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.     

Impact of noble rot on the aroma precursor of 3-sulfanylhexanol content in Vitis vinifera L. cv Sauvignon blanc and Semillon grape juice

The most famous sweet wine in France is made from botrytised grapes in the Sauternes region. Its distinctive, complex aromas are undoubtedly due to noble rot as a result of Botrytis cinerea development on perfectly ripe Sauvignon blanc and Semillon grapes. The contribution of volatile thiols in botrytised wine aroma was recently reported. The objective of this work was to investigate the impact of B. cinerea development on the aromatic potential of grape juice. The level of S-3-(hexan-1-ol)cysteine (P-3SH), the cysteinylated precursor of the most abundant volatile thiol in wine (3-sulfanylhexanol, 3SH), was determined during grape botrytisation and several grape overripening processes. Production was considerably amplified when B. cinerea had developed on the grapes in both on- and off-vine experiments. The P-3SH levels were increased about 100-fold between the healthy and botrytised stages in one week. We demonstrated that the grape metabolism produced aroma precursor under post-harvest conditions. When grapes were left to overrippen, the vine also produced P-3SH, but levels increased more moderately (about 10-fold). Moreover, a determination of P-3SH distribution demonstrated that B. cinerea was not directly responsible for precursor formation but probably stimulated the grape metabolic pathway involved in this formation.     

Studies on Colletotrichum acutatum and Greeneria uvicola: Two fungi associated with bunch rot of grapes in sub-tropical Australia

Vineyards in the Hunter Valley and Hastings Valley (sub-tropical NSW) were examined by unaided eye for visible symptoms of bunch rot diseases at berry maturity in 2003 (for a total of five varieties over seven vineyards). Grey mould ( Botrytis cinerea ) was evident in three vineyards, and ripe rot ( Colletotrichum acutatum ) was evident in four of those seven vineyards surveyed. Other bunch rots at six of the vineyards could not be readily identified by visual inspection. The incidence of fungi on grapevine reproductive structures (and potentially bunch-rot fungi) was then recorded for a Cabernet Sauvignon vineyard in the Hastings Valley during the 2004/5 and 2005/6 growing seasons, and outcomes are reported here in some detail. By berry maturity, C. acutatum and Greeneria uvicola (bitter rot) were the predominant pathogens isolated from those structures, and constitute the first such report of bitter rot fungi on wine grapes in Australia. Indeed, the frequency of latent infection by C. acutatum and G. uvicola increased with berry development during the growing season. Other fungi isolated included Alternaria spp ., Botryosphaeria spp., Cladosporium spp ., Epicoccum sp. , Fusarium spp. , Nigrospora spp. , Pestalotia spp. , Phomopsis viticola and Trichoderma spp . Isolation of B. cinerea from this vineyard was rare. Infection of various wine grape varieties in vitro with C. acutatum and G. uvicola at post veraison revealed all varieties to be susceptible over a range of temperatures (20—35^oC). Based on laboratory studies, there was no infection of berries at a relative humidity (RH) < 50%, and infection diminished at 87% RH. Infection did occur if the berries were first incubated at 100% RH for 24 hours, and then transferred to an environment of lower humidity.     

Anthocyanin fingerprint of clones of Tempranillo grapes and wines made with them

Background and Aims:  Different clones with distinctive enological characteristics have been identified in many grape cultivars, but data on differences in anthocyanin composition of clones of the same cultivar are scarce. Thus, it has been considered of interest to check changes in the anthocyanin fingerprint of six different clones of Tempranillo grapes grown in the same vineyard, and of wines made with them, over three consecutive years.
Methods and Results:  Data were submitted to different statistical procedures. Despite slight differences in the anthocyanin fingerprint of some clones (relative content of different anthocyanins analysed), variations from year to year were more important than differences in the anthocyanin profile of the clones considered. This fact was also observed when the content (mg/kg grapes) of those molecules was considered. Moreover, Tempranillo wines made with different clones could be classified by discriminant analysis, using the anthocyanin fingerprint or the levels (mg/L wine) of several anthocyanins as predictor variables, and the year grapes were collected as a classification factor.
Conclusions:  The anthocyanin fingerprint of six clones of Tempranillo grapes grown in the same vineyard and that of wines made with them over three consecutive years was affected mostly by weather conditions, despite slight differences in the anthocyanin fingerprint of some clones.
Significance of the Study:  This is the first report on the anthocyanin composition of different clones of Tempranillo grapes and of wines made with them, and indicates that anthocyanin fingerprint of Tempranillo wines depends mainly on agroclimatic factors, and not on genetic differences among clones.     

