Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/13/2005
Publication Date: 11/28/2005
Citation: Flores, R.A., Hicks, K.B., Eustace, D.W., Phillips, J.G. 2005. Experimental milling of barley samples. Cereal Chemistry 82, No. 6, p. 727-733. Interpretive Summary: Barley is a crop that is being considered as having great potential for applications in ethanol production and as a source of health promoting compounds, such as beta-glucans. To determine the potential for utilization of barley for these purposes, experimental milling on barley was studied. Experimental milling consists of multiple dry grinding and fractionation processes that simulate a large scale milling operation. Four different experimental milling methods were evaluated with three barley varieties. The study identified milling streams that have the potential for utilization in ethanol production as well as streams with higher concentration of valuable beta-glucans. This information will be of use to groups nationwide who are considering the use of barley as a feedstock for fuel ethanol production.
Technical Abstract: Barley has traditionally been used in the brewing and feed industries. New varieties are being developed that widen the applications of this crop to nontraditional food and non-food value-added applications, such as ethanol production. Hulless or naked varieties present new alternatives and processing or evaluation challenges. This study focuses on the performance of two hulless barley varieties (Doyce and Merlin) and one commercial husked (hulled) sample, using experimental milling as a preliminary indicator of flour performance and the starch and ß glucan concentration in the milling fractions. Four different experimental mills designed for flour production evaluation from wheat were tested with these varieties: Chopin CD1 Auto, Quadrumat Senior, Buhler, and an experimental roller mill walking flow. The flour yields for the Doyce were highest with the Buhler (70%) and lowest with the experimental roller mill walking flow (42%). The Merlin produced the highest flour yield (76%) with the experimental roller mill walking flow and the lowest with the Buhler (24%). The husked variety had the highest flour yield (48%) with the Quadrumat Senior and the lowest (35%) with the experimental roller mill walking flow. Compositional analyses (moisture, starch, protein, ash, and ß-glucan) were conducted on all mill streams. Results indicate that the shorts had the highest levels of ß-glucan from all the mills. However, the ß-glucan content in the break flours was highest with the roller mill walking flow and the Chopin CD1 for the hulless varieties. The lowest ß-glucan content in the break flour was found with the Buhler for the Doyce and the commercial husked samples and with the Quadrumat Senior for the Merlin sample. Break flour and to a slightly lesser extent, reduction flour, from all varieties tested on all mills contained the highest starch content (up to 83%), and are therefore most appropriate for use as feedstock for fuel ethanol production. Conversely, bran and shorts from all varieties and mills were lowest in starch (as low as 25%), making them ideal as low-starch food ingredients. Due to the different yields, when using experimental milling to evaluate new barley varieties, several experimental milling procedures need to be taken into consideration.