G. Vernin

Volatile Constituents of the Jamrosa Aroma Syzygium jambos L. Aston from Reunion Island

ABSTRACT GC/MS analyses on polar and apolar columns of an aromatic extract of the fruit of Jamrosa-tree from Reunion allowed the identification of 80 volatile compounds: 12 hydrocarbons, 8 oxides and acetals, 12 aldehydes, 9 ketones, 5 esters, 31 alcohols, 3 acids. The presence of a few furan derivatives (unsaturated γ-lactones) is suspected. Among the identified compounds, geraniol, nerol, β-phenylethyl alcohol, linalool, hotrienol, citronellol, four linalool oxides (furans and pyrans), rose oxides and nerol oxide are well-known components of the Bulgarian rose oil. Other compounds, such as, (E)- and (Z)-cinnamaldehydes and their corresponding alcohols and acetates, 3-phenylpropyl alcohol and 3-phenyl propanal are responsible for the cinnamon-spicy-like note of this exotic fruit.

Melanoidins in the Maillard reaction

Abstract This paper is a review of the studies on melanoidins, the end heavy products of the Maillard reaction. It deals with the description of melanoidins in foods and model systems as well as their physical and chemical methods of analysis, their chemical properties and their biological and antioxidative activities in vivo and in nature. Some reconstructed mass spectra using our SPECMA 2000 data bank are also reported. The paper includes research prospects in a field which has been almost unexplored until now.

Applications de la théorie de la chromatographie d'adsorption linéaire de Snyder en série hétérocyclique : I. Influence des effets polaires et stériques de substituants divers sur les énergies d'adsorption d'hétérocycles thiazoliques sur alumine

Abstract Applications of Snyders theory on linear adsorption chromatography to heterocyclic compounds. I. The influence of the polar and steric effects of various substituents on the adsorption energy of thiazoles on alumina Snyders theory of linear adsorption chromatography, that was applied to one hundred thiazole derivatives, made it possible to determine experimentally the adsorption energies of the compounds and to compare these with the adsorption energies calculated by means of fixed tables. In a study on thiazoles containing one or two alkyl groups, this comparison enabled us to determine the variations in adsorption energy of the nitrogen atom of the ring due to the polarization effects and to the steric effects induced by the alkyl groups and to relate these effects to the constant relationships which exist between the polarization and steric effects of the substituents. A similar investigation was made on 4-aryl thiazoles with various substituents in the 2-position. In this case variations in the adsorption energy of the molecules due to the polarization effects of the groups substituted para to the phenyl group with respect to the substituents in the 2-position were studied, and the mutual electronic interactions between the various groups were determined.

Les applications de la théorie de la chromatographie d'adsorption lineaire de Snyder en série hétérocyclique : II. Cas de la silice; comparaison avec l'alumine

Applications of Snyders theory on linear adsorption chromatography to heterocyclic compounds. II. Silica gel in comparison with aluminium oxide Snyders theory of linear adsorption chromatography has been applied to one hundred thiazoles, and we have experimentally determined the adsorption energy on silica gel and aluminium oxide (Merck). By comparing these results with the adsorption energy estimated by calculations using data in fixed tables, we could determine the total interactions of different groups inside these molecules. The interactions are additive, in the case of the groups that are weakly adsorbed (alkyl and halogen) and in the absence of steric hindrance on every side of the adsorption center. The sensitivity of these molecules to the steric effects of the alkyl groups is more important on aluminium oxide than on silica gel. In the series of the 4-aryl thiazoles with different groups in the 2-position we have also studied the variation of adsorption energy, under the effects of the subtituents in a position para to the phenyl group in the 4-position and of the substituents in 2-position. This study allows us to relate these variations to the polar and steric effects of these substituents, but, the molecule being complex, other phenomena may also occur.

Geranium (Pelargonium sp.) Essential Oil from Reunion. Minor Compounds: Acids, Phenols, Pyridines

Abstract The essential oil of geranium Bourbon (Pelargonium sp.) from Reunion was separated into acidic/phenolic and basic fractions by acido-basic extraction, respectively. The first fraction was converted into methyl esters and ethers (phenols). The two fractions were analyzed by GC/MS on a nonpolar column. In the acidic/phenolic fraction 75 compounds were separated, of which 30 were newly identified. In the basic fraction, two new pyridines—the 2- isopropyl-4-methylpyridine, and the cis-3-(1-butenyl) pyridine—were identified among other unknown amino compounds.