Search results for "010401 analytical chemistry"
showing 10 items of 1284 documents
A compact linear Paul trap cooler buncher for CRIS
2020
A gas-filled linear Paul trap for the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at ISOLDE, CERN is currently under development. The trap is designed to accept beam from both ISOLDE target stations and the CRIS stable ion source. The motivation for the project along with the current design, simulations and future plans, will be outlined. peerReviewed
Heuristic Algorithm for the Analysis of Fast Field Cycling (FFC) NMR Dispersion Curves
2021
Evaluation of nuclear magnetic relaxation dispersion (NMRD) curves obtained by the fast field cycling nuclear magnetic resonance (FFC-NMR) relaxometry technique is a valuable tool for analyzing the microscopic dynamics of condensed matter systems. However, quantitative data analysis involves several conceptual and practical issues. Moving forward from previous literature approaches, we propose a new analysis method, relying on the elaboration of the inverse integral transform of the NMRD curve. Our approach results in a true heuristic method, able to unambiguously individuate the dynamic domains in the system, thereby avoiding the possible introduction of any element of discretion. The anal…
Untargeted metabolomics of fresh and heat treatment Tiger nut ( Cyperus esculentus L. ) milks reveals further insight into food quality and nutrition
2017
Tiger nut (Cyperus esculentus L.) is a crop traditionally grown in Valencia Region (Spain) and other temperate and tropical regions in the world, where its tubers are commonly consumed as tiger nut milk (horchata). Because of their nutritive potential and original taste, these products are beginning to spread internationally and, as consequence, analytical procedures to assess nutritional profiles, quality control issues are acquiring increasing relevance. The main objective of this study was to use an advance analytical method and chemometrics tools to determine if the ultra-high temperature (UHT) treatment necessary to extend the shelf life of tiger nut milk would affect the profile of nu…
Occurrence and exposure assessment of mycotoxins in ready-to-eat tree nut products through ultra-high performance liquid chromatography coupled with …
2020
Tree nuts have become popular snacks due to their attributed benefits in the health state. Nevertheless, their susceptibility to fungal contamination lead to the occurrence of potentially dangerous mycotoxins. Hence, the aim of this work was to evaluate the presence of mycotoxins in ready-to-eat almonds, walnuts, and pistachios from Italian markets. The most relevant mycotoxin found in almonds was α-zearalanol in 18% of samples (n = 17) ranging from 3.70 to 4.54 µg/kg. Walnut samples showed frequent contamination with alternariol, present in 53% of samples (n = 22) at levels from 0.29 to 1.65 µg/kg. Pistachios (n = 15) were the most contaminated commodity, with β-zear…
From ‘green’ technologies to ‘red’ antioxidant compounds extraction of purple corn: a combined ultrasound-ultrafiltration-purification approach
2018
A pilot scale process consisting of ultrasound-assisted extraction, ammonium sulfate precipitation, cross-flow ultrafiltration and AB-8 macroporous resins purification aiming to recover anthocyanins and zein from purple corn (PC) was optimized and scaled-up. The effects of five independent variables (ethanol concentration, liquid to solid ratio, ultrasound temperature, time and power) were discussed and the most influential factors were optimized.; Results: The highest total anthocyanin (0.45 ± 0.01 g kg-1 ) and zein (17.14 ± 1.73 g kg-1 ) contents from purple corn were obtained using an ultrasound power of 105 W, an extraction time of 90 min, an ethanol concentration of 74% and a liquid to…
Retention of aroma compounds: an interlaboratory study on the effect of the composition of food matrices on thermodynamic parameters in comparison wi…
2010
BACKGROUND: Partition coefficients give an indication of the retention of aroma compounds by the food matrix. Data in the literature are obtained by various methods, under various conditions and expressed in various units, and it is thus difficult to compare the results. The aim of the present study was first to obtain gas/water and gas/matrix partition coefficients of selected aroma compounds, at different temperatures, in order to calculate thermodynamic parameters and second to compare the retention of these aroma compounds in different food matrices. RESULTS: Yogurts containing lipids and proteins induced a higher retention of aroma compounds than model gel matrices. The observed effect…
Retention-release equilibrium of aroma compounds in polysaccharide gels: study by quantitative structure-activity/property relationships approach
2010
The nature and amount of constituents in food greatly influence aroma release. Pectins and carrageenans are common used thickeners, but their effect on the release of aroma compounds has been studied more frequently for non- homogeneous products than for thickeners separately. The purpose of this work was to study and compare their respective effects in simple model systems. In this way, the release of 13 aroma compounds was analysed by headspace analysis at equilibrium in pure water, i-carrageenan and pectin gels. To evaluate the influence of the chemical structure of aroma com- pounds on retention/release equilibrium between vapour phase and gels, we used a quantitative structure-activity…
A new approach to studying sponge cake aroma after storage in treated paper and plastic packaging by direct gas chromatography–olfactometry (D-GC–O)
2007
The objective of this study was to use D-GC–O to compare the global odour of a sponge cake flavoured with either a ‘viennoiserie’ aromatic note or a simplified mixture of aroma compounds (used for physicochemical studies), then stored in a glass packaging (inert and impermeable) or in pouches made with treated papers or with plastic packaging, in accelerated ageing conditions (high temperature and relative humidity gradient). After 1 week of storage, the flavoured sponge cake headspace was SPME-extracted directly into the packaging and analysed by D-GC–O. The sponge cake global odour was better retained if plastic film rather than treated-papers was used, for both flavourings. Changes in th…
Assessment of Human Exposure to Deoxynivalenol, Ochratoxin A, Zearalenone and Their Metabolites Biomarker in Urine Samples Using LC-ESI-qTOF.
2021
Human are exposed to a wide range of mycotoxins through dietary food intake, including processed food. Even most of the mycotoxin exposure assessment studies are based on analysis of foodstuffs, and evaluation of dietary intake through food consumption patterns and human biomonitoring methods are rising as a reliable alternative to approach the individual exposures, overcoming the limitations of the indirect dietary assessment. In this study, human urine samples were analyzed, seeking the presence of deoxynivalenol (DON), ochratoxin A (OTA), zearalenone (ZEA), and their metabolites. For this purpose, 40 urine samples from female and male adult residents in the city of Valencia (Spain) were …
Dietary Exposure to Mycotoxins through Alcoholic and Non-Alcoholic Beverages in Valencia, Spain
2021
The present study investigated the presence of 30 mycotoxins in 110 beverage samples of beer, wine, cava, and cider purchased in Valencia (Spain). A validated method based on dispersive liquid–liquid microextraction and chromatographic methods coupled with tandem mass spectrometry was applied. The method showed satisfactory recoveries ranging from 61 to 116% for the different beverages studied. The detection and quantification limits ranged from 0.03 to 2.34 µg/L and 0.1 to 7.81 µg/L, respectively. The results showed that beer samples were the most contaminated, even with concentrations ranging from 0.24 to 54.76 µg/L. A significant presence of alternariol was found in wine, which reached c…