texture of boiled grains of chalky rice, we tried to use hard water, such as Evian or Contrex, to soak and cook the chalky rice grains. It was shown that the hard water was useful for the prevention of texture deterioration of the boiled rice grains due to inhibition of the activities of endogenous hydrolytic enzymes, such as α-amylase, β-amylase, proteinase, and xylanase. Furthermore, we found that the hard water was useful in increasing the calcium absorption through the meal by 2.6 to 16.5 times.
在本论文中，我们研究了高温下成熟产生的垩白米粒的特性，并将其与整粒米进行比较。我们评估了2021年在日本收获的14个糙米样本，这些样本（原始谷粒）被分为两组（整粒米组和垩白粒组）。我们发现，不仅内源性淀粉酶和蛋白酶的活性，而且木聚糖酶和纤维素酶等细胞壁降解酶在垩白粒和整粒米之间也有显著变化。以混合了30%垩白粒的米粒为原料，我们比较了在普通水或诸如依云矿泉水或康师傅矿泉水等硬水中浸泡和煮熟的米粒的糖分、矿物质含量及质地特性。结果表明，除淀粉酶和蛋白酶外，木聚糖酶可能在改变煮熟的垩白米粒质地方面发挥重要作用。为防止上述垩白米煮熟后质地变差，我们尝试用依云矿泉水或康师傅矿泉水等硬水来浸泡和煮垩白米粒。结果表明，硬水有助于防止煮熟米粒的质地变差，因为它能抑制内源性水解酶如α-淀粉酶、β-淀粉酶、蛋白酶和木聚糖酶的活性。此外，我们发现硬水有助于使通过膳食摄入的钙吸收量增加2.6至16.5倍。
