Search results for "CHROMATOGRAPHY"
showing 10 items of 5037 documents
Influence of flavour transfer between different gel phases on perceived aroma
2007
International audience; Multiphasic models of stirred fruit yoghurts made from a bilayer that consisted of a pectin and a dairy gel were developed in order to study the transfer of strawberry flavour compounds between the two phases. Several parameters (i.e., the flavour concentration, the fat content of the dairy gel and the storage temperature) affecting flavour compound transfer, using an experimental design, together with their effect on sensory perception were investigated. Strawberry flavour transfer between the two gels was high enough to affect the sensory perception of the dairy gels. The parameters that modified the partitioning of ethyl esters between the pectin and dairy gel (i.…
Retention/release equilibrium of aroma compounds in fat-free dairy gels
2010
BACKGROUND: The replacement of fat by thickeners in fat-free yoghurts leads to an important modification of aroma compound partitioning, with an impact on aroma perception. Investigation of retention/release equilibria allows a good understanding of aroma compound behaviour depending on food composition. RESULTS: Vapour/liquid equilibria of ten aroma compounds (two esters, two ketones, three aldehydes and three alcohols) in several media were studied to investigate the influence of pectin addition to fat-free dairy gel on the retention/release equilibrium. The partition coefficient of each aroma compound was measured by headspace analysis at equilibrium in six media (pure water, low-methoxy…
Identification of Abies sibirica L. Polyprenols and Characterisation of Polyprenol-Containing Liposomes
2020
The needles of conifer trees are one of the richest sources of natural polyprenols. Polyprenol homologs from Abies sibirica L. lipophilic 80% purified extract were analyzed and quantified. In total, 10 peaks (Prenol-11 to Prenol-20) were observed in the ultra-high-performance liquid chromatography&ndash
Influence of low methoxyl pectin gel textures and in vitro release of rutin from calcium pectinate beads.
2013
This study described the preparation and characterization of low methoxyl pectin (LMP) gels and beads for controlled release applications. The rheological characterization of the various formulations was proposed. Then the mechanical and morphological characterizations of beads were determined. Finally, the controlled release studies taking rutin as a model drug was evaluated. The results showed that Young's modulus values of non-amidated LMP gels decrease when adding up to 15% sorbitol. Calcium pectinate beads loaded with rutin are about 600 μm, oblong shaped with dense matrix. Beads containing sodium bicarbonate showed about 80% lower rutin encapsulation efficiency by increasing the pH of…
Isolation of Gram-positive n-alkane degraders from a hydrocarbon-contaminated Mediterranean shoreline.
2007
Aims: To investigate the petroleum hydrocarbon (HC)-degrading potential of indigenous micro-organisms in a sandy Mediterranean coast, accidentally contaminated with petroleum-derived HCs. Methods and Results: Using culturable methods, a population of Gram-positive n-alkane degraders was detected in the contaminated soil. Five isolates, identified as one Nocardia, two Rhodococcus and two Gordonia strains, were able to degrade medium- and long-chain n-alkanes up to C36 as assessed by growth assays and gas chromatography-mass spectrometry analysis. Diverging alkane hydroxylase-encoding genes (alkB) were detected by PCR, using degenerated primers, in all the strains; multiple sequences were obt…
Effect of electric currents on antibacterial effect of chlorhexidine against Entrococcus faecalis biofilm : An in vitro study
2018
Background This in vitro study was mainly aimed to evaluate the effect of high-frequency alternating currents (AC) applied by an electronic apex locator (EAL) on the antibacterial properties of chlorhexidine (CHX) on E. faecalis biofilm. Material and Methods The root canals of 120 extracted human single-rooted teeth were prepared using Gates-Glidden drills and hand K-files. After contaminating the root canals with E. faecalis, they were incubated for 60 days. Then, the teeth were randomly divided into six experimental groups (n=20). Group 1, 2% CHX; group 2, normal saline (NS) with direct current (DC); group 3, normal saline (NS) with high-frequency alternating current (AC); group 4, 2% CHX…
Agronomical and chemical characterisation of Thymbra capitata (L.) Cav. biotypes from Sicily, Italy
2015
In this study the agromomical and chemical characterization of 13 sicilian biotypes of Thymbra capitata (L.) Cav. (or Thymus capitatus Hoff. et Link.) collected from different areas of Sicily (Italy) and grown under the same agricultural and environmental condition are reported. The main morpho-productive parameters and quali-quantitative profile of essential oils were determined . Essential oils were extracts from the aerial parts of the plants by hydrodistillation. The essential oils were analyzed by GC-FID and GC-MS. Hierarchical Cluster Analysis and Principal Component Analysis statistical methods were used to group biotypes according to the essential oils chemical composition. The esse…
Different sample treatment approaches for the analysis of T-2 and HT-2 toxins from oats-based media.
2010
A LC-DAD method is proposed for the determination of the T-2 and HT-2 toxins in cultures of Fusarium langsethiae in oat-based and other in vitro media. Test media consisted of freshly prepared milled oats to which T-2 and HT-2 toxin stock solutions were added. Different mixtures of extraction solvent (acetonitrile:water and methanol water), extraction times (30', 60' or 90') and drying methods were investigated. Results showed that extraction with methanol: water (80:20, v/v) for 90 min, drying with N-2 and subsequent analysis by LC-DAD was the fastest and most user friendly method for detecting HT-2 and T-2 toxins production by F. langsethiae strains grown on oat-based media at levels of 0…
Gas chromatography/mass spectrometry characterization of historical varnishes of ancient Italian lutes and violin
2007
The organic constituents of historical vanishes from two ancient Italian lutes and a Stradivari violin, kept in the Musée de la musique in Paris, have been characterized using gas chromatography-mass spectrometry. Results have been compared with the chromatograms and mass spectra of recent as well as old naturally aged reference materials. The three historical varnishes analyzed have been shown to be oil varnishes, probably mixtures of linseed oil with resins. Identification of diterpenoids and triterpenoids compounds, and of the resins that may have been ingredients of the varnishes, are discussed in this paper.
Transfers of small analytes in a multiphasic stirred fruit yoghurt model
2007
International audience; The transfer of small analytes in a multiphasic stirred fruit yoghurt model, made of a pectin gel aimed to mimic fruit pieces and of a dairy gel done with milk acidified by glucono-δ-lactone hydrolysis, have been studied. The concentration gradients between the pectin gel and the dairy gel were the driving force for the migration of small analytes (i.e. water, protons and colorants). Water migrated from the dairy to the pectin gel, causing modifications in the water content of both gels and an equilibration of their water activity at 0.938±0.003. Inversely, protons migrated from the pectin to the dairy gel. These changes in composition of both gels being likely to ha…