Study On Starch And Protein Of Germinated Brown Rice And Preparation Of Its Instant Rice

Germinated brown rice (GBR) is produced by steeping brown rice (BR) in excess water until it germinates. In the process, hydrolytic enzymes were activated, breaking down high molecular weight rice components and generating products with improved nutritional and organoleptic properties. GBR contains vitamins, minerals and dietary fiber, with components particularly rich in phytic acid, glutathione andγ-amino butyric acid, etc. With its improved sensory and nutritional properties, GBR as a functional food has received great attention. The paper studied on the impact of germination on the characteristics of brown rice flour, starch and protein. Germination altered the chemical composition of brown rice, resulting in an increase in reducing sugar and ash content, and a reduction in amylose. Paste viscosity, transition temperatures (To, Tp and Tc) and percentage of retrogradation (%Retrogradation) were decreased, while the content of slowly digestible starch (SDS) was increased. Scanning electron micrographs indicated that starch granules from GBR became smaller and less homogeneous. Moreover, germination shortened the chain length of amylopectin and amylose molecules.Protein molecular weight profile was analyzed by SDS-PAGE methodology. Compared to brown rice, the protein from GBR contained lower molecular-weight (MW) protein fractions. This may result from the fact that, germination triggered the production of protease, which hydrolyzed protein into oligopeptide. Furthermore, germination decreased the ratio ofα-helix,β-sheet and disulfide, accompanied by a corresponding increase of the rest secondary structures and sulfhydryl content. The continuity of the protein network in cooked brown rice grains and their malts observed under confocal laser scanning microscopy (CLSM) indicated that protein network-like structure was destroyed in the process of germination.The processing conditions of germinated brown instant rice production were also studied. The optimal soaking treatment was reached by immersing GBR in 0.1% citric acid solution for 100 min at 55 ?C. Four different cooking methods were discussed, and the method of double cooking technology is considered as the best way. At optimum cooking state, the degree of gelatinization, rehydration rate and the content con GABA of instant rice were 2.64, 95.59%, 28.22 mg/100g, respectively. Finally, the influence of drying temperature was discussed, drying with hot air for 90 min at 80 ?C was chosen.Based on the above process conditions,the effects of three rice products additives(GMS,β-cyclodextrin andα-amylase) on the quality of instant rice were investigated. Both GMS andβ-cyclodextrin can significantly improve the quality of instant rice and rehydration rate, whileα-amylase is not conducive to facilitate the processing of instant rice.