酿造食醋中碳、氧同位素比值的测定及应用研究

Determination of carbon and oxygen isotope ratio in vinegar and its application in brewing vinegar

以酿造食醋为研究对象,建立元素分析/连续流-稳定同位素比质谱法(EA/Gas BenchⅡ-IRMS)测定食醋总碳、水中氧同位素比值(δ^(13)C和δ^(18)O)的方法。通过优化稀释倍数与进样体积,得到δ^(13)C值测定最佳条件为食醋稀释2倍,进样体积1.0μL;通过优化平衡时间和样品体积,得到δ^(18)O值测定时平衡时间为24 h,样品体积为500μL。结果表明,在最佳条件下,食品样品碳同位素比测定值标准偏差(SD)值均<0.30‰,氧的同位素比测定值的SD值均<0.10‰,表明该测定方法的稳定性较好。山西食醋总碳δ^(13)C值分布在-23.26‰^-20.80‰,水中氧的δ^(18)O值在-5.66‰^-4.49‰;镇江食醋总碳δ^(13)C值在-25.93‰^-20.70‰,水中氧的δ^(18)O值在-8.35‰^-5.61‰;结合碳氧同位素比值分析,可以将山西老陈醋、镇江香醋和镇江陈醋区分开(P<0.01)。

Using the vinegar as research object,the method for determination of total carbon isotope ratio in vinegars and oxygen isotope ratio in water(δ13C andδ18O)by EA/GasBench n-IRMS was established.By optimization of dilution ratio and injection volume,the optimum determination conditions of S13C value were vinegar dilution ratio 2 times and injection volume 1.0μL.By optimization of equilibration time and sample volume,the optimum determination conditions of S18O value were equilibration time 24 h and sample volume 500μL.The results showed that under the optimum conditions,the SD values of the carbon isotope ratios of vinegars were all less than 0.30%and the SD values of oxygen isotope ratio were all less than 0.10%.,which indicated that the method showed good stability.The total carbon S13C values in Shanxi matured vinegar were-23.26%..20.80%.,S18O values in water were-5.66%.-4.49%..The total carbon S13C values in Zhenjiang vinegar was-25.93%..-20.70%.δ18O values in water were-8.35%.5.61%.Combined with the carbon and oxygen isotope ratio analysis,the Shanxi and Zhenjiang vinegars could be separated(P<0.01).