Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 26, 2004
Publication Date: March 3, 2007
Citation: Nalesnik, C.A., Onwulata, C.I., Tomasula, P.M. 2007. Drying properties of extruded whey protein concentrates and isolates. Journal of Food Engineering. 80:688-694. Technical Abstract: Extruded whey protein has unique properties as a food ingredient compared to spray-dried whey protein. Extruder texturized whey protein is more amenable to introduction into some food products than the non-texturized spray dried form. The drying properties of extruded whey protein are needed to optimize drying conditions, i.e. to retain product quality and to determine energy requirements. It is desired to reduce the moisture content of the extruded product to 10% to 15% moisture content (w.b). This low-moisture product can then be ground to an appropriate particle size for further processing or for incorporation into food products. In this study, extruded whey protein concentrates (WPC80) and extruded whey protein isolates (WPI) were dried by convection in a batch oven at 57 degrees C. Drying did not substantially change the color or density of the extruded WPC80 and extruded WPI. The drying curves for both extruded products exhibited only a falling-rate period. The extruded WPC80 dried from 36% to 10% moisture content (w.b.) in 2 hours, and the extruded WPI dried from 35% to 10% moisture content (w.b.) in 2 hours 40 minutes. The extruded WPC80, which contains more lactose, dried at a slightly faster rate than the extruded WPI. The drying curves were modelled using a simple diffusion model. The drying rates can be used to calculate parameters for large-scale drying. The drying conditions employed in this work produce high quality whey proteins.