Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae

Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.Jennifer R. Bellon, Frank Schmid, Dimitra L. Capone, Barbara L. Dunn, Paul J. Chamber

Phenolic composition of Nebbiolo grape (Vitis vinifera L.) from Piedmont: characterization during ripening of grapes selected in different geographic areas and comparison with Uva Rara and Vespolina cv

Grapes (Vitis vinifera L.) are rich in polyphenols; the phenolic composition of grape is very complex and depends on several factors, including grape varieties, ripening stage and pedoclimatic conditions. In this work the amount of total polyphenols, anthocyanins and tannins, the antioxidant activity and the chromatic characteristics of Nebbiolo grapes from Piedmont were determined. Four different cultivation areas and three different ripening stages (starting of veraison, veraison completion and physiological ripeness) were considered. The quantification of individual polyphenols and hydroxycinnamates was performed by RP-HPLC/DAD. In a general way, anthocyanins and flavonols increased during ripening, while antioxidant activity and tannin content remained constant. Differences in specific phenolic composition were observed depending on the sample origin. Nebbiolo samples at different maturity stages were compared among them and with Uva Rara and Vespolina cv: overall Nebbiolo showed the lowest anthocyanin content, evidencing a different profile in respect to the other cultivars (major relative content of peonidin-3-O-glucoside). Multivariate statistical methods (principal components analysis and hierarchical clustering) further permitted recognition of Nebbiolo samples of different geographic origin, particularly those dedicated to \u201cBarolo\u201d winemaking

Metabolic changes of genetically engineered grapes (Vitis vinifera L.) studied by 1H-NMR, metabolite heatmaps and iPLS

Introduction: The Deficiens Homologue 9-iaaM (DefH9-iaaM) gene is an ovule-specific auxin-synthesizing gene which is expressed specifically in placenta/ovules and promotes auxin-synthesis. It was introduced into the genome of two grape cultivars Thompson Seedless and Silcora and both transgenic cultivars had an increased number of berries per bunch. Objectives: This study investigates the down-stream metabolic changes of Silcora and Thompson seedless grape cultivars when genetically modified through the insertion of the DefH9-iaaM gene into their genome. Methods: The effects of the genetic modification upon the grape metabolome were evaluated through 1H-NMR and exploratory data analysis. Chemometric tools such as Interval Partial Least Squares regression and metabolite heatmaps were employed for scrutinizing the changes in the transgenic metabolome as compared to the wild type one. Results: The results show that the pleiotropic effect on the grape metabolome as a function of the gene modifications is relatively low, although the insertion of the transgene caused a decrement in malic acid and proline and an increment in p-coumaric acid content. In addition, the concentration of malic acid was successfully correlated with the number of inserted copies of transgene in the Silcora cultivar, proving that the increased production of berries, promoted by the inserted gene, is achieved at the expense of a decrement in malic acid concentration. Conclusion: NMR together with chemometrics is able to identify specific metabolites that were up- or down regulated in the genetically engineered plants allowing highlighting alterations in the down-stream metabolic pathways due to the up-stream genetic modifications