Fungi and mycotoxins in vineyards and grape products

Many fungi may occur on grapes during growth in the vineyard, but the main concern from the viewpoint of mycotoxin contamination is the black Aspergilli, Aspergillus carbonarius and A. niger. These fungi are capable of producing ochratoxin A (OA) which may contaminate grapes and grape products such as wine, grape juice and dried vine fruit. Understanding the ecology and physiology of the black Aspergilli can provide tools for management of OA at all stages of grape production and processing. In the vineyard, careful management of cultivation, irrigation and pruning can assist in minimising the levels of black Aspergilli in the soil, which in turn, can minimise contamination of grapes by these fungi. Minimising damage to grapes on the vine by the use of open vine canopies, grape varieties with resistance to rain damage and by the management of insect pests and fungal diseases (e.g., mildew, Botrytis bunch rot) can reduce the incidence of Aspergillus rot in mature berries. The risk of OA in table grapes can be minimised by careful visual inspection to avoid damaged and discoloured berries. In wine, harvesting grapes with minimal damage, rapid processing and good sanitation practices in the winery assist in minimising OA. During vinification, pressing of grapes, and clarification steps which remove grape solids, grape proteins and spent yeast can also remove a significant proportion of OA. For dried vine fruit production, avoiding berry damage, rapid drying, and final cleaning and sorting to remove dark berries can reduce overall OA levels in finished products.     

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.     

Influence of the heterogeneity of grape phenolic maturity on wine composition and quality

Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest.     

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.     

Influence of sustained deficit irrigation on colour parameters of Cabernet Sauvignon and Shiraz microscale wine fermentations

Background and Aims: This study aimed to explore the influence of sustained deficit irrigation (SDI) on the grape and wine colour parameters of two premium red wine grape varieties grown in the Sunraysia region of South Eastern Australia. Methods and Results: The SDI experiments were conducted during three vintages from 2003 to 2004, 2004 to 2005 and 2005 to 2006 on the Vitis vinfera cultivars Cabernet Sauvignon and Shiraz grafted to 140 Ruggeri (V. berlandieri × V. rupestris) rootstock. The grapevines were drip irrigated providing 100% of estimated ET_c (control) and three graded sustained water deficits (Cabernet Sauvignon 70, 52 and 43% of the control; Shiraz 65, 45 and 34% of the control). Microscale wine fermentations were conducted on grapes from the 2006 harvest to assess wine colour density, wine hue, red pigments, anthocyanins, phenolics and copigmentation products in the wine. Wine anthocyanin and phenolic concentrations for both varieties showed significant increases with increasing intensity of SDI. Conclusion: Increases in wine colour with SDI may result from changes in flavonoid biosynthesis as a result of grapevine responses to water deficit. Alternatively, increases in red wine colour could be caused by changes in chemical properties of the anthocyanins to copigmented or polymeric forms during the winemaking or ageing process. Significance of the Study: The Australian wine industry is currently affected by drought and reduced water allocations resulting in production of wine from grapes exposed to water deficit. Findings from this study provide knowledge to the wine industry as to how sustained deficit irrigation may modify wine colour.     

