Evaluation Of Different Derivative Methods In The Determination Of GABA In Germinated Brown Rice By HPLC And Preliminary Exploration Of Critical Technology On Preparing It

Germinated brown rice is a new type of rice modified product, which has more nutritional value and promotion prospects. But now the analytical methods of gamma-aminobutyric acid which is the most popular one in germinated brown rice are not regulated. Meanwhile, the phenomenon of low efficiency, high cost and inelasticity of the end of germination exist in the production of germinated brown rice, which leads to higher market price, and limits the consumer, and hinders its popularization. Therefore, looking for the ways of improving the productivity of germinated brown rice has important practical value. Physical method is an important mean of improving the germination rate of brown rice, and has higher safety and operability and offers the basic parameters of the development of small germinator. This paper used five varieties of good quality brown rice (Huang Hua Zhan, Xiang Wan Xian13, Jin You207, Star NO.2, Feng Liang You) from Hunan province as raw material to study, and the results were as follows:The determination method of GABA in germinated brown rice was analyzed. The difference of different derivative agent of determining GABA by HPLC was studied. A gradient elution was used for the separation and quantification of GABA pre-column derivatization with OPA, Dansyl-Cl, AQC. The column were intertsil ODS-C18(by the first two), waters AccQ·Tag for free amino acids. GABA was determined with UV detector at332nm,386nm,250nm and linear equations were Y=9.0×106X+2062.5(R2=0.9989),Y=7.0×106X+11337(R2=0.9982),Y=7.1×106X+10025(R2=0.9999), and detection limits were0.005mg/mL,0.01mg/mL,0.001mg/mL, and RSD of peak area of GABA measured in the same sample was1.16%,1.98%,0.94%, and the recoveries were98.5%-106.9%,95.8%-110.6%,99.4%-103.4%, GABA content measured in the same sample was11.24,10.67,13.47mg/100g dry weight, respectively. We learned from the above results that in three kinds of derivative agent determining GABA by HPLC, the most accurate one is AQC, followed by OPA and Dansyl-Cl.Mimicing natural environment, orthogonal experiment was employed to optimize best parameter of the germination of brown rice. The optimum conditions were the first4h:37℃of germination temperature with4000LX of light intensity,4h after germination:30℃of germination temperature with no light, and the aeration of10 min per1.5h.The influence of short-term soaking, ultrasound, stirring-soaking, ozone, microwave, temperature, magnetic water and hydration-dehydration treatment before the germination of brown rice on the germination rate and GABA content in different germination time(6、8、10、12、14h) was studied. The results showed, compared with the brown rice of non-treatment, the eight kinds of pre-processing methods could significantly improve the germination rate and GABA content of brown rice (P<0.05). The influence of germination rate of brown rice:ozone (22.2%)> magnetic water(17.4%)> hydration-dehydration(17.0%)> temperature (15.8%)> stirring and soaking (15.0%)> ultrasound(14.8%)> microwave (12.3%)> short-term soaking (10.3%), and the influence of GABA content of brown rice:magnetic water (12.87mg/100g)> hydration-dehydration (12.84mg/100g)> stirring and soaking (11.59mg/100g)> temperature(10.94mg/100g)> ozone (6.08mg/100g)> ultrasound (5.63mg/100g)> microwave (4.90mg/100g)> short-term soaking (2.95mg/100g). The above methods have low cost, less energy-consumption and easy operation, so they should try to be used in production, according to the actual situation.Third, the change rules of germination rate, GABA, oryzanol and phytic acid in five kinds of brown rice at0-24h (Measured once every2h) were studied. The results showed that the germination rate of brown rice was rising in0-18h, and tended to be stable in18-24h. GABA and Oryzanol in Huanghuazhan, Xiangwanxian13, Jinyou207, Star NO.2, Fengliangyou within0-24h tended to reduce after the first increase, and different varieties had different maximum points(12-20h and12-18h, respectively).Compared with the brown rice before germination,the contents increased116%-715%and20%-101%,respectively. Phytic acid kept downward trend in total, in which phytic acid in Xiangwanxian13was significantly higher than the other (P<0.05), and had the biggest drop (40.24mg/100g).Therefore, the effective control of germination end point of brown rice has great significance for the efficient use of nutrition value of brown rice.