Studies On The Characteristics And Application Of The Stable Isotope In Fruit Wine And Brandy

This paper will focus on technical problems of fruit fermented food authenticity identification,to initially establish stable isotope database and then apply to authenticity identification of fruit distillate liquor based on the stable isotope distribution law in nature.The results offer a technological support for establishing a national standard detection method for fruit wine and brandy.The main research contents and conclusions are as follows:(1)Establishment of determination ?13C value method for ethanol in fruit wine.The study of fruit fermented in different regions showed that the ?13C values of ethanol were similar in the same area,whereas differences existed in different areas;(2)Establishment of determination ?13C value method for sugar in fruit juice and pulp.The results present a good correlation between the ?13C values of fruit juice and pulp(R2=0.98),as well as fruit juice sugar and ethanol observed in fermentation of common fruit wine raw(R2=0.97);(3)We studied,during fermentation process,the effect of four key factors,such as temperature,sugar concentration,strain of yeast,and the initial pH,on the ?13C value of ethanol.The results showed that the temperature and initial pH of the extract can somehow affect the fractionation of stable carbon isotopes of ethanol,but difference was not significant;(4)The inverse vapor pressure isotope effect of carbon isotopoligus was observed during distillation process,but the ?13C value of ethanol main part(50%vol-80%vol)varied slightly,and the mean ?13C value of ethanol in this distillate fraction was consistent with the fermented mash.Simulation test showed that the carbon isotope ratio of ethanol presented positive correlation to those add maize ethanol and sucrose.These results indicated that the?13C value of ethanol would change when sucrose(before fermentation)and maize ethanol were added,but no change with adding beet sugar.The method was shown to be effective in detection of the exougenous alcohol in pear brandy;(5)By optimizing the parameters,a method for the determination of ?18O value of fruit/wine was developed by Gasbench ?-IRMS using on-line equilibration technique.The results showed that the system can automate sample injections to handle large numbers of measurements,with good repeatability and reproducibility(both SD<0.1‰),It meets the international standards for measuring ?18O value in water.The method could be used to determine the authenticity of fruit wines;(6)We analyzed distribution and influence factors of the ?18O value in irrigation water for fruit trees and found that the source of irrigation water contributed to the difference of the ?18O values,whereas the producing area,variety or weather during the harvest season could also play a role affecting ?18O values.Finally the ?18O value of fruit wines could change if exogenous water was added before and after fermentation.In conclusion,one can use a combination of ?18O value of water with ?13C value of ethanol to effectively determine the authenticity of fruit wines.