Interactions between cellulose ethers and a bile salt in the control of lipid digestion of lipid-based systems

In order to gain new insights into the potential of specific dietary fibres to control lipid digestion, the goal of this work is to study the main interactions between commercial cellulose ethers, as dietary fibre, and a bile salt, as an important duodenal component present during the digestibility of lipids. These interactions have been evaluated in two different scenarios found for an oil-in-water emulsion on its transit through the duodenum. Namely, interactions in the continuous phase and competitive adsorption at the oil–water interface have been looked at by means of micro-differential scanning calorimetry (micro-DSC) and interfacial tension (IT). Micro-DSC revealed that the presence of the bile salt affects the thermogelation process of cellulose derivatives, suggesting binding to cellulose ethers. The effect on thermogelation seems to be cellulose type-dependent. IT measurements proved the ability of cellulose ethers to compete for the oil–water interface in the presence of the bile salt. Interactions in the bulk might have an impact on this interfacial scenario. These findings may have implications in the digestion of emulsified lipids, hence providing a springboard to develop new cellulose-based food products with improved functional properties

Instant polysaccharide-based emulsions: impact of microstructure on lipolysis

The development of emulsion-based products through optimisation of ingredients, reduction in energy-input during manufacture, while fulfilling healthy attributes, are major objectives within the food industry. Instant emulsions can meet these features, but comprehensive studies are necessary to investigate the effect of the initial formulation on the final microstructure and, in turn, on the in vitro lipolysis, comprising the double aim of this work. The instant emulsion is formed within 1.5–3 min after pouring the aqueous phase into the oil phase which contains a mixture of emulsifier (Tween 20), swelling particles (Sephadex) and thickeners (hydroxypropylmethylcellulose, HPMC, and guar gum, GG) under mild shearing (180 rpm). The creation of oil-in-water emulsions is monitored in situ by viscosity analysis, the final microstructure visualised by microscopy and the release of free fatty acids under simulated intestinal conditions quantified by titration. Increasing the concentration and molecular weight (Mw) of GG leads to smaller emulsion droplets due to increased bulk viscosity upon shearing. This droplet size reduction is magnified when increasing the Mw of HPMC or swelling capacity of viscosifying particles. In addition, in the absence of the emulsifier Tween 20, the sole use of high-Mw HPMC is effective in emulsification due to combined increased bulk viscosity and interfacial activity. Hence, optimisation of the ingredient choice and usage level is possible when designing microstructures. Finally, emulsions with larger droplet size (>20 μm) display a slower rate and lower extent of lipolysis, while finer emulsions (droplet size ≤20 μm) exhibit maximum rate and extent profiles. This correlates with the extent of emulsion destabilisation observed under intestinal conditions

Simulating human digestion: developing our knowledge to create healthier and more sustainable foods

The gold standard for nutrition studies is clinical trials but they are expensive and variable, and do not always provide the mechanistic information required, hence the increased use of in vitro and increasingly in silico simulations of digestion. In this review, we give examples of the main simulations being used to model upper gastrointestinal tract digestion. This review ranges from the selection of enzymes to the interpretation of results from static models to fully dynamic models. We describe the modifications made to accommodate different demographic groups (infants, the elderly, etc.). We list examples of the application of the different models as well as giving the advantages and disadvantages. A model is only useful if it predicts or aids the understanding of physiological behaviour. Thus, the final section of the review makes a comparison of results obtained from experiments undertaken using in vitro simulations with those obtained in vivo. This comparison will help the reader understand the appropriateness of each model for the type of measurement to be undertaken. In particular, human studies tend to measure bioactive concentrations in blood and not in the gastrointestinal tract whereas in vitro studies often only produce data on release of nutrients into the gut lumen. This is the difficulty of comparing bioaccessibility as generated in vitro with bioavailability as generated in vivo. It is apparent that the models being used are increasingly being validated with in vivo data and this bodes well for the future

