1,720,960 research outputs found
Frazionamento degli aromi durante la pressatura del Traminer aromatico
No full textGli aromi varietali estratti con la pressatura hanno un ruolo importante nella
qualità e shelf-life del vino Gewürztraminer. Lo sfruttamento delle frazioni ottenute a maggior pressione di esercizio è particolarmente giustificato per
la varietà. Va però posta attenzione ai composti prefermentativi e ai potenziali rischi microbiologico-enzimatici legati all'innalzamento del pH
Perturbations produced by electrospray ionization mass spectrometry in the speciation of aluminium(III)/1,6-dimethy1-4-hydroxy-3-pyridinecarboxylate aqueous solutions
No full textElectrospray ionization mass spectrometry (ESI-MS) is very often employed to study metal/ligand equilibria in aqueous solution. However, the ionization process can introduce perturbations whichaffect the speciation results in an unpredictable way. It is necessary to identify these perturbations in order to correctly interpret the ESI-MS speciation results.
Aluminium(III)/1,6-dimethyl-4-hydroxy-3-pyridinecarboxylate (DQ716) aqueous solutions at various pH were analysed by ESI-MS, and speciation results were compared with those obtained by equilibrium techniques. Differences observed were both qualitative and quantitative. The ESIMS
spectral changes due to different settings of the following instrumental parameters were analyzed: the solution flow rate (FS), the nebulizer gas flow rate (FG), the potential applied at the entrance capillary (EC), and the temperature of the drying gas (TG). The effects produced by FS and EC
on the spectra strongly suggest the key role of surface activity in determining the relative fraction of the ions reaching the detector. The experimental effects of FS and TG were interpreted considering the presence of at least two reactions in the gas phase and a dimerization occurring in the droplets.
These perturbations cannot be generalized because they appear to be chemical system-related and instrument-dependent. Therefore, the identification of perturbations is a required task for any metal-ligand equilibrium study performed by ESI-MS. Our results indicate that perturbations can be identified by evaluating the effects produced in the spectra by a change of instrumental parameters
URINARY PURINE AND PYRIMIDINE INCREASE IN PATIENTS WITH METHYLMALONIC ACIDURIA COMBINED TO HOMOCYSTINURIA
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Phthalates determination in wine and spirits using GC-MS and LC-MS/MS
Full text linkPhthalates, widely studied in the last years as insidious and ubiquitous contaminants
of industrially processed foods, have recently been reported also in some wines and spirits. This work presents and compares the performances of two novel analytical approaches for the simultaneous determination of seventeen phthalates (i.e. DMP, DEP, DiBP, DBP, DMEP, BMPP, DEEP, DPP, DHXP, BBP, DBEP, DCHP, DEHP, DPhP, DNOP, DNP, DiNP; EN ISO 1043-3:1999 D) using mass spectrometry in alcoholic beverages. GC-MS analysis requires a preliminary time-consuming sample extraction, the use of perfectly cleaned glassware, highlypurified
extraction solvents, and the concentration of the final organic extract. LC-MS/MS
method is faster (no LLE and concentration steps) and more sensitive, even if it requires ultrapurified eluents, or the adoption of an on-line device for the background removal. Both approaches proved to be rugged and useful for routine and high-throughput analysis. DEHP, DiBP, DBP, DMEP and DiNP were present in more than 70% of spirits, while DBP and DNOP were quantifiable in 60% of wine
Performance aromática e fermentativa de estirpes de leveduras na produção de espumantes de consumo rápido
Full text linkForam analisados seis vinhos de base para a produção de espumantes de Muller-Thurgau (n=3), Prosecco (2) e Chardonnay (1) - cada um com 2 níveis de azoto assimilável (o primeiro com os níveis presentes no vinho de base: modalidade de ensaio TQ; o segundo com adição de +184 mg/L de azoto assimilável: modalidade de ensaio APA (AFA)) fermentaram em garrafa com 6 leveduras enológicas (SP665, DV10, Rhone 2056, FR95, BC, R2), segundo as indicações do Comité Interprofessionnel du Vin de Champagne (Laurent e Lavade 2007). Dois meses após o fim da fermentação em garrafa, foram analisados por GC-FID os compostos aromáticos fermentativos na forma livre dos espumantes conservados em contacto com as borras a 4-5°C.
A segunda fermentação em garrafa alterou o teor de alguns compostos, mas não aumentou a concentração de acetatos de álcoois superiores e de ésteres etílicos de ácidos gordos, normalmente responsáveis pelas notas frutadas. Não foram observadas diferenças estatisticamente significativas ou dignas de nota em termos de composição, devidas às leveduras ou ao nível de azoto disponível nos vinhos de base.
Com um pé-de-cuba preparado de forma adequada, o azoto assimilável dos vinhos de base confirmou não ser um fator particularmente importante para a formação dos principais compostos responsáveis pelo frutado durante a segunda fermentação. Por conseguinte, confirma-se a importância da intensidade do aroma do vinho de base, particularmente no caso dos frisantes charmat "curtos" nos quais o carácter frutado é particularmente apreciado pelos consumidore
Performance aromatico-fermentative di ceppi di lievito nella produzione di spumanti di pronta beva
Full text linkIn un contesto nel quale non solo spumanti classici blasonati ma anche bollicine meno "austere" ma di elevato appeal giovanile stanno ritrovando soddisfazioni di mercato, non ci è apparso peregrino il realizzare un'indagine sul ruolo che rivestono i ceppi di lievito nel determinare e modificare in fase di presa di spuma i contenuti dei composti volatili fermentativi responsabili del tanto desiderato "fruttato" degli spumanti e frizzanti da bersi giovan
Resultados a nivel aromático y fermentativo de cepas de levadura en la producción de espumosos de rápido consumo
Full text linkEn un contexto en el que sólo los espumosos clásicos de renombre pero también los menos “austeros” pero con atractivo juvenil encuentran salidas interesantes en el mercado actual, nos pareció interesante realizar un estudio sobre el papel desempeñado por las cepas de levadura durante la segunda fermentación a la hora de determinar y modificar la composición de los compuestos volátiles responsables del tan deseado "afrutado " de los vinos espumosos y de aguja elaborados para ser bebidos jóvene
Aroma and fermentation performance of yeast strains in ready to drink sparkling wine production
No full textAt present, not only high end classic sparkling wines but also less “austere” sparkling wines with high youth appeal, are finding a satisfying position in the market. It certainly seemed to be a good idea to look into the role that different yeast strains have on the determination and modification, during the refermentation, of the fermentation volatile compounds responsible for the much sought after “fruity sensation” of sparkling wines that are made to be drank youn
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