A Comparative Evaluation of Six Extraction Methods on the Techno-Functional Properties of Black and White Sesame Meal Proteins

Sesame meal protein (SMP) is a promising sustainable protein source, yet its functional performance is often compromised by conventional extraction methods that prioritize yield over structural integrity. This study systematically compares six extraction methods—acid/alkaline pH-shift, Osborne fractionation, salting-out, isoelectric precipitation, and micellization—applied to black and white sesame varieties, aiming to establish a methodological reference for targeted SMP extraction. The extraction method critically dictated the supramolecular architecture and secondary structure of the isolates, which in turn governed their techno-functional properties. Micellization best preserved native protein conformation, yielding isolates with superior pH-dependent solubility (exhibiting a pronounced U-shaped profile) and the highest in vitro digestibility (77.17% for black, 72.85% for white SMP). In contrast, isoelectric precipitation and pH-shift induced severe aggregation and unfolding, as evidenced by SEM and FTIR, leading to significantly impaired functionality. Osborne fractionation offered a viable yield-purity compromise, while salting-out achieved high purity with low recovery. Sesame variety was a key modulator, with black sesame yielding isolates of higher purity and distinct functional properties. These findings provide a practical reference for selecting extraction protocols to tailor SMP for specific food applications, such as protein-fortified beverages, nutritional emulsions, and texturized products.