Low temperature microfiltration of skim milk: Impact of membrane type, configuration and concentration factor on serum protein permeation efficiency

Protein transmission, permeate flux and energy consumption during MF of skim milk was evaluated at 7 °C using two discrete 800 kDa polymeric MF membranes. Filtration trials determined optimum process parameters (i.e., transmembrane pressure and volume concentration factor) and membrane configuration (in-series or in-parallel) to maximise serum protein permeation. This study demonstrated that a combination of higher VCF (3) and lower TMP (75 kPa), with an in-parallel membrane configuration resulted in the most efficient rate of permeation of serum protein per kg of permeate produced. However, from an energy perspective, an in-parallel configuration with a TMP of 75 kPa and a lower VCF2 was the most efficient process, consuming between 1.28 and 1.57 kW h kg⁻¹ of crude protein permeated. Additionally, the permeation of serum β-casein at low temperature was governed by the uniformity of the pore size distribution in discrete MF membranes with the same nominal molecular mass cut-off.