Miguel Palma Lovillo

A new FT-IR method combined with multivariate analysis for the classification of vinegars from different raw materials and production processes.

BACKGROUND Due to the diversity of vinegars on the market and the increase in demand, it is considered necessary to investigate and establish criteria for classifying them in order to obtain more information concerning their real origin. New spectroscopic techniques such us mid-infrared spectroscopy with Fourier transform (FT-IR) are capable of providing information in relation to these aspects. FT-IR combined with multivariate analysis has been used to classify vinegars according to the raw materials and production processes (with or without ageing in wood). Principal component analysis (PCA), partial least-squares discriminant analysis regression (PLS-DA) and stepwise linear discriminant analysis (SLDA) were used. RESULTS The results obtained have been compared to those achieved using different analytical parameters (polyphenolic content, organic acids and volatile compounds). SLDA and PLS-DA results show the ability of mid-FT-IR spectra to discriminate among vinegars from different raw materials and with or without ageing in wood, with correct classification percentages similar to those obtained using different analytical parameters. CONCLUSION The discriminative ability combined with other advantages (e.g. rapid and non-destructive analysis, low cost) makes this new FT-IR method a promising tool for the classification and/or differentiation of vinegars.

Direct determination of phenolic acids and hydroxymethylfurfural in wines elaborated in Vale do São Francisco region-Brazil by HPLC DAD

The present paper describes a direct method for the determination of gallic acid, hydroxymethylfurfural, vanillic, caffeic, p-coumaric, ferulic, caftaric, cis-coutaric, fertaric and trans-coutaric acids in Brazilian red wines by direct injection employing reverse phase high performance liquid chromatography (RP HPLC DAD). The method was performed using a sample volume of 10 μL and the separation process was established employing a monolithic column. The method was applied for analysis of red wine samples collected from the Sao Francisco region, Bahia State, Brazil. Ten wine samples were analysed and the contents of caftaric acid varied from 13.28 to 46.83 mg L−1, cis-coutaric acid from 1.01 to 2.13 mg L−1, trans-coutaric acid from 2.13 to 17.56 mg L−1, fertaric acid from 1.11 to 2.43 mg L−1, ferulic acid from 0.31 to 3.97 mg L−1, hydroxymethylfurfural from 0.59 to 8.83 mg L−1, vanillic acid from 2.90 to 11.57 mg L−1, caffeic acid from 4.20 to 14.20 mg L−1, p-coumaric acid from 0.26 to 12.46 mg L−1 and ferulic acid from 0.31 to 3.97 mg L−1.