Effects of ozone treatment on the molecular properties of wheat grain proteins

International audienceOzone is a powerful and highly reactive oxidizing agent, which has found increasing applications in the field of grain processing. However, in some cases, O3 can potentially promote oxidation and/or degradation of the chemical constituents of grains. Experiments were carried out to evaluate the specific effects of gaseous ozone on the molecular properties of wheat grain proteins and their consequences on the bread-making quality of the resulting flours. Ozonation causes a significant reduction in the SDS solubility of the wheat prolamins, which can reasonably be attributed to conjugate effects of an increase in molecular dimensions and an increase in the compactness of the protein polymers initially present. In fact, our results demonstrate that this general reinforcement of the aggregative status of prolamins due to ozonation of wheat grains results from (i) the formation of new intermolecular S-S bonds, (ii) to a lesser extent, the formation of other types of intermolecular covalent cross-links (dityrosine cross-links) and finally, (iii) significant changes in secondary structure. By significantly affecting the molecular properties of wheat grain prolamins, ozone leads to profound changes in the rheological properties (i.e. increase in the tenacity and a great limitation of the extensibility) of the flours and/or doughs obtained

PROCEDE DE TRAITEMENT DU CRESSON

Ce procédé de traitement du cresson de fontaine (Nasturtium Officinale) est remarquable en ce qu'on procède à une zéodratation de ce cresson au moyen de zéolithe

PROCEDE DE TRAITEMENT DU CRESSON

Ce procédé de traitement du cresson de fontaine (Nasturtium Officinale) est remarquable en ce qu'on procède à une zéodratation de ce cresson au moyen de zéolithe

Effects of Maillard Reaction Products on Sensory and Nutritional Qualities of the Traditional French Baguette

International audienc

Carbamylation and glycation compete for collagen molecular aging in vivo

International audienceTissue aging is a complex phenomenon involving molecular aging of matrix proteins, which mainly results from their progressive alteration by nonenzymatic post-translational modifications (NEPTMs) such as glycation and carbamylation. These two reactions, which correspond to the binding of reactive metabolites ( i.e . reducing sugars and urea-derived cyanate, respectively) on amino groups of proteins, occur during aging and are amplified in various chronic diseases such as diabetes mellitus or chronic renal disease (CKD). Since these reactions target the same functional groups, they can reciprocally compete for protein modification. Determining which NEPTM is predominant in tissues is necessary to better understand their role in the development of long-term complications of chronic diseases. For that purpose, two different murine models were used for reproducing such a competitive context: a CKD-diabetic mice model and a cyanate-consuming mice model. The competition has been evaluated by quantifying glycation and carbamylation products by LC-MS/MS in skin and aorta total extracts as well as in skin type I collagen. The results showed that the simultaneous enhancement of glycation and carbamylation reactions resulted in a decrease of the formation of glycation products (especially Amadori products) whereas the concentrations of homocitrulline, a carbamylation product, remained similar. These results, which have been obtained in both tissues and in purified skin type I collagen, suggest that carbamylation takes precedence over glycation for the modification of tissue proteins, but only in pathological conditions favouring these two NEPTMs. While glycation has been considered for a long time the predominant NEPTM of matrix proteins, carbamylation seems to also play an important role in tissue aging. The existence of competition between these NEPTMs must be taken into account to better understand the consequences of molecular aging of matrix proteins in tissue aging

Effect of fermentation time and temperature on the sensory and nutritional properties of French bread.

International audienc

HPLC-DAD optimization of quantification of vescalagin, gallic and ellagic acid in chestnut tannins

The quantification of hydrolysable polyphenols such as gallic, ellagic acid and vescalagin by HPLC-DAD is classically run after methanol extraction as a reference solvent. Water extraction is usually discarded because of a lower obtention of total polyphenol content compared to methanol extraction. In our study, methanol was compared to water extraction in both the total polyphenol content method and the HPLC-DAD analysis. Total polyphenol content in water extraction was lower than in methanol extraction, but water extraction gave better results on HPLC-DAD. In conclusion, total polyphenol content cannot be used as reference to choose the solvent of extraction to quantify some polyphenols by HPLC-DAD because of the specific properties of each polyphenol. Indeed, recovery results obtained on hydrolysable polyphenols with water extraction were better and with a lower variability than following methanol extraction

Effect of fermentation time and temperature on the sensory and nutritional properties of French bread.

International audienc