Department of Agricultural Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Da'an Dist., Taipei City 106216, Taiwan.
Taiwan Food and Drug Administration, 161-2 Kunyang St., Nangang Dist., Taipei City 115209, Taiwan.
J Food Drug Anal. 2022 Mar 15;30(1):38-45. doi: 10.38212/2224-6614.3398.
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 (δC) was analyzed by elemental analyzer-isotope ratio mass spectrometry. The stable carbon isotope ratio difference between the acetic acid and the rice vinegar protein (ΔδC) 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 ΔδC (0.27‰-2.10‰). An acetic acid adulteration curve of ΔδC 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 ΔδC values of the adulterated vinegars decreased with increasing amounts blended acetic acid, but the δC 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.
米醋在日常生活中扮演着重要的角色。然而，一些无良制造商可能会故意在醋产品中添加合成醋酸，以缩短发酵时间并节省生产成本。为了保护消费者的权益和健康，必须控制醋的真实性。本研究采用米醋酸蛋白作为内源性参比物，利用元素分析仪-同位素比质谱仪分析其稳定的碳同位素比值（δC）。通过计算醋酸和米醋酸蛋白之间的稳定碳同位素比值差异（ΔδC）来评估醋的真实性。分析了 16 个米醋样品，通过置信区间（95%）建立了米醋酸的稳定碳同位素模式（0.27‰-2.10‰）。根据米醋酸样品的数据还假设了一个醋酸掺假曲线，并用不同比例（25%、50%和 75%）故意混合醋酸的米醋酸对其有效性进行了验证。随着掺假醋酸量的增加，掺假醋的ΔδC 值降低，但 δC 值不变，表明米醋酸蛋白可作为鉴别掺假米醋酸的内源性参比物。可以检测到掺有高于约 10%的醋酸的米醋酸。
