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 When
Benjamin Franklin’s kite went soaring into a thunderstorm in
1752, little did he dream that his discovery of electricity
would have such far-reaching implications.
In
2000, electricity moves beyond providing a well-lit home or
milking parlor to help create an ultra-high temperature (UHT)
milk with a fresh, appealing taste.
Existing
commercial methods for UHT treatment of milk create a
“cooked” flavor that can detract from the fresh taste. But
researchers at the Western Dairy Center at Utah State University
in Logan, Utah, in a project managed by Dairy Management Inc. (DMI),
are using electricity to look at a promising new process for UHT
milk processing. By passing electricity current directly through
pasteurized milk, the milk is flash heated to destroy virtually
all bacteria present. This improved technology delivers a more
appealing, fresher-tasting milk with an extended shelf life.
Although
UHT-processed fluid milk is gaining favor in other 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 currently in commercial use
rely on indirect heat exchange through a metal plate or direct
addition of steam into the milk.
“Heat
exchange is a physical process that simply demands time, usually
as much as one to two minutes when using indirect heating,”
says co-investigator Donald McMahon of Utah State University.
“The longer milk is exposed to those high temperatures, the
more cooked flavors are developed 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.”
The
secret of the new technology, known as electroheating and
developed by Raztek Corp., Sunnyvale, Calif., is a fast, direct
heat application.
“By
passing an electrical current directly through the milk itself,
we are able to reach UHT levels in a fraction of a second,
rather than minutes,” McMahon says. “This quicker heating
process is the key to producing a fresh-tasting milk product.”
For
commercial producers, electroheating also has the advantage of
ready regulatory acceptance. While researchers are continuing to
explore a variety of non-thermal ways to extend milk’s shelf
life, these experimental technologies carry a scientific burden
of proof. Electroheating, on the other hand, provides heat
sterilization at temperatures identical to current UHT-processed
milk. Therefore, electroheating milk could effectively meet milk
regulatory and safety compliances while efficiently extending
shelf life.
The
real test of electroheated milk is consumer acceptance. In a
series of taste trials, consumers preferred the taste of the
electroheated milk to a commercial UHT-processed milk sample by
a margin of 2 to 1. A panel of trained professional tasters also
found electroheated milk to be sweeter, with less bitter,
oxidized and stale flavors than UHT-processed milk.
McMahon,
like many others, believes better taste is key to the American
consumer’s acceptance of longer-lasting milk products. Given
the trends in the industry, longer shelf life may be critical to
the future success of American dairy producers.
“Dairy
companies are consolidating to improve their competitive
position in a global market,” McMahon says. “We can expect
to see that trend continue for the foreseeable future. With
consolidation, distribution chains are becoming longer. So to
meet consumer expectations for fresh product, more and more
companies will have to look at ways to extend shelf life.”
For
more information on this or other research products funded by
America’s dairy producers, call the DMI technical hot line at 800.248.8829, or DMI’s web site at
www.dairyinfo.com/.
Reprinted
with permission from Dairy Management Inc.
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