Correlation between key aroma and manufacturing processes of rice-flavor baijiu and awamori, Chinese and Japanese traditional liquors

In this study, we compared the flavor profiles Chinese rice-flavor baijiu and Japanese awamori-traditional liquors with similar manufacturing processes. Citric acid and lactic acid were the major acid constituents in the mash of awamori and rice-flavor baijiu, respectively. The amino acid content of awamori mash was greater than that of rice-flavor baijiu owing to the higher proteolytic activities in the former. The high amino acid content also induced yeast growth at the early stage of fermentation in awamori mash, thus increasing the fermentation rate. Sensory evaluation revealed that rice-flavor baijiu had a significantly stronger alcoholic, floral, and fruity aroma, whereas the awamori had a strong sour, koji-like, oily, and cereal-like aromas. We determined the aroma threshold of (+)-ethyl D-lactate (15,400 mu g/L) and (-)-ethyl L-lactate (12,500 mu g/L). Both compounds have a common sweet, fruity, and green leaves-like aroma and a different nuance; (+)-ethyl D-lactate has a peach- and citrus-like aromas, and (-)-ethyl L-lactate has an apple-like and milky aromas. In rice-flavor baijiu, (-)-ethyl Llactate constitutes the major isoform, as evident from the higher concentration of L (+)-lactic acid in the mash. Higher alcohols, (-)-ethyl L-lactate, and isoamyl acetate contents were greater in rice-flavor baijiu, while 1-octen-3-ol and acetic acid were greater in awamori. These results showed that solid-state saccharification contributed to the production of ethyl lactate by supplying in the mash a large amount of lactic acid produced by Rhizopus oryzae and koji contributed to the production of 1-octen-3-ol via the high fatty acid oxygenase activity produced by Aspergillus luchuensis.