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An increase in bushfires and wildfires globally and consequent smoke exposure of grapevines has seen an elevated need for remediation options to manage the impact of smoke taint in the wine industry. Two commercially available activated carbons (PS1300 and CASPF) were evaluated at 1, 2, and 4 g/L with juice from smoke-affected Pinot Noir and Chardonnay grapes. PS1300 and CASPF treatments removed up to 75 and 92% of the phenolic glycosides in the smoke-affected Pinot Noir rose juice, respectively, and both carbons removed virtually all (i.e., 98-99%) of the phenolic glycosides in the smoke-affected Chardonnay juice at the highest dose rate (4 g/L). The free volatile phenols in the wines were similarly lower in concentration following treatment. Sensory analysis confirmed that the wines made from carbon fined juice had reduced smoke aroma and flavor compared to those from the nontreated controls. However, desirable sensory properties such as color and fruity attributes were also negatively affected by the treatment. The dose rate should be optimized in industry practice to find a balance between reducing the intensity of smoke-related sensory attributes while maintaining or enhancing positive attributes.

International audience; Gas chromatography-olfactometry-mass spectrometry (GC-O-MS) has been very useful in identifying aroma compounds from within the complex matrix of wine. Supplementary separation can be required to overcome co-elution of volatiles or other sensory-directed chromatographic strategies are needed, including multidimensional chromatography and preparative fraction collection coupled to GC. Studies investigating ‘overripe orange’ aroma in sweet Sauternes wine and the similar ‘apricot’ aroma in Viognier wine were conducted. Wines with the targeted aroma attributes were selected and concentrated wine extracts prepared. GC-O found no individual aroma compounds with the targeted aroma attribute. Semi-preparative HPLC was used to obtain less complex fractions of the wine extracts. The fractions were eluted in water/ethanol and, therefore, could be smelled directly. Fractions with the targeted aroma character were further resolved by GC-preparative fraction collection (GC-PFC). Recombinational GC-PFC demonstrated the importance of the components within a 4 min preparative GC fraction to the ‘overripe orange’ aroma of typical Bordeaux dessert wine. In Viognier wine, monoterpenes linalool, α-terpineol and geraniol as well as benzaldehyde were found to be associated with the ‘apricot’ character. Thus, several wine aroma compounds interact for these specific aromas to be perceived. This sensory-led combination of separation techniques is a powerful tool for the identification of key compounds responsible for specific aromas across the wine and beverage industries.

Despite numerous studies, the identity of the compounds that are responsible for 'stone fruit’ aroma in wine has not been conclusively established. This study focussed on wine varieties that often display peach and apricot characters, such as Chardonnay, Viognier and botrytis-affected sweet Semillon wines. Wines with high and low 'stone fruit’ aroma were evaluated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) using extracts representative of the aroma of the wine in a glass. No aroma-active zone was described as 'stone fruit’ aroma across all three wine varietals. However, for the individual varieties, terpenes, such as linalool and geraniol, in the Viognier wines, several esters in the Chardonnay wines, and γ-nonalactone in the botrytis Semillon were associated with 'stone fruit’ aroma. Notably, this is the first study assessing the aroma profile of Viognier wine by GC-O. In addition, an extension study of Viognier grape monoterpene profiles clarified its classification as an aromatic variety. Refereed/Peer-reviewed

