Study On The Process Of Producing High ?-aminobutyric Acid Rice Wine By Ultra High Pressure

Rice wine is popular among people all over the world for its unique sweet flavor.However,the development of health-care rice wine on the market is rare.?-aminobutyric acid(GABA)is a natural active substance with many health care functions such as anti-anxiety and blood pressure lowering.The endogenous enzyme is activated during the germination process of brown rice,which can catalyze the decarboxylation of glutamic acid to form GABA.In this study,germinated brown rice was used as raw material to brew GABA-rich health-care rice wine.The single-factor experiment was used to determine the optimal soaking and germination conditions of brown rice.The high-GABA content germinated brown rice was used to brew rice wine,and the rice wine finished products were subjected to different conditions.The ultra-high pressure treatment,by investigating the content of ?-aminobutyric acid in wine,using single factor experiment combined with response surface method to optimize the ultra-high pressure treatment conditions,by observing the changes of main physical and chemical indicators of germinated brown rice wine under different ultra-high pressure conditions,and the germinated brown rice wines of different treatment groups were tested by headspace solid phase microextraction(HS-SPME)combined with gas chromatography-mass spectrometry(GC/MS)to detect the volatile aroma components in germinated brown rice wine and carried out principal component analysis to discuss the effect of ultra-high pressure treatment on the quality of germinated brown rice wine.The main conclusions of this study are as follows:1.The best soaking condition of brown rice is: soak for 18 h at 36 °C.The GABA content of brown rice obtained under these conditions reached 291.1 ?g/g,which was 567.66% higher than that of the unsoaked treatment group.2.The best germination condition for brown rice is: germinated at 28 °C for 20 h.The GABA content of the germinated brown rice obtained under this condition reached 346.7 ?g/g,which was much higher than that of the ungerminated brown rice.3.The response surface method was used to optimize the conditions of ultra-high pressure treatment of germinated brown rice wine.The optimum treatment pressure was 200 MPa,the temperature was 25 °C,and the holding time was 30 min.The GABA content in the germinated brown rice wine obtained under this condition was 27.4 mg/L.4.The germinated brown rice wine was treated by different ultra-high pressure treatmentconditions to study the effect of ultra-high pressure treatment on the physical and chemical indicators of germinated brown rice wine.Analysis shows:(1)Under the condition of 50-150 MPa,the alcohol content decreased not significantly(P>0.05).When treated at 200 MPa,the alcohol content decreased significantly(P<0.05),and the effect of dwell time on alcohol content was not obvious(P>0.05).(2)The total acid content of germinated brown rice wine was the most obvious at 200 MPa(P<0.05).The change of total acid content under other pressure conditions was not significant(P>0.05).The holding time had significant effect on the total acid content(P<0.05).As the holding time increased,the total acid content decreased.(3)With the increase of pressure,the reducing sugar content showed a downward trend.When treated at 200 MPa for 30 min,the decrease was most significant by 0.09 g/L,and when the pressure increased to about 250 MPa,the amount of reducing sugar was slightly elevated,but the change was not significant(P>0.05).As the holding time increased,the reducing sugar content had a tendency to decrease.(4)Under the same holding time,as the treatment pressure increased,the amino acid nitrogen tended to increase.Under the same treatment pressure,the effect of holding time on amino acid nitrogen content was significant(P<0.05).At 250 MPa,the amino acid nitrogen content was significantly lower than 200 Mpa(P<0.05)..5.After the ultra-high pressure treatment,the volatile aroma components of the germinated brown rice wine are found:(1)The types of volatile flavor substances in the germinated brown rice wine after ultra-high pressure treatment were 52 kinds in the untreated group,51 kinds in the 100 MPa/30 min group,55 kinds in the 150 MPa/30 min group,61 kinds in the 200 MPa/30 min group,51 kinds in the 250 MPa/30 min group and 52 kinds in the 300 MPa/30 min group.Alcohols accounted for the vast majority of aroma components,and their content decreased with increasing pressure,always above 50%;after 5 kinds of ultra-high pressure treatment,the content of esters in germinated brown rice wine increased.The ester content reached the highest at 300 MPa,accounting for 21.51%.The acid substance had the highest content when it was not treated,which was 2.25 %.Aldehydes had a large increase under the treatment at 250 MPa and300 MPa.(2)The aroma components of germinated brown rice wine under different ultra-high pressure treatment conditions were analyzed by principal component analysis.It was found that ultra-high pressure treatment had certain influence on the aroma of germinated brown rice wine.Different ultra-high pressure treatments would influence the germinated brown rice wine differently.There are certain differences in the types and contents of the aroma components.(3)The sensory evaluation scores of the germinated brown rice wine after ultra-high pressure treatment were higher than those of the untreated control group,and the sensory evaluation value of the samples treated at 200 MPa/30 min was the highest,which wasconsistent with the analysis results of volatile flavor substances.