Increase milk's shelf life by flash-heating.

Existing commercial treatments for processing ultra-high temperature (UHT) milk create a cooked flavor that can detract from the product's fresh taste. But scientists at the Western Dairy Center (Utah State University, Department of Nutrition and Food Science, UMC 8700, Logan, UT 84322) are using electricity to process UHT milk

By passing electrical current directly through pasteurized milk, they flash-heat milk to destroy virtually all bacteria present. The technique, known as electroheating and developed by researchers at Raztek Corp. (Sunnyvale, CA), creates a more appealing, fresher-tasting milk that has an extended shelf life.

In a series of taste trials, consumers preferred the taste of the electroheated milk to a commercial UHT-processed milk by a margin of 2 to 1. A panel of trained tasters also found electroheated milk to be sweeter and to have less bitter, oxidized and stale flavor than UHT-processed milk.

By passing an electrical current directly through the milk itself, scientists are able to reach UHT levels in a fraction of a second, rather than in minutes. This quicker heating process is key to producing a fresh-tasting milk product. Although UHT-processed fluid milk is gaining favor in various parts of the world, Americans accustomed to the ready availability of fresh milk have been slow to accept it, in part because of its cooked flavor. UHT processes in commercial use rely on indirect heat exchange through a metal plate or the direct addition of steam into the milk.

Heat exchange is a time-consuming physical process that requires 1 minute to 2 minutes when indirect heating is used. The longer milk is exposed to high temperatures, the more cooked flavors develop in the end product. Direct heating with steam is quicker, but the added water has to be removed by vacuum evaporation during the cooling process.

Electroheating creates heat sterilization temperatures identical to those of current UHT-processed milk. It could effectively meet milk regulatory and safety compliances while extending shelf life.

Further information. Donald McMahon; phone: [phone]; fax: [phone].