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Soaking time of rice in semidry flour milling was shortened by increasing the grains cracks

Tong, Li-Tao, Zhu, Ruizhen, Zhou, Xianrong, Zhong, Kui, Wang, Lili, Liu, Liya, Hu, Xinzhong, Zhou, Sumei
Journal of cereal science 2017 v.74 pp. 121-126
absorption, drying temperature, magnetic resonance imaging, milling, rice, rice flour, soaking, starch
To shorten the soaking time of rice grains in the process of semidry-milling, the changes in moisture absorption, damaged starch, and magnetic resonance images during soaking, as well as effect of increasing grains cracks on moisture absorption were investigated. As the results, the soaking time to reach the maximum moisture of Glutinous and Indica rice grains was 40 min and 20 min, respectively, but was 3 h and 30 min to reach the minimum damaged starch contents in rice flour. The moisture penetrated quickly from the embryo attachment site, ventral side, and cracks into the inside, and then diffused through the cracks. The result showed that homogeneous distribution of moisture in the rice grains was necessary to reduce damaged starch. Moreover, owing to the increase of grains cracks, the soaking time of Glutinous and Indica rice grains was shortened from 3 h to 1 h, and from 30 min to 10 min, respectively, by increasing drying temperature to 60 °C.