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.

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Isolated snail gonadal cells were cultured in the presence of synthetic neuropeptides in order to determine the subsequent effect of these substances on gonadal synthetic activities. Gonadal cells were incubated for 24 h in concentrations of methionine-enkephalin, somatostatin and insulin ranging from 10(-4) M to 10(-9) M, in medium 199 supplemented with 6% Ultroser G. Synthesis of DNA and protein by the cultured cells were simultaneously estimated by measuring incorporation of 3H thymidine and 35S methionine. The rate of labelled precursor incorporation was measured using the liquid scintillation technique. All substances tested exerted a dose-dependent effect. The synthetic activity of the cultured cells was highest when the concentration of the peptides added to the medium approximated the physiological levels. Methionine-enkephalin, somatostatin and insulin at 2 x 10(-8) M significantly increased 3H thymidine incorporation, by 62%, 69% and 69% respectively, and protein synthesis by 42%, 57% and 57%, respectively. In the case of juvenile gonadal cultured cells, a similar increase in 3H and 35S incorporation was registered for a 10(-7) M peptide concentration. Both lower and higher peptide concentrations inhibited 3H thymidine and 35S methionine incorporation. Pharmacological studies suggest the existence of methionine-enkephalin and somatostatin-like receptors on snail gonadal cells. These results indicate that our gonadal cell culture model provides a useful tool for the study of the neuroendocrinological control of the activity of snail gonadal cells.

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