Malt Flavor in Raw Milk Produced By Micrococcus

Abstract

During the past summer (1930) a malt-like flavor was detected in some of the raw milk delivered at the University Creamery. So objectionable was tIns flavor that some of the affected milk could not be used for market milk purposes. Pasteurization did not remove the defect entirely. As the acidity of this milk usually was not over 0.18 per cent the flavor was first attributed to feed the cows had eaten. A survey of the pasture and feed lot on one of the farms sending in the malt flavored milk, however, failed to reveal any weeds or other feeds that might possibly cause the defect. The milk was stored over night in cans in an outside galvanized iron tank away from feed odors. It was found that the first milk through the milking machine developed much more of the off-flavor. It was also noted that the night's milk only was affected at the time of delivery to the plant at about 9 a.m. The milking machine, according to the farmer's statements, was washed once a day and was rinsed with a sodium hypochlorite solution before using. Examination of the machine showed the rubber parts to be in rather poor condition, being full of small crevices on the inside. Upon replacing these tubes with new ones, the flavor disappeared for a few days but later returned suggesting the possibility of bacteria as being the cause of the malt flavor.