Milk may undergo a number of adverse changes during its handling. If held for any length of time without adequate cooling, it is subject to various types of spoilage due to the growth of microorganisms.
In addition, milk may develop various off-flavors due to the feed consumed by the cows, especially when they have fed on wild onions, French weed, or ragweed.
Large proportions of beets, beet tops, potatoes, cabbage or turnips in the fodder provided for cows may also cause the development of off flavors in the milk.
Lipase, an enzyme present in cow’s milk, may cause hydrolysis of fat, splitting off butyric acid, which causes an off flavor and off odor.
Milk that has been cooled, then warmed to about 85 degrees F, then recooled or homogenized in the unpasteurized state, is subjected to this kind of off flavor development.
Off flavors due to the oxidation of some of its traces of copper are present, since copper catalyzes this type of reaction. Milk therefore, should be kept out of contact with equipment that contains copper.
What might happen to the milk during handling?
