Membrane fractionation of a β-lactoglobulin tryptic digest: Effect of the pH

► Tryptic β-lactoglobulin hydrolysate was fractionated by means of a 5 kDa PES membrane. ► Influence of pH (from 4.0 to 10.0) in the fractionation process was investigated. ► Highest transmission values at pH close to peptide pI. ► pH 8.0: highest separation factor between bioactive and non-bioactive peptides. ► Peptide hydrophobicity increases transmission when peptides have zero net charge.