Bran characteristics influencing quality attributes of whole wheat Chinese steamed bread

Authors: MA, FENGYUN - The Ohio State University; LEE, YUYOUNG - Rural Development Administration - Korea; Baik, Byung-Kee

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2017
Publication Date: 1/1/2018
Citation: Ma, F., Lee, Y., Baik, B-K. 2018. Bran characteristics influencing quality attributes of whole wheat Chinese steamed bread. Journal of Cereal Science. 79:431-439.

Interpretive Summary: Steamed bread is one of the major wheat products consumed in China and is also popular in many Asian countries, making it an ideal delivery vehicle for boosting health benefits associated with the consumption of whole wheat foods. As true for whole wheat baked products, whole wheat steamed bread quality and sensory acceptance is inferior to its counterpart produced from refined white flour. Bran present in whole wheat flour increases its health benefits, but at the same time is responsible for low consumer acceptance. To identify varietal differences causing the perceived negative qualities of whole wheat in steamed bread, we examined brans from different varieties and produced steam breads for quality and taste assessment. We obtained brans from the grains of 17 soft red winter wheat varieties using laboratory-scale milling and tested them for variation in compositional and physical characteristics. Additionally, we tested steamed bread quality produced from whole wheat flour blends prepared by blending the 17 ground brans with a refined white flour. The 17 bran preparations showed large differences in compositional characteristics and water retention capacity. As expected from the variations in bran characteristics, steamed bread prepared from the whole wheat flour blends differed widely in quality. We observed that bran phenolics (both bound and total) had a negative influence, whereas water soluble arabinoxylan had a positive influence on the quality attributes of steamed bread. This study shows that wheat bran with low protein content, low bound and total phenolic contents, and high starch and water soluble arabinoxylan contents is desirable for making whole wheat steamed bread when blended with a refined white wheat flour. This information will be useful for establishing guidelines to identify preferred wheat varieties from which to extract the bran for making whole wheat steamed bread, and will help food manufacturers select wheat cultivars suitable for making good-quality whole wheat steamed bread.

Technical Abstract: This study investigated the variations in the characteristics of brans obtained from a pilot-scale milling of 17 soft red winter wheat varieties and their influences on the quality of whole wheat northern-style Chinese steamed bread (CSB) prepared from blends of a base flour and brans of different wheat varieties. Protein, starch, total dietary fiber (DF), water extractable arabinoxylan (WEAX) and total phenolic contents of brans ranged from 14.3 to 19.1%, 12.0-19.4%, 43.5-50.3%, 0.69-1.35% and 14.3-18.9 mg/g, respectively. Surface smoothness, crumb structure and stress relaxation scores of whole wheat CSB ranged from 3.0 to 9.5, 6.5-12.5 and 24.3-34.3, respectively. Bran bound and total phenolic contents exhibited negative relationships with CSB surface smoothness and crumb structure. Bran WEAX content showed positive relationships with CSB specific volume, surface smoothness and stress relaxation scores. Bran insoluble DF content was negatively related to CSB stress relaxation score. Bran protein and starch contents showed negative and positive relationships, respectively, with CSB spread ratio score. Cluster analysis of wheat brans based on CSB surface smoothness and crumb structure indicated that wheat bran with a low protein content, low bound and total phenolic contents, and high starch and WEAX contents is desirable for making whole wheat CSB.