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The objective was to assess the potential bioavailability of phytoene (PT) and phytofluene (PTF) from tomato powders used as raw materials for supplements as compared to the pulp of a common tomato and a cherry tomato. PT and PTF are attracting much interest nowadays as they can provide health and cosmetic benefits. PT and PTF levels in the more concentrated powder were up to 1000 times higher than in the tomatoes. The bioaccessibility from the powders was lower as compared to the tomato fruits and increased markedly when sunflower oil was added. However, the best source of potentially absorbable PT and PTF (0.5 and 2 mg g-1 respectively) was by far the powder with higher levels of them. This result could be due to the higher carotenoid concentration in the powder, the reduction of the particle sizes, and the rupture of cell structures compared to the pulps.

The aim of this study was to find a lipase suitable as a surrogate for Human Gastric Lipase (HGL), since the development of predictive gastrointestinal lipolysis models are hampered by the lack of a lipase with similar digestive properties as HGL. Three potential surrogates for HGL; Rhizopus Oryzae Lipase (ROL), Rabbit Gastric Lipase (RGL) and recombinant HGL (rHGL), were used to catalyze the in vitro digestion of two infant formulas (a medium-chain triacylglyceride enriched formula (MC-IF) and a predominantly long-chain triacylglyceride formula (LC-IF)). Digesta were withdrawn after 0, 5, 15, 30, 60 min of gastric digestion and after 90 or 180 min of intestinal digestion with or without the presence of pancreatic enzymes, respectively. The digesta were analyzed by scanning electron microscopy and gas chromatography to quantify the release of fatty acids (FAs). Digestions of both formulas, catalyzed by ROL, showed that the extent of gastric digestion was higher than expected from previously published in vivo data. ROL was furthermore insensitive to FA chain length and all FAs were released at the same pace. RGL and rHGL favoured the release of MC-FAs in both formulas, but rHGL did also release some LC-FAs during digestion of MC-IF, whereas RGL only released MC-FAs. Digestion of a MC-IF by HGL in vivo showed that MC-FAs are preferentially released, but some LC-FAs are also released. Thus of the tested lipase rHGL replicated the digestive properties of HGL the best and is a suitable surrogate for HGL for use in in vitro gastrointestinal lipolysis models.

The understanding of the disintegration and gastric emptying of foods in the stomach is important for designing functional foods. In this study, a dynamic stomach model (human gastric simulator, HGS) was employed to investigate the disintegration and subsequent emptying of two differently structured whey protein emulsion gels (soft and hard gels).The gels were mechanically ground into fragments to reproduce the particle size distribution of an in vivo gel bolus. The simulated gel bolus was prepared by mixing gel fragments and artificial saliva, and exposed to 5 hours of simulated gastric digestion in the presence and absence of pepsin. Results showed that regardless of pepsin, the soft gel always disintegrated faster than the hard gel. The presence of pepsin significantly accelerated the disintegration of both gels. In particular, it enhanced abrasion of the soft gel into fine particles (<0.425 mm) after 180 min of processing. The emptying of the gels was influenced by the combined effects of the original particle size of the gel boluses and their disintegration kinetics in the HGS. In the presence or absence of pepsin, the larger particles of the soft gel emptied slower than the hard one during the first 120 min of process. However, in the presence of pepsin, the soft gel emptied faster than the hard one after 120 min because of a higher level of disintegration. These findings highlight the role of food structure, bolus properties and biochemical effects on the disintegration and gastric emptying patterns of gels during gastric digestion.

In this study, we examined the physicochemical nature of sunflower seed oil bodies (in the absence and presence of added protein) exposed to gastrointestinal conditions in vitro: crude oil bodies (COB); washed oil bodies (WOB); whey protein isolate-enriched oil bodies (WOB-WPI); and, sodium caseinate enriched-oil bodies (WOB-SC). All oil body emulsions were passed through an in vitro digestion model that mimicked the stomach and duodenal environments, and their physicochemical properties were measured before, during, and after digestion. Oil bodies had a positive charge under gastric conditions because the pH was below the isoelectric point of the adsorbed protein layer, but they had a negative charge under duodenal conditions which was attributed to changes in interfacial composition resulting from adsorption of bile salts. Oil bodies were highly susceptible to flocculation and coalescence in both gastric and duodenal conditions. SDS-PAGE analysis indicated degradation of oleosin proteins (ca. 18-21 kDa) to a greater or lesser extent (dependent on the emulsion) during the gastric phase in all emulsions tested; there is evidence that some oleosin remained intact in the crude oil body preparation during this phase of the digestion process. Measurements of protein displacement from the surface of COBs during direct exposure to bile salts, without inclusion of a gastric phase, indicated the removal of intact oleosin from native oil bodies.

