Homogenized milk packaged in polyethylene containers exposed to fluorescent lights showed flavor and vitamin deterioration. Off-flavor development began within 2 to 4 h after exposure to a lighting system simulating commercial display cases. Detection of light-induced flavor was slight, medium, and strong after 4, 7 and 24 h of exposure. Decreases in riboflavin and ascorbic acid were directly proportional to the amount of light exposure. Various types of colored lamps and lamp filters were tested to prevent this off-flavor and vitamin degradation in milk. Yellow lamps or yellow and green filters protected milk from off-flavor development for 30 to 40 h. It is evident that light-induced off-flavors and vitamin destruction in fluid milk packaged in polyethylene containers can be reduced by colored lamps and lamp filters.
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.