Impact of particle size fractions on composition, antioxidant activities, and functional properties of soybean hulls

Authors: Liu, Sean; Chen, Diejun; Plumier, Benjamin; Berhow, Mark; Xu, Jingyuan - James; Byars, Jeffrey

Submitted to: Journal of Food Measurement and Characterization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2020
Publication Date: 11/23/2020
Citation: Liu, S.X., Chen, D., Plumier, B.M., Berhow, M.A., Xu, J., Byars, J.A. 2020. Impact of particle size fractions on composition, antioxidant activities, and functional properties of soybean hulls. Journal of Food Measurement and Characterization. 15:1547-1562. https://doi.org/10.1007/s11694-020-00746-0.
DOI: https://doi.org/10.1007/s11694-020-00746-0

Interpretive Summary: This research investigated potential soybean hull utilization in value-added products studying 5 different size milled fractions, ranging from 20 to 140 mesh. The focus of the research is on the effect of size fractions on the amount of proteins, dietary fiber, minerals, soluble sugars, essential amino acids, and antioxidant activities of soybean hulls, as well as rheological properties of the fractions, which are pertinent to applications of soyhulls in food products. This study also for the first time compared the protein properties from soybean hulls with commercial soy protein products using gel electrophoresis and concluded that the proteins extracted from soyhulls are comparable to soy proteins extracted from whole beans. The insight of the physical properties of soyhull fractions provides useful information for developing functional food ingredients in the future. This study showed that soybean hulls, a low value byproduct of soybean processing, could be utilized as a source of several value-added applications including functional food products that require plant-based protein, minerals, dietary fibers, antioxidants, and amino acids. Increased utilization of soybean hulls in higher value applications would increase soybean value-chain profitability along with the great impact on functional food applications for countering heart health problems, diabetes, and obesity.

Technical Abstract: This research investigated potential soybean hull utilization in high value products by determining the amount of proteins, dietary fiber, minerals, phenolics, antioxidant activities, as well as rheological properties that are pertinent to applications of soyhulls in food products, of soybean hull samples in 5 different size fractions from 20 to 140 mesh. The contents of protein and ash, soluble sugar, and most amino acids increased with decreasing sizes. This study first reported the quantities of bound phenolic contents and antioxidant activities, soluble sugars, and amino acids in soybean hulls. The free phenolic contents and antioxidant activities increased significantly with decreasing particle sizes in the study. Overall, slightly higher free phenolic contents were observed compared to bound phenolic contents whereas the free antioxidant activities were considerably lower than bound antioxidant activities for the same fraction, which suggested that a portion of antioxidant activities were not released during neutral extraction. Furthermore, the extracted protein from soybean hulls showed similar patterns with soybean products using gel electrophoresis. The content of water-soluble solids increased with decreasing size. By contrast, water holding capacities decreased with decreasing particle sizes. The final viscosity peak of soybean hulls increased as the sizes increased. The trend of final peaks from blends appeared to be related to their water holding capacities. This study evaluated the effect of size fractions on compositions, antioxidant activities, water holding capacity, pasting, rheological and thermal properties of soybean hulls and their great potential for use in functional foods and industrial applications.