and Bacteriological
Changes.--It cannot be said that the beneficial results derived from
the cooking of foods are due to either chemical, physical, or
bacteriological change alone, but to the joint action of the three. In
order to secure a chemical change, a physical change must often precede,
and a bacteriological change cannot take place without causing a change
in chemical composition; the three are closely related and
interdependent.

33. Esthetic Value of Foods.--Foods should be not only of good
physical texture and contain the requisite nutrients, but they should
also be pleasing to the eye and served in the most attractive manner.
Some foods owe a part of their commercial value to color, and when they
are lacking in natural color they are not consumed with a relish. There
is no objection to the addition of coloring matter to foods, provided it
is of a non-injurious character and does not affect the amount of
nutrients, and that its presence and the kind of coloring material are
made known. Some foods contain objectionable colors which are eliminated
during the process of manufacture, as in the case of sugar and flour. As
far as removal of coloring matter from foods during refining is
concerned, there can be no objection, so long as no injurious reagents
or chemicals are retained, as the removal of the color in no way affects
the nutritive value or permits fraud, but necessitates higher
purification and refining. The use of chemicals and reagents in the
preparation and refining of foods is considered permissible in all cases
where the reagents are removed by subsequent processes. In the food
decisions of the United States Department of Agriculture, it is stated:
"Not excluded under this provision are substances properly used in the
preparation of food products for clarification or refining and
eliminated in the further process of manufacture." [15]

CHAPTER III

VEGETABLE FOODS

34. General Composition.--Vegetable foods, with the exception of
cereals, legumes, and nuts, contain a smaller percentage of protein than
animal food products. They vary widely in composition and nutritive
value; in some, starch predominates, while in others, sugar, cellulose,
and pectin bodies are most abundant. The general term "vegetable foods"
is used in this work to include roots, tubers, garden vegetables,
cereals, legumes, and all prepared foods of vegetable origin.

35. Potatoes contain about 75 per cent of water and