Risk Reduction Factors: Acidity (pH drop): Lactic acid bacteria lower the pH during fermentation, making the environment hostile to many pathogens. Salt and low moisture: Further inhibit bacterial growth. Aging (≥60 days rule in the U.S.): Cheeses aged for at least 60 days at ≥35°F are legally allowed to be made from raw milk, under the assumption that pathogens will die off during this time.