The effect of Uncinula necator (powdery mildew) and Botrytis cinerea infection of grapes on the levels of haze-forming pathogenesis-related proteins in grape juice and wine

Powdery mildew on Chardonnay grapes resulted in increased levels of a grape thaumatin-like protein, VvTL2, in the free run juice compared to that from uninfected grapes. These increased levels persisted through winemaking and at the highest level of infection (> 30% of bunches infected) had a significant impact on the haziness in the wine following a heat test. Infection of Cabernet Sauvignon grapes (1–20% of bunches infected) did not affect the protein concentration of free run juice, and only traces of pathogenesis-related (PR) proteins remained detectable in the Cabernet Sauvignon wines from either infected or healthy grapes. In contrast, infection of Chardonnay or Semillon grapes by Botrytis cinerea in the vineyard resulted in decreased levels of all PR proteins in the free run juice and in a total protein extract from infected berries compared to that from uninfected grapes. Similar trends were observed when B. cinerea was grown in the laboratory on surface-sterilised berries or in filter-sterilised juice.     

Effects of the rootstock Ramsey (Vitis champini) on ion and organic acid composition of grapes and wine, and on wine spectral characteristics

The influence of Ramsey, used as rootstock of the scion cvs Muscat Gordo Blanco (syn. Muscat of Alexandria), Shiraz (syn. Syrah), Riesling, Cabernet Sauvignon and Chardonnay, on the characteristics of the grape berries and of wine made from them was investigated, comparing ‘own-rooted’ and ‘grafted’, and comparing wine fermented as juice (without skins) and must (juice and skins). The study involved the partitioning of K+ within berries, changes in juice K+, malic and tartaric acid through fermentation, wine inorganic ion and organic acid composition, and wine spectral characteristics. K+ concentration was higher in berries from grafted than from own-rooted for all varieties except Chardonnay, and highest for grafted Shiraz. It was higher in skin than in pulp and seeds. In the pulp, it was highest for grafted Shiraz. K+ concentrations in all ferments using must (i.e. juice plus skins) increased during the initial two days after crushing, with the increase reflecting extraction from skins, being greatest for Shiraz and Muscat Gordo Blanco. Tartaric acid concentration in must also increased during the initial two days after crushing and then decreased. Malic acid concentration was higher in juice of Ramsey-grafted than own-rooted vines, especially for Shiraz; concentrations did not change markedly during the initial 12 days of fermentation, except where malo-lactic fermentation occurred. Wine made from grapes of grafted contained significantly less tartaric and more malic acid than that made from own-rooted for all varieties and for both fermentation types, with the exception of tartaric acid in wine of Muscat Gordo Blanco fermented as must. Wine made from juice had significantly higher tartaric acid and lower malic acid than that made from must for all varieties except for tartaric acid in wine from grafted Shiraz and malic acid in own-rooted Chardonnay. Wine had a smaller tartaric acid/malic acid ratio when made from must. Wine pH was positively correlated with K+ but negatively with tartaric acid and with the tartaric acid to malic acid ratio. Overall, Shiraz wine contained highest Cl?, Na+ and K+ concentrations. Red wines obtained from grafted had higher colour hue, especially those from Shiraz. Wines made from fruit borne on own-rooted Cabernet Sauvignon had the highest concentration of total anthocyanins, ionised anthocyanins and total phenolics.     

Assessment of some Australian red wines for price, phenolic content, antioxidant activity, and vintage in relation to functional food prospects