It is well established that the choice of yeast used to perform wine fermentation significantly influences the sensory attributes of wines; different yeast species and strains impart different profiles of esters, volatile fatty acids, higher alcohols, and volatile sulphur compounds. Indeed, choice of yeast remains one of the simplest means by which winemakers can modulate the sensory characteristics of wine. Consequently, there are more than 100 commercially available Saccharomyces cerevisiae wine yeast strains available, mostly derived by isolation from vineyards and successful fermentations. Nevertheless, some desirable characteristics such as 'rose' and 'floral' aromas in wine are not present amongst existing strains. Such aromas can be conferred from the higher alcohol 2-phenylethanol (2-PE) and its acetate ester, 2-phenylethyl acetate (2-PEA). These metabolites of the aromatic amino acid phenylalanine are present at concentrations below their aroma detection thresholds in many wines, so their contribution to wine style is often minimal. To increase the concentration of phenylalanine metabolites, natural and chemically mutagenised populations of a S. cerevisiae wine strain, AWRI796, were exposed to toxic analogues of phenylalanine. Resistant colonies were found to overproduce 2-PE and 2-PEA by up to 20-fold, which resulted in a significant increase in 'floral' aroma in pilot-scale white wines. Genome sequencing of these newly developed strains revealed mutations in two genes of the biosynthetic pathway of aromatic amino acids, ARO4 and TYR1, which were demonstrated to be responsible for the 2-PE overproduction phenotype.

Pioneering investigations into precursors of fruity and floral flavors established the importance of terpenoid and C 13 -norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides, amino acid conjugates, odorless volatiles, hydroxycinnamic acids, and many others. Flavor precursors mainly originate in the grape berry but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and nonenzymatic transformations, via microbial glycosidases, esterases, C-S lyases, and decarboxylases, and through acid-catalyzed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine. Refereed/Peer-reviewed

The aim of this study was to verify what factors influence the likelihood of wine choice in a developing wine market (China). Previous studies have shown that country of origin is either the first or second most important choice cue for a product such as wine, with consumers relying on country perception and associations. In this study, the same respondents completed a repeated discrete choice experiment, with simulated wine bottles on a shelf, to test the effectiveness of different messages about Australia, a relatively new supplier of wine to this market. In the first experiment, messages were shown in an advertorial format as a way of building consumer associations. The second experiment assessed messages' memory decay after approximately ten days. Wine quality ratings were the most important attribute to influence choice, while country of origin messages increased the relative attribute importance for country, which practically doubled for most of the articles. The messages about clean environment and the taste of the wine were the most effective in increasing choice of wine in both the short and medium term. Consumer choices changed overtime and the results provided evidence regarding the retest reliability of repeated choice experiments. Respondents of the control group became considerably more price sensitive in their wine choice in Stage 2. Overall, repeated discrete choice experiment methodology provided useful insights into the decay effect of advertorial messages over a 10 day period and can be applied in any relatively high involvement product type in specific markets. Refereed/Peer-reviewed

The performance of the recently developed rapid sensory descriptive method Pivot© Profile (PP) was assessed with a set of 17 Shiraz/Syrah red wines using a group of 49 sommeliers and 11 winemakers. The PP results were compared to results from descriptive analysis (DA) performed by a trained panel. The PP from the two groups of experts gave similar sample configurations, although the terms used differed, with one notable difference being less detailed information on wine colour provided by the sommeliers. The data showed that the PP results from the two panels were also closely equivalent to that obtained from descriptive analysis, with similar sample space configurations, relatively high RV coefficient values and comparable attributes discriminating the samples. PP allowed interpretation of complex terms used by the two groups of experts, and gave insight into the major sensory differences discriminating the wines. DA provided better information regarding attributes that differed more subtly among the sample set, including bitterness. This study demonstrated for the first time that PP and DA provide similar insights into the sensory properties of products, and confirmed that PP with expert panellists allows a rapid understanding of the main sensory differences among samples, with some advantages over DA in obtaining a more holistic overview of each sample.

(Z)-6-Dodeceno-γ-lactone is a potent aroma compound that has been little studied and its prevalence in wines is unknown. An efficient stable isotope dilution assay was developed using a simple, direct immersion solid-phase microextraction and gas chromatography-tandem mass spectrometry method suitable for routine use with a low ng/L limit of quantitation. Using this method, 99 out of 104 young white wines analysed were found to contain detectable (Z)-6-dodeceno-γ-lactone. The highest concentrations were found in Riesling and Viognier wines. (Z)-6-Dodeceno-γ-lactone was found to have an aroma detection threshold of 700 ng/L in a neutral white wine. This study established that (Z)-6-dodeceno-γ-lactone is widely present in Australia's most popular white wine varieties, but generally at concentrations below its aroma detection threshold. Refereed/Peer-reviewed

