Comparative Analysis of the Physicochemical Properties of Kafirin‐Enriched Proteins Extracted From Various Grain Sorghums and Their Distillers' Grains

ABSTRACT Sorghum is a globally significant cereal crop that can be a potential source of innovative plant proteins. Kafirin is the primary storage protein in grain sorghum. This study aims to conduct a comparative analysis of the physicochemical and functional properties of kafirin‐enriched proteins extracted using the 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 protein content of extracted kafirin‐enriched proteins ranged from 75% to 85%. The α‐helix structure was predominant in the extracted proteins. SDS‐PAGE results showed that the proteins 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 protein samples from flours but not DGs. The surface hydrophobicity of the proteins varied between 51.37 and 59.02 μg SDS/mg protein, and the fermentation process further altered the surface hydrophobicity of the extracted proteins to some extent. The kafirin‐enriched proteins from DGs of black sorghum had slightly lower in vitro protein digestibility (around 74.80%) compared to that from other DGs (75.34%–79.33%), which may be due to the high tannin content in the black sorghum. The functional properties of the proteins varied to some extent. This study provides fundamental knowledge of the protein properties associated with different sorghum types and their DGs, which will aid in the future production and wider applications of sorghum‐derived proteins.