Degree of starchy endosperm separation from bran as a milling quality trait of wheat grain

Authors: KONG, LINGYAN - The Ohio State University; Baik, Byung-Kee

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2016
Publication Date: 5/1/2016
Publication URL: http://handle.nal.usda.gov/10113/63348
Citation: Kong, L., Baik, B.-K. 2016. Degree of starchy endosperm separation from bran as a milling quality trait of wheat grain. Journal of Cereal Science. 69:49-56.

Interpretive Summary: The most valued quality trait of Eastern soft winter wheat for millers is high flour yield, and it consequently receives primary consideration by breeders in the development of wheat varieties. Flour yield is known to be a highly heritable trait, but the genes that control the flour yield of wheat have not been identified. This is mainly due to the complexity of the linkage between genetics and the grain characteristics influencing flour yield. Wheat grain characteristics, including test weight, kernel weight, kernel size, and kernel hardness, are known to influence the flour yield of wheat, but their relationships are often either not significant or too weak to serve as reliable estimates or indicators of flour yield. Despite considerable efforts to improve wheat flour yield through advances in breeding, cultivation, and milling technologies, the theoretical maximum flour yield has yet to be achieved. A better understanding of the biochemical grain characteristics related to flour yield and the identification of measurable grain traits for the effective selection of breeding lines for high flour yield are necessary to further improve the flour yield potentials of wheat varieties, and for the efficient and effective prediction of flour yield. The easy and clean separation of starchy endosperm from bran during milling undoubtedly affects milling and flour yield. The residual endosperm content of bran could be an indicator for the degree of endosperm separation from bran during milling and eventually be used as an important grain milling trait. We achieved a reliable estimation of the residual endosperm content of bran using a dimethyl sulfoxide extraction method. The residual endosperm content of bran as an index of the degree of endosperm separation from bran showed a large variation among soft red winter wheat varieties, ranging from 33.9 to 47.4% (w/w). The residual endosperm content of bran exhibited a much better relationship with flour yield than test weight, kernel hardness and kernel weight, suggesting that the degree of starchy endosperm separation from bran contributes significantly to flour yield and should be considered in the development of soft wheat varieties with improved flour yield potential.

Technical Abstract: Flour yield is an important quality trait of wheat, especially for flour millers because it directly affects profitability. In addition to the grain characteristics and milling conditions known to affect flour yield, easy and clean separation of starchy endosperm from bran during milling could have a significant contribution to the increased flour yield. Starch content and DMSO extractable content of bran were determined as the estimates for remnant endosperm content of bran, thus indicating the degree of starchy endosperm separation from bran during milling, for 61 and 100 soft red winter (SRW) wheat genotypes grown in 2013 and 2014, respectively. DMSO extractable content was found to be more reliable in the estimation of remnant endosperm content of bran than was starch content with better reproducibility. Flour yields of the 2013 and 2014 SRW wheat varieties tested ranged from 65.1 to 72.4% (w/w), and 63.6 to 73.9% (w/w), respectively. The remnant endosperm content of bran estimated using the DMSO extractable content ranged from 33.9 to 43.6% (w/w) and 35.4 to 47.4% (w/w) for the 2013 and 2014 crops, respectively. The remnant endosperm content was significantly related to flour yield with a correlation coefficient of r=-0.54 (P<0.001) from the 2014 crop, which was greater than that for any other grain characteristic including test weight, kernel hardness, and kernel weight. The degree of endosperm separation varied with different wheat varieties, different bran pieces and even different parts of the same piece of bran.