Microencapsulation of pepsin in the spray-dried WPI (whey protein isolates) matrices for controlled release

The microencapsulation and controlled release of pepsin have been achieved by spray drying with the original, hydrolysed and gelled whey protein isolates (WPI, HWPI, GWPI). The pepsin is in an amorphous state in the spray-dried particles. The survival rate of pepsin is around 84.3-89.4% during spray drying and decreases with increasing inlet temperature from 110 to 190 degrees C. The optimal inlet temperature for a high yield and a high survival rate of pepsin is 150 degrees C. The spray-dried proteins have wrinkled surfaces, which are related to high Peclet numbers during drying. FTIR spectra show free amino acids for HWPI and the change in protein structure for GWPI upon gelation, compared with WPI. The spray-dried samples with microencapsulated pepsin have been tableted for the controlled release studies. The release time is controllable within 4 h by changing the release matrices or the pepsin ratio. Zero-order release of pepsin has been relatively achieved with the highest R-squared value of 0.989 using a sandwich-like multilayer design for a matrix containing 50% GWPI and 50% WPI.