Study On Urethane Of Hakka Rice Wine

Guangdong Hakka rice wine, called Hakka rice wine,is a traditional folk fermented ricewine in Lingnan area in China, It is an important branch of yellow rice wine in China.Urethane is a known genotoxic carcinogen which is contained widespread in fermented drink.It can not be ignored the fact that the existence of urethane in Hakka rice wine is harmful tohuman health.Four fields are mainly studied in this paper as below:1. The measurement of citrulline content in Hakka rice wine was established in thispaper. Taking OPAas precolumn derivatization agent, use sodium acetate-acetonitrile-methanol-water mixed system to carry out gradient elution with a flow rate of2.0ml/min andthe DAD detection wavelength of UV-338nm. In the range of20～400mg/L, there is a goodlinear relationship between concentration and response value with the correlation coefficientgreater than0.999, the relative standard deviation of0.153%～0.921%and the recovery rateof98.44.70%～100.81%The detection limit was1.048mg/L and the quantitative detectionlimit was3.460mg/L mg/L. The detection result showed that the citrulline content in Hakkaniang wine was58.84～80.83mg/L, and the citrulline content in rice wine of Jiang su and zhejiang province was162.61～178.26mg/L.2. The content of total sugar, total acid, alcohol, polyphenols, oligosaccharides, urea,organic acids,amino acids and urethane in Hakka rice wine were determined and analyzed.Though Multiple linear regression analysis,the results showed that urethane wassignificantly associated with arginine,citrulline, urea, and ornithine. The linear regressionequation was: y=370.907-15.002x1-4.416x2+2.159x3+0.609x4(y: urethane,x1: urea,x2:citrulline,x3: arginine,x4: ornithine)3. The urethane precursors dynamic change of Hakka rice wine were studied duringthe fermentation process.The results show that the content of arginine would first decline,and increase, and then decline, finally keep invariability;the content of urea would firstfirst decline, and increase,and then decline,finally increase.During the process of bioling the Hakka rice wine,the content of urea would reduce from12.76mg/L to9.10mg/L. Thecontent of ornithine and arginine have the same change tendency.the content of citrullinewould first decline,then increase singnificantly,from5.57mg/L to38.13mg/L, finally keepinvariability.The content of urethane in Hakka rice wine showed a gradual increase duringthe fermentation. After secondary fermentation The content of urethane was10.38μg/kg. thecomparison of results before and after bioling process,showed that the content of ofurethane reach65.52μg/kg with with evident increase. The content of of urethane Hakka ricewine have increase obviously during storage period.4. The enzymatic removal of urethane from Hakka rice wine with acid urease wasoptimized by using randomcentriod optimization through random search, centroid search andoptimal mapping of the random centroid diffraction procedure. The optimal enzymatichydrolysis conditions were found to be hydrolysis at21℃, initial pH4.3for50h with anenzyme of48.06mg/L repeated twice. The urea content in Hakka rice wine after theenzymatic treatment was decreased to (2.130±0.018) mg/L. The urethane content in Hakkamother liquor after one-year storage was measured to be (25.632±0.017) μg/kg, whichshowed an88.5%reduction compared to that without enzymatic treatment. Therefore, theurethane content in Hakka rice wine can be reduced effectively by the optimized enzymatictreatment and the consumption safety is improved greatly.The results showed that there wasno evident difference in organic acids,amino acid and volatile flavour compounds betweenthem.