International audience; A 'stone fruit' aroma is important in many white wine varieties and styles, but little is known about the chemical basis of this wine aroma attribute. A set of Viognier and Chardonnay wines that featured 'stone fruit' aroma attributes were selected by a panel of wine experts. The selected wines were characterized by sensory descriptive analysis and detailed volatile chemical composition analyses. This comprehensive data also allowed Viognier wine to be profiled for the first time. By partial least-squares regression, several esters and fatty acids and benzaldehyde were indicated as contributing to the 'peach' attribute; however, a reconstitution sensory study was unsuccessful in mimicking this attribute. A mixture of γ-lactones, monoterpenes, and aldehydes were positively correlated to the 'apricot' aroma, which were generally higher in the Viognier wines. Reconstitution studies confirmed that the monoterpenes linalool, geraniol, and nerol were the most important compounds for the mixture being perceived as having an 'apricot' aroma.

A series of five Vitis vinifera L. cv Cabernet Sauvignon wines were produced from sequentially-harvested grape parcels, with alcohol concentrations between 12% v/v and 15.5% v/v. A multidisciplinary approach, combining sensory analysis, consumer testing and detailed chemical analysis was used to better define the relationship between grape maturity, wine composition and sensory quality. The sensory attribute ratings for dark fruit, hotness and viscosity increased in wines produced from riper grapes, while the ratings for the attributes red fruit and fresh green decreased. Consumer testing of the wines revealed that the lowest-alcohol wines (12% v/v) were the least preferred and wines with ethanol concentration between 13% v/v and 15.5% v/v were equally liked by consumers. Partial least squares regression identified that many sensory attributes were strongly associated with the compositional data, providing evidence of wine chemical components which are important to wine sensory properties and consumer preferences, and which change as the grapes used for winemaking ripen.

Background With increased prevalence of saline irrigation water applied to vines worldwide, the issue of appropriate nitrogen management is of concern. Different rates of nitrogen per vine as urea were applied to Shiraz vines on own roots over four seasons in a low-rainfall, saline growing environment. Results Application of nitrogen in the vineyard early in the season not only altered the vine nitrogen status but also increased some other elements in the petioles, notably chloride and sodium but also manganese and magnesium. In contrast, nitrogen application decreased petiole phosphorus. In comparison with the majority of nitrogen studies on non-saline sites, nitrogen-induced growth responses were restricted under the saline conditions in this study. While some changes in canopy density in response to nitrogen were observed, this did not affect light interception in the fruit zone. Yield responses were varied and could be related to the nutritional conditions under which bud development and flowering took place. Conclusion This study demonstrated that current best practice guidelines, in terms of rate of nitrogen applied, for correcting a nitrogen deficiency on a non-saline site may not be appropriate for saline sites and that application of nitrogen can increase the potential for salt toxicity in vines. © 2013 Society of Chemical Industry

This study investigated the sensory significance of monoterpene glycosides during tasting, by retronasal perception of odorant aglycones released in-mouth. Monoterpene glycosides were isolated from Gewürztraminer and Riesling juices and wines, chemically characterised and studied using sensory time-intensity methodology, together with a synthesised monoterpene glucoside. When assessed in model wine at five times wine-like concentration, Gewürztraminer glycosides and geranyl glucoside gave significant fruity flavour, although at wine-like concentrations, or in the presence of wine volatiles, the effect was not significant. Gewürztraminer glycosides, geranyl glucoside and guaiacyl glucoside were investigated using a sensory panel (n = 39), revealing large inter-individual variability, with 77% of panellists responding to at least one glycoside. The study showed for the first time that grape-derived glycosides can contribute perceptible fruity flavour, providing a means of enhancing flavour in wines, and confirms the results of previous studies that the effect is highly variable across individuals. Refereed/Peer-reviewed

