Screening of Leuconostoc mesenteroides strains suitable for kimoto-style brewing of sake with high antioxidant capacity

Sake brewed using the kimoto-style exhibits high antioxidant capacity and is expected to inhibit the deterioration of sake quality due to oxidation. However, the antioxidant capacity of the added lactic acid bacteria has not been explored. We aimed to screen the lactic acid bacterium, Leuconostoc mesenteroides, with excellent brewing and antioxidant capacity, to develop sake with high antioxidant capacity. Three Le. mesenteroides strains (19-2, 19-5, and 19-23) were selected from eight screened strains based on their alcohol intolerance, growth performance in koji extract, aroma compound, and low biogenic amine production. Among these, Le. mesenteroides 19-23 exhibited a significantly higher hydrophilic-oxygen radical absorbance capacity (H-ORAC) in the culture medium than the control strain, Le. mesenteroides NBRC102481. In a medium-scale sake brewing test, sake prepared with Le. mesenteroides 19-23 had a significantly higher H-ORAC value than that prepared using the sokujo-style (without Le. mesenteroides). Additionally, metabolome analysis using capillary electrophoresis time-of-flight mass spectrometry identified ferulic acid, p-coumaric acid, 3-hydroxyanthranilic acid (3-HAA), and 6,8-thioctic acid in the main mash. High-performance liquid chromatography-based quantification revealed that antioxidants in the unrefined filtrates of the main mash prepared using the kimoto-style tended to be more abundant than in those prepared using the sokujo-style. Specifically, 3-HAA and ferulic acid were more concentrated in some unrefined filtrates of the kimoto-style than sokujo-style. In conclusion, the screened Le. mesenteroides strain demonstrated potential for brewing sake with high antioxidant capacity using the kimoto-style, offering a promising method for antioxidant-rich sake production.