The second edition of Basic Food Microbiology follows the same general outline as the highly successful first edition. The text has been revised and updated to include as much as possible of the large body of infor mation published since the first edition appeared. Hence, foodborne ill ness now includes listeriosis as well as expanded information about Campylobacter jejuni. Among the suggestions for altering the text was to include flow sheets for food processes. The production of dairy products and beer is now depicted with flow diagrams. In 1954, Herrington made the following statement regarding a review article about lipase that he published in thejournal of Dairy Science: "Some may feel that too much has been omitted; an equal number may feel that too much has been included. So be it." The author is grateful to his family for allowing him to spend the time required for composing this text. He is especially indebted to his partner, Sally, who gave assistance in typing, editing, and proofreading the manuscript. The author also thanks all of those people who allowed the use of their information in the text, tables, and figures. Without this aid, the book would not have been possible. 1 General Aspects of Food BASIC NEEDS Our basic needs include air that contains an adequate amount of oxy· gen, water that is potable, edible food, and shelter. Food provides us with a source of energy needed for work and for various chemical reactions.