Chapter I: Preface: To the Tenth Edition

This text was originally the outgrowth of a series of lectures on the subject of dairy bacteriology to practical students in the winter Dairy Course in the University of Wisconsin. The importance of bacteriology in dairy processes has now come to be so widely recognized that no student of dairying regards his training as complete until he has had the fundamental principles of this subject.

The aim of this volume is not to furnish an exhaustive treatise of the subject, but an outline and sufficient detail to enable the general student of dairying to obtain as comprehensive an idea of the bacteria and their effects on milk and other dairy products as may be possible without the aid of laboratory practice. When possible the dairy student is urged to secure a laboratory knowledge of these organisms, but lacking this, the student and general reader should secure a general survey of the field of bacteriology in relation to dairying.

In this, the tenth edition, the effort has been made to include all of the recent developments of the subject. Especially is this true in regard to the subject of market milk, a phase of dairying that has gained greatly in importance in the last few years. The changes in the methods of handling market milk have been marked. The results of these changes in influencing the quality of milk offered to the consumer are fully discussed.

H. L. R.

E. G. H.

CONTENTS

Structure, Growth and Distribution of Bacteria 7

Methods of Studying Bacteria 20

Contamination of Milk 28

Infection of Milk with Pathogenic Bacteria 62

Fermentations of Milk 82

Preservation of Milk 113

Bacteria and Butter Making 136

Bacteria and Cheese Making 161

Bacteria in Market Milk 189