Effects of Long-Term Aging on the Quality Characteristics and Functional Components of Traditionally Fermented Soy Sauce

This study investigated the changes in the physicochemical properties, free amino acid composition, antioxidant-related characteristics, and total viable counts of traditionally fermented soy sauce aged for one, three, five, seven, and nine years.The moisture content and pH decreased with aging, whereas the salinity and soluble solids increased.The lightness (L) and yellowness (b) decreased, while the redness (a) increased.Most free amino acids increased, particularly glutamic acid and aspartic acid, while asparagine, histidine, and arginine decreased.γ -Aminobutyric acid was detected only at the later stages of aging.The total polyphenol and flavonoid contents and DPPH and ABTS radical scavenging activities increased significantly with aging.The total viable counts also increased but remained relatively low.In particular, glutamic acid showed no significant additional increase after seven years, whereas salinity and several bitter taste-related amino acids continued to increase.These findings suggest that long-term aging enhances several quality-and antioxidant-related characteristics but may also alter the balance of taste-related components.Therefore, approximately seven years of aging may represent a potential aging period under the conditions examined, but further studies using independent batches, microbial community analysis, volatile compound profiling, and sensory evaluation are required.