Okara protein extracted by alternating ultrasonic/alkali treatment and its improved physicochemical and functional properties

Okara protein (OP) is a potential plant-based protein that is beneficial to human health. In this work, an alternating ultrasonic/alkali treatment method with non-continued cavitation and thermal energy output was used to extract protein (AUA-OP) from okara to enhance the functional properties of OP and improve the stability of OP-based emulsions. The purity of AUA-OP was greater than 80%. Compared with traditional (physical-assisted) alkali treatment, FTIR and SDS-PAGE revealed that AUA-OP retained the chemical structure of the protein, but the number of ultrasound-induced exposure sites increased, with increased fluorescence intensity, surface hydrophobicity, and absolute ζ-potential. After alternating ultrasonic/alkali treatment, the protein particles were looser and smaller. In addition, the water/oil holding capacity, EAI, and ESI of AUA-OP further increased. The viscosity of the AUA-OP-stabilized emulsion was also greater. Finally, a 28-day emulsion storage assay revealed that the AUA-OP-stabilized emulsion was stable with a relatively low droplet size and creaming index, indicating great potential for the development of stable protein-based emulsions.

豆渣蛋白（OP）是一种对人体健康有益的潜在植物蛋白。在这项工作中，采用一种具有非连续空化和热能输出的交替超声/碱处理方法从豆渣中提取蛋白（AUA - OP），以增强OP的功能特性并提高基于OP的乳液的稳定性。AUA - OP的纯度大于80%。与传统（物理辅助）碱处理相比，傅里叶变换红外光谱（FTIR）和十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）显示AUA - OP保留了蛋白质的化学结构，但超声诱导的暴露位点数量增加，荧光强度、表面疏水性和绝对ζ - 电位均增加。经过交替超声/碱处理后，蛋白质颗粒更松散且更小。此外，AUA - OP的持水/持油能力、乳化活性指数（EAI）和乳化稳定性指数（ESI）进一步提高。AUA - OP稳定的乳液的粘度也更大。最后，一项为期28天的乳液储存试验表明，AUA - OP稳定的乳液稳定，液滴尺寸和乳析指数相对较低，这表明其在开发稳定的基于蛋白质的乳液方面具有巨大潜力。