Effects of ultrasonic pretreatment on fibrillation kinetics, morphologies, and functional properties of bovine serum albumin fibrils

Amyloid fibrils (AFs) are generally believed to contribute to the functional properties of food matrix. In order to improve the application accessibility of protein fibrils, a better understanding of the mechanisms regulating their functional properties and fibrillation is needed. In this work, the fibrillation kinetics of bovine serum albumin (BSA) under static acid-heating and how ultrasonic pretreatment (USP) affects their ability to form stable emulsions and foams were investigated. BSA fibrils were generated under diverse acidic pHs (pH 2.0 to 4.0) by heating at 65 degrees C for 12 h. The formation kinetics, physicochemical properties, and morphologies of BSA fibrils were studied using thioflavin T fluorescence, electrophoretic gel, spectroscopic methods, viscosity profiling, and transmission electron microscope. Emulsions and foams were made and evaluated for functional capacity and stability. Results showed that the fibrillated BSA at pH 3.0 possesses the best performance in emulsifying and foaming properties. USP can lead to finer, shorter, and more flexible fibrils, compared to the untreated control. The mature BSA fibrils mediated by 20-min USP may be efficient in covering around oil droplets/bubbles, resulting in stronger emulsifying and foaming properties. The attempts were made to provide referable meaning to the functional application of BSA in the food industry.