Advances in starch-based binary and ternary complexes with lipids and proteins: mechanisms, digestibility, and applications in low-glycemic foods

Abstract

Starch-rich foods significantly contribute to elevated postprandial blood glucose levels, primarily due to the rapid enzymatic digestion of starch, although the magnitude of this response is also influenced by the starch's botanical origin, processing history, food-matrix structure, and the presence of lipids and proteins. Recent studies highlight that the formation of starch–lipid and starch–protein complexes can effectively retard starch digestion by reducing rapidly digestible starch (RDS) and/or increasing slowly digestible starch (SDS) and resistant starch (RS) fractions. Such structural modifications are closely associated with reduced starch hydrolysis and a lowered predicted or estimated glycemic index, which vary with starch source, complexing agent and processing conditions. While both binary systems have been extensively studied, a systematic comparison of their structural properties, inhibitory mechanisms, and digestibility-related functional outcomes is still lacking. This review comprehensively examines the interactions, multi-scale structural characteristics, physicochemical properties, and digestion resistance of starch–lipid, starch–protein, and starch–lipid–protein ternary complexes. We critically compare the distinct mechanisms by which lipids and proteins reduce enzymatic susceptibility and modulate digestion-related outcomes. Particular emphasis is placed on how molecular inclusion or association, supramolecular ordering, crystalline organization, and microscopic matrix architecture jointly regulate enzyme accessibility, hydrolysis kinetics, and the resulting structure–digestibility relationship. Furthermore, we discuss the potential applications of these complexes in the development of low-glycemic-index functional foods, providing a scientific basis for the design of starch-based foods with tailored digestibility. Nevertheless, this review also recognizes important limitations, including inconsistencies among in vitro digestion protocols, differences in starch and non-starch component sources, and the relatively limited availability of in vivo evidence directly connecting complex-induced structural changes with postprandial glycemic responses.