Effect of yeast strain selection on the concentration of cis- and trans-resveratrol glucoside isomers in wine.
Clare,-S-S; Skurray,-G-R; Shalliker,-R-A
Cent. for Advanced Food Res., Univ. of Western Sydney, Hawkesbury, Richmond, NSW 2753, Australia. Fax +61 2 4570 1369.
E-mail: ST.Clare@uws.edu.au
Australian-Journal-of-Grape-and-Wine-Research. 2005; 11(1): 9-14 ; 40 ref.
Effects of 4 strains of winemaking yeast Saccharomyces cerevisiae on concn. of cis- and trans-resveratrol and resveratrol glucoside isomers in Shiraz wines were assessed. During fermentation, concn. of both free resveratrol and resveratrol glycosides increased up to 3-5 days (depending on resveratrol form) after which variable yeast beta-glucosidase activity was observed up to dryness of the wines, with a general increase in free resveratrol forms and a decrease in the corresponding glucosides. In finished wines, total resveratrol + glycosides reflected manufacturers' polyphenol extraction ratings for the yeast strains. Relative extraction of total phenols between yeast strains in red winemaking paralleled relative stilbene concn.
Prefermentative cold maceration in Pinot Noir winemaking.
Ponte,-C; Cravero,-M-C; Bonello,-F; Pazo-Alvarez,-M-C; Olivero,-M; Stefano,-R-di
Istituto Sperimentale per l'Enologia, 14100 Asti, Italy.
E-mail: analisi.sensoriale@isenologia.it
Rivista-di-Viticoltura-e-di-Enologia. 2004; 58(4): 33-62 ; 34 ref.
Effects of pre-fermentation cold maceration on phenols composition, colour stability and sensory properties of Pinot Noir wines were investigated in trials on the 2000 and 2001 vintages. Apart from cold maceration, winemaking techniques were identical for experimental and control wines. Wines made with cold maceration had higher anthocyanins and polyphenols concn. than control wines. Sensory properties of the control and experimental wines differed at the start of barrel ageing and for the 1st yr of ageing; subsequently, sensory properties differed little between wines. In 2001, the cold macerated wine was browner than the control wine, possibly due to the higher concn. of low mol. wt. tannins and their oxidative polymerization. Anthocyanins showed similar changes in the 2 wines during ageing.
Sensory attributes of Cabernet Sauvignon wines made from vines with different crop yields.
Chapman,-D-M; Matthews,-M-A; Guinard,-J-X
Dep. of Food Sci. & Tech., Univ. of California, Davis, CA 95616, USA.
E-mail: jxguinard@ucdavis.edu
American-Journal-of-Enology-and-Viticulture. 2004; 55(4): 325-334 ; 39 ref.
Trials were conducted to assess effects of crop yield of Cabernet Sauvignon grapes on sensory properties of the resulting red wines. Vines grown in the Napa Valley region of California were subjected to 6 winter pruning treatments over 2 vintages, and 8 cluster-thinning treatments in 1 vintage, to achieve a range of crop yields from 4.3 to 22.32 t/ha. The aroma and flavour of the resulting wines were assessed using descriptive analysis. Results for the winter pruning treatment showed that vines pruned to low bud numbers (and hence giving low yield) showed more intensive vegetative aroma and flavour, bell pepper aroma, astringency and bitterness but less intensive red/black berry aroma, jam aroma, fresh fruit aroma and fruity flavour than vines pruned to have more buds and hence higher yield. In general, intensity of vegetative type aroma and flavour properties decreased and intensity of fruity aroma and flavour properties increased with increasing bud number and yield. Cluster thinning had litte effect on sensory properties of the wines. It is concluded that, in this cultivar, wine aroma and flavour respond to yield alteration measures performed early, but not measures performed late in grape development.
Control of variables in maceration of red grapes.
