Добірка наукової літератури з теми "Additif E171"

E171 (titanium dioxide) is a food additive that has been authorized for use as a food colorant in the European Union. The application of E171 in food has become an issue of debate, since there are indications that it may alter the intestinal barrier. This work applied standardized and validated methodologies to characterize representative samples of 15 pristine E171 materials based on transmission electron microscopy (TEM) and single-particle inductively coupled plasma mass spectrometry (spICP-MS). The evaluation of selected sample preparation protocols allowed identifying and optimizing the critical factors that determine the measurement of the particle size distribution by TEM. By combining optimized sample preparation with method validation, a significant variation in the particle size and shape distributions, the crystallographic structure (rutile versus anatase), and the physicochemical form (pearlescent pigments versus anatase and rutile E171) was demonstrated among the representative samples. These results are important for risk assessment of the E171 food additive and can contribute to the implementation of the European Food Safety Authority (EFSA) guidance on risk assessment of the application of nanoscience and nanotechnologies in the food and feed chain.

Titanium dioxide (TiO2) is one of the most extensively utilized food additives (E171) in the food industry. Along with nanotechnology development, the concern about the presence of nanostructured particles in E171 TiO2 and commercial food products is growing. In the present study, the physicochemical properties of commercially available E171 TiO2 particles, including particle size distribution, were investigated, followed by their cytotoxicity and intestinal transport evaluation. The fate determination and quantification of E171 TiO2 in commercial foods were carried out based on the analytical procedure developed using simulated foods. The results demonstrated that TiO2 is a material mainly composed of particles larger than 100 nm, but present as an agglomerated or aggregated particle in commercial foods with amounts of less than 1% (wt/wt). Titanium dioxide particles generated reactive oxygen species and inhibited long-term colony formation, but the cytotoxicity was not related to particle size distribution or particle type (food- or general-grade). All TiO2 particles were mainly transported by microfold (M) cells, but also by intestinal tight junction. These findings will be useful for TiO2 application in the food industry and predicting its potential toxicity.

This study investigated the DNA damage and apoptosis in colon cancer cells HCT-116 and Caco-2 induced by engineered titanium dioxide nanoparticles (TiO2-NPs) (60 nm) and titanium dioxide food additive E171. MTT assays showed that both chemical forms significantly reduced cancer cell viability in a dose-dependent manner. In particular the food additive E171 induced a pronounced inhibitory effect on the growth of HCT-116 and Caco-2 cell lines (E171 IC50: 3.45 mg/L for HTC-116 and 1.88 mg/L Caco-2; TiO2-NPs 60 nm IC50: 41.1 mg/L for HTC-116 and 14.3 mg/L for Caco-2). A low level of genotoxicity was observed in Caco-2 cells, especially when treated with TiO2 60 nm. Western blot analysis showed that HCT116 and Caco-2 treated cells did not overexpress apoptotic markers such as cleaved Caspase 3 and cleaved Parp. Moreover, further analysis by quantitative real-time PCR (qRT-PCR) showed that TiO2-NPs and E171 did not promote the expression of Bax or downregulation of Bcl-2, nor did they increase the Bax/Bcl-2 ratio. The assay data provide clear evidence that TiO2 can cause DNA damage but does not induce apoptosis or decrease long-term cell proliferation. In addition, the results show that E171 has a slightly higher level of cytotoxicity and genotoxicity. This suggests that exposure to E171 may be hazardous to health and that further research on biological effects is needed to promote safer practices in the use of this compound.

Titanium dioxide (TiO2) is present in many different food products as the food additive E171, which is currently scrutinized due to its potential adverse effects, including the stimulation of tumor formation in the gastrointestinal tract. We developed a transgenic mouse model to examine the effects of E171 on colorectal cancer (CRC), using the Cre-LoxP system to create an Apc-gene-knockout model which spontaneously develops colorectal tumors. A pilot study showed that E171 exposed mice developed colorectal adenocarcinomas, which were accompanied by enhanced hyperplasia in epithelial cells, lymphatic nodules at the base of the polyps, and increased tumor size. In the main study, tumor formation was studied following the exposure to 5 mg/kgbw/day of E171 for 9 weeks (Phase I). E171 exposure showed a statistically nonsignificant increase in the number of colorectal tumors in these transgenic mice, as well as a statistically nonsignificant increase in the average number of mice with tumors. Gene expression changes in the colon were analyzed after exposure to 1, 2, and 5 mg/kgbw/day of E171 for 2, 7, 14, and 21 days (Phase II). Whole-genome mRNA analysis revealed the modulation of genes in pathways involved in the regulation of gene expression, cell cycle, post-translational modification, nuclear receptor signaling, and circadian rhythm. The processes associated with these genes might be involved in the enhanced tumor formation and suggest that E171 may contribute to tumor formation and progression by modulation of events related to inflammation, activation of immune responses, cell cycle, and cancer signaling.

