Effect of different membrane separation technologies (ultrafiltration and microfiltration) on the texture and microstructure of semihard low-fat cheeses

Semihard low-fat cheeses made from ultrafiltered (UF) or microfiltered (MF) milk were compared. The use of MF membranes and milder pasteurization of t he milk reduced the retention of whey proteins in the retentate to 35%, com pared with similar to 100% retained in the UF process. Microbiological deve lopment, physicochemical composition, and cheese ripening were not altered by the concentration processes. The lower retention of whey protein in MF c heeses accounted for their higher hardness, which correlated with higher fi rmness values in the textural analysis. Microstructure showed a protein mat rix with open spaces through the protein network, although micrographs of U F cheeses showed the presence of spongy structures linked to the casein, wh ich did not appear in MF cheeses and which correspond to the denatured whey protein bound to the casein. Firmness was scored better in MF cheeses, alt hough when MF membranes were used, the optimum yields achieved using UF mem branes were not attained.