Transfer of inorganic elements and oxygen stable isotopes during Japanese sake production: Application to geographic origin determination

Sake, a traditional Japanese alcoholic beverage, is produced from rice and water throughout (and increasingly outside of) Japan. Hence, methods of identifying the geographic origin of sake are urgently required. Herein, we characterized a series of sakes and the corresponding raw materials (brewing water and rice) in terms of their oxygen stable isotopic compositions (δ18O values) and contents of 22 elements, aiming to identify brewing water–specific elements suitable for determining the geographic origin of sake. Based on the results of small-scale brewing tests and correlation analyses, eight brewing water–specific elements (Li, Na, Mg, Si, Ca, V, Sr, and Ba) were identified. The contents of these elements in sake and its δ18O values showed significant positive correlations with the corresponding parameters of brewing water but not rice. Preliminary principal component analysis, multinomial logistic regression analysis, partial least squares discriminant analysis, and sparse partial least squares discriminant analysis were conducted using the contents of these eight elements in sake. For three sake production areas in Japan, the scores of discrimination analyses obtained for the eight water-specific elements were separated, and model accuracies were high. The results suggested that these contents may be used to discriminate between sake production areas and improve the accuracy of existing methods for determining the geographic origin of Japanese sake.