Twenty-three Cabernet Sauvignon wines from the Mudgee region and thirty-two Shiraz wines from the Hunter Valley region were analyzed for phenolic content and antioxidant activity. Concentrations of (+)-catechin, quercetin, and transresveratrol, total phenolic content, and DPPH antioxidant activity varied considerably, both within and between varieties. Individual phenols, total phenols, and antioxidant activity were correlated with price and vintage. Shiraz wines showed positive and significant correlations for catechin and quercetin concentrations with total phenols, antioxidant activity, and vintage; and for total phenols and antioxidant activity with vintage. Cabernet Sauvignon wines showed positive and significant correlations for quercetin concentration with total phenols and antioxidant activity. There was a negative and significant correlation found between price and antioxidant activity for Cabernet Sauvignon wines. Results are discussed in terms of the potential for wine to be considered a functional food. PRACTICAL APPLICATION: We report on potential health benefits (antioxidant activity) of 55 wines typical of 2 geographically close, but distinct, wine regions of Australia. Our results highlight the variability in functional components as an issue that needs further research and consideration in relation to wine as a functional food. The price of studied wines is not reflective of their health functionality, based on antioxidant activities.     

Antioxidant capacity and stilbene contents of wines produced in the Snake River Valley of Idaho

Forty-two wines produced from grapes grown in Idaho were examined in this study. The samples examined were from four monovarietal wines (12 Cabernet Sauvignon, 9 Merlot, 7 Riesling, 14 Chardonnay). Wine samples represented twelve wineries that obtain their fruit from vineyards located within Idaho’s Snake River Valley. Titratable acidity, pH, specific gravity, colour measurements (lightness, chroma, and hue), % haze, total anthocyanins, total phenolics, total tannins, antioxidant capacity, and individual stilbene measurements were performed. The antioxidant capacities (ORAC values) of Idaho wines ranged from 3.1 (Merlot wine) to 87.0 (Cabernet Sauvignon wine) μmol of Trolox/ml (mean = 38.5 μmol of Trolox/ml). Mean ORAC values of Merlot wines (mean = 27.6 μmol of Trolox/ml) were lower than the other three styles (mean for Cabernet Sauvignon wines = 41.0 μmol of Trolox/ml, mean for Chardonnay wines = 42.8 μmol of Trolox/ml, and mean for Riesling wines = 39.4 μmol of Trolox/ml). Free stilbene levels (four different stilbenes) were examined by direct-HPLC/DAD/ESI-MS/MS method. Piceid and resveratrol (both trans- and cis-) were found in the samples. Stilbene levels ranged from 0.97 (Riesling wine) to 12.88 (Cabernet Sauvignon wine) mg (expressed as trans-resveratrol)/l. This is the first paper to report the current chemical composition of Idaho wines.     

Influence of sour rotten grapes on the chemical composition and quality of grape must and wine

This study evaluated the effect of grape sour rot on wine fermentation and characterized the chemical composition and the sensory changes in wines produced from rotten musts. Microvinifications were performed during two vintages using healthy Trincadeira and Cabernet Sauvignon red grape varieties to which were added grapes affected by sour rot. Increasing sour rot percentages, up to 50%, contributed to a clear decrease in free run must and final wine yields and induced significant changes in grape must chemical composition expressed by the increase in sugar content, total acidity, volatile acidity, anthocyanins, total phenols, and color intensity. After malolactic fermentation, wines from rotten grapes showed higher values of alcohol content, dry extract, reducing sugar content, total and volatile acidity, anthocyanins, total phenols, and color intensity. Despite the higher levels of reducing sugars, the microbial stability was similar to that of healthy wines. The sensorial evaluation, after malolactic fermentation, showed that both types of wine were not statistically different regarding color, aroma, taste, and overall quality. During 6–8 month storage, wines from rotten grapes showed a significant higher percentage of color loss, suggesting that sour rot is responsible for the decrease in color stability. Nevertheless, the results of sensorial analysis demonstrated that the fermentation of grape musts containing up to 30% sour rot yields wines with similar or even higher-quality scores than wines made with healthy grapes.     