Foods of plant origin contain flavonoids. In the adzuki bean, (+)-catechin, quercetin 3-O-rutinoside (rutin), and quercetin 7-O-β-D-glucopyranoside (Q7G) are the major flavonoids. During mastication of foods prepared from the adzuki bean, the flavonoids are mixed with saliva and swallowed into the stomach. Here we investigated the interactions between Q7G and (+)-catechin at pH 2, which may proceed in the stomach after the ingestion of foods prepared from the adzuki bean. Q7G reacted with nitrous acid producing nitric oxide (˙NO) and a glucoside of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone. (+)-Catechin reacted with nitrous acid producing ˙NO and 6,8-dinitrosocatechin. The production of the dinitrosocatechin was partly suppressed by Q7G, and the suppression resulted in the enhancement of Q7G oxidation. 6,8-Dinitrosocatechin reacted further with nitrous acid generating the o-quinone, and the quinone formation was effectively suppressed by Q7G. In the flavonoids investigated, the suppressive effect decreased in the order Q7G≈quercetin>kaempferol>quercetin 4'-O-glucoside>rutin. Essentially the same results were obtained when (-)-epicatechin was used instead of (+)-catechin. The results indicate that nitrous acid-induced formation of 6,8-dinitrosocatechins and the o-quinones can be suppressed by flavonols in the stomach, and that both a hydroxyl group at C3 and ortho-hydroxyl groups in the B-ring are required for efficient suppression.

Despite the considerable number of in vivo and in vitro studies on the digestive fate of lipophilic nutrients, micronutrients, and bioactives, the effects of the structure and composition of foods on the physicochemical mechanisms of luminal digestion are still poorly understood. Studying them is indeed complex because the number of parameters is high and many of them are interdependent. To solve this problem, an in silico simulation based on a multi-agent system was recently proposed to study the intestinal bioaccessibility of lipophilic nutrients and micronutrients from a single oil droplet. The roles of lipolysis and solubilization in bile salt were included. The effects of several food and digestion parameters were in line with those reported in the experimental literature. The goal of the research reported in this new article was to include more digestion parameters in the simulation in order to make it more realistic against complex cases. This was done in one specific digestion condition reflecting in vitro experiments, using droplets of tricaprylin or triolein containing vitamin A. The structure and principles of the original model were kept, with independent local modifications in order to study each factor separately. First, a gastric step was added where lipolysis took place, and only a marginal effect on the following intestinal step was found. Then, the chemical form of vitamin A, either non-hydrolyzed retinyl ester or retinyl ester instantly hydrolyzed into retinol, was investigated by considering different localizations in the droplet, resulting in a higher bioaccessibility for the retinol. The case of a mixture of tricaprylin and triolein indicated an influence of the oil phase viscosity. The consideration of mixed micelles compared to simple bile salt micelles was also investigated, and resulted in a higher vitamin A bioaccessibility, especially with triolein. Finally, a full model including the most influential parameters was tested to simulate the digestion of triglyceride-limonene mixtures, giving bioaccessibility trends in very good agreement with the literature.