Bile salts in digestion and transport of lipids

Because of their unusual chemical structure, bile salts (BS) play a fundamental role in intestinal lipid digestion and transport. BS have a planar arrangement of hydrophobic and hydrophilic moieties, which enables the BS molecules to form peculiar self-assembled structures in aqueous solutions. This molecular arrangement also has an influence on specific interactions of BS with lipid molecules and other compounds of ingested food and digestive media. Those comprise the complex scenario in which lipolysis occurs. In this review, we discuss the BS synthesis, composition, bulk interactions and mode of action during lipid digestion and transport. We look specifically into surfactant-related functions of BS that affect lipolysis, such as interactions with dietary fibre and emulsifiers, the interfacial activity in facilitating lipase and colipase anchoring to the lipid substrate interface, and finally the role of BS in the intestinal transport of lipids. Unravelling the roles of BS in the processing of lipids in the gastrointestinal tract requires a detailed analysis of their interactions with different compounds. We provide an update on the most recent findings concerning two areas of BS involvement: lipolysis and intestinal transport. We first explore the interactions of BS with various dietary fibres and food emulsifiers in bulk and at interfaces, as these appear to be key aspects for understanding interactions with digestive media. Next, we explore the interactions of BS with components of the intestinal digestion environment, and the role of BS in displacing material from the oil-water interface and facilitating adsorption of lipase. We look into the process of desorption, solubilisation of lipolysis, products and formation of mixed micelles. Finally, the BS-driven interactions of colloidal particles with the small intestinal mucus layer are considered, providing new findings for the overall assessment of the role of BS in lipid digestion and intestinal transport. This review offers a unique compilation of well-established and most recent studies dealing with the interactions of BS with food emulsifiers, nanoparticles and dietary fibre, as well as with the luminal compounds of the gut, such as lipase-colipase, triglycerides and intestinal mucus. The combined analysis of these complex interactions may provide crucial information on the pattern and extent of lipid digestion. Such knowledge is important for controlling the uptake of dietary lipids or lipophilic pharmaceuticals in the gastrointestinal tract through the engineering of novel food structures or colloidal drug-delivery systems

In vitro digestibility of O/W emulsions co-ingested with complex meals: Influence of the food matrix

Oil-in-water (O/W) emulsions are promising delivery systems of lipophilic bioactive compounds into meals composed mainly of water. The colloidal stability of β-carotene-loaded O/W emulsion incorporated into whole milk, oatmeal and whole milk-oatmeal meals. Their subsequent gastric emptying rate, lipid digestibility and β-carotene retention during in vitro gastrointestinal digestion were evaluated using a semi-dynamic gastric model followed by a static small intestinal model. The dispersed particles within the meals, lipid droplets, casein micelles as well as protein and β-glucan aggregates, were responsible for the bigger average particle sizes of both O/W-oatmeal and O/W-whole milk-oatmeal (13.07 ± 1.81 and 7.60 ± 1.21 μm, respectively) compared to the O/W emulsions and O/W-whole milk (0.56 ± 0.03 and 0.44 ± 0.04 μm, respectively). Semi-dynamic in vitro gastric digestion of O/W-whole milk showed lipid droplets embedded into an insoluble protein network emptied earlier than the O/W emulsion. Conversely, O/W-oatmeal and O/W-whole milk-oatmeal had delayed lipid emptying, probably because of the gelation of the β-glucan from oats. During the in vitro small intestinal digestion, the rate of the FFA release was linked to the gastric emptying rate. Indeed, both O/W emulsion and O/W-whole milk presented an exponential increase in the FFA release, whereas the O/W-oatmeal and O/W-whole milk-oatmeal followed a stepwise trend. The β-carotene retention during in vitro gastrointestinal digestion depended on the lipid amount at each digestion time moment. Hence, this work provides valuable insight into the behaviour of O/W emulsions incorporated into meals and during their subsequent in vitro gastrointestinal digestion

Chloroplast-rich material from the physical fractionation of pea vine ( Pisum sativum ) postharvest field residue (Haulm)

An innovative procedure for plant chloroplasts isolation has been proposed, which consists of juice extraction by physical fractionation from plant material and recovery of its chloroplast-rich fraction (CRF) by centrifugation. This simple method has been applied to pea vine haulm subjected to different post-harvest treatments: blanching, storage at different relative humidity values and fermentation. Additionally, freeze storage of the extracted juice was carried out. The macronutrient (total lipids, proteins, ash and carbohydrates) and micronutrient (fatty acids, chlorophylls, β-carotene, α-tocopherol and ascorbic acid) content and composition of the CRF have been determined. The CRF isolated from fresh pea vine haulm is a potential source of essential micronutrients (α-linolenic acid, β-carotene, α-tocopherol) and carbohydrates, whereas the post-harvest treatments trialled have a detrimental effect on the nutritional content. Industrial applications for the recovered nutritionally rich fraction, such as food supplement ingredient or animal feeding, are likely envisaged, while optimising the use of green haulm

Impact of caseins and whey proteins ratio and lipid content on in vitro digestion and ex vivo absorption

