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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #416642
Research Project: New Sustainable Processes, Preservation Technologies, and Product Concepts for Specialty Crops and Their Co-Products

Location: Healthy Processed Foods Research

Title: Comparative analysis of the physicochemical properties of kafirin proteins extracted from various grain sorghums and their distillers’ grains

Author
item XIAO, RUOSHI - Kansas State University
item HONG, SHAN - Kansas State University
item LI, SANG - Kansas State University
item ZHENG, YI - Kansas State University
item WANG, DONGHAI - Kansas State University
item Xu, Yixiang
item LI, YONGHUI - Kansas State University

Submitted to: Sustainable Food Proteins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2025
Publication Date: 4/22/2025
Citation: Xiao, R., Hong, S., Li, S., Zheng, Y., Wang, D., Xu, Y., Li, Y. 2025. Comparative analysis of the physicochemical properties of kafirin proteins extracted from various grain sorghums and their distillers’ grains. Sustainable Food Proteins. 3(2). Article e70010. https://doi.org/10.1002/sfp2.70010.
DOI: https://doi.org/10.1002/sfp2.70010

Interpretive Summary: Sorghum, a globally significant cereal crop, is a potential source of innovative plant proteins. Kafirin is the primary storage protein in grain sorghum. However, isolating kafirin from sorghum grains poses challenges due to its distribution within the endosperm to form agglomerations with the glutelin matrix around starch granule. In this study, glacial acetic acid was utilized as the primary solvent to extract kafirins from sorghum samples. Subsequent pH adjustment to the isoelectric point of sorghum proteins further facilitated protein precipitation and isolation. Different types of sorghums and their distillers’ grains (DGs) were used to to understand the effect of sorghum type and fermentation process on structural characteristics, physicochemical and functional properties. This study provides baseline information to support the future production and wider applications of sorghum-derived proteins.

Technical Abstract: This study aims to conduct a comparative analysis of the physicochemical and functional properties of kafirin proteins extracted using glacial acetic acid method from different types of sorghums, as well as their distillers’ grains (DGs), and to understand the effect of sorghum type and fermentation process on the protein properties. The structural characteristics, physicochemical properties, and other functionalities of the kafirin proteins were characterized. The protein content of extracted kafirins ranged from 75% to 85%. The a-helix structure was predominant in kafirin proteins. SDS-PAGE results showed that the kafirins from different sorghum raw materials had similar band profiles, except that new bands in the range of 15-20 kDa and 25-37 kDa were observed for the kafirin samples from flours but not DGs. The surface hydrophobicity of the kafirins varied between 51.37-59.02 µg SDS/mg protein, and the fermentation process further altered the surface hydrophobicity of the extracted kafirin to some extent. The kafirin from black sorghum DGs had slightly lower in vitro protein digestibility (around 75.53%) compared to that from other sorghum DGs (75.34-79.33%), which may be due to the high tannin content in the black sorghum variety.