Study on authentication of ingredients and geographical origin of Japanese sake based on hydrogen stable isotope analysis by deuterium NMR.

This study investigates the authentication of Japanese sake ingredients and geographical origin through the application of hydrogen stable isotope analysis by deuterium nuclear magnetic resonance (NMR) spectroscopy. Ethanol was purified from sake, and the hydrogen stable isotope ratios of its methyl and methylene groups of ethanol were measured. The results indicated that the (D/H)methyl ratio reflects differences in the ingredients, while the (D/H)methylene ratio reflects differences in the water utilized in the brewing process. This discrepancy was attributed to the different origins of hydrogen in these functional groups during ethanol biosynthesis by yeast. This study demonstrates that hydrogen stable isotope analysis by NMR can provide accurate information about sake ingredients and brewing water, thus providing a scientific basis for Japanese sake authentication.