The effects of processing and mastication on almond lipid bioaccessibility using novel methods of in vitro digestion modelling and micro-structural analysis

Abstract

A number of studies have demonstrated that consuming almonds increases satiety but does not result in weight gain, despite their high energy and lipid content. To understand the mechanism of almond digestion, in the present study, we investigated the bioaccessibility of lipids from masticated almonds during in vitro simulated human digestion, and determined the associated changes in cell-wall composition and cellular microstructure. The influence of processing on lipid release was assessed by using natural raw almonds (NA) and roasted almonds (RA). Masticated samples from four healthy adults (two females, two males) were exposed to a dynamic gastric model of digestion followed by simulated duodenal digestion. Between 7·8 and 11·1 % of the total lipid was released as a result of mastication, with no significant differences between the NA and RA samples. Significant digestion occurred during the in vitro gastric phase (16·4 and 15·9 %) and the in vitro duodenal phase (32·2 and 32·7 %) for the NA and RA samples, respectively. Roasting produced a smaller average particle size distribution post-mastication; however, this was not significant in terms of lipid release. Light microscopy showed major changes that occurred in the distribution of lipid in all cells after the roasting process. Further changes were observed in the surface cells of almond fragments and in fractured cells after exposure to the duodenal environment. Almond cell walls prevented lipid release from intact cells, providing a mechanism for incomplete nutrient absorption in the gut. The composition of almond cell walls was not affected by processing or simulated digestion.

Impact of the Breakdown Behavior on Chinese Traditional Stewed Pork with Brown Sauce: Physical Properties Using Microstructural Analysis

“…Thus, the mean particle sizes are 231 m (SEM 43) and 110 m (SEM 34) for the lean and fat samples at the swallowing point, respectively. These may be related to the structure and initial food moisture content [9].…”

“…This indicated subject mastication could not arouse significant particle disintegration for both samples. Small changes could be observed across the entire range of particle size distribution, possibly owing to internal structural changes or the local saliva content in the bolus [9].…”

“…Therefore, the bolus particle size and mechanical properties related to the degree of structure could significantly influence texture perception in the mouth. Furthermore, bolus microstructure is another factor in evaluating the degree of structure during mastication [9].…”

Dynamic Gastric Model (DGM)

“…The effect of mastication and processing on the lipid release from almond seeds in the upper GI tract has recently been investigated (Mandalari et al 2014a ). The bioaccessibility of pistachio polyphenols, xanthophylls and carotenoids during simulated human digestion was recently assessed using the DGM followed by duodenal incubation: results demonstrated that the presence of a food matrix, such as muffi n, decreased the bioaccessibility of certain polyphenols in the upper GI tract (Mandalari et al 2013 ).…”

A review of the impact of processing on nutrient bioaccessibility and digestion of almonds

“…mouth, stomach and intestine). Obtaining information about the changes occurring to the structure of the almond tissue as the digestion process progresses and the mechanisms of lipid release is of crucial importance (Ellis et al ., ; Mandalari et al ., ; Grundy et al ., ,b). For instance, the size and microstructure of the particles following oral processing have a significant effect on nutrient bioaccessibility (release), digestion kinetics and other physiological processes in the GI tract (Grundy et al ., ).…”