Enhancing rheology and reducing lipid digestion of oil-in-water emulsions using controlled aggregation and heteroaggregation of soybean protein isolate-peach gum microspheres

There is a growing interest in developing highly viscous lipid foods using plant protein and polysaccharide gum-based emulsion technology. However, gaps remain in understanding the rheological, microstructural, and digestive properties of plant proteins like soybean protein isolate (SPI) in combination with various gums. This study investigates how combining SPI and peach gum (PG) affects rheology and lipolysis of oil-in-water (O/W) emulsions containing 20 wt% soybean oil. Emulsions with varying SPI and PG compositions including SPI-PG single and SPI/PG mixed droplet systems were prepared. Heating induced alterations in viscosity (e.g., SPI-PG from 14.88 to 90.27 Pa·s and SPI/PG from 9.66 to 85.32 Pa·s) and microstructure revealing aggregate formation at oil-water interface. The viscosity decreased significantly from the oral to intestinal phase (SPI-PG: 28.10 to 0.19 Pa·s, SPI/PG: 21.27 to 0.10 Pa·s). These changes affected lipid digestion, notably in SPI-PG and SPI/PG emulsions where a compact interface hindered lipolysis during digestion. Interestingly, free fatty acid (FFA) release during small intestinal phase followed a different order: SPI (82.51 %) > SPI-PG (70.77 %) > SPI/PG (63.60 %) > PG (56.09 %). This study provides insights into creating highly viscous O/W spreads with improved rheology, stability, and delayed lipid digestion, offering potential benefits in food product formulation.