snif-nmr (3)

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NMR has been used for the authenticity of wines for over 30 years, but has evolved significantly in the last two decades. It was developed as the official method for added water and sugar to wine, but its use in metabolomics gives a lot of information on grape varieties, cultivation techniques and vintage. NMR can also yield information on geographic origin.

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6845726263?profile=RESIZE_400xIsotopic methods have been recognised by CEN (European Committee for Standardisation) and in part by the OIV (Organisation Internationale de la vigne et du vin) as a means of detecting the non-permitted presence of exogenous acetic acid and water in vinegar (CEN) and specifically wine vinegar (OIV). The methods used are EN 16466-1 for D/H in the methyl site of acetic acid [(D/H)CH3] using 2H-SNIF-NMR (Site Specific Natural Isotope Fractionation-Nuclear Magnetic Resonance), EN 16466-2 and OIV 510/2013 for analysis of 13C/12C in acetic acid (δ13C ‰) using IRMS (Isotope Ratio Mass Spectrometry), and EN 16466-3 and OIV 511/2013 for analysis of 18O/16O in water (δ18O ‰) using IRMS.

An international collaborative trial has been undertaken in 7 laboratories to define standard deviations of repeatability (sr) and reproducibility (sR) for vinegar and balsamic vinegar stable isotope ratios of H (D/H), C (δ13C) and O (δ18O), in order to establish them as fully recognised official standards. The laboratories analysed two samples of wine vinegar, one cider vinegar, and four balsamic vinegars. The results of the trial are in line with those in the literature or reported in corresponding official methods, and sr and sR of balsamic vinegar are in line with those of vinegar and must.

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This study examines the variations in isotopes and trace elements in relation to grape variety, environmental factors and provenance in order to address the wine authenticity in Cyprus. ICP-AES assessed the wines’ elemental content. SNIF-NMR and isotope ratio mass spectrometry methodologies determined in authentic and commercial wines the distribution of the naturally occurring stable isotopes of the deuterium/hydrogen (D/H) ratios and carbon (13/12C) in ethanol of wine and oxygen ratio (18/16O) in wine water. PCA (principle component analysis) highlighted the importance of grape variety and provenance, while supervised analysis pinpointed the vineyard effect and highlighted the contribution of the vintage year. These results can be incorporated to the EU Wine Isotopic Databank database providing both a guide and a tool for eventual candidatures for denomination of origin and support both Cypriot wine and winemakers. 

Read the abstract at: http://link.springer.com/article/10.1007/s12161-017-0959-2
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