Pre-gelation assisted spray drying of whey protein isolates (WPI) for microencapsulation and controlled release

Abstract

Pre-gelation of whey protein isolates (WPI), a milk protein, has been performed before spray drying to decrease the solubility of WPI. The heat-induced pre-gelation at 80 °C aims to produce the gelled WPI for microencapsulation and sustained releases. The gelation time has been studied for a good spray drying, since the feed solutions with higher viscosities cannot be spray dried. WPI solutions cannot be gelled at lower pHs. SEM images show that the spray-dried WPI-acetaminophen particles have wrinkled surfaces. With longer gelation, the spray-dried particles show larger particle sizes and greater changes in the protein structure. FTIR and DSC analysis suggest that the model ingredient (acetaminophen) is amorphous in the spray-dried particles. The release profiles of pre-gelled WPI tablets show good fittings to a first-order release model. Overall, the releases of acetaminophen have occurred over periods from 3 h to two days for different pre-gelation times. The first-order release constants have been determined.