Study On The Anti-Aging Effect Of Germinated Brown Rice Flour On Rice Cakes

The anti-aging effect of germinated brown rice flour on rice cakes was studied in this paper. Under certain storage conditions, the anti-aging properties of rice cakes made by brown rice flour were evaluated via TPA, DSC and sensory analysis by altering the germination stages and the different ratio of mixture. The anti-aging effect was also studied via the evaluation of main component changes in brown rice during germination and determination of retrogradation ratio of flour reunited by starch and protein with different germination stages using separation and recombinant methods to clarify the main reasons of anti-aging effect of germinated brown rice flour on rice cakes.Results showed that anti-aging properties of rice cakes were improved by prolonging of germination time. Meanwhile germinated brown rice flour mixed with a specific blending ratio would also further improve the anti-aging effect. The retrogradation degree of rice cakes was tightly linked with germination time of brown rice and mixing ratio via TPA, DSC and sensory analysis. The most excellent quality factors and anti-aging effect of rice cakes were observed as the 2-day and 3-day germinated brown rice flour mixed at a ratio of 1:2. And the more additive proportions of this compound germinated brown rice in rice cakes, the better anti-aging performance.The key reason of rice cakes’ anti-aging effect was starch degradation when brown rice germinated. The degradation resulted in changes of starch content, composition, properties and its degradation products were the important reasons accounting for germination treatment delaying the aging of rice cakes. After 4-day’s germination, α-amylase and β-amylase activities increased from 61.99 U/g and 11.05 U/g to 128.66 U/g and 42.03 U/g. The total amylose、amylopectin and amylose decreased from 77.26%、4.08%、73.18% to 46.77%、2.56%、44.21%, respectively. Reducing sugar content in brown rice increased from 0.98% to 8.22%. DSC thermal properties of brown rice flour and the brown rice starch isolated by enzyme from different germination stages showed the retrogradation degree of brown rice flour and starch decreased along with prolonging of the germination time. And the brown rice starch was easier to aging than brown rice flour at the same germination stages. Scanning electron micrograph of the brown rice starch showed the pits and holes on starch surface were more and more obvious with prolonging of the germination time. Soluble starch molecular weight distribution diagram showed the Mp decreased with prolonging of the germination time, and the content of small molecular weight of dextrin and starch sugar gradually increased. The amylopectin fine structures and chain-length distribution analysis of brown rice starch from different germination stages showed that amylase was likely to hydrolyzed side chains of starch. After germination, brown rice starch short chain content decreased and it brought a corresponding increase in long chain content. Starch retrogradation trend decreased.Changes of protein, fat and their degradation products of brown rice during the germination also may be the factors influencing anti-aging of rice cakes. After 4-day’s germination, content of-S-S- in brown rice decreased from 3.84 μmoL/g to 1.36μmoL/g, and the content of –SH increased from 5.32 μmoL/g to 6.74 μmoL/g. So germination treatment had much effect on the protein conformational stability leading to the change of interaction degree of starch and protein. And the change of content of fat, DAG and MAG, fatty acid composition, which also may be one of the reasons for the different aging effect of mixing germinated brown rice flour. In addition, the retrogradation properties of flour reunited by starch and protein showed protein could inhibit the aging of starch.