Soy Proteins Enhance the Bioaccessibility of Oleic Acid: The Role of the Interactions with Bile Salts under In Vitro Digestion

Abstract

This study investigates the potential of soy protein isolate (SPI) to enhance the bioaccessibility of oleic acid (OA), a beneficial fatty acid linked to reduced blood pressure and cardiovascular risk. Using an in vitro digestion model, we examined how the interactions between SPI-derived peptides and bile salts (BS) evolve during gastric and gastroduodenal digestion and how these interactions influence OA micellar solubility. SPI with a soluble fraction (SF) of 16% was digested for 10 and 60 min (tg10 and tg60), and the resulting digesta were evaluated for their ability to enhance OA solubilization in BS micelles. SF increased to 52.3% (tg10) and 64.7% (tg60) and reached 95.8% in the presence of BS under duodenal conditions. Consequently, OA solubilization improved by up to 82% compared to that of BS alone, highlighting the role of soy peptides in promoting lipid bioaccessibility through BS-peptide interactions during digestion.