Effect of freezing grape berries and heating must samples on extraction of components and composition parameters of red wine grape varieties

Juices from grape samples subjected to two storage methods (fresh and frozen) and two post-homogenisation treatments (21^oC and 71^oC) were examined for extraction of grape berry components and compared to a microvinified wine made from the same lot of fresh grapes. Cabernet Franc ( Vitis vinifera ) and Cynthiana ( Vitis aestivalis ) grapes were evaluated in 2003. Cabernet Franc, Cabernet Sauvignon ( Vitis vinifera ), Chambourcin (interspecific hybrid) and Cynthiana grapes were evaluated in 2004. Fresh grapes from each variety were sampled, analysed and prepared for microvinification. Frozen grapes of all varieties were thawed and analysed at the same time. For all varieties in both years, heating the must of fresh or frozen grapes increased the titratable acidity (11–58%), tartaric acid levels (12–110%), potassium content (15–62%), darkness (31–97%), red colour (54–1517%) and total red pigment values (36–1171%) of juice as compared to the juice from unheated must. For all varieties in 2004, heating the must from fresh or frozen grapes increased total phenolics (43–619%) of juice as compared to the juice from unheated must. Compared to fresh grape processing, freezing the grapes and then processing at 21^oC or 71^oC had varying results (increases and decreases) regarding the extraction of components in all varieties and both years but usually provided juice with composition most similar to that of the red wine produced by microvinification. Although the degree of extraction of individual components in the juice is influenced by selection of grape storage and must processing procedures, consistency of handling and procedure provided consistent results with low variability.     

Chemometric investigation of the volatile content of young South African wines

The content of major volatiles of 334 wines of six different cultivars (Sauvignon Blanc, Chardonnay, Pinotage, Shiraz, Cabernet Sauvignon and Merlot) and vintage 2005 was used to investigate the aroma content of young South African wines. Wines were sourced from six different regions and various producers. Thirty-nine volatile components partially responsible for the flavour of wine were quantified. In order to investigate possible correlation between volatile content and grape variety and/or geographical origin, analysis of variance, factor analysis (FA), principal component analysis (PCA) and linear discriminant analysis (LDA) were used. Significant differences in the levels of certain volatiles were observed as a function of region and cultivar, with the latter factor proving to be more influential. A few volatile compounds were identified as potential predictors of the white wine cultivars. Prediction for red wine cultivars was poor, with the exception of Pinotage wines, for which three compounds (isoamyl acetate, isoamyl alcohol and ethyl octanoate) were identified as accurate predictors. The reasons for the importance of these three volatile compounds in distinguishing young Pinotage wines are discussed, and possible reasons for the unique levels in wines of this cultivar are highlighted.     

An ethanol spray at veraison enhances colour in red wines

Aqueous ethanol (5% v/v) was sprayed onto bunches of Vitis vinifera L. cv. Cabernet Sauvignon 8–9 weeks following full flowering (controls were sprayed with water). Internal ethylene concentration in treated berries increased to a maximum within 6 hours, and berry colour subsequently increased substantially (maximum attained 2–3 weeks after spraying). Berry fresh weight at harvest was unaffected by ethanol treatment, but wine made from treated grapes showed greater colour intensity compared with control grapes.     

The chemical and sensorial effects of lysozyme addition to red and white wines over six months' cellar storage

Lysozyme is an enzyme with muramidase activity which can lyse Gram-positive bacteria, including wine lactic acid bacteria. This enzyme provides a practical method for delaying or preventing the growth of Oenococcus oeni and consequently the onset of malolactic fermentation during the vinification of red and white wines. This paper reports the impact of lysozyme on the chemical and sensorial properties of commercially vinified red (Cabernet Sauvignon and Shiraz) and white (Riesling) wines. The addition of lysozyme to these wines had little or no effect on the content of alcohol, free and total sulfur dioxide and titratable acidity, and pH value. The lysozyme retained 75–80% activity in the Riesling wine after six months, however no detectable activity remained in the Cabernet Sauvignon and Shiraz wines after two days. Upon addition of lysozyme to both of the red wines, a rapid initial decrease (up to 17%) in red wine colour density and phenolic content occurred in association with the formation of a light precipitate. The reduction in red wine colour was also noted by the sensory panel. When added to the Riesling wine, lysozyme did not cause an increase in browning over the six month storage time, but did induce heat instability (haze), suggesting that white wines may require protein stabilisation following treatment with lysozyme. Sensory assessment by triangle difference testing revealed that, during the six month storage period, treatment with lysozyme did not cause important changes to either the aroma or palate of the red and white wines tested.     

