New Barley Enzymes Discovered

According to a story in the Sept. 2006 issue of Agricultural Research, scientists at USDA's Agricultural Research Service (USDA-ARS) Cereal Crops Research Unit, Madison, WI, recently uncovered plant enzymes that improve barley malting to yield a higher percentage of sugars than conventional enzymes. They can also withstand higher temperatures during processing. USDA-ARS reports that the enzymes have the potential to benefit both beer brewing and baked-goods applications (see http://www.ars.usda.gov/is/AR/archive/sep06/barley0906.htm for the complete story).

The researchers reportedly have an ongoing mission dedicated to discovering different types of barley kernels to unearth any with superior malting qualities. In some recent work along these lines, Cynthia Henson, plant physiologist, Cereal Crops Research Unit--along with her colleagues--discovered some barley enzymes that might make malting more efficient to yield up to 30% more sugars than conventional enzymes. The Agricultural Research article notes that this increased sugar translates into more fermentable product for brewing beer and possibly for ethanol production.

"Two of barley's starch-degrading enzymes are heat-sensitive," says Henson in the article. "One of those is the second-most-important enzyme for converting starches into fermentable sugars." This enzyme, alpha-glucosidase, stops its activity under higher temperatures. "At high temperatures," she continues, "alpha-glucosidase has less than 5% the activity it normally would."

During the course of their research, Henson and her colleagues analyzed enzymes, in terms of their heat stability, from a variety of plants, including sugar beets, spinach and Arabidopsis, a plant related to mustard and cabbage that's frequently used as a model for biological studies. They found that enzymes from sugar beets had the best heat tolerance. This led to the creation of a new barley enzyme that includes an amino acid from sugar beets. In all, the researchers have developed--and patented--three new heat-stable barley enzymes.

This work is ongoing as the researchers continue to look for naturally occurring enzymes in a variety of plants that might potentially match the capabilities of the newly created enzymes. "We're also looking for variation in another barley enzyme, called beta-amylase," says Henson. "We're looking for differences in the enzymatic activities of various malting and feed barleys." The goal is to cross-breed barley varieties that have desirable characteristics--like enzymes with heat stability--with proven cultivars to create "the ultimate malting barley."

This research is part of the Plant Biological and Molecular Processes National Program (see http://www.ars.usda.gov/research/programs/programs.htm?NP_CODE=302for more information).