CHAPTER I_Human Foods and Their Nutritive Value

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HUMAN FOODS AND THEIR NUTRITIVE VALUE

HARRY SNYDER, B.S.

New York

The MacMillan Company

1914

by the MacMillan Company.

Set up and electrotyped. Published November, 1908. Reprinted

October, 1909; September, 1910; February, 1911; September, 1912;

May, December, 1913; June, 1914.

Norwood Press

J. S. Cushing Co.--Berwick & Smith Co.

Norwood, Mass., U.S.A.

PREFACE

Since 1897 instruction has been given at the University of Minnesota,

College of Agriculture, on human foods and their nutritive value. With

the development of the work, need has been felt for a text-book

presenting in concise form the composition and physical properties of

foods, and discussing some of the main factors which affect their

nutritive value. To meet the need, this book has been prepared,

primarily for the author's classroom. It aims to present some of the

principles of human nutrition along with a study of the more common

articles of food. It is believed that a better understanding of the

subject of nutrition will suggest ways in which foods may be selected

and utilized more intelligently, resulting not only in pecuniary saving,

but also in greater efficiency of physical and mental effort.

Prominence is given in this work to those foods, as flour, bread,

cereals, vegetables, meats, milk, dairy products, and fruits, that are

most extensively used in the dietary, and to some of the physical,

chemical, and bacteriological changes affecting digestibility and

nutritive value which take place during their preparation for the table.

Dietary studies, comparative cost and value of foods, rational feeding

of men, and experiments and laboratory practice form features of the

work. Some closely related topics, largely of a sanitary nature, as the

effect upon food of household sanitation and storage, are also briefly

discussed. References are given in case more extended information is

desired on some of the subjects treated. While this book was prepared

mainly for students who have taken a course in general chemistry, it has

been the intention to present the topics in such a way as to be

understood by the layman also.

This work completes a series of text-books undertaken by the author

over ten years ago, dealing with agricultural and industrial subjects:

"Chemistry of Plant and Animal Life," "Dairy Chemistry," "Soils and

Fertilizers," and "Human Foods and their Nutritive Value." It has been

the aim in preparing these books to avoid as far as possible repetition,

but at the same time to make each work sufficiently complete to permit

its use as a text independent of the series.

One of the greatest uses that science can serve is in its application to

the household and the everyday affairs of life. Too little attention is

generally bestowed upon the study of foods in schools and colleges, and

the author sincerely hopes the time will soon come when more prominence

will be given to this subject, which is the oldest, most important, most

neglected, and least understood of any that have a direct bearing upon

the welfare of man.

HARRY SNYDER.

CONTENTS

CHAPTER I

PAGE

GENERAL COMPOSITION OF FOODS 1

Water; Dry Matter; Variations in Weight of Foods;

Ash; Function of Ash in Plant Life; Organic Matter;

Products of Combustion of Organic Matter; Classification

of Organic Compounds; Non-nitrogenous Compounds;

Carbohydrates; Cellulose; Amount of Cellulose in Foods;

Crude Fiber; Starch; Microscopic Structure of Starch;

Dextrin; Food Value of Starch; Sugar; Pectose Substances;

Nitrogen-free-extract; Fats; Fuel Value of Fats;

Iodine Number of Fats; Glycerol Content of Fats; Ether

Extract and Crude Fat; Organic Acids; Dietetic Value

of Organic Acids; Essential Oils; Mixed Compounds;

Nutritive Value of Non-nitrogenous Compounds; Nitrogenous

Compounds; General Composition; Protein; Sub-divisions

of Proteins; Crude Protein; Food Value of

Protein; Albuminoids; Amids and Amines; Alkaloids;

General Relationship of the Nitrogenous Compounds.