Search results for "Grape"
showing 10 items of 291 documents
Analysis of the main factors influencing the quality of wine from mechanically harvested grapes
2009
The wine sector is going today through a period of severe crisis mainly due to the process of globalization in which all the countries producing wine have entered into fierce competition with each other. As a consequence, the achievement of the product on the market exclusively depends on a good value for money. One of the main factors that affect the cost of running the vineyard and, therefore, the final price of the wine is certainly the grape harvest. For the reasons given above this technique, used to be performed manually, is today impossible to support except that there would be the use of the harvesting machine. It’s well known that the use of the harvesting machine has the limit of …
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
2014
The present work was undertaken to evaluate the effect of natural wine making on the microbial and chemical composition of Marsala base wine. To this purpose, a large-scale vinification process of Grillo grape cultivar was monitored from the grape harvest to the final product. Total yeasts (TY) showed a rapid increase after must pressings and reached values that were almost identical to those registered during conventional wine makings. Lactic acid bacteria (LAB) were registered at the highest levels simultaneous to those of yeast growth at the beginning of the process. Saccharomyces cerevisiae was the species found at the highest concentrations in all samples analysed. Several strains (n =…
Characterisation of Vernaccia Nera (Vitis vinifera L.) Grapes and Wine
2017
Vernaccia Nera (VN) is a minor Italian red grape cultivar whose oenological properties have not been investigated yet. Traditional winemaking procedures with VN can include grape drying and even triple sequential fermentations, but a rational vinification approach should be based on the grape composition. Since a comprehensive characterisation of the VN grape is still missing, the ripening of VN grapes was monitored by evaluating flavour compounds, proanthocyanidins and anthocyanins. The grapes were used to produce red wine whose chemical composition and sensory properties were assessed. Ripe VN grapes contained high amounts of extractable anthocyanins (0.88 g/kg). The most abundant anthocy…
Effects of traditional and light pruning on viticultural and oenological performance of bobal and tempranillo vineyards
2015
<p style="text-align: justify;"><strong>Aim</strong>: Light pruning may improve vine yield and quality although vineyard responses are variable. We assessed the effects of traditional manual pruning and mechanical light pruning on the viticultural and oenological performance of <em>Vitis vinifera </em>cv. Bobal and cv. Tempranillo.</p><p style="text-align: justify;"><strong>Methods and results</strong>: During 2008-2011, Bobal and Tempranillo vineyards underwent traditional pruning or light pruning. The effects of both pruning techniques were determined in vine vigour and yield, and grape and wine characteristics. Both cultivars responde…
Effect of leaf removal and ripening stage on the content of quercetin glycosides in Sangiovese grapes
2021
Quercetin haze has been observed over the last few years in some aged Sangiovese wines. This problem could be due to an excess of the quercetin in the wine. Leaf removal increases the exposition of clusters to sunlight, which may enhance flavonol synthesis in the grapes. In this study, we evaluated the dynamics related to extractable flavonols in grapes grown in three usually defoliated Vitis vinifera (L.) cv. Sangiovese vineyards, whose wines showed quercetin precipitates. The particular structure of the vineyards in which the leaf removal experiments were carried out allowed the influence of vineyard, biotype and rootstock on grape flavonol contents at mid-maturation and technological mat…
Effects of postharvest partial dehydration and prolonged treatments with ethylene on transcript profiling in skins of wine grape berries.
2010
For certain food products, postharvest controlled stresses or treatments with specific elicitors are applied to induce desired physical/chemical changes and/or to positively affect phytochemical content. This is the case of wine grapes where both strategies, singularly applied or coupled, can be used to modulate berry composition and, as a consequence, affect wine quality traits. Since the knowledge of the effects of these postharvest treatments on berry metabolism and the regulation of gene expression is very limited, a large-scale transcriptome analysis has been carried out, using an oligo-based microarray (14,562 probes) on skins of wine grape (Vitis vinifera L.) berries subjected to deh…
Etude d'une microflore levurienne champenoise
1982
<p style="text-align: justify;">Pendant quatre années consécutives, on a suivi en Champagne, l'évolution de la microflore levurienne depuis la baie de raisin jusqu'au vin clair. Les résultats montrent une influence sensible sur la microflore, d'une part de certains traitements phytosanitaires et d'autre part des opérations liées à la vendange et au traitement des moûts. Grâce à un milieu de culture électif spécial, les auteurs ont amélioré la séparation des colonies de <em>S. cerevisiae</em> et de <em>S. bayanus</em>.</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">For four consecutive years the evolution of yea…
Determination of YLOID in soil and grapevine systems (Vitis vinifera L.) by ICP-MS technique: a hopeful proxy for the geographical characterization o…
2011
Chemical behavior of YLOID (Y and Lanthanoid) into soil was extensively studied both to evaluate geochemical process. Metal cations can be immobilized onto particle surface of soil due to the formation of stable complexes with organic matter. If environmental conditions change metals can be mobilized and therefore to became bioavailable [1]. In recent years identification of the geographical origin of food has acquired very importance because consumers are more and more interested in knowing the provenance of the food purchased and/or eaten [2]. Then the knowledge of a relationship between the chemistry of the substrates and the food could be an important tool for the quality guarantee of t…
Antimicrobial Activity of Resveratrol Analogues
2014
Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of acti…
Optimal control of spin-systems: Applications to Nuclear Magnetic Resonance and Quantum Information
2016
The goal of this thesis is to apply the optimal control theory to Nuclear Magnetic Resonance and Quantum Information. In a first step, we introduce the different topics and the dynamics of the analyzed systems. We give the necessary tools to use the Pontryagin Maximum Principle, and also an optimization algorithm, namely GRAPE. The first work is an application of the PMP to the control of a three-spin chain with unequal couplings. We continue with the study of a classical problem called "the tennis racket effect", which is a non-linear phenomenon occuring during the free rotation of a three-dimensional rigid body. We use the results in the following chapter to determine some control laws fo…