ABSTRACT Sorghum, an ancient grain, is generating much interest in the plant‐based diversified protein market. Sorghum's major protein is the alcohol‐soluble kafirin, whose hydrophobicity and limited functionality have posed challenges for extraction and protein quality using conventional methods. The current work evaluated a blended solvent approach (ethanol: alkali) to improve sorghum protein yield and properties. Ground, undefatted or defatted pearled sorghum (UPS or DPS) and sorghum protein meal from wet‐milling (control; WSPM) were each extracted with anhydrous ethanol:0.1 N NaOH (1:1.2, v:v) at 50°C and 250 rpm for 2 h, centrifuged, membrane filtered, then freeze‐dried. Protein recovery, composition, and functional properties were determined. Sorghum samples contained predominantly kafirins (> 30%) and glutelins (ca. 20%). Ethanol‐alkali extraction had high protein recoveries (78%–83%) and produced high‐purity (87%–97%) protein extracts, with WSPM having the greatest protein content. Starting UPS and DPS protein solubility index (PSI) values (30%) were five‐fold greater than that of WSPM. Protein isolates showed markedly improved solubility, with PSI of 99% for UPS or DPS and 20% for WSPM. Solubility‐pH profile affirmed UPS and DPS protein isolates are significantly more soluble than WSPM protein isolate at pH > 6.0. DPS and WSPM protein produced substantial foam (100 mL), but only DPS showed moderately stable foam (64% remaining foam after 15 min). Emulsification activity for the sorghum protein extracts were similar at pH 7.0 and pH 10.0, but WSPM protein emulsions were the most stable. This work demonstrated extraction using ethanol: alkali can produce sorghum protein with enhanced yield and utility as a diversified plant‐based protein.
Hojilla‐Evangelista et al. (Wed,) studied this question.