Functional and biological activities of casein glycomacropeptide as influenced by lipophilization with medium and long chain fatty acid

This study determined the functional and different biological activities of casein glycomacropeptide (GMP) after conjugation with fatty acids. Medium (i.e. caproic, lauric and myristic acid) and long (i.e palmitic and stearic acid) fatty acids were conjugated to GMP at the available amino group. Functionalities of lipophilized GMP conjugates included foaming and emulsifying activities, and biological activities for bacterial growth inhibition, cell damage and anti-invasion. Greater lipophilization of GMP was achieved with medium chain fatty acids (p < 0.05), which resulted in reduced GMP solubility regardless of fatty acid conjugate. Foaming activity of GMP was lost after lipophilization, but emulsification activity of GMP was enhanced (p < 0.05). A parallel increase in growth inhibition of Salmonella spp. coupled with anti-invasion of Salmonella enteritidis (Inv A) into mammalian cells was induced by lipophilization of GMP with long chain fatty acid. Our results show that GMP modified by lipophilization with specific fatty acids provides improved functionality as a surfactant with enhanced antibacterial activity towards gram negative bacteria.