Multi-response Modelling of the Maillard reaction in a model cheese

International audienceProcessed cheese derives from a secondary milk processing step that involves mixing and heating dairy (cheese, butter and milk powders) and non-dairy products (emulsifiers). This processing yields a homogeneous product, usually spreadable, with a shelf-life often longer than 6 months. During cheese processing and storage, lipid oxidation, caramelization and Maillard reactions occur and produce odour-active compounds. In this study, a methodological approach was used in order to (i) identify odorants responsible for flavor attributes or compouds involved in the reaction chain, (ii) monitor the evolution of these markers during the heat treatment applied to the matrix, (iii) establish an observable reaction scheme and (iv) model and predict the evolution of these compounds during thermal operations. In this aim, a model cheese and a cooking cell were elaborated. Various couplings of gas chromatography with olfactometry were used to identify odorous compounds. Two-dimensional comprehensive chromatography allowed a semi-quantitation of trace and ultra-trace compounds, while precursors were quantitated by high performance liquid chromatography. An observable reaction scheme of the Maillard reaction was extracted from these data and makes the multi-response modeling step possible despite a partial quantitation of the volatile compounds. Finally, we obtained a formal model combining 19 components (including four odorants) connected by 14 stoechiometric balanced reactions. This model makes it possible to predict the evolution of these components depending on the initial content of lactose, galactose and according to the heat treatment applied to the cheese matrix. This work was carried out with the financial support of the ANR-Agence Nationale de la Recherche-The French National Research Agency under the Programme National de Recherche en Alimentation et nutrition humaine , project ANR-06-PNRA-023REACTIAL "Prediction and control of the appearance or disappearance of reactional markers during food process and conservation "

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Proton-decoupled carbon-13 NMR spectroscopy in a lyotropic chiral nematic solvent as an analytical tool for the measurement of the enantiomeric excess

International audienceOrganic solutions of poly-ç-(benzyl-L-glutamate) (PBLG) generate a sufficient differential ordering effect (DOE) to discriminate enantiomers using proton decoupled carbon-13 NMR in natural abundance. Discrimination between enantiomers is observed through the carbon-13 chemical shift anisotropy (CSA) differences. This method is successfully applied to a large number of chiral molecules including a case of axial chirality and offers the advantage that no labeling or chemical modification of molecules is needed. In most cases, the chemical shift differences are large enough to measure the enantiomeric excess with accuracy. We show that this new tool is an attractive and powerful alternative to the existing enantiomeric analytical techniques

Volatile components of dry cured iberian ham

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Analytical contribution of deuterium 2D-NMR in oriented media to H-2/H-1 isotopic characterization: the case of vanillin

International audienceThe evaluation of intramolecular H-2 or C-13 isotopic composition of vanillin by liquid-state nuclear magnetic resonance (NMR) is an illustrative example of the analytical challenges associated with molecular authenticity/traceability investigations in food products, and the determination/understanding of metabolic/synthetic pathways. Although isotopic ratio monitoring by C-13 NMR (irm-C-13 NMR) provides a valuable new source of isotopic information, the analysis of position-specific (H-2/H-1) isotopic fractionation of vanillin remains incomplete because of the overlap of two aromatic H-2 resonances, and the impossibility of separating these fortuitous isochronous nuclei by isotropic NMR. Exploiting the analytical potential of H-2 2D-NMR in media containing polypeptide-based liquid crystals, we show that all aromatic monodeuterated isotopomers can be spectrally discriminated on the basis of H-2 residual quadrupolar couplings, (Q)(H-2), thus enabling the determination of their relative proportions for the first time. After discussing the multiple relevant cofactors leading to the best discrimination and optimization of experimental conditions for reliable quantitative measurements by anisotropic 2D-NMR, a comparative analysis of six vanillin samples from diverse origins is reported. How the H-2 distribution might relate to the biosynthesis of vanillin is discussed

Identification of odour active compounds generated in a processed cheese-like model system

International audienceThis work aimed at modelling, predicting and controlling the formation or consumption of key compounds in a processed cheese-like model system during its elaboration and storage. Oxidative degradations and Maillard reactions produce a huge number of neo-formed compouds and lead to major changes in food texture, colour, nutritional value and flavour. The first step presented here is the identification of these compounds. Odour activity was used in order to to find out which ones may influence the product flavour. In the model system native caseinate and anhydrous milk fat were used instead of cheese and butter respectively. This enabled both a simplification and a better reproductibility of the initial volatile fraction and permitted a better tracking of the compounds formed during heating. An hermetically closed cooking cell was designed to heat uniformely ten grams of sample from 5 to 150°C as quickly as possible without any flavour leak. This cell was built with stainless steel, copper and aluminium and heated using superheated steam jets (1). The shortest treatment enabled an increase in the sample temperature from 20 to 150°C in about 3,5 minutes. Numerical simulations were used to estimate the reproductibility and homogeneity of the treatment using a " worst case scenario ". It showed that the thermal gradient inside the product was less than 15°C when the sample reached 150°C in a 3,5 minutes treatment. Odour-active compounds were searched using a gas-chromatograph-eight-way-olfactomer device (8 sniffers simultaneously) (2). Structural identification was performed with a gas-chromatograph-mass-spectrometer-olfactometer system (one sniffer) and a comprehensive-gas-chromatograph-time-of-flight-mass-spectrometer. More of 500 compounds were identified. Among them 46 exhibited an odor activity and only 16 were found to be significantly influenced by the thermal treatment. 2,3-butanedione, acetic acid, butanoic acid, hexanal, 2-methylpropanal, 3-methylbutanal, methional, 2-acétyl-1-pyrazine and furaneol were found to be the most influenced compounds and are probably of major significance for the flavour of the cheese matrix. Odour-activity of 2-acetyl-1-pyrroline was found to be significantly lower in the heated sample than in its unheated counterpart

Le concept de "resistance" a l'aspirine: mecanismes et pertinence clinique

Aspirin, a 110-year-old molecule, is a cornerstone in the treatment of atherothrombotic patients. The concept of aspirin "resistance" emerged approximately 15 years ago and is of growing interest. Aspirin resistance, defined as a lack of inhibition of cyclo-oxygenase-1 (COX-1), is a rare phenomenon and its clinical relevance can hardly be studied. On the contrary, residual platelet hyperactivity is more common and affects 20 to 30% of aspirin-treated patients. This latter phenomenon corresponds to sustained platelet reactivity despite a proper inhibition of COX-1 by aspirin. Several meta-analyses suggest that residual platelet hyperactivity could be a risk factor for the recurrence of ischemic events in aspirin-treated patients. Causes of biological non-responsiveness to aspirin are discussed, including the role of compliance, drug-drug interactions, genetic polymorphisms and diabetes mellitus. Ongoing studies are designed to find out the mechanisms of residual platelet hyperactivity, determine its potential clinical relevance and delineate the more appropriate assays in order to identify patients who may benefit of a tailored antiplatelet therapy