Lesson 4b - A is for Acidity

pH line

The degree of acidity or alkalinity (base) of a substance is measured by its pH. pH is measured on a scale from 0 to 14.0. An environment with a pH of 7.0 is exactly neutral. Foods with a pH below 7.0 are acidic; a pH above 7.0 is alkaline. The lower the pH, the higher the acidity; the higher the pH, the lower the acidity.
Bacteria grow best in an environment that is neutral or slightly acidic. Most bacterial growth is inhibited in very acidic conditions. That is why acidic foods, like vinegar and fresh fruits (especially citrus), seldom provide a favorable climate for pathogenic bacteria. Most bacteria will not grow at pH levels below 4.6 because the environment is too acidic. Microorganisms thrive in a pH range between 6.6 and 7.5.
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