PurposeThe purpose of this paper is to determine the degree to which wine consumers in South Australia have different liking for white wine styles, and to relate reported liking to wine knowledge and demographic differences.Design/methodology/approachA group of 150 regular white wine drinking consumers from the Adelaide metropolitan area responded to a wine habits and attitudes questionnaire. Consumers were segmented based on self‐reported liking of white wine styles, with three distinct segments identified.FindingsSauvignon Blanc wine likers were mainly younger females with low wine knowledge who reported not drinking Chardonnay wines. Conversely, “Riesling wine likers” were generally older with higher wine knowledge. These consumers were interested in the region, vintage and alcohol level when purchasing white wine. The final group (40 percent of the total sample) had a lower liking for Riesling wines, but liked all types relatively highly, had low to moderate wine knowledge and took more note of expert opinion than the other clusters.Research limitations/implicationsThe findings of this study can be extrapolated to the South Australian population, however, the sample size may restrict the generalisation of the results to the broader Australian population.Originality/valueThe results of this study provide initial insights into the behaviour of white wine consumers and highlight the importance of wine knowledge in differentiating consumer liking. Some strategies for influencing consumers' preference are suggested.

Inorganic nitrogen salts, and to a growing extent organic nitrogen preparations, are widely used to ameliorate a nitrogen deficiency in wine fermentation, but the impact of nitrogen supplementation on perceived wine sensory profile is essentially unknown. Supplementation of a low nitrogen Chardonnay grape juice with either ammonium nitrogen or combined amino acid and ammonium nitrogen showed that the type of nitrogen and concentration in the range 160-480mgN/l had a substantial impact on the formation of yeast volatile compounds and perceived wine aroma. Addition of amino acid and ammonium nitrogen increased both acetate and medium chain fatty acid esters to a greater extent and decreased higher alcohols to a lesser extent than ammonium nitrogen alone whereas ammonium nitrogen substantially increased ethyl acetate and acetic acid. Low nitrogen wines were rated relatively low in floral/fruity aroma descriptors, while moderate nitrogen wines showed a good balance between desirable and less desirable attributes, whereas high nitrogen produced either an acetic/solvent character or highest ratings for floral/fruity attributes, depending on nitrogen type. These results show that amount and type of nitrogen supplement can substantially modulate Chardonnay wine volatiles composition and perceived aroma.

Fermentations using different yeast strains can result in varying concentrations of volatile thiols and substantial sensory effects in young Sauvignon blanc wines. These yeast-derived aroma differences are generally thought to be short lived; therefore, Sauvignon blanc wines made using different yeast strains in two separate studies were investigated after three years of cellar storage. Differences were observed in the volatile composition and sensory profiles of the three-year-old wines that, when compared with the six-month data, demonstrated the continued influence of yeast strains. This observation provides further evidence that choice of yeast strain is important to wine flavor.

The effects of yeast assimilable nitrogen (YAN) supplementation on Shiraz volatile composition and sensory properties have been investigated. A low YAN Shiraz must (YAN 100 mg/L) was supplemented with nitrogen in the form of diammonium phosphate (DAP) to a final YAN of either 250 or 400 mg/L. Fermentation was carried out with either Saccharomyces cerevisiae or Saccharomyces bayanus , with maceration on skins. For both yeast strains, high DAP additions increased the ratings of positive sensory attributes such as "red fruit" and "dark fruit" and decreased the "yeast/cheese", "vegetal", and "earth/dirty" attributes. For the S. cerevisiae yeast moderate DAP addition resulted in higher "reduced" attribute scores. DAP supplementation had a strong influence on formation of acetates, fatty acid ethyl esters, higher alcohols, hydrogen sulfide, ethyl mercaptan, methyl mercaptan, DMS, and DES. Partial least-squares regression analysis of chemical and sensory data indicated that esters, sulfides, and mercaptans were associated with fruit-related descriptors, whereas hydrogen sulfide was associated with the "reduced" attribute. Nitrogen-related variations in the concentration of other yeast metabolites such as ethanol and 2- and 3-methylbutanoic acids also affected perceived fruitiness. Depending on yeast species DAP supplementation to a low nitrogen must can result in increased reduction off-odor.