The effect of juice clarification, static or rotary fermentation and fining on ochratoxin A in wine

Semillon and Shiraz grapes containing ochratoxin A (OA) were produced by inoculation of bunches on the vine with Aspergillus carbonarius . Small scale vinification of these grapes was performed and the OA content at various stages was analysed. Semillon must was treated with pectolytic enzymes and the juice after pressing was fined with bentonite. Neither pectolytic enzymes nor bentonite influenced the OA content of the clarified juice. Shiraz must was vinified by either static or rotary fermentation. No differences in the OA content of wine after pressing were noted. OA was concentrated in juice lees and gross lees. However, additional juice or wine recovered from lees after centrifugation did not display increased OA contamination compared to racked juice or wine. Addition of bentonite at 2.5 g/L to a Semillon wine containing 56 mg grape-derived protein/L and ca. 8 μg OA/kg resulted in a 67% reduction in OA concentration. Potassium caseinate showed some effect, whereas gelatin, isinglass and PVPP did not significantly diminish OA in white wine compared to wine settled without fining agents. Addition of yeast hulls at 5.0 g/L to a Shiraz wine containing ca. 5 μg OA/kg yielded a 43% reduction. Gelatin was also slightly effective. Storage of wine for 10–14 months resulted in a decrease in OA concentration of 22% and 29% for white and red wines, respectively.     

Exclusion of sunlight from Shiraz grapes alters wine colour, tannin and sensory properties

The aim of this study was to determine how changes in grape composition brought about by artificial shading (sunlight exclusion) influence wine properties including colour, flavonoid composition and sensory attributes. Prior to flowering, bunches of Shiraz grapes were enclosed in boxes designed to eliminate light without altering bunch temperature and humidity. This artificial bunch shading had little effect on berry ripening and accumulation of sugar but at harvest the shaded bunches had smaller berries and higher seed weight, juice pH and titratable acidity. The amount of anthocyanins in the fruit was not changed significantly but anthocyanin composition in the shaded berries was shifted towards dioxygenated anthocyanins (the glucosides of cyanidin and peonidin derivatives). Shaded fruit had increased seed tannins and decreased skin tannins but the largest relative change in flavonoids was a marked decrease in flavonols in the shaded fruit, similar to previous studies. Wines made from shaded fruit had lower wine colour density, total phenolics, anthocyanins and tannins when the wine was bottled and after ageing for up to three years. Analysis of potential flavour compounds following acid hydrolysis indicated that the wines made from shaded fruit had decreased levels of glycosides of β-damascenone and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN). Sensory analysis of the wines indicated no significant difference in aroma attributes but the wines made from shaded fruit were rated lower for astringency, fruit flavour and flavour persistence in-mouth sensory attributes. The results indicate that extreme shading of Shiraz fruit can decrease wine colour, anthocyanins and tannins as well as altering sensory attributes.     

