Chemical composition, bioactive compounds, and volatiles of six table grape varieties (Vitis vinifera L.)

Chemical profile and antioxidant potential of four table grape (Vitis vinifera) cultivars grown in Douro region, Portugal

The aim of this work was to improve the knowledge about the potential of Douro region (North of Portugal) to produce table grapes of superior quality. Skin, pulp, and seeds of four table grapes ‘Alphonse Lavallée’, ‘Cardinal’, ‘Dona Maria’ and ‘Muscat Hamburgo’ produced in Dour region, collected at commercial maturity stage, were evaluated. Phenolic compounds, organic acids and sugars were determined in each cultivar and in the different parts of the grape by HPLC-DAD, while the antioxidant properties were evaluated by DPPH, Cuprac and lipid peroxidation assays. Phenolics from different classes were found: four anthocyanins (delphynidin, cyanidin, petunidin and malvidin), two hydroxibenzoic acids (gallic acid and protocatechuic acid), three hydroxycinnamic acids (caffeic, chlorogenic and coumaric acids), one flavonol (rutin), three flavan-3-ols ((+)-catechin, (-)-epicatechin, and (-)-epicagallocatechin)), one oligomer (procyanidin B2) and one stilbene (resveratrol). In addition, three organic acids (tartaric, malic and citric acids) and two types of sugars (glucose and fructose) were detected in all samples. Differences were found between cultivars (p<0.001) and sample material type (p<0.001). Skins presented the higher content in anthocyanins, seeds in flavan-3-ols and pulps in phenolic acids, organic acids and free-sugars. The cultivar ‘Cardinal’ showed the highest content in phytochemicals, while ‘Dona Maria’ was the cultivar with the lowest content. Nonetheless, the content of flavan-3-ols and organic acids in ‘Dona Maria’, associated with its higher antioxidant capacity, makes it an interesting choice as table grape from healthier point of view. According to our results, Douro region have proper environmental conditions to produce these table grapes.

A thaumatin-like genomic sequence identification in Vitis vinifera l., stormy wines and musts based on direct pcr

Direct polymerase chain reaction method was use to amplify a thaumatin-like sequence of Vitis vinifera L. in grapes as well as in stormy wines and musts. Thaumatin-like proteins (TLPs) of Vitis vinifera possess beside its function in abiotic and biotic stress response another one - they are able to cause protein haze in wine unless removed prior to bottling. Direct PCR is an approach where omission of DNA extraction is typical prior the amplification of the target site of plant genome. Crude extract or small pieces of plant tissues are used in the analysis directly without steps of extraction and purification of gDNA. The biological material that was used in analysis was collected during August - October 2017 in local stores and winery Sabo and comprises from cultivars Iršai, Muškát, Savignon Blanc, Svätovavrinecké, Dornfelder and Pálava. Direct PCR was performed by a cutted piece of grape tissue and a dilution buffer was use in 1:2 for stormy wine or must, respectively. Direct amplification of thaumatin-like protein sequence of Vitis vinifera was performed along with the control reactions with the primers for conserved region of plant chloroplast. Possitive amplification of thaumatin-like allergen sequence resulted in 570 bp amplicon. The most abundant amplicons were amplified in stormy wines, followed by musts and the amplicons from grapes were weaker when comparing them to others. The amplicon specificity checking of obtained PCR product of thaumatin-like allergen was performed by restriction cleavage by Psi I and resulted in restriction amplicons of the 80 bp, 81 bp, 94 bp and 315 bp in length. Confirmation of the amplicon specificity by restriction cleavage support the potential of direct PCR to become a reproducible method that will be fully applicable in routine analysis of not only plant genomes in the future, but it was demonstrated, that it works in liquids, too.