An online discrete choice experiment was combined with a separate informed sensory hedonic test in a two-stage process to understand the interplay of wine sensory characteristics and extrinsic attributes such as packaging, price and brand awareness. This approach simulated the process of a consumer choosing a product from the shelf, tasting the product, and making a repurchase decision. The response measures were validated by relating them to market sales data. Twenty-one commercial Australian Shiraz red wines were characterised by a trained sensory panel. Four hundred and twenty-six regular wine consumers chose a wine for a dinner with friends from simulated shelves of the wines represented by photographs. Their choices were mainly a result of extrinsic wine attributes and the frequency of choice was found to be highly related to a wine’s market share. The same consumers evaluated liking and made a repurchase decision in a central location tasting in an incomplete design, which included photos of each of the 21 wines. Price was found to be a strong positive driver of informed liking, and liking did not relate to the sales volume or to the initial choice in the online experiment. In contrast, the previously measured online choice was a strong predictor for repurchase with tasting, confirming that both product expectations at the initial purchase and intrinsic sensory attributes during product consumption substantially influence the repurchase decision. A number of common sensory characteristics were also positively and negatively related to both liking and repurchase intent. The study provided an insight into the relative importance of product expectation and actual sensory experience on informed repurchase intent. The combination of the discrete choice methodology with sensory descriptive data and consumer sensory testing shows promise.

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.

The combination of mass spectrometry (MS) based electronic nose (eNose) with visible (VIS) and near infrared spectroscopy (NIR) was explored as an objective tool to measure sensory attributes in commercial Riesling wines grown in Australia. Calibration models were developed between instrumental data and sensory scores using partial least squares (PLS) regression with full cross validation. Good correlations (r > 0.70, root mean square standard error in cross validation (RMSECV): 0.66) were found for developed and floral; intermediate (0.70 > r > 0.60, RMSECV: 0.84 and 0.63) for tropical and low (r < 0.50, RMSECV: 0.98) for green characters measured by a sensory panel and the combination of both techniques. The results suggested that data from instrumental techniques coupled with chemometrics might be related with sensory scores measured by a trained panel. The study is considered a starting point in order to evaluate useful sources of information generated by different instrumental techniques with the objective to select combination of sensors for specific wine quality attributes.

Chardonnay juice from grape batches with increasing severity of powdery mildew (0-100%) was assessed over three seasons (2001-2002, 2002-2003 and 2003-2004). In each season, grapes across infection categories were harvested at a rarger total soluble solids (TSS) value. to 2001-2002, wine was made under replicated conditions. In each year there was an increase in titratable acidity (TA), total phenolics, hydroxyciooamates and flavonoids in grapes and wine, corresponding with increasing severity of infection. Grape bunches with the most severe disease accumulated TSS earlier. Also, there was a trend for mean bunch and berry weights to decrease with increase in powdery mildew severity. The total microbial population was larger on powdery mildew-affected grapes than on healthy grapes. Sensory descriptive analysis of Chardonnay wines from the 2002 vintage showed that wines made from grapes with powdery mildew, even the least affected, were perceived as having more produced viscosity/oiliness mouth-feel than wines made from disease-free grapes. This attribute was correlated with the phenolic composition of the wines. In addition, samples from powdery mildew-affected grapes were more produced in fuogal, earthy and cooked tomato aroma attributes (wine) and dusty and mushroom aroma (juice) than healthy controls. This study demonstrated that compositional and sensory changes were detected in juice and wines made from grape batches with as little as l-5% of bunches affected by powdery mildew.

