In vitro and in vivo modeling of lipid bioaccessibility and digestion from almond muffins: The importance of the cell-wall barrier mechanism

Terri Grassby,Giuseppina Mandalari,Myriam M.-L Grundy,Cathrina H Edwards,Carlo Bisignano,Domenico Trombetta,Antonella Smeriglio,Simona Chessa,Shuvra Ray,Jeremy Sanderson,Sarah E Berry,Peter R Ellis,Keith W Waldron

doi:10.1016/j.jff.2017.07.046

Abstract

This study compares in vitro and in vivo models of lipid digestion from almond particles within a complex food matrix (muffins) investigating whether the cell-wall barrier regulates the bioaccessibility of nutrients within this matrix. Muffins containing small (AF) or large (AP) particles of almond were digested in triplicate using an in vitro dynamic gastric model (DGM, 1h) followed by a static duodenal digestion (8h). AF muffins had 97.1±1.7% of their lipid digested, whereas AP muffins had 57.6±1.1% digested. In vivo digestion of these muffins by an ileostomy volunteer (0–10h) gave similar results with 96.5% and 56.5% lipid digested, respectively. The AF muffins produced a higher postprandial triacylglycerol iAUC response (by 61%) than the AP muffins. Microstructural analysis showed that some lipid remained encapsulated within the plant tissue throughout digestion. The cell-wall barrier mechanism is the main factor in regulating lipid bioaccessibility from almond particles.

Highlights

It is well established that intact cell walls play an important role in regulating the bioaccessibility of intracellular lipid and other nutrients in almond seeds (Ellis et al, 2004; Mandalari et al, 2008)
Accumulating evidence suggests that the limited bioaccessibility of lipids within intact almond tissue can be attributed to the structural integrity of almond cell walls, which protect encapsulated lipids from digestion during passage through the GI tract
We recently demonstrated that a decrease in almond particle size resulted in an increased rate and extent of lipolysis in an in vitro model of duodenal digestion (Grundy, Wilde, Butterworth, Gray, & Ellis, 2015)

Summary

Introduction

It is well established that intact cell walls play an important role in regulating the bioaccessibility of intracellular lipid and other nutrients in almond seeds (Ellis et al, 2004; Mandalari et al, 2008). Accumulating evidence suggests that the limited bioaccessibility of lipids within intact almond tissue can be attributed to the structural integrity of almond cell walls, which protect encapsulated lipids from digestion during passage through the GI tract. The lipid release from masticated almonds was in close agreement with that predicted by a theoretical model for almond lipid bioaccessibility, which had particle size and cell diameter as variables

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Conclusion