Influence of filtration treatments on grapevine DNA traceability in wine

Wine authentication through grapevine DNA traceability could be affected by wine technological processing treatments. In this study, filtration treatments including depth filter treatment using kieselguhr, perlite and membrane filtration using different types and pore sizes (0.22 and 0.45 mu m) were applied on 'Nebbiolo' wine at an experimental scale. We used 'Nebbiolo' because it is an important Italian winegrape variety used to produce high-quality wines. Phenolic composition and color properties of the treated wines were examined using spectrophotometric and HPLC methods, while grapevine DNA traceability was evaluated using PCR based assays. The filtration treatments, as expected, significantly decreased turbidity compared to the unfiltered control, although total phenolics, total flavonoids and total non-flavonoids were not significantly affected. A significant reduction of acetylated anthocyanins by 6.1%-43.3% was observed in filtered wines, which could account for the reduced in total anthocyanins and color intensity of these wines. Grapevine DNA was significantly reduced in filtered wine by 37.2%-99.7%, with the reduction rate depending mainly on the properties of filter material. Polyvinylidene difluoride (PVDF) membranes with a pore size of 0.22 mu m showed highest reduction of grapevine DNA in wine, resulting in the failure of TaqMan (R) single nucleotide polymorphisms (SNPs)-based assays used to detect grape DNA in wines.