Intervals and the pH limits involved in microbial growth of food

F. Castelvetri, R. Orlandini, F. Di Giovanni, O. Pellerey in the paper “Alimenti confezionati – Come si determinano i tempi della shelf-life. E’ fondamentale controllare gli indicatori microbici”

FOOD pH Interval Inhibition of micro-organisms
Low acid foods 7,0-5,0 Some Bacillus and  Clostridium
Medium acid foods 5,0-4,0 / 6,0-4,7 Several Bacillus e Clostridium (Cl. botulinum)
Acid foods 4,6-4,1 / 3.9 All sporogenes and all non acidophilic bacteria
Very acid foods Lower than 3,9 All micro-organisms with the exception of lactobacillus, yeast and moulds