Sylvain Chéreau

First mass spectrometry metabolic fingerprinting of bacterial metabolism in a model cheese.

Metabolic fingerprinting is an untargeted approach which has not yet been undertaken to investigate cheese. This study is a proof of concept, concerning the ability of mass spectrometry (MS) metabolic fingerprinting to investigate modifications induced by bacterial metabolism in cheese over time. An ultrafiltrated milk concentrate was used to manufacture model cheeses inoculated with Lactococcus lactis LD61. Metabolic fingerprints were acquired after 0, 8 and 48h from two different fractions of the metabolome: the water-soluble fraction using liquid chromatography-high resolution-MS and a volatile fraction using gas chromatography-MS. Metabolic fingerprints differed significantly over time. Forty-five metabolites were identified, including well-known cheese metabolites, such as 12 amino acids and 25 volatile metabolites, and less studied ones, such as four vitamins, uric acid, creatine and l-carnitine. These results showed the relevance of cheese MS fingerprinting to generate new findings and to detect even slight differences between two conditions.

Potential of mass spectrometry metabolomics for chemical food safety

This review aims to describe the most significant applications of mass spectrometry-based metabolomics in the field of chemical food safety. A particular discussion of all the different analytical steps involved in the metabolomics workflow (sample preparation, mass spectrometry analytical platform and data processing) will be addressed.

Identification of Cows Treated with Recombinant Bovine Somatotropin

A method for the specific detection and quantification of recombinant bovine somatotropin (rbST) in bovine blood has been validated according to criteria described in the EU Commission Decision 2002/657/EC. The method is based on a thorough purification procedure followed with the detection by LC-ESI-MS/MS of the tryptic N-terminal peptide specific of the rbST. The recombinant equine somatotropin (reST) is used as internal standard. Performance of the method was assessed based on specificity, linearity, trueness and repeatability. Decision limit (CCalpha) and detection capability (CCbeta) were found to be 2.5 ng mL(-1) and 6.8 ng mL(-1), respectively. This method was subsequently applied to the analysis of serum and plasma collected from two different animals treated with 500 mg of rbST. No significant variations were observed when analyzing either serum or plasma, but an important difference between animals was encountered. In all cases, recombinant bovine somatotropin was still detected two weeks after administration.