Influence of fruit maturity at harvest on the intensity of smoke taint in wine

Bushfire smoke can affect the composition and sensory properties of grapes and wines, in some cases leading to wines which exhibit undesirable "smoky", "ashy" and "medicinal" characters. This study investigated the extent to which fruit maturity (i.e., ripeness) influences the perception of smoke taint in wine. Two white grape varieties (Chardonnay and Sauvignon Blanc) and two red grape varieties (Merlot and Shiraz) were exposed to smoke under experimental conditions, at approximately seven days post-veraison. Fruit was then harvested at two levels of maturity: Harvest A, when total soluble solids were 16-20 °Brix, i.e., the berry ripeness typically required for production of sparkling or light-bodied wines; and Harvest B, when total soluble solids were 22-25 °Brix, i.e., the berry ripeness typically required for production of full-bodied wines. The intensity of smoke taint in resulting wines was found to be influenced by fruit maturity, but differed between grape varieties. Smoke-related sensory attributes were apparent in Sauvignon Blanc wine made from early-harvested fruit and in Chardonnay wine made from late-harvested fruit, only; whereas Merlot and Shiraz wines exhibited smoke taint irrespective of fruit maturity. Smoke-derived volatile phenols, and various alcohols, esters and acids, were also quantified to determine the impact of smoke exposure and fruit maturity respectively, on wine composition.Renata Ristic, Paul K. Boss and Kerry L. Wilkinso

Propuesta de mejora del Sistema Interno de Garantía de Calidad de la Facultad de Medicina

La garantía de calidad en el ámbito universitario puede considerarse como la atención sistemática, estructurada y continua a las titulaciones ofertadas. La garantía de calidad se compromete a poner en marcha los medios que aseguren y demuestren la calidad de los programas formativos que se desarrollan en cada una de las titulaciones ofrecidas por la Universidad y así cumplir con la obligación que tiene con la sociedad. El presente proyecto nace como fruto de la responsabilidad adquirida para el cumplimiento de las funciones encomendadas y, con el objetivo de seguir adoptando una estrategia de mejora continua de la calidad de la docencia y satisfacción de los colectivos implicados en el proceso de enseñanza-aprendizaje (Profesorado, Estudiantes y PAS)

Functional Divergence in the Genus Oenococcus as Predicted by Genome Sequencing of the Newly-Described Species, Oenococcus kitaharae

Oenococcus kitaharae is only the second member of the genus Oenococcus to be identified and is the closest relative of the industrially important wine bacterium Oenococcus oeni. To provide insight into this new species, the genome of the type strain of O. kitaharae, DSM 17330, was sequenced. Comparison of the sequenced genomes of both species show that the genome of O. kitaharae DSM 17330 contains many genes with predicted functions in cellular defence (bacteriocins, antimicrobials, restriction-modification systems and a CRISPR locus) which are lacking in O. oeni. The two genomes also appear to differentially encode several metabolic pathways associated with amino acid biosynthesis and carbohydrate utilization and which have direct phenotypic consequences. This would indicate that the two species have evolved different survival techniques to suit their particular environmental niches. O. oeni has adapted to survive in the harsh, but predictable, environment of wine that provides very few competitive species. However O. kitaharae appears to have adapted to a growth environment in which biological competition provides a significant selective pressure by accumulating biological defence molecules, such as bacteriocins and restriction-modification systems, throughout its genome

Metabolic characterization of Palatinate German white wines according to sensory attributes, varieties, and vintages using NMR spectroscopy and multivariate data analyses

1H NMR (nuclear magnetic resonance spectroscopy) has been used for metabolomic analysis of ‘Riesling’ and ‘Mueller-Thurgau’ white wines from the German Palatinate region. Diverse two-dimensional NMR techniques have been applied for the identification of metabolites, including phenolics. It is shown that sensory analysis correlates with NMR-based metabolic profiles of wine. 1H NMR data in combination with multivariate data analysis methods, like principal component analysis (PCA), partial least squares projections to latent structures (PLS), and bidirectional orthogonal projections to latent structures (O2PLS) analysis, were employed in an attempt to identify the metabolites responsible for the taste of wine, using a non-targeted approach. The high quality wines were characterized by elevated levels of compounds like proline, 2,3-butanediol, malate, quercetin, and catechin. Characterization of wine based on type and vintage was also done using orthogonal projections to latent structures (OPLS) analysis. ‘Riesling’ wines were characterized by higher levels of catechin, caftarate, valine, proline, malate, and citrate whereas compounds like quercetin, resveratrol, gallate, leucine, threonine, succinate, and lactate, were found discriminating for ‘Mueller-Thurgau’. The wines from 2006 vintage were dominated by leucine, phenylalanine, citrate, malate, and phenolics, while valine, proline, alanine, and succinate were predominantly present in the 2007 vintage. Based on these results, it can be postulated the NMR-based metabolomics offers an easy and comprehensive analysis of wine and in combination with multivariate data analyses can be used to investigate the source of the wines and to predict certain sensory aspects of wine

Expression variability of co-regulated genes differentiates Saccharomyces cerevisiae strains

Background: Saccharomyces cerevisiae (Baker’s yeast) is found in diverse ecological niches and is characterized by high adaptive potential under challenging environments. In spite of recent advances on the study of yeast genome diversity, little is known about the underlying gene expression plasticity. In order to shed new light onto this biological question, we have compared transcriptome profiles of five environmental isolates, clinical and laboratorial strains at different time points of fermentation in synthetic must medium, during exponential and stationary growth phases. Results: Our data unveiled diversity in both intensity and timing of gene expression. Genes involved in glucose metabolism and in the stress response elicited during fermentation were among the most variable. This gene expression diversity increased at the onset of stationary phase (diauxic shift). Environmental isolates showed lower average transcript abundance of genes involved in the stress response, assimilation of nitrogen and vitamins, and sulphur metabolism, than other strains. Nitrogen metabolism genes showed significant variation in expression among the environmental isolates. Conclusions: Wild type yeast strains respond differentially to the stress imposed by nutrient depletion, ethanol accumulation and cell density increase, during fermentation of glucose in synthetic must medium. Our results support previous data showing that gene expression variability is a source of phenotypic diversity among closely related organisms.Fundação para a Ciência e TecnologiaThe authors wish to thank Adega Cooperativa da Bairrada, Cantanhede, Portugal, for providing the commercial strains

Metabolic constituents of grapevine and grape-derived products

The numerous uses of the grapevine fruit, especially for wine and beverages, have made it one of the most important plants worldwide. The phytochemistry of grapevine is rich in a wide range of compounds. Many of them are renowned for their numerous medicinal uses. The production of grapevine metabolites is highly conditioned by many factors like environment or pathogen attack. Some grapevine phytoalexins have gained a great deal of attention due to their antimicrobial activities, being also involved in the induction of resistance in grapevine against those pathogens. Meanwhile grapevine biotechnology is still evolving, thanks to the technological advance of modern science, and biotechnologists are making huge efforts to produce grapevine cultivars of desired characteristics. In this paper, important metabolites from grapevine and grape derived products like wine will be reviewed with their health promoting effects and their role against certain stress factors in grapevine physiology