Protein valorisation from acid whey – Screening of various micro- and ultrafiltration membranes concerning the filtration performance

Cross-flow filtration allows a product-preserving and energy-saving unit operation for the production of whey protein concentrates (WPC) from acid whey. In micro- and ultrafiltration applications, size-exclusion is the governing separation mechanism. Flux and retention characteristics of 12 organic membranes of pore sizes between 5 and 450 nm were compared. Screening on a laboratory filtration plant revealed large differences regarding hydraulic resistance of the membrane and resistance of the deposit layer that forms on the membrane surface during filtration. As a result, notable variations in the permeate flux were observed between membranes. In contrast, the differences in protein retention were less pronounced. The protein transmission for all ultrafiltration membranes was below 5% whereas microfiltration membranes showed a deposit layer-dependent transmission behaviour. Compared with the conventional WPC35 production, the overall filtration efficiency with regard to the process duration for a comparable membrane area was 3-fold enhanced by a more appropriate membrane selection.