Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 4/14/2008
Publication Date: 9/21/2008
Citation: Liu, K., Woolman, M.J., Barrows, F., Obert, D.E. 2008. Methods of dry fractionation to produce barley fractions varying in protein and/or beta-glucan contents. Book of Abstracts, American Association of Cereal Chemists Annual Meeting, Honolulu, Hawaii. Sept 21-24.
Technical Abstract: On average, barley contains 64% starch, 11% protein, and 5% glucan. The remaining 20% includes moisture, fiber, ash and other minor components. Among them, protein and beta-glucan are of higher values. Dry fractionation has been the primary and low cost means to enrich protein and other nutrients in cereal grains. In this study, two barley genotypes (hulled and hulless) were sequentially pearled for 1 to 6 cycles, each with 8% removal. The 6 pearled kernels plus the whole kernel were subjected to one of the two milling methods (impact and abrasive), followed by sieving with a series of U.S. standard sieves. The objective was to determine 1) factors affecting efficiency of nutrient shifts, 2) which method (single or combined one) was best for separating barley into fractions with highest variations in protein, beta-glucan or both among them. Results show that genotype, milling method and particle size all had significant effects on contents of protein and beta-glucan in sieved fractions, while the cycle of pearling significantly affected protein but not glucan content. Furthermore, abrasive milling produced sieved fractions with much higher variation in protein content than impact milling, but the opposite effect was observed for shifting beta-glucan content. When the recovery rate was taken into consideration, pearling was more effective than the method of milling and sieving in producing fractions with high protein content, but for beta-glucan the later method was better. Among sieved fractions, for beta-glucan, the lowest content was about 7% of the whole kernel value, whereas the highest level was about 280%; for protein, the lowest content was about 45% and the highest was about 145%. Therefore, dry fractionation offers a method of choice for separating barley into fractions with varying levels of proteins and/or glucan, but selection of a specific one is needed for achieving maximum shifts of a particular nutrient.