Celotti,-E; Franceschi,-D
Dipartimento di Sci. degli Alimenti, Univ. degli Studi di Udine, Udine, Italy
Revue-des-Oenologues-et-des-Techniques-Vitivinicoles-et-Oenologiques. 2004; (110): 24-27
Trials were conducted to assess effects of various maceration techniques on polyphenols and anthocyanins concn. in Merlot and Cabernet musts, and quality of the resulting wines. Maceration conditions considered include maceration at increased temp., oxidative or reductive maceration, addition of exogenous tannins, and combinations of these techniques. The results are discussed in detail with reference to optimization of quality of wines and matching maceration techniques to individual winemaking grape cultivars.
Evolution of flavanols, anthocyanins, and their derivatives during the aging of red wines elaborated from grapes harvested at different stages of ripening.
Perez-Magarino,-S; Gonzalez-San-Jose,-M-L
Dep. of Biotech. & Food Sci., Univ. of Burgos, 09001 Burgos, Spain. Tel. +34 947 258815. Fax +34 947 258831.
E-mail: marglez@ubu.es
Journal-of-Agricultural-and-Food-Chemistry. 2004; 52(5): 1181-1189 ; 43 ref.
Effect of the degree of grape ripening on red wine colour and levels of flavanol and anthocyanin compounds, which are chiefly responsible for wine colour attributes, was determined. 2 different cultivars and 3 different degrees of ripening were studied in 2 consecutive yr. The wines were aged for 1 yr in American oak barrels of medium-high char followed by 6 months in the bottle. Results showed that wines made from more mature grapes had a generally higher free anthocyanin content, and that the decrease in free anthocyanins and flavanols during ageing took place in conjuction with an increase in the levels of anthocyanin derivatives or 'new pigments', which are responsible for maintaining colour intensity and adding violet hues in aged wines. It was ascertained that the characteristics and composition of grapes harvested later (7-8 days in this region and for these varieties) than the usual time are quite beneficial to obtaining quality aged wines. The phenolic composition of wines made from the last harvested grapes was mainly responsible for the stability of their colour; this is extremely important for product acceptance, and hence markedly increases product quality.
The polysaccharides of red wine: total fractionation and characterization.
Vidal,-S; Williams,-P; Doco,-T; Moutounet,-M; Pellerin,-P
Australian Wine Res. Inst., PO Box 197, Glen Osmond, SA 5064, Australia. Fax +61 8 8303 6601.
E-mail: stephane.vidal@awri.com.au
Carbohydrate-Polymers. 2003; 54(4): 439-447 ; 43 ref.
Polysaccharides in red wine were fractionated and structurally characterized. Red wine from Carignan Noir grapes was subjected to anion-exchange, size-exclusion and affinity chromatography and the glycosyl residue composition of the polysaccharide fractions was determined by GC MS analysis of their trimethylsilylated methyl glycoside derivatives. The major polysaccharides in the wine were mannoproteins, arabinogalactan-proteins and rhamnogalacturonans I and II, which comprised 35, 42, 4 and 19%, respectively of the polysaccharides present. Strong binding of neutral xyloglucans to an anion-exchange resin, followed by their co-elution with highly acidic rhamnogalacturonans, suggests the existence of cross-linkages between pectic and hemicellulosic regions in grape and other plant cell primary walls. Results also suggest that use of hemicellulolytic enzymes during winemaking may loosen cell wall structures, promoting release of polyphenols and flavour compounds, thus enhancing the quality of the wine.
Direct method for determining seed and skin proanthocyanidin extraction into red wine.
Peyrot-des-Gachons,-C; Kennedy,-J-A
Dep. of Food Sci. & Tech., Oregon State Univ., Corvallis, OR 97331, USA. Tel. +1-541-737-9150. Fax +1-541-737-1877.
E-mail: James.Kennedy@oregonstate.edu
Journal-of-Agricultural-and-Food-Chemistry. 2003; 51(20): 5877-5881 ; 27 ref.
