15C-16 |
Compressive properties of composite gels consisting of fractionated whey proteins and fractionated milkfat |
M. ROSENBERG1, Y. Mor-Rosenberg, and C. F. Shoemaker. (1) Department of Food Science and Technology, University of California, Davis, One Shields Ave., Davis, CA 95616 Proportion, composition, and properties of matrix and filler components, distribution pattern of filler and mass ratio of matrix-to-filler affect mechanical properties of composites. Objective of our study was to investigate effect of protein composition and of load and melting properties of lipid filler on compressive properties of emulsion gels consisting of fractionated whey proteins and fractionated milkfat. Gels (13% proteins in 0.1M NaCl, pH 7.0) containing 0-30% filler phase (mean particle size 0.4 micron) were prepared at 90°C. The ratio a-Lac:b-Lg ranged from 0:100 to 100:0. Filler consisted of AMF (M.P. 38°c) or of one of its fractions (VLM, MM2, HM1 or VHM with M.P. of 13, 29, 40 and 50°C, respectively). Uniaxial compression was carried out at 4, 25, 40 and 50°C, 50 mm/min, to 80% deformation. Compressive properties were significantly affected by a combined effect of proportion and melting properties of the filler, protein composition and by temperature. For a given filler, maximum compressive force at first fraction (FFF) was proportionally related to filler load and inversely related to temperature. For a given lipid type and load, FFF increased with b-Lg load. Effect of temperature could be attributed to its influence on compressive strength of the matrix, fluidity of the interface and on the solid-to-liquid ratio of lipids. Effect of filler load on FFF could be attributed to its effect on the formation of 3D domains connecting the filler interfaces and the matrix network. Effect of mass ratio of protein components could be attributed to the differences in type and extent (at a given temperature) of inter- and intra-molecular interactions that governed the participation of each of the protein components in the formation of the matrix. Results may open new application for fractionated milk-derived proteins and lipids in developing gelled products of desired compressive properties.
Session 15C, Dairy Foods
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