Enhanced egg white powder through liquid-state ultrasound-heating pretreatment: Properties and digestibility

Egg white protein's functional properties and digestibility can be significantly affected by processing methods. In this study, a novel combined ultrasound-heating (UH) pretreatment protocol was developed, where liquid egg white was subjected to ultrasonic treatment (0.4 W/mL, 10 min) followed by mild heating (72 °C, 10 min) prior to drying processes. The effects of this liquid-state pretreatment on the properties of subsequently produced freeze-dried and spray-dried egg white powders were systematically evaluated. Results indicated that the foaming stability, emulsifying activity, and emulsifying stability of UH pre-treated freeze-dried egg white powder increased by 52.1 %, 45.5 %, and 197.7 %, respectively. The emulsifying activity of UH pre-treated spray-dried egg white powder increased by 94.3 %. UH pre-treatment effectively improved the physicochemical properties of egg white powder. The treatment induced structural modifications characterized by increased particle size and zeta potential. Thermal analysis revealed selective denaturation of heat-sensitive proteins, while maintaining the structural integrity of more stable proteins. In vitro digestion experiments showed that UH pre-treatment significantly improved protein digestibility, particularly for proteins over 30 kDa, while effectively reducing avidin activity. These findings suggest UH pre-treatment offers a novel approach to enhance the functional properties and digestibility of egg white powder.