Enhanced rheology and lipid absorption modulation in oil-in-water emulsions by aggregation of pea protein isolate and peach gum microspheres

Abstract

The encapsulation of plant-based materials, particularly in emulsion systems, is gaining attention for enhancing the texture, digestibility, and health benefits of food products. However, the impact of interactions between plant proteins, such as pea protein isolate (PPI), and polysaccharides, like peach gum (PG), on the rheological properties, digestion, and absorption behaviors of emulsions is leaving a gap for further investigation. This study investigates the formulation of four 20 wt% oil-in-water (O/W) emulsions: PPI emulsion (4 wt% PPI), PG emulsion (4 wt% PG), PPI-PG emulsion (2 wt% each in aqueous phase), and a 1:1 mixture of individually prepared PPI and PG emulsions (PPI/PG). The emulsions underwent thermal processing to induce particle aggregation and heteroaggregation, followed by in vitro digestion and ex vivo absorption using a rat small intestine model. The mixed emulsions exhibited significantly higher viscosities and moduli than single emulsions, along with larger and denser microstructures. Consequently, free fatty acids (FFAs) released at the end of digestion were lowest for PPI-PG (33.7 %), followed by PPI (44.92 %), PG (39.93 %), and PPI/PG (36.32 %). Correspondingly, ex vivo FFA absorption was slower for PPI-PG (9.83 %) and PPI/PG (10.81 %) than for PG (14.95 %) and PPI (16.33 %), reflecting reduced enzyme accessibility due to stronger interfacial structures. These findings highlight the potential of PPI-PG and PPI/PG emulsions in creating reduced-fat O/W products, such as mayonnaise and sauces, with higher viscosity but controlled lipid digestion.