Decreasing crack additional percentage and improving yield in preparation of germinated brown rice with cyclic moisture conditioning treatment

Abstract: Compared with the polished rice and brown rice, germinated brown rice is rich in γ-aminobutyric acid. Germinated brown rice prepared by the traditional soaking treatment has the problem that crack percentage is extremely high, resulting in lower-quality germinated brown rice. Therefore, research to improve the quality of the germinated brown rice is necessary. Based on the use of moisture conditioning technology to improve the quality of brown rice, this study proposes a new method for the preparation of germinated brown rice. According to the principle of natural moisture absorption and germination of the rice seeds in the soil, germinated brown rice is prepared by gradually increasing the moisture content, until the moisture content is suitable for germination. The experiment of moisture conditioning for brown rice was carried out in a self-made test bed. Spray humidification was carried out according to certain amount of single humidification. Sealing was carried out at a certain temperature in accordance with a pre-set time interval. The brown rice after repeated moisture conditioning treatment was taken and placed under certain temperature and humidity conditions for germination. A central composite rotatable orthogonal experimental design of response surface methodology was employed. The influences of the three parameters, including the amount of moisture added, the interval time, and the temperature, on the crack additional percentage and germinated brown rice yield in repeated moisture conditioning treatment were investigated. Mathematical models for the influences of various parameters on the crack additional percentage and germinated brown rice yield were established. The test data were processed in Excel and Design Expert. Experimental results showed that the parameters of repeated moisture conditioning treatment had significant impacts on the crack additional percentage and germinated brown rice yield. The optimum parameters are added moisture in the range 1.2%-1.6%, interval time 45-75 min, and temperature 30℃. The crack additional percentage of germinated brown rice using the repeated moisture conditioning treatment is 20%-70% lower than that using the traditional soaking treatment. The yield of germinated brown rice using the repeated moisture conditioning treatment is 1%-16% higher than that using the traditional soaking treatment. The decrease of crack additional percentage and the increase of germinated brown rice yield are of great significance for improving the quality of the germinated brown rice. The research results can provide a reference basis for the preparation of germinated brown rice in industrial production by using the technology described in this paper.