New method for a two-step hydrolysis and chromatographic analysis of pectin neutral sugar chains

in Journal of Agricultural and Food Chemistry (2004), 52(15), 4652-4659

A new method for the determination of the main neutral sugars in pectin has been developed. The sample preparation involves a mild chemical attack followed by an enzymatic hydrolysis. The completeness and ... [more ▼]

A new method for the determination of the main neutral sugars in pectin has been developed. The sample preparation involves a mild chemical attack followed by an enzymatic hydrolysis. The completeness and nondestructive character of the method are demonstrated by comparison of the results obtained with different acids such as H2SO4, HCI, and trifluoroacetic acid (TFA) at different concentrations (2, 1, or 0.2 M) at two temperatures (80 or 100 degreesC). The chemical hydrolysis of pectin neutral sugar chains with strong acid (1 or 2 M) and high temperature (100 degreesC) shows that the liberation of the pectin sugars is not realized at the same rate for each sugar. Different optimum conditions are thus obtained. However, the chemical pectin hydrolysis with 0.2 M TFA at 80 degreesC is characterized by the liberation of pectin neutral sugar side chains without any degradation within 72 h of hydrolysis. Under these conditions, the liberation of some pectin sugars, essentially galactose, glucose, and rhamnose, was not complete. An enzymatic hydrolysis is necessary to obtain a complete release of all the sugars. The combination of the two treatments, a chemical hydrolysis realized with diluted acid (0.2 M) for 72 h at low temperature (80 degreesC) on one hand and an enzymatic hydrolysis on the other hand, allow a total liberation of pectin sugars. The quantitative analysis of the carbohydrates is realized with accuracy, high selectivity, and sensitivity with high-performance anion-exchange chromatography with pulsed-amperometric detection. The sugars can be analyzed without any derivatization with a limit of quantification of 0.1 mM. [less ▲]

Enfin "Tubambe" devoile son identite! Hadraphe ethiopica (Bethune-Baker) (Limacodidae), une chenille comestible des forets claires zambeziennes.

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2003), 7(2), 67-77

La consommation humaine de chenilles de Limacodidae avait été signalée en Afrique centro-australe. L’une de ces espèces, Hadraphe ethiopica, a été déterminée. Des données relatives à sa biologie ont été ... [more ▼]

La consommation humaine de chenilles de Limacodidae avait été signalée en Afrique centro-australe. L’une de ces espèces, Hadraphe ethiopica, a été déterminée. Des données relatives à sa biologie ont été rassemblées. Des analyses d’échantillons séchés ont permis de préciser leur composition chimique et leur valeur nutritionnelle, notamment sur le plan des acides aminés et des acides gras. [less ▲]

Study on isoenzymes polymorphism in Lima bean (Phaseolus lunatus L.)

Poster (2003)

High-Performance Liquid Chromatography Analyses Of Pyoverdin Siderophores Differentiate Among Phytopathogenic Fluorescent Pseudomonas Species

in Applied and Environmental Microbiology (2003), 69(2),

Nouvelles fractions d'inuline. Leur préparation et leur utilisation.

Patent (2002)

Fast And Reliable Chromatographic Procedure For The Purification Of Virginiamycin M-1 Factor

in Chromatographia (2002), 56(5-6),

(EN) NOVEL INULIN FRACTIONS, PREPARATION AND USE

Patent (2001)

The invention concerns novel inulin fractions, characterised by endothermal peaks of differential calorimetric analysis and by domains of polymerising degree, methods for obtaining said fractions by ... [more ▼]

The invention concerns novel inulin fractions, characterised by endothermal peaks of differential calorimetric analysis and by domains of polymerising degree, methods for obtaining said fractions by fractionating solutions, solutions saturated or dispersed with inulins, hydrocolloidal compositions and gels obtained with said fractions, and uses of said fractions in food composition or the like. [less ▲]

Influence of culture conditions on lipopeptide production by Bacillus subtilis

in Applied Biochemistry and Biotechnology (2001), 91-3

Bacillus subtilis produces various families of lipopeptides with different homologous compounds. To produce "new molecules" with improved activities and to select strains that produced a reduced number of ... [more ▼]

Bacillus subtilis produces various families of lipopeptides with different homologous compounds. To produce "new molecules" with improved activities and to select strains that produced a reduced number of homologs or isomers, we studied the effects of different media on the nature of the synthesis of fatty; acid chains for each lipopeptide family. This study focused on two B. subtilis strains cultivated in flasks. Optimized medium for lipopeptide production and Landy medium modified by replacing glutamic acid with other alpha -amino acids were used. We found that the intensity of production of homologous compounds depends on the strain and the culture medium. Analysis of these lipopeptides by high-performance liquid chromatography showed that the strain R. subtilis NT02 yielded various homologous compounds when cultivated in Landy medium (L-Glu), but primarily one homologous product in hi,oh relative amounts when cultivated in the optimized medium. Mass spectrometric analysis and determination of the amino acid composition of this molecule enabled us to identify it as Bacillomycine L c15. [less ▲]

Influence of the culture conditions on lipopeptide production by Bacillus subtilis

Poster (2000, May)

1897-1997, 100 ans de Chimie et Industries agricoles

Book (2000)