Enzymatic and chemical conversions taking place during in vitro gastric lipid digestion: The effect of emulsion droplet size behavior

Abstract

This investigation reports the effect of droplet size behavior on the overall lipolysis profile and molecular lipolysis mechanisms under in vitro gastric conditions. O/W emulsions (5% triolein, 1% sodium taurodeoxycholate) with different initial droplet sizes (fine: 0.58 μm; medium: 1.82 μm; and large: 4.00 μm) were subjected to static in vitro digestion. For the first time, multiple lipolysis products including diolein and monoolein regioisomers were quantified within a single HPLC run. An inverse relation was found between the droplet size and the initial rate and final extent of lipolysis based on the digested triolein. Furthermore, a mechanistic gastric lipolysis model was established based on a reaction scheme including enzymatic and chemical isomerization conversions. The estimated rate of the sn-1/3 hydrolysis was around two-to thirty-fold faster compared to the rates of sn-2 cleavage and isomerization, respectively. These findings resulted in a profound insight in in vitro gastric molecular lipolysis mechanisms.

Integral Stereoselectivity of Lipase Based on the Chromatographic Resolution of Enantiomeric/Regioisomeric Diacylglycerols

“…No previous works reported strict stereoselectivity (100% enantiomeric excess) of lipase with TO as a substrate; however, several reports have suggested the potential of lipases with such stereoselectivity derived from fungal and microalgal sources. − This ambiguity could be clarified by determining the integral stereoselectivity of lipases based on the methodology used in this study. Also, the analytical system of the present study shows more complete description of the whole reaction process compared with the previous work on the analysis of gastric lipid digestion, which quantified DO and MO regioisomers without separation of 1,2- sn -DO and 2,3- sn -DO . Furthermore, kinetic modeling by fitting the data collected from not only DAG enantiomeric excess calculations but also the time course of the DAG and MAG regioisomers could determine the reaction rate constants for each step of reaction, further quantifying the integral stereoselectivity of each lipase.…”

“…Also, the analytical system of the present study shows more complete description of the whole reaction process compared with the previous work on the analysis of gastric lipid digestion, which quantified DO and MO regioisomers without separation of 1,2-sn-DO and 2,3-sn-DO. 34 Furthermore, kinetic modeling by fitting the data collected from not only DAG enantiomeric excess calculations but also the time course of the DAG and MAG regioisomers could determine the reaction rate constants for each step of reaction, further quantifying the integral stereoselectivity of each lipase. This would provide further insights into the molecular mechanisms of stereochemistry of lipase in terms of chiral recognition based on the structural features, as well as the differences in selectivity between TAG and DAG, which are not well understood.…”

Utilizing Hydrothermal Processing to Align Structure and In Vitro Digestion Kinetics between Three Different Pulse Types

“…To quantitatively determine the microstructural changes and mode of tissue failure upon mechanical disintegration of the hydrothermally treated material, volumetric particle size distributions (PSD) of raw, WSM, and ICC samples were assessed using an LS 13 320 particle size analyzer (Beckman Coulter Inc., Brea, CA, USA) equipped with a Universal Liquid Module as described elsewhere [ 40 ] in triplicate. This approach was aimed to establish a link between the macrostructural (hardness) and microstructural characteristics of the sample.…”

Kinetic Modeling of In Vitro Small Intestinal Lipid Digestion as Affected by the Emulsion Interfacial Composition and Gastric Prelipolysis

“…These oil droplet properties are indicators for the emulsion stability evolution during in vitro digestion. 24 water and was adjusted to pH 3, or to pH 7 before analysis. We performed these measurements in duplicate per sample type.…”