Microscopic and rheological studies of fat crystal networks

This talk discusses the quantification of microstructure in fat crystal networks by using the relationship of the elastic moduli (G') to the solid fat content (SFC) via the fractal dimension (D) of the network. Results from application of a scaling theory developed for colloidal gels [W.H. Shih et al., Phys. Rev. A 42 (1990) 4772] to chemically and enzymatically interesterified and non-interesterified butterfat/canola oil mixtures and to cocoa butter and Salatrim(TM) are presented and discussed. In situ images from confocal laser microscopy and polarized light microscopy of the crystal network of butterfat and butterfat-canola oil blends yielded fractal dimensions of D = 1.88 and D = 2.02 +/- 2% respectively, which are in good agreement. The use of rheological measurements to calculate a fractal dimension of the crystal network of butterfat-canola oil blends yielded D = 1.99, in good agreement with D calculated from the confocal laser microscopy and the polarized light microscopy images. (C) 1999 Elsevier Science B.V. All rights reserved.