冰酒：酒中贵妇

冰酒是一种由藤蔓上冰冻的葡萄酿制而成的甜酒。葡萄内的糖分和其他溶化的固体不会被冰冻．但是水会被冰冻．所以会产生非常甜的葡萄酒。冰冻发生在发酵之前,而不会在之后。不像用来酿制其他酒（如法国产的苏特恩白葡萄酒．托卡依葡萄酒,或者贵腐酒）的葡萄．制造冰酒用的葡萄不会被灰霉病和贵腐病影响。只有健康的葡萄会一直保持美好的外型,直到采摘的最佳时机。在北半球极特殊的情况下,采摘很有可能是在新年之后。这使得冰酒中有特色的沁凉甜度和高酸度达到平衡。当葡萄远离霉菌时,     

Effects of noble rot on must composition and aroma profile of Amarone wine produced by the traditional grape withering protocol

The effects of noble rot on the overall quality of Amarone wine, a “Passito” dry red wine, produced by a traditional withering grape process are poorly understood. Wines obtained from healthy and selected grapes infected by noble rot were compared. Validation of the experimental plan was carried out by determining glycerol and gluconic acid content, laccase activity and microbial analysis of the musts. Botrytis cinerea infection produced significant variation in esterase and β-glucosidase activity of grape must. Aroma analysis in healthy and botrytised wines was carried out by SPE extraction followed by GC–MS quantification. A decrease of several fermentative esters was observed in botrytised wine, while wine produced from healthy grapes showed a higher fatty acid content. Molecules such as 1-octen-3-ol, phenylacetaldehyde and furaneol were positively linked to the noble-rotten grapes. Interestingly, γ-nonalactone and 4-carbethoxy-γ-butyrolactone increased, while sherry lactones decreased in botrytised wine. The strong increase of N-(3-methylbutyl)acetamide was related to B. cinerea grape infection.     

Rootstock and salinity effects on rates of berry maturation, ion accumulation and colour development in Shiraz grapes

Shiraz grapevines on either their own roots, or on the rootstocks Ramsey, 1103 Paulsen, 140 Ruggeri or 101–14, were grown at two separate sites within the Murray‐Darling viticultural region with similar irrigation regimes but with an irrigation water salinity of either 0.43 dS/m (low salinity site) or 2.3 dS/m (high salinity site). Rootstock effects on grape berry development, ion concentrations, soluble solids and acidity were followed during one season. Wines were also made and compared using spectral analysis and sensory evaluation. Rootstock effects that were common across both sites were (1) a close relationship between K+and soluble solids accumulation in developing grape berries which commenced at the onset of veraison and was indicative of a link between K+and sucrose transport in the phloem, and (2), higher wine K+, pH and colour hue for all rootstocks with one exception, namely 101–14 at high salinity where 101–14 responded similarly to own roots. Juice K+, pH and loss of K+from juice during winemaking were highest for grapes from the high salinity site. Mean berry weight was smaller and the range in berry size across rootstocks was narrower at the saline site. The narrower range in berry sizes may have contributed to fewer rootstock effects on wine spectral characteristics at high salinity. There was no effect of rootstock on CO₂ assimilation rate or stomatal conductance at either site, although intrinsic leaf‐based water‐use efficiency measured as A/g was 50% higher at the saline site. All treatments exhibited berry shrivel at maturity, but the extent was smaller at high salinity. Slower development of berry colour during veraison was observed on some rootstocks, for example 101–14, and while unrelated to canopy size per se, a higher leaf‐to‐fruit ratio for 101–14 may have been a factor. Slower berry colour development during veraison had no bearing on the colour density of wine made from the harvested grapes.     

不同产量对山西乡宁产区赤霞珠葡萄与葡萄酒品质的影响

通过疏穗处理设置不同产量（450 kg/667 m2、720 kg/667 m2和990 kg/667 m2）,探究不同产量对山西乡宁地区赤霞珠葡萄果实及葡萄酒品质的影响,以期在保产的基础上通过限产为山西乡宁地区生产优质酿酒葡萄原料提供理论基础。结果表明,赤霞珠葡萄在产量为720 kg/667 m2、果穗数为16穗/株时,成熟葡萄果实中总酚、单宁含量及葡萄酒中酚类物质含量与其他两种产量无显著差异（P＞0.05）,但葡萄果实成熟度最好（成熟系数31.45）,成熟葡萄果实中总糖含量最高（211.00 g/L）,总酸含量最低（6.72 g/L）,总花色苷含量最高（33.33 mg/L）,酿造的干红葡萄酒基本理化指标符合GB 15037—2006《葡萄酒》要求,感官评分最高（80.8分）,说明该产量下赤霞珠葡萄品质和酿酒品质最优。表明通过疏穗适度控制产量有利于提高山西乡宁地区的赤霞珠葡萄品质和葡萄酒质量。     