贺兰山东麓产区不同地块对酿酒葡萄果实香气物质的影响

为明确宁夏贺兰山东麓产区小产区划分的意义,以该产区4 个葡萄园的2 个酿酒葡萄品种成熟期果实为材料,采用气相色谱-质谱联用技术对果实游离态和结合态香气物质进行测定,就地块差异对果实香气物质组成的影响进行分析。结果表明,4 个地块的土壤都属于砂壤土类型,高家闸地块的土壤质地含有更多的黏土,志辉地块的土壤更靠近砂土,华西地块和金山地块的土壤质地介于两者之间;在‘霞多丽’葡萄果实中,志辉地块的果实百粒质量、百粒体积和可滴定酸含量显著高于高家闸地块,在‘赤霞珠’葡萄果实中,不同地块果实百粒质量和百粒体积不存在显著差异,而金山地块的‘赤霞珠’葡萄果实中有更低含量的可溶性固形物和更高的可滴定酸;‘霞多丽’和‘赤霞珠’浆果中的香气物质种类和含量在不同地块中有显著差异,主要体现在C6/C9、酯类、降异戊二烯类和萜烯类化合物。志辉地块的‘霞多丽’果实香气差异化合物中的游离态(E)-2-己烯醛、β-大马士酮以及结合态辛酸乙酯的含量更高,结合相应的香气活性值（odor activity value,OAV）,志辉地块的‘霞多丽’葡萄果实中有更加浓郁的生青味、花香和果香;金山地块的‘赤霞珠’葡萄果实香气差异化合物中有更高含量的游离态(E)-2-己烯醛和(Z)-3-己烯-1-醇,结合相应的OAV,其果实香气中有更多的生青味。总之,基于不同地块葡萄果实香气的差异分析,具有明确不同地块葡萄果实品质和葡萄酒风格的潜在价值,为小产区的划分提供一定理论基础。     

Malo-lactic fermentation in australian dry red wines

Malo-lactic fermentation occurred in 62% of 466 Australian dry red wines of 1968 vintage at 6 months of age. In a further 9 % of wines the fermentation was still in progress. Wines which had undergone the fermentation were less acid than those which had not. The difference was greater in wines made from Cabernet Sauvignon than from Shiraz or Grenache grapes. The winery in which the wine was made strongly influenced the occurrence of malo-lactic fermentation in a particular wine-growing area, and was the most important factor involved. Incidence of malo-lactic fermentation was closely correlated with the presence of Leuconostoc and Coccus in the wine, but less so with Lactobacillus. Leuconostoc, Lactobacillus and sometimes Coccus occurred together, but no wines contained both Lactobacillus and Coccus. Diacetyl content of the wines ranged from 0 to 7.5 ppm. In wines which had undergone malo-lactic fermentation the mean diacetyl content was 2.8 ppm, compared with 1.3 ppm for wines which had not undergone this. Diacetyl content of wines made from Grenache was not significantly different, with respect to the occurrence or absence of malo-lactic fermentation. The statistical significances of the various inter-relationships between malo-lactic fermentation, type of bacteria present and certain wine constituents are assessed. Estimates of variance components of II constituents of Australian dry red wines are given, and these may be used in designing future sampling surveys.     

Interaction of pH, ethanol concentration and wine matrix on induction of malolactic fermentation with commercial 'direct inoculation' starter cultures

The effect of the interaction between pH (2.9–3.5), alcohol concentration (12.5–14.5% v/v) and wine matrix (Chardonnay, Grenache blend and Cabernet Sauvignon) on malolactic fermentation (MLF) induced by two commercially available directly inoculated Oenococcus oeni starter cultures was determined. Wine matrix had greatest impact on the rate of MLF, followed by pH and alcohol; the matrix effect was significantly modified by pH and bacterial culture. The rate of L-malic acid degradation by starter culture A was 3.3–61.3% in the Grenache blend and 3.3–4.5% in the Chardonnay wine compared to the Cabernet Sauvignon wine, for the pH/alcohol ranges 2.9/14.5 to 3.5/12.5. L-malic acid degradation rate by starter culture B was lower but less affected by wine matrix. The rate of L-malic acid degradation was closely related to culture viability, with a high rate of L-malic acid degradation being associated with bacterial growth and vice versa . Treatment of two wines in which MLF had previously failed to complete with various combinations of nutrients, carbon fining and heating, restored MLF, suggesting that a growth-limiting nutrient was absent and/or a toxic substance not related to pH, alcohol or SO₂ concentration was present. This work demonstrated that the wine matrix may affect culture viability more significantly than either pH or alcohol concentration. A high rate of MLF was shown to depend on factors permitting bacterial growth, however, the two strains studied responded differently to the wine matrix, suggesting that malolactic bacteria vary in tolerance to various stresses in the wine environment.     

