EFFECT OF THE PROCESSING AND THE DIGESTIBILITY MODEL ON THE LIPID DIGESTIBILITY OF SOY PROTEIN-BASED EMULSIONS

There is a growing demand for the development of healthy and sustainable food products. In this context, plant proteins that combine these two characteristics have been studied to replace animal-based ingredients. However, there are still few studies on understanding how different plant protein-based systems behave under simulated gastrointestinal (GIT) conditions. In addition, studies on how the dynamic parameters of digestion (e.g., peristalsis, gradual pH adjustment) affect the digestive behavior of these systems are also scarce, as in vitro static assays are the most used methodology for digestibility studies. Thereby in this study, soy protein-based liquid and gelled emulsions were prepared using two different approaches: heating of the aqueous phase before homogenization (Process A); or heating the emulsion after homogenization (Process B). Next, in vitro digestion of the emulsions was performed using static (composed of a static gastric reactor and a static intestinal reactor) or semi-static (composed of a dynamic gastric reactor and a static intestinal reactor) assays, aiming to understand the effect of processing and the digestion model on the digestibility of soy protein-based systems. In vitro digestion parameters were based on the COST INFOGEST 2019 international protocol, and the amount of fatty acid released in the intestinal phase was estimated using the pH-stat methodology. For static digestion, all emulsions showed similar results of fat acid release (25-30 %). However, for the semi-static approach, gelled emulsions released a slightly higher amount (over 30 %), while liquid emulsions presented a decrease in the fatty acids release (to about 20 %). Thereby, the presence of forces on the dynamic reactor was able to increase the breakdown of the gel network, allowing greater release of fatty acids on the intestinal step. On the other hand, peristaltic forces did not affect the behavior of liquid emulsions. Instead, the fatty acid release was overestimated in the static approach, as enzyme concentration and pH (near optimum) are kept constant in this assay. Thus, the choice of digestion model is critical to assess the digestibility of soy protein-based emulsions. Besides that, as both liquid and gelled emulsions behaved similarly in static and semi-static approaches, it is concluded that the processing did not significantly affect the digestibility of these systems.