Digestive fate of emulsions formulated with pea and lupin protein ingredients : Modulation of lipid digestibility and bioaccessibility by the interfacial composition?

Pea and lupin protein ingredients are suitable sources to promote the transition towards more plant proteins in foods, as they display promising nutritional and emulsifying properties. Oil-in-water emulsions (10 wt% oil, 2.5 g proteins/L) were prepared with pea and lupin protein isolates and concentrates. The homogenization pressure was adapted to obtain droplets with an average diameter around 2.2 µm. The digestive fate of emulsions was examined using the INFOGEST in vitro static protocol to elucidate how the microstructure and interfacial composition influenced lipid digestibility and bioaccessibility. Lipolysis was evaluated through lipid class analysis via HPLC. During the oral phase, the microstructure of the emulsions prepared with protein isolates was altered, as the introduction of α-amylase led to the loss of the proteinaceous network bridging the droplets, without inducing coalescence. Comparable lipolysis extent was reached for all four emulsions at the end of the gastric phase (from 11 to 17 % mol/total mol), and after the intestinal phase (from 72 to 81 % mol/total mol). However, lipid bioaccessibility varied depending on the protein source, with approximately 85 wt% of bioaccessible lipids measured for pea protein-based emulsions, against 49 to 63 wt% for lupin ingredients-based ones. These results suggest a marked role of the components present in plant-based ingredients on the digestive fate of the emulsions. As food systems increasingly focus on plant-based innovations, understanding how the composition of these ingredients—particularly their often-overlooked endogenous components—affects their processing and nutritional properties can help the development of more sustainable and nutritious foods.