Search results for "gas chromatography."

The aroma of strawberry (Fragaria ananassa): Characterisation of some cultivars and influence of freezing

1990

The volatiles of six strawberry (Fragaria ananassa Duch) cultivars, both fresh and deep-frozen, were isolated by direct dichloromethane extraction. Sixty compounds were identified and quantified by GC—MS. Characterisation of cultivars was achieved by applying principal component analysis to the chromatographic data. Great differences were observed. Maxim and Directeur Paul Wallbaum are rather low in volatiles while Gariguette and Tioga are rich in mesifurane (2,5-dimethyl-4-methoxy-2,3-dihydrofuran-3-one), furaneol' (2,5-dimethyl-4-hydroxy-2,3-dihydrofuran-3-one) and nerolidol. Esters are the major compounds in Senga Sengana and Vicomtesse Hericart de Thury. This last cultivar is also chara…

Modifications Over Time of Volatile Compounds in Coriander (Coriandrum sativum L.)

2009

Effect of fat nature and aroma compound hydrophobicity on flavor release from complex food emulsions.

2004

Complex food emulsions containing either hydrogenated palm kernel oil (vegetable fat) or anhydrous milk fat (animal fat) were flavored by using different aroma compounds. The fats differed by their fatty acid and triacylglycerol compositions and by their melting behavior, while the aroma compounds (ethyl butanoate, ethyl hexanoate, methyl hexanoate, mesifurane, linalool, diacetyl, cis-3-hexen-1-ol, and gamma-octalactone) differed by their hydrophobicity. Application of differential scanning calorimetry to fat samples in bulk and emulsified forms indicated differences in the ratio of solid-to-liquid between temperatures ranging from 10 to 35 degrees C. Solid-phase microextraction coupled wit…

Stabilization of a nutraceutical omega-3 fatty acid by encapsulation in ultrathin electrosprayed zein prolamine.

2010

Docosahexaenoic acid (DHA) is a long chain polyunsaturated fatty acid of the omega-3 series (omega-3), which exerts strong positive influences on human health. The target of this study was the stabilization by encapsulation of this bioactive ingredient in zein ultrathin capsules produced by electrospraying. The zein ultrathin DHA encapsulation was observed by ATR-FTIR spectroscopy to be more efficient against degradation under both ambient conditions and in a confined space (so-called headspace experiment). In the latter case, that more closely simulates a sealed food packaging situation, the bioactive DHA was considerably more stable. By fitting the degradation data to a specific auto-deco…

Analysis of furan in coffee of different provenance by head-space solid phase microextraction gas chromatography-mass spectrometry: effect of brewing…

2009

A simple, sensitive and accurate method for the analysis of furan in roasted coffee has been used based on headspace-solid-phase micro-extraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The extraction was performed using 75-microm carboxen/polydimethylsiloxane fiber. Ionic strength, extraction time and temperature, and desorption time were assessed as the most important parameters affecting the HS-SPME procedure and d(4)-furan was used as the internal standard. The linearity range was in the range 0.0075-0.486 ng g(-1); the LOD and LOQ calculated using the signal-to-noise ratio approach were 0.002 and 0.006 ng g(-1), respectively. The inter- and intra-day precisio…

Thermal degradation and isomerisation kinetics of triolein studied by infrared spectrometry and GC–MS combined with chemometrics

2008

Authors version of article published in the journal: Chemistry and Physics of Lipids Published version available on Science Direct: http://dx.doi.org/10.1016/j.chemphyslip.2008.12.002 Triolein, a triglyceride containing oleic acid as the only acid moiety in the glyceride molecules has been isothermally treated at 280,300,and 325 degrees C in glass vials under nitrogen atmosphere. The products formed during the thermal treatment at each temperature have been analysed both by infrared spectrometry and GC-MS. The CC-MS analysis was performed after derivatisation of the fatty acids into their methyl esters (FAMEs). Chemometric tools were used in determining the concentrations of the main produc…

Analysis of hybrid silica materials with the aid of conventional NMR and GC/MS.

2009

Two simple and straightforward procedures for determining the organic content of hybrid silica materials by means of conventional NMR and GC/MS techniques are described. The methods involve dissolving the hybrid material either in a concentrated solution of sodium hydroxide in deuterated water containing a suitable reference or in a solution of hydrogen fluoride in water and extracting with methylene chloride. These methods constitute useful routine techniques for obtaining immediate information concerning both the amount and chemical composition of the organic compounds on the silica surface.

Understanding fat, proteins and saliva impact on aroma release from flavoured ice-creams

2017

Publication également référencée sous le numéro WOS:000437803400018; The release profile of fourteen aroma compounds was studied in ice cream samples varying in fat and protein, both in level and type. In vitro aroma release was monitored by solid phase micro-extraction gas chromatography using an innovative saliva reactor, which imitated human chewing under temperature control. The results showed that the effect of the fat type on aroma release was smaller than that of fat level. Ice creams with low fat level released more hydrophobic aroma compounds than ice creams with high fat level. At low fat level more aroma compounds were released from ice creams with lower protein content. At high …

Gas chromatographic determination of organochlorine pesticides in cow milk.

2004

A gas chromatographic method of use in determining the following organochlorine pesticides in cow milk has been adapted and validated: alpha-hexachlorocyclohexane (alpha-HCH), beta-HCH, lindane, delta-HCH, hexachlorobenzene, aldrin, heptachlor, heptachlor epoxide, mirex, 2,4-dichlorodiphenyltrichloroethane (2,4-DDT), 4,4-DDT, 2,4-dichlorodiphenyldichloroethane (2,4-DDD), 4,4-DDD, 2,4-dichlorodiphenylethane (2,4-DDE) and 4,4-DDE. The method studied consists of three steps: the extraction of fat by centrifugation, mixing with anhydrous sodium sulfate, and transfer to a glass column and elution with hexane; purification of the extract via concentrated sulfuric acid treatment; and determination…

A new potential toxaphene congener: synthesis, GC/EI-MS study, crystal structure, NMR analysis, and ab initio calculations of 3-endo,5-endo-dichloro-…

2001

Abstract A new potential toxaphene congener 3- endo ,5- endo -dichloro-7,7-bis-chloromethyl-4-dichloromethyl-tricyclo[2.2.1.0 2,6 ]heptane 2 has been isolated from reaction mixture obtained by the chlorination of 2- exo ,10,10-trichlorobornane 1 . The X-ray structural analysis of 2 revealed an unusual tricyclic structure, where the two chlorine atoms occupying endo -positions are in close spatial proximity with each other and near to the neighbouring CHCl 2 group. Further, it revealed that the symmetry of the molecule is distorted. The 1 H and 13 C NMR spectra of 2 have been assigned by means of 1 H, 1 H d ouble- q uantum f iltered co rrelation s pectroscop y (DQF COSY), PFG 1 H, 13 C HMQC …