Physical and chemical stability of microencapsulated okara protein hydrolysate by spray drying

Abstract Microencapsulation is a process used for protecting substances that are susceptible to degradation or reduction of their functionality due to different reactions such as oxidation, hydrolysis, among others. This study aimed to evaluate the effect of microencapsulation, using maltodextrin or modified starch as wall materials, on the stability of okara protein hydrolysates. We analyzed the microstructure, antioxidant capacity, and color of the samples during powder storage for 120 days at 35 °C. Micrographs obtained by scanning electron microscopy indicated that the microencapsulation process favored the particles’ physical integrity. The color difference observed between the encapsulated and unencapsulated samples was probably due to the addition of wall materials that contributed to color change of the powder obtained by spray drying. The results indicated that the microcapsules obtained by spray drying using maltodextrin or modified starch maintained the powder color and showed good ability to sequester the free radical ABTS and content of reducing substances from the Folin-Ciocalteau reagent during storage.

摘要 微囊化（Microencapsulation）是一种用于保护易因氧化、水解等多种反应发生降解或功能减退的物质的工艺。本研究旨在评估以麦芽糊精或改性淀粉作为壁材的微囊化工艺对豆渣蛋白水解物稳定性的影响。我们于35℃条件下对样品粉末开展为期120天的储存实验，并分析了储存过程中样品的微观结构、抗氧化能力与色泽特征。扫描电子显微镜所得显微图像显示，微囊化工艺可有效维持颗粒的物理完整性。包埋样品与未包埋样品间的色泽差异，大概率源于壁材的添加——该添加改变了喷雾干燥所得粉末的色泽表现。研究结果表明，以麦芽糊精或改性淀粉为壁材通过喷雾干燥制备的微胶囊，在储存过程中可维持粉末的色泽稳定性，并对ABTS自由基与福林-酚试剂（Folin-Ciocalteau reagent）法测得的还原物质含量展现出良好的清除能力。