CLASSIFICATION OF FOODS ACCORDING TO pH

In chemistry, pHis a numeric scale used to specify the acidityor basicityof an aqueous solution. It is approximately the negative of the logarithm to base 10 of the molar concentration, measured in units of molesper liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion.  Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.

CLASSIFICATION OF FOODS ACCORDING TO pH

Most foods are derived either from plants or from animals. In this course, we

are concerned with foods of plant origin and are known as vegetables or fruits

based on their use. These foods have different pH and are classified as low acid

foods, medium acid foods, acid foods and high acid foods.

a) Low acid foods

The foods having pH above 5.3 are called low acid foods. For example:

peas, corn, lima beans etc.

b) Medium acid foods

The foods which have pH between 4.3 and 5.3 are called medium acid

foods. For example: asparagus, beets, pumpkin, spinach etc.

c) Acid foods

Foods which have pH between 3.7 and 4.5 are called acid foods. For

example: pears, pineapple, tomatoes etc.

d) High acid foods

Foods having pH 3.7 or lower are included in this category. For example:

Berries and sauerkraut.