In Vitro Digestion of Chia Seed Oil Nanoemulsions

Oil-in-water (O/W) nanoemulsions offer significant potential for protecting and delivering sensitive ingredients such as chia seed oil, which is rich in ω-3 fatty acids (approximately 64% α-linolenic acid, ALA). This research work aimed to study the in vitro fat digestibility of chia O/W nanoemulsions (Cas1000) with 10% (w/w) of chia oil and 2% (w/w) of sodium caseinate prepared by microfluidization (1000 bar, 3 passes) and characterized through their droplet size, superficial droplet charge, and global stability. In terms of the in vitro fat digestibility, three different matrices were studied: a water solution of sodium caseinate, a chia O/W nanoemulsion, and a bulk chia oil. The particle size distribution, mean diameter, and microstructure were evaluated after in vitro stomach and small intestine simulation according to the INFOGEST method. Free fatty acids (% FFA) produced during lipolysis were quantified at the end of digestion through their neutralization by acid-base volumetric assay. The droplet size of the Cas1000 had slight changes during the gastric phase while a significant variation of this parameter was observed at the end of the intestinal phase. A higher %FFA was obtained in Cas1000 compared to bulk chia oil with values of 58.26 and 38.13%, respectively. The ALA content in the lipid phase was quantified at the end of the gastrointestinal digestion process. The results indicated no significant changes compared to the initial oil, suggesting no losses of active compounds during digestion.