Defatting of sweet whey by electrodialysis with bipolar membranes: Effect of protein concentration factor

Abstract

Every year, sweet whey is generated in huge quantities and its valorization is often accompanied by a preliminary skimming step by centrifugation. However, some residual lipids may still be present after skimming process and cause technological issues. Electrodialysis with bipolar membrane (EDBM) can be used to remove these residual lipids as it simultaneously decreases pH and ionic strength allowing the formation of lipoprotein complexes than can further be recovered. The aim of this work was to treat whey protein concentrates (WPCs) with different protein concentration factor (2.27X, 3.34X, 3.56X and 3.80X) by EDBM and to evaluate the impact of the protein concentration factor on the process efficiency, particularly on the defatting rate (when a dilution was applied or not). It appeared that, whatever the protein concentration factor, a dilution was needed to reach higher defatting rates (ex.: 8.37 ± 1.72% without dilution vs 78.02 ± 0.66% with a 6X dilution for WPC 3.80X), as EDBM was not sufficient alone to lower ionic strength to promote lipoprotein complex formation. Furthermore, when a dilution was applied after EDBM treatment, a higher protein concentration factor slightly increased the defatting rate (ex.: 72.76 ± 0.71% for WPC 2.27X vs 78.02 ± 0.66% for WPC 3.80X) as a further lower ionic strength and a higher protein content favorized the lipoprotein complex formation. The increase in the defatting rate was however not proportional to the protein concentration factor. Furthermore, these conditions also allowed proteins to form protein complexes that precipitated along with the lipoprotein complexes. To our best knowledge, it was the first time that protein concentration factor of sweet whey was studied regarding the defatting rate after treatment by EDBM.