In the above paragraphs attention has been directed particularly to the nutritive and economic properties of food. It must not be considered that mere nutrition is the sole object of foods, especially for man. It is the first object to be conserved in the feeding of domesticated animals, but is only one of the objects to be kept in view in the feeding of man. Man is a social animal and, from the earliest period of his history, food has exercised a most important function in his social life. Hence in the study of food and of its uses a failure to consider this factor would be regrettable. For this reason it is justifiable in the feeding of man to expend upon the mere social features of the meal a sum which often is equal to or greater than that expended for the mere purpose of nutrition. This part of the subject, however, belongs especially to the kitchen and dining room, and, therefore, will not be discussed at greater length at the present time.
It is believed that a more careful study of the food he consumes will benefit man in many ways. It will lead to a wider public interest in the problem of the purity of food and the magnitude of the crime committed against mankind in the debasement, adulteration, and sophistication of food articles.
This study will impart to the social function of food an additional charm, in that the origin and character of the material consumed will be known and the properties which they possess for nourishing the body understood. This will enable man, as a social animal, to so conduct himself at table as to secure the greatest possible pleasure and social benefit therefrom and at the same time avoid any injury which ignorance might permit and invite.
It may appear that the inartistic treatment of a subject of this kind, as indicated in the following pages, is not one which is calculated to excite any sympathetic interest or appeal to the natural desire for literary and artistic expression. Yet the importance of the subject is so great as to warrant the experiment of presenting the matter in this form rather than in any more elaborate and connected way.
DEFINITION AND COMPOSITION OF FOODS.
Food, in its general sense, is that which nourishes the body without regard to its physical state, that is, it may be solid, liquid, or gaseous. More particularly defined, food is that material taken into the body in the ordinary process of eating which contains the elements necessary for the growth of tissues, for the repair of the destruction to which the tissues are subjected during the ordinary vital processes and for furnishing heat and energy necessary to life. Incident to the utilization of these elements there is consumed, also, a considerable quantity of matter inextricably mingled with food in a natural way, which takes no direct part in nutrition and yet which is useful, as a mass, in promoting the digestive processes. These bodies are certain indigestible cellular tissues which are present in foods, mineral matter, and other materials which are naturally found in food products. Included in this broad definition, therefore, are many substances which are usually not thought of in the sense of food; among these are water and air. Air, however, would probably be excluded because it is not introduced into the stomach, that is, not in quantities which have any significance in the vital processes. Water, on the contrary, is one of the most indispensable constituents of food and is also used in considerable quantities as a beverage. The water, itself, is indispensable to nutrition and is also one of those bodies mentioned above which are necessary to secure the proper conduct of the digestive processes.
By means of the oxygen in the air the combustion of food in the various parts of the body is secured, and thus animal heat and energy developed. In this respect the combustion of a food product is similar in every way to the burning of coal in the production of heat and motion. The same calorific laws which govern the steam-engine are applicable, in all their rigidity, to the animal engine. The quantity of heat produced by the combustion of a certain amount of fat or sugar is definitely measured in a calorimeter and is found to correspond exactly to the quantity of heat produced by the ordinary combustion of such bodies. The term “food,” therefore, in this respect, would include the oxygen of the air without which the development of animal heat and energy would be impossible. It also includes those bodies of a liquid character which are classed as beverages rather than as foods. All of these bodies have nutritive properties, although their chief value is condimental and social.
That large class of food products, also, which is known as condiments is properly termed food, since they not only possess nutritive properties but through their condimental character promote digestion and by making the food more palatable secure to a higher degree the excellence of its social function.
It is now possible to condense into a distinct expression the definition of food in the following language: Food in a general sense embraces those substances taken into the body which build tissues, restore waste, and furnish heat and energy.