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item Tunick, Michael
item Onwulata, Charles
item Tomasula, Peggy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2005
Publication Date: 8/28/2005
Citation: Tunick, M.H., Onwulata, C.I., Tomasula, P.M. 2005. Rheological properties of extruded milk powders. Abstract. American Chemical Society. Paper No. AGFD075.

Interpretive Summary: n/a

Technical Abstract: Whey protein concentrate (WPC), whey protein isolate (WPI), and nonfat dry milk (NDM) may be processed through a twin-screw extruder to produce an ingredient for protein-fortified food. Small amplitude oscillatory shear measurements showed that the rheological properties varied with extrusion temperature and moisture content. The elastic modulus (G'), viscous modulus (G"), and complex viscosity decreased as moisture was increased, and the trends were more pronounced at extrusion temperatures of 50 and 75 deg C than at 100 deg C. The values for G"/G', an indication of the solid-like nature of the sample, were always in the 0.19-0.32 range for NDM and for the 100 deg C samples of WPC and WPI. The values for the whey protein powders at lower temperatures were frequently > 0.5, evidence that these samples were more fluid-like. WPC and WPI showed different effects than NDM due to the type and amount of protein present. The characteristics of extruded milk powders can be manipulated through processing parameters to obtain texturized products.