Search results for "Volatilization"
showing 10 items of 49 documents
Behavior of Flavor Compounds in Model Food Systems: a Thermodynamic Study
2003
Physicochemical parameters, such as hydrophobicity, water solubility, and volatility, of four flavor compounds (ethyl acetate, ethyl butyrate, ethyl hexanoate, and 2-pentanone) were determined. The amount of flavor compounds released from different model matrices (mineral water, purified triolein, an oil-in-water emulsion, a carbohydrate matrix, and a complex matrix containing lipids and carbohydrates) into the gaseous phase was determined at thermodynamic equilibrium, at 37 degrees C, by static headspace gas chromatography. The degree of interaction between the flavor compounds and the matrix components was shown by measuring the percentage retention using the water matrix as the reference…
Identification of volatile synomones, induced by Nezara viridula feeding and oviposition on bean spp., that attract the egg parasitoid Trissolcus bas…
2004
Bean plants ( Vicia faba L. and Phaseolus vulgaris L.) damaged by feeding activity of Nezara viridula (L.) ( Heteroptera: Pentatomidae), and onto which an egg mass had been laid, produced volatiles that attracted the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae). Extracts of volatiles of broad bean and French bean plants induced by adults of N. viridula as a result of their feeding activity, oviposition activity, and feeding and oviposition activity combined were analyzed by gas chromatography-mass spectrometry (GC-MS), and tested in Y-tube olfactometer bioassays as attractants for T. basalis females. In extracts from undamaged leguminous plants, green-leaf volati…
A Method to Quantitatively Trap Volatilized Organoselenides for Stable Selenium Isotope Analysis
2011
If volatile organoselenides are to be analyzed for their stable Se isotope composition to elucidate sources and formation processes, organoselenides need to be trapped quantitatively to avoid artificial Se isotope fractionation. We developed an efficient trap of organoselenides to be used in microcosms designed to determine the Se isotope fractionation by microbial transformation of inorganic Se to volatile organoselenides. The recoveries of volatilized dimethyldiselenide (DMDSe) from aqueous standard solutions by activated charcoal and alkaline peroxide solution with subsequent freeze-drying and purification via a cation exchange resin were tested. Microcosm experiments with the Se-methyla…
Chemotaxonomic value of the essential oil compounds in species of Teucrium pumilum aggregate
2000
Volatile compounds from the aerial parts of Teucrium lepicephalum Pau and Teucrium carolipaui C. Vicioso ex Pau, both belonging to the Teucrium pumilum aggregate, were analysed by capillary GC and GC-MS. From the common and specific compounds (mono- and sesquiterpenes) of the two taxa, chemical characterization was carried out and taxonomic relationships were assessed. Application of the cluster and k-means discriminant analysis shows a differential chemical relationship between T. lepicephalum and Teucrium carolipaui.
Volatile constituents of the aerial parts of white salsify (Tragopogon porrifolius L., Asteraceae).
2010
Tragopogon porrifolius L. grows as a vegetable in southern Italy and all parts of it are edible. In the present study the volatile components of the aerial part are described. Gas chromatography and gas chromatography-mass spectrometry analysis showed the presence of 38 components in all. On the whole, the volatile fraction was constituted mainly by carbonylic compounds (24.6%), phenols (21.5%) and fatty acids and esters (19.7%). The most abundant compounds were 4-vinyl guaiacol (19.0%), hexadecanoic acid (17.9%), hexahydrofarnesylacetone (15.8%) and hentriacontane (10.7%).
Ethyl Hexanoate Transfer Modeling in Carrageenan Matrices for Determination of Diffusion and Partition Properties.
2007
; Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtaine…
A method for the determination of dimethylamine in air by collection on solid support sorbent with subsequent derivatization and spectrophotometric a…
2005
A new method for dimethylamine determination in air is reported. The proposed assay is based on the employment of C18-packed solid phase extraction cartridges for sampling. The retained amine is then derivatized inside the cartridges with the reagent 1,2-naphthoquinone-4-sulfonate. By observing the coloured area of the cartridge, a semiquantitative estimation of the amine can be made. It was also possible to distinguish between primary and secondary amines by visual inspection. Quantitative tests entailed desorption from the cartridges of the derivatives formed, and measurement of the absorbance of the collected extracts. The selected conditions were applied to quantify dimethylamine up to …
Polar organic marker compounds in PM2.5 aerosol from a mixed forest site in western Germany
2008
The molecular composition of PM2.5 (particulate matter with an aerodynamic diameter2.5 microm) aerosol samples collected during a very warm and dry 2003 summer period at a mixed forest site in Jülich, Germany, was determined by gas chromatography/mass spectrometry in an effort to evaluate photooxidation products of biogenic volatile organic compounds (BVOCs) and other markers for aerosol source characterization. Six major classes of compounds represented by twenty-four individual organic species were identified and measured, comprising tracers for biomass combustion, short-chain acids, fatty acids, sugars/sugar alcohols, and tracers for the photooxidation of isoprene and alpha-/beta-pinene.…
Leachate and gaseous emissions from initial phases of landfilling mechanically and mechanically-biologically treated municipal solid waste residuals.
2008
In this study, the behaviour, and leachate and gaseous emissions during the initial phases of landfilling mechanically (M) and mechanically-biologically (MB) treated municipal solid waste residuals in northern climatic conditions was compared using two landfill lysimeters (112 m3). The results demonstrate that the strong acid phase of M residuals degradation lasts at least 2 years, while in the MB residuals the acid phase lasts only a few months. The SCOD and NH4-N concentrations varied 20-100g/l and 600-1800 mg/l in M leachate and 1-4 g/l and 100-400mg/l in MB leachate, respectively. The leaching of SCOD was approximately 40-fold (24.2 and 0.6 kg/t TS) and leaching of NH4-N approximately 5…
Pilot scale experiment with MBR operated in intermittent aeration condition: analysis of biological performance.
2014
The effect of intermittent aeration (IA) on a MBR system was investigated. The study was aimed at ana- lyzing different working conditions and the influence of different IA cycles on the biological performance of the MBR pilot plant, in terms of organic carbon and ammonium removal as well as extracellular poly- meric substances (EPSs) production. The membrane modules were placed in a separate compartment, continuously aerated. This configuration allowed to disconnect from the filtration stage the biological phenomena occurring into the IA bioreactor. The observed results highlighted good efficiencies, in terms of organic carbon and ammonium removal. It was noticed a significant soluble micr…