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SummaryF m e s s at 5 "C, dynamic viscoelastic moduli (G', G") and capillary extrusion profiles at 20 "C, were obtained on double cream cheese after the different steps of processing (curd obtention, mixing at 70 "C and 500 r.p.m. with heat-denatured WPC, heating at 85 "C, homogenizing at 20 MPa (1st stage) and 5 MPa (2nd stage) and cooling to 20 "C and 13 "C) and storage 7-9 days at 5°C. It was found that double cream cheese became f m e r and more elastic after heating and homogenization, although it became softer and more viscous after mixing and cooling. Transmission Electron Microscopy (EM) and cryo-Scanning Electron Microscopy (SEM) micrographs showed that rheology results could be related to aggregation (during heating and homogenization) and disruption (during cooling) of milk fat globule/ casein complexes. Dispersion of homogenization clusters after cooling, and aggregation of milk fat globules during storage caused double cream cheese structural instability to appear. It was suggested that the heterogeneity of capillary extrusion profiles could be quantified through application of fractal concepts and FOURIER analysis and related to structure and texture of double cream cheese.

As estimated on-line, the viscosity after cooling of double cream cheese curd containing heat-denatured WPC (DCC + ) increased from 1.4 Pa.s to 1.7 Pa.s when cooled to the range of 45ЊC to 24ЊC, and then decreased from 1.7 Pa.s to 1.0 Pa.s when cooled from 24ЊC to 15ЊC. The viscosity of DCC Ϫ (without heat-denatured WPC) increased from 1.5 Pa.s to 2.2 Pa.s at temperature shift from 40ЊC to 15.5ЊC. The firmness of stored DCC + and DCC Ϫ , respectively, decreased from 15.1N to 6.5N when cooled to temperatures from 45ЊC to 15ЊC, and from 17.9N to 9.9N when cooled from 40ЊC to 15.5ЊC, as recorded by cone penetrometry. The structure of DCC + cooled to 15ЊC collapsed after penetrometry, and DCC + cooled to 20ЊC destabilized during shearing in coaxial cylinder rheometer. A new phase in DCC + based on milk fat globules liberated by cluster disruption may be the cause of the structural and textural instability.