This work intended to evaluate the effect of high hydrostatic pressure (HHP) on the lactic acid fermentation that occurs during yogurt production. The evaluated physicochemical parameters (pH, titratable acidity, and concentration of reducing sugars) indicated that HHP reduced the fermentation rate. Microbiological analysis (counts of Streptococcus thermophilus, Lactobacillus bulgaricus, and Bifidobacterium lactis) confirmed the inhibitory effect of pressure on the growth of these microorganisms. However, extension of the fermentation time at 5 MPa yielded a typical pH for yogurt with survival of the yogurt microorganisms. No fermentation was found in samples subjected to 100 MPa for 180 min, but these samples revealed normal metabolic activity when they were returned to atmospheric pressure. This finding indicates that the microorganisms did not undergo inactivation during this period at 100 MPa; instead, the microorganisms were metabolically inhibited, which did not hinder the subsequent fermentation at atmospheric pressure. This result opens the possibility of using pressure as an on/off switch to stop/start fermentation, similar to refrigeration. (C) 2015 Elsevier Ltd. All rights reserved.