Caseins and whey proteins are known as ‘slow’ and ‘fast’ proteins, respectively, based on their amino acid absorption rate. However, there is limited understanding of the mechanisms controlling their behaviour during gastro-intestinal transit. A protein model system (8% total protein) with varying casein:whey protein ratios (0:100, 20:80, 50:50 and 80:20) were subjected to in vitro gastro-intestinal digestion using a semi-dynamic gastric model, a static intestinal model and an ex vivo absorption model (Ussing chambers). The casein-rich (≥ 50%) samples showed the formation of solid coagula that were persistent throughout gastric digestion, which caused a delay in nutrient emptying, slower digestion and leucine absorption kinetics. In contrast, whey proteins formed more soluble aggregates during the gastric phase, which led to faster gastric emptying, rapid intestinal hydrolysis, and higher and faster leucine absorption. This work shows the key role of the gastric restructuring for the overall digestive mechanism and kinetics of food, in particular proteins

Identification of the thistle milk component Silibinin(A) and Glutathione-disulphide as potential inhibitors of the pancreatic lipase: Potential implications on weight loss

This work has been supported by Ministerio de Ciencia e Innovacion de Espana (under project RTI2018101309BC21) , by the Fundacion Seneca del Centro de Coordinacion de la Investigacion de la Region de Murcia (under Project 20988/PI/18) and by a grant from Ministerio de Economia y Competitividad de Espana (CTQ201787974R) . This research was partially supported by the supercomputing infrastructure of Poznan Supercomputing Centre, and by the einfrastructure program of the Research Council of Norway, and the supercomputer centre of UiTthe Arctic University of Norway. The authors also thankfully acknowledge the computer resources and the technical support provided by the Plataforma Andaluza de Bioinformatica of the University of Malaga. Powered@NLHPC: This research was partially supported by the supercomputing infrastructure of the NLHPC (ECM02)Peripheral targets like pancreatic-lipase appear to be the most suitable pharmacological alternative for obesity, as with orlistat, although its adverse effects limit its use. Therefore, the aim of this work was to identify new natural compounds able to inhibit pancreatic-lipase in an in vitro model. The DrugBank database was used to perform docking calculations. The best fitting-score compounds were further evaluated in vitro. Our data revealed that glutathione-disulphide (GSSG) and silibinin(A) inhibit pancreatic-lipase. This was confirmed by measuring hydrolysis in an emulsion model, obtaining that the suppression of lipid digestion by silibinin(A) was higher than that of GSSG and close to the effect of orlistat. Combined analysis established the existence of different inhibition mechanisms for each compound. In summary, silibinin(A) and GSSG inhibited pancreatic-lipase and, therefore, may be served as promise natural compounds to face with obesity. Further studies comprise the next step to fully validate the suitability of these compounds.Spanish Government RTI2018-101309-B-C21Fundacion Seneca 20988/PI/18Ministerio de Economia y Competitividad de Espana CTQ2017-87974-RSupercomputing infrastructure of Poznan Supercomputing CentreEinfrastructure program of the Research Council of NorwaySupercomputer centre of UiTthe Arctic University of NorwaySupercomputer centre of UiTthe Arctic University of Norwa

Human gastrointestinal conditions affect in vitro digestibility of peanut and bread proteins

As plant proteins are increasingly used as a source of amino acids in the diet, studies on in vitro digestion of plant proteins are key to understand the different factors affecting proteolysis, with the ultimate goal of optimising the nutritional composition/intake of plant protein-rich products. More realistic scenarios including the most likely food matrix and physiologically relevant gastrointestinal (GI) conditions should be considered when assessing the in vitro digestion of proteins. The research described here compares the extent of hydrolysis of proteins from peanuts and wheat bread, in particular the vicilin-like 7S globulin (Ara h 1) and gliadin, respectively, with three GI scenarios simulating either infant, early phase adult (fed state) or late phase adult (fasted state) conditions. The digestibility of these proteins, in isolation or when naturally present in the respective food matrix, has been evaluated with SDS-PAGE, LC-MS/MS and a spectrophotometric assay. Results from the food matrices showed lower extent of total protein GI digestion under simulated infant conditions, intermediate behaviour under fed state adult conditions and larger extent under fasted state adult conditions. This was also the case for isolated gliadin. However, isolated Ara h 1 only showed lower extent of proteolysis in the gastric phase under infant conditions, reaching a similar extent to both adult conditions over the course of the intestinal phase. The food matrix seems to have delayed the proteolysis. Choosing an appropriate GI scenario as well as the matrix of the end food product is paramount when assessing in vitro protein digestion