In the digestive tract of humans, bioactive peptides, i.e. protein fragments impacting the physiological activity of the body, may be released during the digestion of food proteins, including those of fish. The aim of the study was to establish the method of human ex vivo digestion of carp muscle tissue and evaluate the angiotensin I-converting enzyme inhibitory and antioxidant activities of hydrolysates obtained after digestion. It was found that the hydrolysates of carp muscle tissue obtained with the three-stage method of simulated ex vivo digestion showed ACE inhibitory as well as antioxidative activities. It was demonstrated that the degree of hydrolysis depended on the duration of individual stages and the degree of comminution of the examined material. Although the applied gastric juices initiated the process of hydrolysis of carp muscle tissue, the duodenal juices caused a rapid increase in the amount of hydrolysed polypeptide bonds. The antihypertensive and antioxidative activities of the hydrolysates of carp muscle tissue increased together with progressive protein degradation. However, the high degree of protein hydrolysis does not favour an increase in the activity of free radical scavenging. The presented results are an example of the first preliminary screening of the potential health-promoting biological activity of carp muscle tissue in an ex vivo study.

This study investigated the fate of acrylamide in thermally processed foods after ingestion. An in vitro multistep enzymatic digestion system simulating gastric, duodenal and colon phases was used to understand the fate of acrylamide in bakery and fried potato products. Acrylamide levels gradually decreased through gastric, duodenal and colon phases during in vitro digestion of biscuits. At the end of digestion, acrylamide reduction was between 49.2% and 73.4% in biscuits. Binary model systems composed of acrylamide and amino acids were used to understand the mechanism of acrylamide reduction. High-resolution mass spectrometry analyses confirmed Michael addition of amino acids to acrylamide during digestion. In contrast to bakery products, acrylamide levels increased significantly during gastric digestion of fried potatoes. The Schiff base formed between reducing sugars and asparagine disappeared rapidly, whereas the acrylamide level increased during the gastric phase. This suggests that intermediates like the Schiff base that accumulate in potatoes during frying are potential precursors of acrylamide under gastric conditions.

An aqueous suspension of almond oil bodies (about 10% lipids) was prepared and subjected to in vitro gastric (with pepsin) and intestinal (with bile salts and pancreatin) digestion, simulating fasting conditions. The physicochemical and structural changes of the almond oil body emulsion were examined. The almond oil body emulsion behaved similarly to a protein-stabilized emulsion, with flocculation of the oil bodies occurring under gastric conditions. Proteins, peptides, and phospholipids covered the surface of the oil bodies throughout gastric digestion. Under intestinal conditions, bile salts displaced the interfacial peptides and phospholipids, and disrupted the flocs. Gastric pepsinolysis of almond proteins was a prerequisite for their digestion in the duodenum. The oil body membrane had a negative impact on the efficiency of gastric digestion, and long chain fatty acids, the main lipolytic products, accumulated at the surface of the oil bodies and therefore limited the activity of pancreatic lipase.

There is a growing interest in the optimization of dietary emulsions for monitoring postprandial lipid metabolism in the frame of preventing metabolic diseases. Using various emulsions, we investigated in a systematic scheme the combination of (i) in vitro gastrointestinal lipolysis and (ii) absorption and metabolism of lipolysis media in Caco-2 cells. Four emulsions based on either milk fat olein (OL) or rapeseed oil (RA) as the dispersed phase and either lecithin (LE) or sodium caseinate (CA) as the emulsifier were tested. After a sequential incubation of these emulsions with gastric and pancreatic enzymes, lipolysis media were incubated with Caco-2 cells, after dilution (1 : 20) to maintain the barrier integrity. Both gastric and duodenal lipolysis levels were similar to values reported in vivo and the rates of lipolysis were higher with LE-stabilized emulsions than with CA-stabilized emulsions (P < 0.05). TAG secretion by Caco-2 cells was found to be higher using (i) duodenal vs. gastric media (P < 0.001) and (ii) emulsions stabilized with CA vs. LE (P < 0.01). Consistently, gene expression of both FABP2 and FATP4 induced by the duodenal media was (i) higher than that with gastric media (P < 0.001) and (ii) faster than that with model mixed micelles. Using gastric media, TAG secretion of Caco-2 cells after 12 h was higher with RA than with OL (P < 0.001). Moreover, the RA-CA emulsion increased the size of secreted lipoprotein particles (514 nm vs. 61 to 130 nm; P < 0.01). In conclusion, it was possible to observe distinct responses in the lipid metabolism of Caco-2 cells incubated with lipolysis media obtained from different dietary emulsions digested by gastrointestinal lipases in vitro.