The bland, slightly sweet flavor of milk comes from its lactose, salts, sulfur compounds, and short-chain fatty acids. The percentage of fat determines the mouthfeel and body of a particular milk.
Exposure to heat or sunlight, oxidation, the use of copper equipment or utensils, and the feed ingested by the source animal are just some of the other factors that can influence the flavor of milk. For example, off-flavor develops when the amino acid methionine reacts with the sunlight-sensitive riboflavin (vitamin B2). The “cooked” flavor of heated milk develops in part because heating denatures whey proteins to release volatile sulfur compounds, which contribute to off-flavors. Dairy cattle allowed to feed off wild onions, ragweed, French weed, beets, potatoes, cabbage, or turnips produce off-flavored milk.
