Biomedical subjects

Jacques Potus

Publications and source records attributed to Jacques Potus.

4 recordsLinked to original sources

PubMed2006

Wheat lipoxygenase activity induces greater loss of carotenoids than vitamin E during breadmaking.

The current study was undertaken to provide solutions to optimize the unsaponifiable antioxidants content of bread. We report a complete description of changes in wheat carotenoids and vitamin E content from grain to bread and highlight the most important processing steps affecting their level in wheat bread. Major carotenoids losses occurred during kneading. A close correlation (r(2) = 0.97; P = 0.05) was found between carotenoid pigment losses and lipoxygenase (LOX) activity, both parameters depending on wheat genotype. The use of wheat species exhibiting high carotenoid contents and low LOX activity was shown to preserve significant carotenoid level in the bread. No relation was found between vitamin E losses during doughmaking and LOX activity. In addition, moderate kneading resulted in higher vitamin E retention in comparison with carotenoids (12% and 66% losses, respectively). It is concluded that carotenoids are more susceptible to oxidation by endogenous lipoxygenase than vitamin E during breadmaking. This study showed that bread nutritional quality, in terms of antioxidant content, could be improved by selecting suitable cereal genotypes, if this potential is preserved by milling and baking processes.

Bread↗

PubMed2004

Separation and quantification by high-performance liquid chromatography with light scattering detection of the main wheat flour phospholipids during dough mixing in the presence of phospholipase.

Phospholipids (PL) are minor components of wheat flour involved in baking quality and exogenous phospholipids are used as emulsifiers giving better loaf volume and crumb grain. Few biochemical data are available on the phospholipid evolution during mixing, probably because of the time-consuming methods proposed for their extraction, separation and quantification. In the present study, the extraction, separation and quantification of the main wheat flour phospholipids were carried out. Total lipids (2% dry mass of wheat flour) were extracted from flour or dough by a mixture of chloroform-methanol-water (1:1:1 (v/v)). The phospholipids were separated from the lipid extract on silica cartridge by solid-phase extraction (SPE) procedure under a 1.5-4 mmHg vacuum, at a 0.8 mL min(-1) flow rate (1 mmHg = 133.322 Pa). The recovery of the lipid extract was 100%, whereas the SPE yield for the PLs was 50%. The resulting fraction was then submitted to HPLC with evaporative light scattering detection on a Diol stationary phase allowing the separation and quantification of each class of phospholipids, in less than 16 min. The developed method allowed to quantify the phospholipid amounts from eight wheat flours as well as their evolution during mixing in the presence of phospholipase.

Chromatography, High Pressure Liquid↗

PubMed2004

Separation and identification by gel filtration and high-performance liquid chromatography with UV or electrochemical detection of the disulphides produced from cysteine and glutathione oxidation.

Methods for quantification of oxidised and reduced forms of glutathione (GSSG and GSH) and cysteine (CSSC and CSH) and the disulphide glutathione-cysteine (GSSC) resulting from the oxidation of the mixture of CSH and GSH are performed by RP-HPLC with coulometric and UV detection after separation of these compounds by size-exclusion fast protein liquid chromatography. The fractionation of the disulphides (GSSG, GSSC and CSSC) was achieved by size exclusion using a Superdex peptide column coupled with an UV detection at 254 nm. The conditions of separation of these compounds by RP-HPLC were optimised using the response surface methodology. Optimal peak resolution and retention times were obtained on a C18 YMC ODS AQ column with 20 mM of ammonium phosphate at pH 2.5 and 2% of acetonitrile in the elution phase. In these experimental conditions, CSH, CSSC, GSH and GSSG were eluted within 20 min. Coulometric detection enabled a sensitivity 100 times higher for the disulphides than the UV detection at 220 nm. These methods were applied to follow the consumption of thiols and the disulphide formation by three oxidising systems, sulphydryl oxidase, glutathione dehydroascorbate oxidoreductase and potassium bromate. This study revealed that the relative proportions of the disulphides formed were similar for the three oxidising systems when the reactions are in their state of equilibrium.

Chromatography, Gel↗

PubMed2002

Oxidation of ferulic acid or arabinose-esterified ferulic acid by wheat germ peroxidase.

The oxidation of ferulic acid (FA) or 5-O-(trans-feruloyl)-L-arabinose (EFA) by a purified wheat germ peroxidase was followed by UV spectrophotometry and high-performance liquid chromatography using an electrochemical detection. Wheat peroxidase (POD) exhibits a ping-pong bireactant mechanism forming phenoxy radicals more rapidly from FA than from EFA in routine assay conditions. When both the free and the esterified forms of FA are present, the reverse was found. This result could be due to a nonenzymatic cooxidation of FA by the phenoxy radicals of EFA leading to the formation of phenoxy radicals of FA and the EFA regeneration. Addition of ascorbic acid (AA) provokes a delay of FA consumption. AA reduced very rapidly the phenoxy radicals formed by POD back to initial phenol avoiding the formation of ferulate dimers until it was completely oxidized in dehydroascorbic acid. Conversely, cysteine addition slowed but did not delay the FA consumption. The thiol reduced a fraction of the phenoxy radicals produced by wheat POD and was oxidized into cystine, while the other part of phenoxy radicals formed ferulate dimers. These results could be of interest to understand the POD effect on the wheat dough rheological properties.

Arabinose↗