Protein/lipid ratio influence on microstructure and physicochemical properties of dulce de leche enriched with maltodextrin and inulin

This work explored the structural arrangement of inulin and maltodextrin within the protein-lipid matrix of functional and healthier dulce de leche (DL) compositions and their influence on the physicochemical properties. Two basic formulations of dulce de leche with low and high protein/lipid ratios were produced. They were added with inulin, maltodextrin, or their mixture in equal proportion. This study provides novel structural images of dulce de leche obtained through confocal laser scanning microscopy. Inulin alone or combined with maltodextrin formed residual inulin-crystal aggregates, occupying a considerable volume in high protein/lipid ratio DL formulations. In contrast, it appeared as dispersed particles and better integrated into the structure of low protein/lipid ratio DL formulations. The presence of inulin decreased the elastic (G’) and viscous (G”) moduli and the consistency index (k) of both regular and low-fat formulations. Still, its effect on the mechanical properties depended on the protein/lipid ratio. Fat reduction increased n’ (rate of change of G’ with frequency), and decreased values of k, all texture parameters, and all colour parameters.