Science: Frozen Milk

Milk is about the last important food to resist preservation by freezing. It can be preserved in several ways with its food value intact, but its flavor is apt to be ruined by any kind of tinkering. The U.S. Department of Agriculture now says that frozen, concentrated milk might soon join orange juice in the family icebox.

The trick of guarding the flavor is to heat it just enough. Too little heating allows it to oxidize and acquire a “cappy” (i.e., bottle cap) flavor. Too much heating makes it taste cooked. The best bet, says DOA, is to heat grade-A milk to 155° for 30 minutes (or to 170° for one minute). Then it is homogenized, concentrated to one-third its volume, and frozen in sealed containers. The product will keep for two weeks in a home icebox, or for eight weeks in a freezer at —10°. When thawed and diluted with good water, it tastes like fresh milk.

Frozen milk is not on the market yet, but dairy companies are experimenting and the armed services are interested.