Physical and molecular properties of egg-white lipid films

Polyethylene glycol-plasticized films were cast from alkaline (pH 11.25), heated (45 degrees C for 20 min), aqueous egg white (EW) solutions, with or without (10% or 20% w/w of EW) milkfat (two fractions), oleic acid, or egg yolk lysophospholipid (LPL). The lipids did not reduce (P > 0.05) film water vapor permeability. Oleic acid increased (P < 0.05) tensile strength and elongation, and surface sulfhydryl group (SH) concentrations In EW solutions. Oleic acid probably increased negative charges on EW proteins, unfolding protein chains, and exposing SH groups. LPL also slightly increased (P < 0.05) surface SH concentrations in non-heated mixtures. Electrophoretic patterns suggested oleic acid interactions with ovalbumin, ovotransferrin, and lysozyme. No lysinoalanine was in film-forming mixtures based on lysine measurements.