The Quality of Raw Milk From Selected Ohio Markets.

Abstract

Summary An 8-month survey was made on the flavor of raw milk supplies from four major Ohio markets. A total of 317 milk samples obtained from farm bulk tanks and from tank trucks were examined fresh and after storage at 38–40 F for 48 hours. Approximately 40% of the industrial producer's fresh milk supply had highly satisfactory flavor quality and the flavor of 10% of the shipments was completely undesirable. The combining of the producers' milk in the tank pick-up truck resulted in milk for the plants having a flavor that was neither very good nor very bad. The most common flavor defect was “feed” but other flavors frequently encountered were “cowy” and “rancid.” A significant flavor deterioration occurred in the raw milk during its storage for 48 hr at 38–40 F. The principal changes involved the development of such flavors as “rancid,” “unclean” and acid-associated flavors such as “malty.” The rancid flavor was a common defect in the milk after storage during the winter season, and unclean, musty, oily and the acid-associated flavors were frequently found in the milk after storage during the summer season. The results suggest the need for more adequate milk flavor control measures and that milk should be processed as soon as possible after reaching the plant if it is to possess the finest possible flavor.

Advances in the Microbiology of Milk and Dairy Products

“…The major effect of this change has been to reduce the quantity of milk spoiled by souring which occurred when it was produced under poor conditions of hygiene and inadequately cooled. Unfortunately the introduction of refrigerated cooling and storage has not removed spoilage defects in raw milk supplies; an investigation by Ohri & Slatter (1966) of milk from farm tanks revealed that 10 per cent of the milk on arrival at the depots had undesirable flavours. These undesirable flavours which have been variously described as unclean, fruity, rancid, bitter and even putrid are largely due to the hydrolytic activities of psychrotrophic micro-organisms on milk fat and protein.…”