Enhancement of ultrafiltration-performance and improvement of hygienic quality during the production of whey concentrates

Ultrafiltration (UF) is used for the concentration of whey proteins from whey. Membrane fouling during processing results in a decrease in flux, while the predominant molecular fouling reaction and fouling species are still largely unknown. Heat-induced whey protein aggregates are inevitably generated in industrial cheese-making processes, and were found to accelerate membrane fouling during whey concentration. By means of upstream microfiltration prior to UF, these aggregates can be selectively removed. By this means, UF flux could be increased up to twofold for the UF of sweet whey and threefold for acid whey. For filtration of sweet whey, significant calcium retention was observed. Therefore, membrane fouling for both whey types seem follow different molecular mechanisms. Besides the removal of whey protein aggregates, the retention of microorganisms and a log-reduction of up to log 3.5 was achieved by pre-filtration. Shelf-life of whey could be increased to two weeks without pasteurisation.