谈葡萄酒酿造的几项基本原则

葡萄酒应该充分体现葡萄原料的特点，新技术的介入是为了提升葡萄酒的价值，而不能改变其本来面目。葡萄的质量是葡萄酒质量的根本保证，葡萄的品种、成熟度与酒种密切相关；葡萄酒的病害以预防为主；对原料的改良无法达到正常成熟的葡萄所具有的质量；对葡萄汁进行处理要优于对酒进行处理；对葡萄酒的任何处理都是以牺牲酒的质量作为代价的。     

葡萄多酚的保健作用及其在酿酒葡萄成熟度判定中的应用

葡萄酒含有极其复杂的物质,其中葡萄多酚对葡萄酒品质具有决定性的作用。本文综述了当前葡萄多酚的研究成果以及在酿酒葡萄成熟度判定中的应用。通过实验证明,酿酒葡萄中葡萄多酚含量的测定值可以用于判断葡萄成熟度,对酿酒葡萄的适时采收具有普遍的指导意义。     

Changes in sour rotten grape berry microbiota during ripening and wine fermentation

This study investigated the microbiota of sour rotten wine grapes and its impact on wine fermentations. Yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB) were enumerated and identified on sound and sour rot grapes during the ripening stage. The alteration of the ecological balance induced by sour rot was particularly evidenced by the unequivocal increase of yeast and AAB counts on rotten grapes, since the beginning of ripening. Yeast and AAB species diversity in rotten grape samples were much higher than those found in sound grapes. LAB populations were low detected from both healthy and sour rotten grapes. The yeast species Issatchenkia occidentalis, Zygoascus hellenicus and Zygosaccharomyces bailii and the AAB species Gluconacetobacter hansenii, Gluconacetobacter intermedius and Acetobacter malorum, were recovered from damaged grapes and resulting grape juices in the winery. Acetobacter orleaniensis and Acetobacter syzygii were only recovered from sour rotten grapes. Dekkera bruxellensis and Oenococcus oeni were only recovered after wine fermentation induced by starter inoculation, irrespective of grape health, probably originating from cellar environment. After malolactic fermentation, racking and sulphur dioxide addition the only remaining species were the yeast Trigonopsis cantarellii and Saccharomyces cerevisiae, independently of the grape health status.     

Grape and wine analysis - enhancing the power of spectroscopy with chemometrics.

Spectroscopic techniques offer the potential to simplify and reduce analytical times for a range of grape and wine analytes. It is this aspect, together with the ability to simultaneously measure several analytes, which was the impetus for developing spectroscopic methods. The Australian Wine Research Institute (AWRI) has long used spectroscopic analysis of wines in the ultraviolet (UV) and visible (Vis) wavelengths, and since 1998 has been investigating applications of spectroscopic techniques in the near infrared (NIR) and mid-infrared (MIR) wavelength regions of the electromagnetic spectrum for the rapid analysis and quality control of both grapes and wine by the Australian wine industry. This paper reviews the use of several spectroscopic techniques, including NIR, MIR, and Vis, combined with chemometrics, to assess grape and wine composition in the Australian wine industry. The achievements, current research, and proposed further applications of different spectroscopic techniques are discussed in studies into the assessments of red grape composition and of fungal diseases in grapes, monitoring phenolic compounds during red wine fermentations, quality grading of red, white and fortified wine styles, monitoring wine distillation processes, and yeast strain classification.