Mat Ferguson, age 9, of Eureka, Mo., for his question:

WHAT IS GRAHAM FLOUR?

We use wheat flours very extensively in our baking. Nutritionists tend to rate it higher in food value than white flour.

Whole wheat flour contains the germ of the wheat which has a wider variety of B vitamins than does regular wheat, and some trace minerals as well. Graham flour contains both the germ and the bran, the outer covering of the grain.

The refining process strips wheat flour of much of its vitamins and minerals, with the bleaching process further damaging the wheat. Niacin, iron, riboflavin and thiamine are put back into some flours to ''enrich'' it, but experts believe it is done at the expense of other vital nutrients.