Biomedical subjects

M Marlier

Publications and source records attributed to M Marlier.

8 recordsLinked to original sources

PubMed2006

Estimating fatty acid content in cow milk using mid-infrared spectrometry.

Interest in the fatty acid composition of dairy products is increasing; however, the measurement of fatty acids requires using gas-liquid chromatography. Although this method is suitable, it involves a time-consuming procedure, expensive reagents, and qualified staff. By comparison, the mid-infrared (MIR) spectrometry method could be a good alternative for assessing the fatty acid profile of dairy products. The objective of this study was to explore the calibration of MIR spectrometry for estimating fatty acid concentrations in milk and milk fat. Estimated concentrations in milk fat were less reliable than those for the same fatty acids in milk. Results also showed that when the fatty acid concentrations in milk increased, the efficiency of the infrared analysis method in predicting these values simultaneously increased. Selected prediction equations must have a high cross-validation coefficient of determination, a high ratio of standard error of cross-validation to standard deviation, and good repeatability of chromatographic data. Results from this study showed that the calibration equations predicting 12:0, 14:0, 16:0, 16:1cis-9, 18:1, and saturated and monounsaturated fatty acids in milk could be used. Thus, with its potential for use in regular milk recording, this infrared analysis method offers the possibility of assessing and improving the quality of milk produced. Indeed, it enables the fatty acid composition in milk to be estimated for each cow and the estimates to be used as indicator traits to determine the genetic values of underlying fatty acid concentrations. The knowledge of these genetic values would open up opportunities for animal selection aimed at improving the nutritional quality of cow milk.

Animals↗

PubMed2001

The homolytic and heterolytic fatty acid hydroperoxide lyase-like activities of hematin.

Pentenols and pentene dimers are biosynthetized in plants by homolytic fatty acid hydroperoxide lyase (HPL) or HPL-like enzymes. It has been found that these compounds can modify the flavor of olive oil. Reactions between hematin and 13-hydroperoxyoctadecatrienoic acid resulted in the formation of the same compounds via a free radical reaction in which an alkoxyl radical derived from linolenic acid hydroperoxide undergoes a beta-scission. (Z)-3-Hexenal has also been detected as a minor product of the reaction. It is bioconversed from the same substrate in plants by heterolytic HPL. Thanks to the redox cycle of its central iron, hematin has both homolytic and heterolytic HPL-like activities.

Aldehyde-Lyases↗

PubMed2001

Modelling migration from high-density polyethylene containers into concentrated solutions used as food flavourings.

Migration from high-density polyethylene into different liquids (hexane, ethanol, lemon terpenes and their emulsions) was modelled using the response surfaces method. Polynomial equations (z = A + Bx + Cy + Dx2 + Ey2 + Fxy) were established and parameters determined for each compound. Correlation coefficients were generally > 90%. Analysis indicated that 2,4-bis(1,1-dimethylethyl)phenol, probably due to the degradation of the antioxidant additive tris(2,4-bis(1,1-dimethylethyl)phenyl)phosphite, migrated into each liquid tested, whatever the temperature. Oligomers (10-30 carbons) terminated by a vinyl group were also detected.

Chromatography, Gas↗

PubMed2000

Characterization of two Acacia gums and their fractions using a langmuir film balance.

The mechanical properties of monolayers from two Acacia gums [Acacia senegal (L.) Willd. and Acacia seyal Del.] and their three fractions isolated by hydrophobic interaction chromatography were studied with a Langmuir film balance to obtain a more complete understanding of their action mode. The analysis of compression isotherms revealed that A. senegal gums globally exhibit better interfacial properties than A. seyal ones. The behavior of the whole gums appeared to be strongly influenced by their arabinogalactan-protein complex.

Chromatography↗

PubMed2000

Potato tubers exhibit both homolytic and heterolytic hydroperoxide fatty acid-cleaving activities.

The action of a crude potato-tuber extract on 9- and 13-hydroperoxides of linoleic and linolenic acids was investigated. HPLC analysis revealed that 50% of the 9-hydroperoxide isomers and almost all the 13-hydroperoxide isomers were rapidly enzymically metabolized. No degradation of fatty acid hydroperoxides was observed with a thermally denatured enzymic extract. GC-MS identification of the volatiles formed by the reaction revealed that no volatiles were detected from the 9-hydroperoxide isomers, whereas 13-hydroperoxide of linolenic acid was cleaved into (Z)-3-hexenal, pentenols or dimers of pentene.

Alkenes↗

PubMed1995

Measurement of glucosinolates in rapeseeds.

Several ring tests have been organized by the International Organisation for Standardization (ISO) and the Measurement and Testing Programme (BCR) for improving glucosinolate methods. Finally, HPLC of desulphoglucosinolates is recommended by ISO, the European Committee for Standardization (CEN), and the European Commission (EC) as the official method. X-ray fluorescence has also become particularly common for fast analysis. After checking stability of intact glucosinolates in whole rapeseeds, the BCR has three reference materials (CRM 366, CRM 190, CRM 367) available, certified for their total glucosinolate and sulphur contents. Currently, the Measurement and Testing Programme is supporting a research project concerning the stability of desulphoglucosinolates and intact glucosinolates extracts. At the present time, best results are observed with lyophilized extracts sealed in brown glass ampoules and stored at -18 degrees C.

Brassica↗

PubMed1989

Validation of a quantitative procedure for the extraction of sterols from edible oils using radiolabelled compounds.

The work described in this paper is integrated in an analytical programme organised by the Community Bureau of Reference with the aim of developing reference materials certified for sterol content. Preliminary inter-comparison of methods showed that the level of agreement of the results was insufficient for certification purposes. Errors could occur in the different steps before the final determination by gas-liquid chromatography. It was, therefore, decided to validate a quantitative procedure for the isolation of sterols. A well defined saponification-extraction method was tested using labelled sterols ([3H]cholesterol and [3H]cholesteryl oleate) and radiochemical measurements. The study has shown that total cholesterol recovery reached 100.5 +/- 1.4%, that cholesteryl ester was saponified quantitatively and that there were no appreciable amounts of degradation products. The procedure has been used as the basis for the certification of three reference materials and it has been shown that the saponification and extraction procedure leads to the quantitative recovery of sterols regardless of the nature of the fatty material tested.

Cholesterol↗

PubMedDate not supplied

Dexamethasone bovine pharmacokinetics.

Dexamethasone phosphate (DXM-PHO) is an ester which is quickly hydrolysed by the bovine and the dexamethasone (DXM) plasma half-life was 5.16 h. It has been demonstrated that 54 h after DXM-PHO injection, DXM concentrations were lower than 0.1 mg/ml. Tritiated dexamethasone was also administered twice to an another young bull for metabolite investigation. The elapsed time required to recover, in plasma, half of the radioactivity injected was 8.8 h. Radioactivity recovery in the urine reached 36.4% and 22.6% for the first and the second injections respectively.

Animals↗