Introduction. Titanium dioxide in the Russian Federation is approved for use in the food industry, in the production of medicines and hygiene products. The food additive E171 is a mixture of micro- and nanoparticles of TiO2. In 2010, IARC classified TiO2 in nanoform as a probably carcinogenic to humans (Group 2B). In vitro and in vivo studies of the genotoxicity of titanium dioxide revealed contradictory results, indicating both the presence and absence of TiO2 mutagenicity. The aim of the work is to evaluate the mutagenicity of the food additive E171 in the Ames test using standard and modified protocols. Materials and methods. The ability of food additive E171 (China) to induce reverse gene mutations in 5 strains of Salmonella typhimurium was studied under standard and modified conditions (cultivation of bacteria in the presence of methylated b-cyclodextrin (MCD) and/or pre-incubation for 1 hour in potassium phosphate buffer, pH 5.5 containing 10 mM NaCl and/or 3M MCD). Results. A sample of food additive E171 based on rutile titanium dioxide does not induce gene mutations in S. typhimurium in standard experiments. Modification of the Ames test protocol (decrease of the incubation mixture pH, addition of 10 mM NaCl) revealed statistically significant dose-dependent effects in TA100, TA98, and TA97 strains under metabolic incubation conditions. However, the fold increase of the number of revertants in the experimental plates compared to the negative control was < 2. Limitations. The research is limited to the mutagenicity assessment of food additive E171 (titanium dioxide) in the Ames test. Conclusion. The evaluation of the mutagenicity of titanium dioxide in other in vitro and in vivo tests taking into account the size and shape of the particles, is necessary to resolve the issue of its genetic safety as a food dye. A full range of studies will be performed on other samples of titanium dioxide presented in the market of the Russian Federation.

We present our investigation on the gasochromic reaction of E141 (ii) towards the toxic gas nitrogen dioxide (NO2). E141 (ii) is a chlorophyllin-based food additive, typically used as green coloring for nearly all kinds of sweets. In this presentation we show an alternative approach for using E141 (ii) as optical gas indicator. All solid samples are prepared by multi-layer screen printing on different substrates like paper and PE-foil. Gas measurements are performed using an UV/Vis spectrometer. The influence of the substrate and according layer thickness is shown.

