If sushi rice can sit near room temperature during service, what makes vinegar more than just a flavoring?

Answer: Lowers the rice pH

Lowers the rice pH ✓ — Right. Vinegar acidifies sushi rice, and many health departments use pH limits such as 4.6 or 4.2 as the control that lets acidified rice avoid ordinary refrigeration rules. A 2020 LWT study found pH 4.2 rice held at room temperature inhibited Bacillus cereus and Clostridium perfringens for 24 hours. The surprise is that the same ingredient that brightens flavor is also a food-safety hurdle.

Adds alcohol preservative — No. Vinegar is made through fermentation, but the safety mechanism cited here is not adding alcohol as a preservative. The public-health sources talk about acidification and measured pH, and the LWT study tested acidified rice at specific pH levels. Thinking 'fermented equals alcoholic' misses the chemistry that matters in sushi rice.

Dries the rice surface — Not quite. A wooden tub and fanning can remove excess surface moisture, but vinegar is not mainly a drying agent. Sushi rice still needs enough moisture to stay glossy and tender. Food-safety plans focus on acidity and measured pH because bacteria respond strongly to chemical environment, not because the grains have been dried like crackers.