Traditional naturally brewed soy sauce possesses an exceptionally long shelf life and rarely spoils in a dangerous microbiological sense due to its high salt content and natural fermentation acids, which naturally inhibit bacterial and mold growth. However, over extended periods spanning several years, opened or improperly stored bottles can undergo gradual oxidation, losing their complex aromatic notes, fading in color, and developing a slightly stale flavor. While older unopened bottles remain safe to consume, their peak culinary quality and vibrant umami depth diminish significantly over time.