Research On The Volatile Flavor Compounds And Antioxidant Activity Of Red Rice Wine

Chinese rice wine(CRW)is a traditional Chinese brewing,which is one of the world's three major brewings.Red rice wine is very popular among the Fujian and Zhejiang province because of its bright red color and mellow,soft mouthfeel.Compared to the researches on the flavor of CRW,there were little studies on the flavor metabolism of Red rice wine.The studies on flavor of Red rice wine could contribute us to understand the fermentation process and to guarantee the quality of Red rice wine.Meanwhile,the researches on the antioxidant activity in vitro could provide a theoretical basis to improve the healthcare function of Red rice wine.This paper was aimed at researching the effect of Monascus anka on the volatile flavor compounds and antioxidant activity during the pure-fermentation of Red rice wine.In order to get the optimized Red rice wine,the fermentation parameters(glucoamylase addition,red kojic rice addition,material / water ratio,and temperature)were optimized by single factor experiment.The result showed that the optimal condition was as follow: 0.72% glucoamylase,10% red kojic rice addition,1:2 material / water ratio,30°C for 6d.Meanwhile,the fermentation parameters(red kojic rice addition,material / water ratio,temperature)were optimized by the response surface method,and the same results were obtained with the single factor experiment.In order to research the flavor metabolism of Red rice wine,the volatile compounds were quantitative(semi-quantitative)and qualitative by HPLC and GC-MSD.The results showed that there were 33 compounds were detected,and an effect of Monascus anka on the composition and metabolism of organic acids were found,while those of esters and higher alcohol has little effect.Combining with OVAs method,4-hydroxyphenylethyl alcohol,phenylacetaldehyde were found the key flavor substance which may due to the effect of Monascus anka.The antioxidant activity of Red rice wine is derived from raw materials,red kojic rice and polyphenolic compounds which are transformated during the fermentation of Red rice wine.In order to study the antioxidant activity which was derived from raw materials and red kojic rice,total polyphenols(TP),total flavonoids(TF)and antioxidant activities of unfermented rice,fermented rice and commercially red kojic rices were researched.It showed that TP,TF and scavenging ability of DPPH and ABTS free radicals was 101.85,30.74,21.65 and 96.21 times respectively,compared with those of unfermented rice.And TP,TF and scavenging ability of DPPH and ABTS free radicals was increased by 32.60%,101.64%,109.08% and 68.15% respectively,compared with those of 10 commercially red kojic rices(the highest content of each parameter).Meanwhile,the correlation analysis showed that the content of TP and TF were positively correlated with antioxidant activity.Which may indicate that the antioxidant activity of red kojic rices mainly due to the transformation of polyphenolic compounds.In order to study the antioxidant activity of Red rice wine,TP,TF and antioxidant activities of the pure yeast group(group Y),the mixed culture group(MY group)and the commercial Red rice wines were researched.It was found that TP,TF,scavenging ability of DPPH free radical and reducing capacity of MY group were increased by 17%,12.4%,56.8% and 26.1% respectively,compared with Y group.Which indicated the advantages of aerobic solid-state fermentation in the transformation of polyphenolic compounds.Compared with the 11 commercial Red rice wine,the MY group was in the middle level.The correlation analysis showed that the TP and TF of red wine had low correlation with antioxidant activity.Which may due to the different types of antioxidants in Red rice wine.Further research showed that the main polyphenolic compounds were gallic acid and chlorogenic acid.And compared with Y group,the contents of chlorogenic acid,caffeic acid,quercetin and rutin in MY group increased 33.2%,33.5%,58.6% and 31.3% respectively,which indicated Monascus anka could promote the transformation of polyphenolic compounds during the fermentation of Red rice wine.