In vitro digestion simulation of medium chain fatty acids

Abstract

Gastric digestion involves physical and chemical processes, which affect food breakdown and nutrient absorption. In vitro digestion studies have been widely used to elucidate the mechanisms of food hydrolyses during digestion. They can be used to evaluate metabolic properties of macronutrients such as lipids. The gastric digestion phase is particularly crucial for digestion of medium-chain fatty acids (MCFA), fatty acids molecules comprised by 8 to 10 carbons, because the stomach also mediates the direct absorption of these components through the gastric mucosa. In this work, the static in vitro digestion protocol [Brodkorb et al., Nature Protocols, 14, (2019) p. 9911014] has been applied to investigate the gastric digestion of medium-chain triglyceride (MCT) oil samples. The total release of free fatty acids (FFA) was measured using a pH-stat device and gas chromatography (GC) was used to obtain FFA profiles. It was observed that 47.93 % of samples FFAs were released during the gastric digestion phase, which is not in accordance with the literature, which establishes 20 % of lipolysis in the gastric digestion. However, it is important to notice that medium-chain fatty acids (MCFA) are preferably metabolized by gastric lipase in the stomach digestion phase. In accordance with the MCT oil composition, GC analyses showed that 97.69 % of FFAs released at the gastric phase are MCFAs, namely, caprylic (50.01 %), capric (32.28 %), and lauric acids (15.39 %). It was noticed that the simulation of the digestion gastric phase it was crucial for determining accurate lipolysis rates in the overall lipid digestion process, particularly when oil samples rich in MCFA were submitted to digestion protocols.