Rice vinegar plays an important role in daily life. However, some unscrupulous manufacturers may deliberately add synthetic acetic acid in vinegar products to reduce fermentation time and save production costs. To protect the rights and health of consumers, vinegar authenticity must be controlled. The rice vinegar protein was used as an intrinsic reference and its stable carbon isotope ratio (δ13Cprotein) was analyzed by elemental analyzer-isotope ratio mass spectrometry. The stable carbon isotope ratio difference between the acetic acid and the rice vinegar protein (Δδ13Cacetic acid-protein) was calculated to evaluate vinegar authenticity. Sixteen rice vinegar samples were analyzed and a stable carbon isotopic pattern of rice vinegar was established by the 95% confidence interval for Δδ13Cacetic acid-protein (0.27‰-2.10‰). An acetic acid adulteration curve of Δδ13Cacetic acid-protein was also assumed according to the data from rice vinegar samples, and its validity was confirmed by rice vinegar deliberately blended with acetic acid at different ratios (25, 50, and 75%). The Δδ13Cacetic acid-protein values of the adulterated vinegars decreased with increasing amounts blended acetic acid, but the δ13Cprotein values did not, showing that rice vinegar protein could be used as an intrinsic reference for identifying the adulterated rice vinegar. The rice vinegar adulterated with acetic acid at higher than approximately 10% could be detected.

中文翻译：

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米醋蛋白质的稳定碳同位素表征作为鉴别酿造米醋真伪的内在参考。

米醋在日常生活中起着重要作用。然而，一些不法厂商可能会故意在食醋产品中添加合成醋酸，以减少发酵时间，节省生产成本。为了保护消费者的权益和健康，食醋的真伪必须得到控制。以米醋蛋白为内参，采用元素分析仪-同位素比质谱法对其稳定碳同位素比值（δ13C蛋白）进行分析。通过计算醋酸与米醋蛋白的稳定碳同位素比值差异（Δδ13C醋酸-蛋白）来评价醋的真伪。分析了 16 个米醋样品，并通过 Δδ13C 乙酸蛋白 (0.27‰-2.10‰) 的 95% 置信区间建立了米醋的稳定碳同位素模式。还根据米醋样品的数据假设了 Δδ13C 乙酸-蛋白质的乙酸掺假曲线，并通过故意与不同比例（25%、50% 和 75%）混合的米醋证实了其有效性。掺假醋的Δδ13C乙酸蛋白值随着混合醋酸量的增加而降低，但δ13C蛋白值没有变化，表明米醋蛋白可以作为鉴定掺假米醋的内参。可以检测到掺有高于约 10% 醋酸的米醋。掺假醋的Δδ13C乙酸蛋白值随着混合醋酸量的增加而降低，但δ13C蛋白值没有变化，表明米醋蛋白可以作为鉴定掺假米醋的内参。可以检测到掺有高于约 10% 醋酸的米醋。掺假醋的Δδ13C乙酸蛋白值随着混合醋酸量的增加而降低，但δ13C蛋白值没有变化，表明米醋蛋白可以作为鉴定掺假米醋的内参。可以检测到掺有高于约 10% 醋酸的米醋。