In a field study involving 26 Grade A milk producers a detergent-sanitizer was compared with the customary method of cleaning and sanitizing milking equipment. The producers were divided into two comparable groups and placed on a double-reversal trial with three 5-week periods. Milking utensils appeared cleaner and milk-stone deposits were reduced when the detergent-sanitizer was used in place of the regular procedure. The difference between the two methods of cleaning and sanitizing utensils was not statistically signifcant as measured by thermoduric and total bacterial counts. The relation between the effectiveness of the detergent-sanitizer and the hardness of water was not statistically significant. There was no appreciable amount of quaternary ammonium compound in any of the milk samples as determined by direct measurement and by the activity of a buttermilk culture.

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Author notes

Marvin L. Speck was educated at the University of Maryland and Cornell University. He was bacteriologist at Western Maryland Dairy, Baltimore, 1935–36; instructor in bacteriology at the University of Maryland, 1940–41; assistant chief bacteriologist with National Dairy Research Laboratories, 1941–47; and employed in his present position in 1947. He also has held temporary appointments as bacteriologist in the Dairy Research Laboratories, U.S.D.A., 1936, and with the Dairymen's League, Poughkeepsie, N. Y., in 1940.