A direct measurement method was developed for determining the amount of grape seed and grape skin proanthocyanidin extraction into red wines during winemaking. This method was based upon the analysis of proanthocyanidin cleavage products after acid catalysis in the presence of excess phloroglucinol. On the basis of the analysis of proanthocyanidin extracts from grape tissues, 2 observations were made: the seed and skin proanthocyanidin extension subunit compositions were considerably different from each other; and their compositions did not vary with extraction time. Thus, by comparing the proportional extension subunit composition of proanthocyanidins in wine relative to their proportional composition in corresponding grape seed and skin, it was possible to determine the contribution of each to wine. To provide additional information, the procedure was used to investigate seed and skin proanthocyanidin extraction during commercial-scale fermentations that had undergone 4 or 10 day low temp. prefermentation skin contact prior to the onset of fermentation. Results for both fermentations indicated that the proportion of skin proanthocyanidins declined during fermentation, and that the amount and proportion of skin proanthocyanidins were the same at the end of fermentation.
Red wines: pigment phenomena in vinification and maturation.
Somers,-C
Tel. (08) 82963096.
E-mail: chrisssomers@ozemail.com.au
Australian-&-New-Zealand-Wine-Industry-Journal. 2003; 18(2): 30, 32, 34-35, 37 ; 14 ref.
Pigment phenomena of importance in relation to colour of red wines are discussed with reference to: changes in wine colour and pigments during ageing; changes in total and individual anthocyanins in wines; formation of polymeric pigments; self-association of anthocyanins; copigmentation phenomena; problems with analysis of pigments in wines; the role of SO2 in relation to wine colour; decreases in colour density during alcoholic fermentation of red wines; the proportion of total anthocyanins which are in the coloured form; colour synergism; and the possibility that anthocyanins are present in labile complexes even at the start of the winemaking process.
The role of oxygen in the ageing of bottled wine.
Hart,-A; Kleinig,-A
Tarac Technologies, PO Box 78, Nuriootpa, SA 5355, Australia
Australian-&-New-Zealand-Wine-Industry-Journal. 2005; 20(2): 46-50 ; 23 ref.
Studies were conducted to assess the importance of O2 in ageing of bottled red wines. A super premium red Shiraz/Cabernet Sauvignon wine was bottled under screw caps, natural cork or synthetic closures. Samples were investigated after ageing for 2.5, 4.5 or 6.5 yr; chemical, spectroscopic and sensory analyses were conducted. SO2 loss from the still wine was greatest for the synthetic closures and least for the screw caps. Colour of the wines differed between closure types. In wines bottled with screw caps, phenolic reactions which influence wine colour progressed, even in the practical absence of O2, permitting development of colour and tannin structure with time. Sensory quality rankings were similar for wines bottled with screw caps or natural corks. Synthetic closures resulted in more rapid development. It is concluded that O2 is not a vital component for maturation of red wines; reductive characteristics may develop under these conditions, but in this investigation any reductive properties were insufficient to impair sensory quality scores.
Phenolic composition and magnitude of copigmentation in young and shortly aged red wines made from the cultivars, Cabernet Sauvignon, Cencibel, and Syrah.
Hermosin-Gutierrez,-I; Sanchez-Palomo-Lorenzo,-E; Vicario-Espinosa,-A
Escuela Univ. de Ingenieria Tec. Agric., 13071 Ciudad Real, Spain. Tel. +34 926 295300. Fax +34 926 295351.
E-mail: isidro.hermosin@uclm.es
Food-Chemistry. 2005; 92(2): 269-283 ; 44 ref.
Phenols composition and impact of copigmentation on wine colour were investigated in young and slightly aged red wines made from single cultivar grapes (Cabernet Sauvignon, Cencibel and Syrah). Wines prepared from different grape cultivars could be distinguished on the basis of their anthocyanins, flavonol and hydroxycinnamic acid contents. Decreases in contents of monomeric anthocyanins and flavonol were observed in all wines during ageing. The proportion of red colour that was caused by copigmented anthocyanins was 32-43% at the end of the alcoholic fermentation period, decreasing to 20-34% after ageing for 3 months. Flavonol decreases after 3 months were greatest in Cencibel wines. However, flavonols appeared to be replaced by other copigmentation cofactors, such as hydroxycinnamic acids and (-)-epicatechin, reducing overall loss of copigmentation, such that Cencibel wines demonstrated smaller decreases than the other wines in copigmentation during ageing. A bathochromic shift to bluish hues was also observed in Syrah and Cencibel wines, but was only maintained at all ageing times in Syrah wines.
