Fatty acid bioaccessibility and structural breakdown from in vitro digestion of almond particles.

Previous studies have shown that the size of almond particles influences lipid bioaccessibility during digestion. However, the extent of structural breakdown of almond particles during gastric digestion and its impact on lipid bioaccessibility is unclear. In this study, in vitro digestion of almond particles was conducted using a dynamic model (Human Gastric Simulator) and a static model (shaking water bath). Structural breakdown of particles during the gastric phase occurred only in the Human Gastric Simulator, as evidenced by a reduction in particle size (15.89 ± 0.68 mm2 to 12.19 ± 1.29 mm2, p < 0.05). Fatty acid bioaccessibility at the end of the gastric phase was greater in the Human Gastric Simulator than in the shaking water bath (6.55 ± 0.85% vs. 4.54 ± 0.36%, p < 0.01). Results showed that the in vitro model of digestion which included peristaltic contractions (Human Gastric Simulator) led to breakdown of almond particles during gastric digestion which increased fatty acid bioaccessibility

Developing site-specific guidelines for orchard soils based on bioaccessibility – Can it be done?

Horticultural land within the periurban fringe of NZ towns and cities increasingly is being developed for residential subdivision. Recent surveys have shown that concentrations of As, Cd, Cu, Pb, and ΣDDT (sum of DDT and its degradation products DDE and DDD) in such soils can exceed criteria protective of human health.¹ Soil ingestion is a key exposure pathway for non-volatile contaminants in soil. Currently in NZ, site-specific risk assessments and the derivation of soil guidelines protective of human health assume that all of the contaminant present in the soil is available for uptake and absorption by the human gastrointestinal tract. This assumption can overestimate health risks and has implications for the remediation of contaminated sites.² In comparison, the bioavailability of contaminants is considered when estimating exposure via dermal absorption and by ingestion of home-grown produce.³ Dermal absorption factors and plant uptake factors are included in the calculations for estimating exposures via these routes

Improving the in vitro bioaccessibility of β-carotene using pectin added nanoemulsions

The intestinal absorption of lipophilic compounds such as β-carotene has been reported to increase when they are incorporated in emulsion-based delivery systems. Moreover, the reduction of emulsions particle size and the addition of biopolymers in the systems seems to play an important role in the emulsion properties but also in their behavior under gastrointestinal conditions and the absorption of the encapsulated compound in the intestine. Hence, the present study aimed to evaluate the effect of pectin addition (0%, 1%, and 2%) on the physicochemical stability of oil-in-water nanoemulsions containing β-carotene during 35 days at 4 °C, the oil digestibility and the compound bioaccessibility. The results showed that nanoemulsions presented greater stability and lower β-carotene degradation over time in comparison with coarse emulsion, which was further reduced with the addition of pectin. Moreover, nanoemulsions presented a faster digestibility irrespective of the pectin concentration used and a higher β-carotene bioaccessibility as the pectin concentration increased, being the maximum of ≈36% in nanoemulsion with 2% of pectin. These results highlight the potential of adding pectin to β-carotene nanoemulsions to enhance their functionality by efficiently preventing the compound degradation and increasing the in vitro bioaccessibility.This work was funded by the project AGL2015-65975-R (FEDER, MINECO, UE) and project RTI2018-094268-B-C21 (MCIU, AEI; FEDER, UE)

The solid phase distribution and bioaccessibility of potentially harmful elements in natural ironstone soils in the UK

Chemical reactions and physical and biological processes influence the mobility of potentially harmful elements (PHEs) present within soils. In the UK, soil PHE such as arsenic (As), chromium (Cr) and nickel (Ni) occur at elevated concentrations in soils derived from ironstone parent materials. Exposure to soil PHE via oral ingestion, inhalation or dermal uptake poses a potential risk to human health. However, PHE mobility in soils is governed by its solid phase distribution within the soil matrix and therefore the presence of PHE may not indicate a risk to human health. This study examines the geochemical forms of As, Cr Ni, found in ironstone derived topsoils from north Oxfordshire in the UK, where total concentrations were in the range 14.0 – 417 mg kg-1 As, 51.0 – 447 mg kg-1 Cr and 17.0 – 218 mg kg-1 Ni. Solid phase distribution information was determined by the application of a non-specfic sequential extraction methodology combined with self modelling mixture resolution of the concentrations of elements in the extract solutions, determined by ICP-AES. Seven distinct physico-chemical components, including iron (Fe), manganese (Mn) and aluminium (Al) oxides, calcium (Ca) carbonates, organic and fertilizer sources were identified in the Oxfordshire soils, all of which were identified as being hosts to one or more of the PHE of interest. Estimates of PHE intake via the oral ingestion route were determined using an in vitro physiologically based gastro-intestinal simulation bioacessibility test. Bioaccessible PHE concentrations ranged from 1.60 – 12.8 mg kg-1 As, 0.55 – 2.02 mg kg-1 Cr and 1.18 – 4.52 mg kg-1 Ni. The combination of bioaccessobility data with mobility/solid phase distribution information provided by the sequentional extraction methodology indicates that: Fe oxides are the predominant host of immobile As and Cr; mobile As is associated with carbonates and organic phases; relatively mobile Cr with Mn/Al oxides; mobile/relatively mobile Ni is predominant in Al/Mn oxide components and carbonate soil components. The coupling of sequential extraction and bioaccessibility techniques provides a robust approach to understanding the relationship between PHE mobility and the potential human health risks from soil exposure via ingestion

