Cereal Chem 63:142-145   |  VIEW ARTICLE
Fractionation and Characterization of Protein-Rich Material from Barley After Alcohol Distillation.

Y. V. Wu. Copyright 1986 by the American Association of Cereal Chemists, Inc. 

Because of current industrial interests and plans to use barley grain for alcohol production, methods for efficient recovery and utilization of stillage were investigated. Ground barley was fermented to ethanol, the ethanol was distilled, and the residual stillage was separated into distillers' grains, centrifuged solids, and stillage solubles. Distillers' grains and centrifuged solids had protein contents (nitrogen x 5.67, dry basis) of 33 and 61%, respectively, and accounted for 71 and 6% of total barley nitrogen. The protein in distillers' grains was much less soluble than that in barley. Lysine, expressed as grams per 16 g of nitrogen, was 3.9- 4.4 for barley and its fractions after fermentation. Eighty-eight percent of the nitrogen in stillage solubles passed through a 10,000 molecular weight cut-off membrane. Permeate from stillage soluble processed by ultrafiltration and reverse osmosis had much lower nitrogen and solids contents than those of stillage solubles; high pressure reverse osmosis was especially effective for reducing nitrogen and solids contents. Thus, ultrafiltration and reverse osmosis can be used to concentrate barley stillage solubles for potential feed utilization while providing a permeate which can be reused for water or safely discarded.