Le projet de thèse NanoTi-Food vise principalement à améliorer la fiabilité de la caractérisation des nanoparticules de TiO2 (NPs) et à acquérir des connaissances sur l'additif alimentaire E171 y compris la migration de ces NP à partir des emballages alimentaires. Dans la première partie de l'étude (à réaliser à Anses), une nouvelle approche pour la caractérisation des NP de TiO2 sera développée et optimisée en utilisant l'approche « single particle » en combinaison avec la spectrométrie de masse à plasma à couplage inductif triple quadripôle (Sp-ICP- QQQMS). À cette fin, les paramètres analytiques les plus critiques, tels que les méthodes de calcul de l'efficacité du transport (TE) et le système d'introduction des échantillons seront évalués dans différentes conditions de travail (par exemple gaz de réaction, choix de l'isotope). Dans ce dernier cas, deux systèmes d'introduction d'échantillons à haut rendement (type APEX) seront comparés. Par ailleurs, une approche Sp complémentaire basée sur la MS-ICP haute résolution (Sp-ICP-HR MS) sera développée au LNE. La nouveauté dans ce cas sera l'utilisation d'un ICP-MS à haute résolution (champ de secteur magnétique) pour la détection, qui est la technique de pointe pour la détermination des éléments traces métalliques fortement interférés tels que le Ti. Un système d'injection interne sera également optimisé pour augmenter l'efficacité et la sensibilité du transport de l'échantillon. La validation de la méthode sera réalisée par comparaison inter-laboratoires entre le LNE et l'Anses. Une véritable valeur ajoutée du projet sera l'évaluation de l'incertitude de mesure liée à la caractérisation des NP de TiO2 par les deux approches Sp-ICP-MS (QQQ et HR). Les calculs d'incertitude prendront en compte non seulement la reproductibilité expérimentale et les incertitudes de chacune des variables nécessaires pour convertir le signal ICP-MS en taille et concentration de NPs, mais aussi et pour la première fois, l'effet du choix du seuil pour discriminer le signal ionique ICP-MS de celui des NP. L'effet des écarts par rapport à la forme sphérique sur les tailles sera également étudié et comparé à la microscopie électronique à balayage (MEB), qui est la méthode de référence pour la caractérisation des NP. Le projet vise également la préparation et la caractérisation exhaustive d'un matériau de référence réel (additif alimentaire) contenant des nanoparticules de TiO2. Une étude de faisabilité du développement d'une MR à base de E171 sous forme de suspension sera réalisée. À cette fin, un échantillon E171 représentatif sera préparé et entièrement caractérisé par un panel de techniques complémentaires, telles que SEM, Sp-ICP-QQQMS, Sp-ICP-HR MS, diffraction des rayons X (XRD) pour évaluer avec précision les principaux paramètres d'intérêt, tels que le diamètre médian et moyen, la distribution de taille, la fraction de nanoparticules, les impuretés chimiques et la fraction cristallographique. Enfin, les deux approches analytiques développées à l'Anses et au LNE, dont la méthode développée pour l'évaluation de l'incertitude globale, seront appliquées à l'étude du transfert des NP de TiO2 à partir des emballages alimentaires. Tout au long du projet, les données de taille obtenues en utilisant les nouvelles approches basées sur l'approche « single particle » pour la caractérisation des NP de TiO2 seront comparées aux mesures SEM, qui est la méthode de référence pour la taille dans ce domaine d'étude. Les études sur la migration des emballages alimentaires sont en effet une étude de cas sélectionnée où la Sp-ICP-MS a le potentiel de fournir des informations supplémentaires par rapport à d'autres paramètres tels que la concentration de particules, la proportion de particules par rapport à la forme dissoute, qui sont également importantes pour la migration qui est important afin d'améliorer les études d'évaluation des risques
This PhD project aims primarily to improve the reliability of the characterisation of TiO2 nanoparticles (NPs) and to gain knowledge of the food additive E171 and in real-life applications such as migration of these NPs from food packaging. In the first part of the study (to be carried out at Anses), a new approach for TiO2 NPs characterisation will be developed and optimized by using the single particle approach in combination with inductively coupled plasma-triple quadrupole mass spectrometry (Sp-ICP-QQQMS). For this purpose, the most critical analytical parameters, such as the transport efficiency (TE) calculation methods and the sample introduction system will be assessed under different working conditions (e.g. reaction gas, choice of isotope). In the latter case, two high efficiency sample introduction systems (APEX type) will be critically compared. Further, a complementary Sp approach based on ICP-high resolution MS (Sp-ICP-HRMS) will be developed at LNE. The novelty in this case will be the use of a high resolution (magnetic sector field) ICP-MS for detection, which is the state-of-the art technique for trace and ultra-trace metals determination of highly interfered elements such as the case of Ti. An in-house injection system will also be optimized to increase the transport efficiency and sensitivity. Method validation by inter-laboratory comparison between LNE and ANSES will be achieved here. A truly added value of the project will be the assessment of the measurement uncertainty related to TiO2 NPs characterization by both Sp-ICP-MS (QQQ and HR) approaches. The uncertainty calculations will take into account, not only the experimental reproducibility and the uncertainties of each variables required to convert ICP-MS signal into NPs size and concentration, but also and for the first time, the effect of the choice of the cut-off to discriminate the ICP-MS ionic signal from that of NPs. The effect of deviations from the spherical shape on the sizes will also be explored and compared with scanning electron microscopy (SEM), which is the reference method for NPs characterisation. The project also aims at the preparation and exhaustive characterization of a real-life (food additive) reference material containing TiO2 nanoparticles. A feasibility study of the development of an E171-based RM under a suspension form will be carried out. For this purpose, a representative E171 sample will be prepared and fully characterized by a panel of complementary techniques, such as SEM, Sp-ICP-QQQ MS, Sp-ICP-HRMS, X-ray diffraction (XRD) to accurately assess the main parameters of interest, such as the median and mean diameter, size distribution, fraction of nanoparticles, chemical impurities and crystallographic fraction. Finally, both analytical approaches developed at Anses and LNE, including the developed method for global uncertainty assessment, will be applied to the study of the transfer of TiO2 NPs from food packaging. All along the project, the size data obtained by using the newly developed “single particle” based approaches for TiO2 NPs characterisation will be compared to SEM measurements, which is the reference method for size in this study field. Food packaging migration studies is indeed a selected case study where Sp-ICP-MS has the potential of supplying additional information compared to other instruments, such as: particle concentration, proportion of particulate vs. dissolved form, which are of importance for migration as well as to improve risk assessment studies