Effect of weathering product assemblages on Pb bioaccessibility in mine waste: implications for risk management

General assessments of orebody types and associated mine wastes with regards to their environmental signature and human health hazards are needed to help managing present and historical mine waste facilities. Bioaccessibility tests and mineralogical analysis were carried out on mine waste from a systematic sampling of mine sites from the Central Wales orefield, UK. The bioaccessible Pb widely ranged from 270 to 20300 mg/kg (mean 7250 mg/kg; median 4890 mg/kg) and the bioaccessible fraction from 4.53 % to >100 % (mean 33.2 %; median 32.2 %), with significant (p=0.001) differences among the mine sites. This implies sensitivity of bioaccessibility to site-specific conditions and suggests caution in the use of models to assess human health impacts generalised on the basis of the mineral deposit type. Mineralogical similarities of the oxidation products of primary galena provided a better control over the observed Pb bioaccessibility range. The higher Pb bioaccessibility (%) was related to samples containing cerussite, irrespective of the presence of other Pb minerals in the mineral assemblage; lower Pb bioaccessibility resulted where anglesite was the main Pb mineral phase and cerussite was absent. A solubility diagram for the various Pb minerals in the waste was derived using PHREEQC model and the experimental Pb concentration measured in the simulated gastric solution compared with the equilibrium modelling results. For samples containing cerussite, the model well predicted the soluble Pb concentrations measured in the experimental simulated gastric solution, indicative of the carbonate mineral phase control on the Pb in solution for these samples and little kinetic control on the dissolution of cerussite. On the contrary, most mine waste samples containing dominant anglesite and or plumbojarosite (no cerussite) had lower solution Pb values, falling at or below the anglesite and plumbojarosite solubility equilibrium concentrations, implying kinetic or textural factors hindering the dissolution

Plant cell walls: impact on nutrient bioaccessibility and digestibility

Cell walls are important structural components of plants, affecting both the bioaccessibility and subsequent digestibility of the nutrients that plant-based foods contain. These supramolecular structures are composed of complex heterogeneous networks primarily consisting of cellulose, and hemicellulosic and pectic polysaccharides. The composition and organization of these different polysaccharides vary depending on the type of plant tissue, imparting them with specific physicochemical properties. These properties dictate how the cell walls behave in the human gastrointestinal tract, and how amenable they are to digestion, thereby modulating nutrient release from the plant tissue. This short narrative review presents an overview of our current knowledge on cell walls and how they impact nutrient bioaccessibility and digestibility. Some of the most relevant methods currently used to characterize the food matrix and the cell walls are also described

Use of isotope dilution method to predict bioavailability of organic pollutants in historically contaminated sediments.

Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes

Fruit carotenoids affect the bioaccessibility and cellular uptake of ß-carotene from orange fleshed sweet potato

Context and motivation of the work: To fight against vitamin A deficiency in developing countries, consumption of orange fleshed sweet potato (OFSP) which contains high concentrations of beta-carotene (provitamin A) is currently promoted. Indeed, clinical studies show that the vitamin A status was increased in children fed with OFSP (1). However, information on how well provitamin A was absorbed by intestinal cells is unclear and depends of bioaccessibility. Bioaccessibility of carotenoids depends on various factors included food matrix, food preparation method, presence of fiber and dietary fat or other microconstituants in the food (2).This last point and especially the interaction between carotenoids could be well documented. Moreover, few studies reports informations about the interaction through food matrix. The objective of this study is to assess the effect of carotenoids from fruits juices on the bioaccessibility and cellular uptake of BC from OFSP by using the in vitro digestion coupled with Caco-2 cell culture model. Materiel and methods: To simulate gastric and small intestinal phases of digestion, boiled OFSP (5g) mixed with fruit juice samples (30 ml) in saline solution were incubated at 37 °C (pH 4, pepsin, 30 minutes).Then, the pH was adjusted 6 and bile extract and pancreatin were added for 30 minutes. Micelles were collected in aqueous fraction after centrifugation and filtration (0.22?m). A micellarisation test without food matrix was also investigated (equimolar quantity of carotenoids, 5 ml of 100 mg/ml bile, 17h, 37 °C). Digestat from in vitro digestion were incubated (1h30) on Caco-2 TC7cells cultivated 21 days on wells in order to study the intestinal absorption. Extraction and HPLC analysis of carotenoids from micelles and from OFSP food products were carried out according previous study (3). Results: Effect of fruit juice on the micellarization of beta-carotene from OFSP showed that addition of Pink grapefruit reduces BC micellarization whereas kiwi juice and Clementine increased all-trans BC, but decreased 13-cis BC. Lycopene, beta-cryptoxanthine and lutein carotenoids as standard carotenoids were added to OFSP instead of fruit juices during in vitro digestion and confirmed some carotenoid interactions particularly for lycopene. Micellarization test showed that lycopene decreased and BCX increased. Cellular uptake of all- trans BC from digested OFSP (36%) and 13-cis BC (13 %) significantly decreased in presence of fruit juices. Conclusion: This study shows that carotenoids from fruit juice modify the bioaccessibility and cellular uptake of BC from OFSP. However, further investigations are needed to identify other components responsible of interactions in order to show efficacy of OFSP for maintaining adequate vitamin A status in a meal. (Texte intégral