Preface to the first edition Two books on dairy microbiology were published in 1957: Dairy Bacteriology, 4th Edition(B. W. Hammer and F J. Babel, John Wiley and Sons, New York) ind Dairy Microbiology(E M. Foster, F. E. Nelson, M. L. Speck, R N. Doetsch, and J. C. Olson, Jr, Prentice-Hall, Englewood Cliffs, New Jersey). Since then, no book on this subject has been published in the United States(although a two- volume work on dairy microbiology appeared in Europe). When the two aforementioned books were published, there were numerous small dairy farms and dairy factories, and they produced a limited number of products. As time went on, dairy farms evolved into fewer but larger units with cows that produced more milk than in earlier years. Factories, too, decreased in number and increased in size and complexity. Furthermore, these factories began producing a far greater array of products than in the 1950s. All these changes have lad an impact on dairy microbiology as it is currently understood and practiced. Much of the information in the dairy microbiology books of the 1950s resulted from research done in dairy industry or closely related departments of most land grant universities. These departments also trained many of the workers in the dairy industry. As time went on, when problems occurred in other segments of the food industry, faculty in dairy industry departments were often consulted. In some instances, existing faculty responded to the new challenges; in others faculty were added to work in various non-dairy segments of the food industry Eventually, most dairy industry departments evolved into food science depart ments. This led to publication of several books on food microbiology--thesePreface to the First Edition Two books on dairy microbiology were published in 1957: Dairy Bacteriology, 4th Edition (B. W. Hammer and F. J. Babel, John Wiley and Sons, New York) and Dairy Microbiology (E. M. Foster, F. E. Nelson, M. L. Speck, R. N. Doetsch, and J. C. Olson, Jr., Prentice-Hall, Englewood Cliffs, New Jersey). Since then, no book on this subject has been published in the United States (although a two￾volume work on dairy microbiology appeared in Europe). When the two aforementioned books were published, there were numerous small dairy farms and dairy factories, and they produced a limited number of products. As time went on, dairy farms evolved into fewer but larger units with cows that produced more milk than in earlier years. Factories, too, decreased in number and increased in size and complexity. Furthermore, these factories began producing a far greater array of products than in the 1950s. All these changes have had an impact on dairy microbiology as it is currently understood and practiced. Much of the information in the dairy microbiology books of the 1950s resulted from research done in dairy industry or closely related departments of most land grant universities. These departments also trained many of the workers in the dairy industry. As time went on, when problems occurred in other segments of the food industry, faculty in dairy industry departments were often consulted. In some instances, existing faculty responded to the new challenges; in others, faculty were added to work in various non-dairy segments of the food industry. Eventually, most dairy industry departments evolved into food science depart￾ments. This led to publication of several books on food microbiology—these v