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Sparrow A.M.,University of Tasmania | Smart R.E.,Smart Viticulture | Dambergs R.G.,Wine TQ | Close D.C.,University of Tasmania
American Journal of Enology and Viticulture | Year: 2016

Modifying phenolic composition can improve the quality of Pinot noir wines and overcome common challenges associated with deficiencies in color, tannin, and aging potential. During fermentation, extraction of desirable components from the skin takes place primarily through the inner skin surface of the berry and from broken skin edges. Ostensibly, the extraction of phenolic compounds located in the skin may be enhanced by reducing the skin particle size. Theoretical analysis indicated that moderate fragmentation substantially decreased the surface area to perimeter ratio of grape skins. Three experiments showed that cutting grape skins into smaller fragments facilitated egress of color and tannin from the skin into the wine matrix. In each case, the treatment in which grapes were cut was compared with a crushed berry control made using conventional methods. Homogenization of berry tissues increased tannin concentration by 6-fold, stable pigment concentration by 45%, wine color density by 25%, and blue-purple coloration by 20% in wines at six months bottle age. Undifferentiated cutting of grapes increased tannin by 6.5-fold, stable pigment concentration by 70%, wine color density by 60%, and blue-purple coloration by 10%. A cutting technique that reduced grape skins to 6% of their original size without damaging the seeds produced wines that had 3-fold higher tannin concentration, 95% higher stable pigment concentration, 50% greater wine color density, and 20% increase in blue-purple coloration. The effects of reducing skin particle size on phenolic extraction were found to be much greater than those achieved using pectolytic enzymes. This innovative skin fragmentation technique has the potential to increase skin-derived red wine phenolics and is a viable alternative to maceration techniques currently used during winemaking. © 2016 by the American Society for Enology and Viticulture. All rights reserved. Source

King P.D.,Eastern Institute of Technology | Smart R.E.,Smart Viticulture | Mcclellan D.J.,Eastern Institute of Technology
Australian Journal of Grape and Wine Research | Year: 2014

Background and Aims: Spatial and temporal variability of vine vigour within a vineyard block, associated with variation in soil physical and chemical properties, affects yield, and fruit and wine composition. The objectives of this study were to measure this variability and possible causes for a commercially important vineyard area in Hawke's Bay, New Zealand. Methods and Results: Three vigour classes, and measurement of vine nutrient and water status, vegetative growth and canopy attributes, yield, fruit ripening profiles, and grape and wine composition over two seasons characterised vigour variability of Cabernet Sauvignon vines growing on the 'Gimblett Gravels' area of Hawke's Bay, New Zealand. Vine nutrition and growth differed between vigour zones with extreme nitrogen deficiencies recorded. Vigour did not affect vine phenology. Normalised Difference Vegetative Index measurements quantified vigour differences. High vigour vines showed a higher yield, but fruit ripeness, wine anthocyanins and phenolics, and some sensory attributes were significantly reduced. Excessively leafy canopies associated with high vigour were responsible for these effects. Conclusions: Soil-induced vine nutrient deficiencies, rather than differences in vine water status, influenced vine vigour. Measures of vegetative growth and canopy attributes suggested negative implications of excessive shading with high vine vigour. Significance of the Study: This study showed the relative significance of nutrition in affecting vine vigour on sandy gravel soils. A good correlation between remotely sensed vigour zones, and grape and wine composition permit on-ground zonal management to minimise the negative effects of spatial variability. © 2014 Australian Society of Viticulture and Oenology Inc. Source

King P.D.,Eastern Institute of Technology | McClellan D.J.,Eastern Institute of Technology | Smart R.E.,Smart Viticulture
American Journal of Enology and Viticulture | Year: 2012

Manipulation of vine balance is widely practiced to enhance grape and wine quality. Reported benefits from crop thinning are ambiguous. Studies were undertaken over two growing seasons (2006-2008) in Hawke's Bay, a cool-climate region of New Zealand, to investigate the influence of basal leaf and crop removal on fruit and wine composition and the indices of vine balance associated with optimum quality. Three levels of basal leaf removal in the fruiting zone were used. Crop removal achieved average reductions of 15% with moderate treatment and 35% with severe treatment below the average nonthinned yield of 17.5 t/ha. Treatments were undertaken at the preveraison growth stage on Merlot vines. Leaf removal had no effect on fruit composition, but levels of total anthocyanins and the flavonol quercetin-3-glucoside were enhanced in the wines. In contrast, crop removal increased sugar concentration and decreased titratable acidity of the must. While crop removal had no effect on wine anthocyanins, the proportions of anthocyanins as malvidin-3-glucosides and total phenolics in the wines were significantly increased. Relative to accepted indices of vine balance, the study vines were unbalanced with excessive shoot growth and dense canopies. A crop reduction of ~6.0 t/ha brought the capacity of the exposed leaf area into balance with that required to ripen fruit to optimum maturity and produce high-quality wines. © 2012 by the American Society for Enology and Viticulture. All rights reserved. Source

Song J.,Oregon State University | Song J.,Northwest University, China | Smart R.E.,Smart Viticulture | Dambergs R.G.,Australian Wine Research Institute | And 4 more authors.
Food Chemistry | Year: 2014

The relationship between grapevine vigour and grape and wine composition was investigated in this study. Own-rooted Pinot Noir grapevines were grown in a commercial vineyard in Tasmania, Australia, with uniform vineyard management practices. Vine vigours were determined by plant cell density (PCD) obtained from aerial photography. As vine vigour decreased, total soluble solid in grapes, total phenolics and anthocyanins in wines increased, while titratable acidity and yield decreased. Wines from the ultra low vine vigour zone had the highest concentrations of esters and alcohols. Higher level of linalool, nerol, geraniol, vitispirane, and β-ionone were observed in ultra low vigour and low vigour zones, but there was no obvious trend for citronellol and β-damascenone. Principal component analysis and discriminant analysis of the volatiles illustrated the differences among wines from the four vine vigour zones. © 2013 Elsevier Ltd. All rights reserved. Source

Sparrow A.M.,University of Tasmania | Smart R.E.,Smart Viticulture
South African Journal of Enology and Viticulture | Year: 2015

Experimental vinification is often used to evaluate changes in viticultural and oenological practices in research trials. Microvinification procedures are used to overcome constraints that make standardised comparisons in commercial wineries difficult. Prior to 2009, a dedicated micro-winery research facility in northern Tasmania used conventional 12 L volume ferments that provided sufficient wine for both sensory and chemical analysis. Since then, much smaller ferment volumes of 1.5 L and of 250 mL have been introduced, and these provide a sufficient sample size for the chemical analysis of phenolic components in the wine. This study reports a comparison of the phenolic attributes of Pinot Noir wines in a replicated trial using must weights of 0.2, 1.0 and 10 kg fermented in vessels of volume 250 mL, 1.5 L and 20 L respectively. Using the same parcel of fruit, a single larger ferment of 330 kg and a vessel volume of 780 L was conducted concurrently. At bottling, six weeks after the end of fermentation, there was no significant difference in the phenolic composition of the wine made from grape musts with a mass of 0.2, 1.0 or 10 kilograms in the replicated trial, and the results were consistent with those for the 330 kg ferment size. We therefore have confidence in using small micro-scale fermenters, which greatly enhance research capability. Source

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