Protein-lipid interactions in food matrices and their roles in gastrointestinal lipid digestion

Dietary proteins and lipids coexist in foods in diverse structural forms, and their interactions influence lipid digestion and the subsequent intestinal absorption of lipolysis products, including free fatty acids and monoacylglycerols. This review examines the role of protein-lipid interactions (PLIs) in lipid digestion, with emphasis on bile salt displacement, lipolysis, mixed micelle formation, and the transport of lipid-soluble nutrients. PLIs occur mainly at interfaces within food matrices and are further modulated by matrix organisation, processing-induced structural changes, and physiological conditions during digestion, including changes in bile salt concentration, enzyme activity and pH. It further compares PLIs across dairy, meat, plant-derived, and protein-stabilised food systems, and discusses recent methodological advances for investigating their dynamic changes during digestion. A key challenge for future research is to determine how well-established in vitro relationships between interfacial structure and lipid digestion translate to physiologically relevant conditions and in vivo outcomes.