Coagulated skim milk was ultrafiltered in ceramic tubular membrane with cut off 0.08mum with the objective of evaluating the influence of different milk heat treatments on permeate flux, on protein retention coefficient, on calcium retention coefficient and on protein yield during the petit suisse cheese process. Heat treatment of milk was 85°C/30min and 72°C/15sec. No differences in the retention of protein and calcium, nor in the protein yield due to heat treatment of milk, were observed. A significant increase in permeate flux was observed when the milk was heated to 72°C/15sec. The most intense heat treatment could result in a higher attraction between the casein micelles and between the micelles and the membrane surface, increasing the protein adsorption on the membrane surface and, consequently, reducing the permeate flux. Denaturated alpha-lactoalbumin and beta-lactoglobulin may have plugged the membrane pores, which would also help to increase fouling.
ultrafiltration; heat treatment; petit suisse cheese; permeate flux
