Biofortification Of Germinated Brown Rices With Iron And Assessment Of Their Antioxidant Activity

The purpose of this research was mainly to investigate the changes of the nutritional vaiues,antioxidant enzyme activities and antioxidant capacities of brown rice at germination and iron biofortification conditions.Due to the strong iron enrichment ability,brown rice(BR)was selected as the experimental subject.Iron-enriched germinated brown rice(Fe-GBR)was prepared by iron biofortification using soaking seeds with different solutions of ferrous sulfate at different concentrations.Based on eight varieties of brown rice experiments,three cultivars of brown rices were selected for iron biofortification process,namely Teyou 128,Tyou 458 and Y Liangyou 865.The germination rate,water absorption and biological yield of Fe-GBR were investigated by experiments.To evaluate the nutritional value and nutrient changes of Fe-GBR,the contents of iron,y-aminobutyric acid,?-olianol,total phenolics,total flavonoids and protein were determined in our study.The antioxidant abilities of Fe-GBR were evaluated in terms of the internal connection between antioxidant enzyme activities and antioxidant capacities simultaneously.Meanwhile,the effects of germination and iron biofortification on the antioxidant activities in BR were also determinated.The main results were summarized as follows:(1)Germination rates of BR were greatly affected by the variety of BR.The maximum germination rates of BR were observed in cultivar Teyou 128 at 50.35 mg/L iron solution(94.35%).Meanwhile,the results showed that germination rates of BR were increased after iron biofortification process.For germinated brown rice cultured with 201.40 mg/L iron solution,germination rate of BR in Y Liangyou 865 was significantly(p<0.05)increased 25.4%compared with rice seed.However,there were no significant differences(p>0.05)between water absorption and biological yield in all varieties of brown rice,indicating that iron biofortification had no effect on water absorption and biological yield.(2)Total iron contents of Fe-GBR were measured by flame atomic absorption spectrophotometer.Results indicated that the contents of total iron were significantly(p<0.05)increased after iron biofortification process.The iron contents of Fe-GBR in Teyou 128,Tyou 458 and Y Liangyou 865 were significantly increased 132-1650%compared to the brown rice germinated with deionized water(GBR).According to the Chinese residents Dietary Recommended Intake(DRI),our research calculated that three brown rice varieties cultured with 50.35 mg/L iron solution could meet the ordinary iron intake(16.1-19.5 mg/kg dry weight).The contents of iron,GABA,total phenolics,total flavonoids and protein in GBR were noticeably increased compared with rice seed.Meanwhile,different varieties of BR have diverse impacts on nutritional value of Fe-GBR during iron biofortification process.The content of GABA in Teyou 458 at 50.35 mg/L of iron solution was significantly(p<0.05)increased by 56.4%compared with rice seeds.However,iron biofortification had no significant(p>0.05)effect on the contents of y-olizanol.The contents of total phenolics in Teyou 458 and total flavonoids in Teyou 128 were significantly(p<0,05)increased within the process of iron biofortification.The content of protein from Fe-GBR in Teyou 458 with 50.35 mg/L iron solution was significantly(p<0.05)increased 51.4%compared with rice seed.The results indicated that iron biofortification could promote the nutritional value in somebrown rice cultivars.(3)Brown rice germinated with deionized water could increase catalase(CAT)activities and decrease peroxidase(POD)activities.Different rice cultivars may result in a wide variety of malonaldehyde(MDA)contents and enzyme activities.For low concentrations of iron biofortification(<100.70 mg/L),CAT activities were significantly(p<0.05)increased,but iron biofortification had no effect on POD activities.Superoxide dismutase(SOD)activity was significantly(p<0.05)increased 83.1%and content of MDA was significantly(p<0.05)decreased 65.8%by iron biofortification process in cultivar Teyou 458 at 50.35 mg/L iron solution compared with rice seed.(4)DPPH/ABTS radical scavenging activities in GBR were significantly(p<0.05)increased by 3.0-11.6%and 8.1-18.3%compared with rice seed.Ferric reducing antioxidant power(FRAP)and reducing power were significantly(p<0.05)increased by iron biofortification process,but superoxide anion(O2'· radical scavenging abilities were reduced.By comparing with rice seed,DPPH/ABTS radical scavenging activity and reducing power of Fe-GBR in cultivar Teyou 128 at 50.35 mg/L iron solution were significantly(p<0.05)increased 17.0%?8.48%and 496%,respectively.Meanwhile,a significant increase in FRAP was observed in cultivar Teyou 128 with 402.80 mg/L iron solution,which increased by 36.9%during iron biofortification process compared with raw seed.In conclusion,iron biofortification might have highly beneficial to improve the antioxidant capacities,but the varieties of BR may have great influences on antioxidant capacities.(5)Total phenolics contents had a great correlation with DPPH radical scavenging activities(r = 0.851-0.924,n = 8).Total flavonoids contents showed a high correlation with DPPH radical scavenging activities in Teyou 458 and Y Liangyou 865(r = 0.883-0.913,n =8).Meanwhile,total phenolics and total flavonoids contents had the highest correlation in cultivar Teyou 458(r = 0.982,n = 8).However,total phenolics,flavonoids contents and DPPH free radicals were not related to ferric reducing antioxidant power values in all rice varieties.