Effect of Colletotrichum acutatum ripe rot on the composition and sensory attributes of Cabernet Sauvignon grapes and wine

Background and Aim:  The impacts of the fungal bunch rot pathogen Colletotrichum acutatum (ripe rot) on grape growing are documented; however, little is known about how the disease affects the resulting wine. This work aimed to investigate how ripe rot affects wine composition and sensory properties.
Methods and Results:  Wine was made using Cabernet Sauvignon grapes grown in the Hastings Valley (NSW). Berries with ripe rot tended to shrivel and acquired a distinctive off flavour and bitterness, described as hessian sack and musty. Wine made from the infected fruit had a higher pH and a higher level of residual sugar, but lower titratable acidity. Volatile acidity in wine made from uninfected fruit was 0.57 g/L, but increased to 0.83 and 1.06 g/L with 1.5 and 3% infection, respectively. Wine made from infected fruit had higher levels of both glycerol and gluconic acid indicative of fungal contamination. Alcohol concentration was also higher in wine made from infected fruit. Sensory analysis indicated that wine made from as low as 3% infected fruit had a similar colour density to control fruit, but a distinctive off-flavour, and browner colour hue.
Conclusions:  As far as we are aware of, this is the first report of a correlation between the level of grape infection by C. acutatum and wine composition in Australia.
Significance of the Study:  These results underline the problems of red grapes infected with C. acutatum . It provides viticulturists and winemakers with information to be considered when assessing grape quality and winemaking process for red wines.     

Antioxidant activity of South African red and white cultivar wines and selected phenolic compounds: In vitro inhibition of microsomal lipid peroxidation

In vitro inhibition of microsomal lipid peroxidation (MLP) by the major South African red (Cabernet Sauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) and white (Sauvignon blanc, Chenin blanc, Chardonnay, Colombard) commercial cultivar wines is presented for the first time. Of the red wines, Merlot was the most effective MLP inhibitor, with Ruby Cabernet and Pinotage being the least effective. Of the white wines, Chenin blanc and Chardonnay were the least and most effective MLP inhibitor, respectively. The mean antioxidant potencies (AP) of the red and white wine total phenols were 14.25 and 4.19, respectively. Ascorbic acid, present in some white wines, counteracted their ability to inhibit MLP. Inhibition of MLP significantly (P<0.001) correlated with the total phenol content of red (r=0.90) and white (r=0.73) wines, as well as the flavanol content (r=0.88) of red wines and the flavanol (r=0.79) and tartaric acid ester (r=0.73) contents of white wines. The MLP inhibitory activities of selected flavonoids were in the order: Quercetin > procyanidin B3 > malvidin > cyanidin ≈ (−)-epicatechin > (+)-catechin ≈ delphinidin.     

酿酒葡萄品种及产区对贺兰山东麓葡萄酒香气质量的影响研究

为研究酿酒葡萄品种及产区对葡萄酒香气的影响,采用气相色谱-质谱联用（GC-MS）技术分析了贺兰山东麓产区四种不同品种葡萄酒、中国四个不同大产区以及贺兰山东麓四个小产区的赤霞珠葡萄酒品种香气差异并对结果进行主成分分析（PCA）。结果表明：四种不同品种葡萄酒中共检测出香气物质50种,其中酯类21种、醇类15种、酸类7种、醛类4种以及其他类3种,香气活性值（OAV）＞1的香气物质有11种,其中霞多丽、赤霞珠葡萄酒中OAV最高的风味物质均为乙酸异戊酯和异戊酸,而马瑟兰和北玫葡萄酒中OAV最高的风味物质为大马士酮。PCA结果显示,宁夏贺兰山东麓不同小产区赤霞珠葡萄酒香气成分之间无明显差异;中国不同酿酒葡萄产区的赤霞珠葡萄酒香气成分之间差异明显。