Interfacial activities of milk total proteose-peptone: Contribution and miscibility of nonhydrophobic and hydrophobic fractions

Surface properties of a nonhydrophobic fraction of proteose-peptone (NHFPP) and a hydrophobic fraction of proteose-peptone (HFPP), obtained by hydrophobic interaction chromatography, were investigated. Adsorption of NHFPP and HFPP on the surface activity of total proteose-peptone (TPP) followed a competitive mechanism, especially during the penetration phase and molecular rearrangements. Compression of mixed monolayers was used to study the miscibility of NHFPP and HFPP within TPP films. When NHFPP was mixed with HFPP, in a TPP film, both fractions were immiscible at the beginning of adsorption; they only became miscible when the polypeptide chains had moved from the surface to the aqueous phase, thus allowing a better organisation of proteins. The equation of excess free energy of compression was used to determine the interactions of NHFPPHFPP within the TPP film through the mixed monolayer (thermodynamic properties); interactions between NHFPP and HFPP appeared less important than those that occurred between molecules within each fraction.