Protease-Induced Aggregation and Gelation of Whey Proteins

Aggregation and gelation of whey proteins induced by a specific protease from Bacillus licheniformis was revealed by turbidimetry, size exclusion chromatography, dynamic light scattering and rheology. The microstructure of the gel was examined by transmission electron microscopy. During incubation of 12% whey protein isolate solutions at 40°C and pH 7, the major whey proteins were partly hydrolyzed and the solution gradually became turbid due to formation of aggregates of increasing size. The viscosity of the hydrolysate simultaneously increased and eventually a gel formed. The gel had a particulate type of microstructure. We hypothesized that the aggregates forming the gel were held together by noncovalent interactions.