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ural, as in most fruits, or added, as in pickled products. Foods are grouped as “acid” and "low-acid” for purposes of selecting the appropriate processing method. Acid protects against the growth of spoilage organisms, particularly Clostridium botulinum. Thus, the heat treatment need not be as severe for foods in the “acid” group as for foods in the “low-acid” group.
The degree of acidity or alkalinity is expressed as pH using a scale from 0 to 14. The center of the scale — 7 is neutral, neither acid nor alkaline. As the pH moves away from 7, the foods become increasingly acid or alkaline. Pumpkin has a pH of 5.3; red cherries
93.9%