An important flavour compound associated with malolactic fermentation (MLF) is the volatile di-ketone, diacetyl (2,3-butanedione), which is considered as the major contributor to buttery flavour in wines. Commercial Chardonnay, Cabernet Sauvignon, Merlot and Shiraz wines from eight vintages (1992- 1999), 20 viticultural regions and 28 wine producers were analysed for diacetyl and also the buttery aroma intensity was rated by a trained sensory panel. The wines examined were found to have a wide range of diacetyl concentration, i.e. 0.3 to 0.6 mg/L (mean value 0.4 mg/L) for the 24 Chardonnay wines, and 0.3 to 2.5 mg/L (mean value 1.1 mg/L) for the 43 red wines. The buttery aroma, while significantly correlated with diacetyl concentration in the Chardonnay wines (P < 0.01), was not predicted very well by the regression equation, but the prediction was improved when the free sulfur dioxide concentration of the wines was taken into account (adjusted R2 = 0.43, P < 0.01). There was a weak, although statistically significant, correlation between diacetyl concentration and the buttery rating for the red wine data set, when the sulfur dioxide concentration was taken into account (adjusted R2 = 0.12, P < 0.05). This weak correlation may have been, in part, due to the generally low concentration of diacetyl in relation to the published aroma threshold in red wine. It was also noted that there was a substantial decrease in diacetyl concentration for a subset of red wines, but not for white wines, of various vintages cellared for three years at 15°C.

The key aroma compounds of premium Australian Shiraz wines from the warm Barossa Valley and cooler Margaret River regions were characterized. GC–Olfactometry was conducted to determine the most important volatile compounds, which were then quantitated. The wine from the Barossa Valley had higher concentrations of ethyl propanoate, dimethyl sulfide (DMS), and oak-derived compounds, whereas the Margaret River wine contained above threshold concentrations of the ‘cheesy’ compounds 2- and 3-methylbutanoic acid, as well as rotundone, the ‘pepper’-smelling compound. The aromas were reconstituted by combining 44 aroma compounds, and sensory descriptive analysis was used to investigate the importance of the omission of several compounds, including DMS, rotundone, fatty acids, and β-damascenone, and the influence of nonvolatiles was also assessed. The study showed that the aroma of the Shiraz wines could be reconstituted in both cases, with the changes in the nonvolatile fraction having a large influence.

The use of yeasts other than Saccharomyces cerevisiae to produce wines with novel aroma and flavour profiles is gaining increased attention. The present study is concerned with the sensory impact on wine of fermentation with two selected Saccharomyces bayanus strains. The S. bayanus strains AWRI 1176 and AWRI 1375 were compared to S. cerevisiae strain AWRI 838 for their ability to affect the aroma profile and chemical composition of Chardonnay wine. Wines that were made with the S. bayanus strains contained more glycerol, succinic acid, acetaldehyde and SO 2 than reference wines made with the S. cerevisiae wine yeast, but less acetic acid, malic acid and ethyl acetate. There were significant differences in the aroma profile of wines made with each yeast, as quantified by formal sensory descriptive analysis. Wines made with S. cerevisiae AWRI 838 were rated highly in the attributes 'estery', 'pineapple', 'peach' and 'citrus'. Wines made with S. bayanus AWRI 1176 were rated lower than AWRI 838 in each of these attributes, but higher in the attributes 'cooked orange peel', 'yeasty', 'nutty' and 'aldehyde'. The aroma profile of wine made using AWRI 1375 was different from that of wine made with the other yeasts, showing intermediate scores for the 'estery', 'citrus', 'nutty' and 'aldehyde' attributes, and no significant difference from the AWRI 838 strain in the attributes 'pineapple' and 'peach'. These results demonstrate that, in addition to producing wine which has a different chemical composition, S. bayanus strains can produce a different sensory profile in wine when compared to a widely used S. cerevisiae wine yeast.

A hierarchically structured vocabulary of mouth-feel sensations elicited by red wines has been produced. Represented as a wheel, this structured vocabulary should assist tasters in their interpretation and use of terminology relating to 'in mouth' sensations produced by red wines. These terms and their definitions were generated by consulting the opinions of experienced wine tasters following exposure to an extensive range of commercial red wines. Logical relationships among the derived terms were formulated by analysis of 'sorting data' provided by a combined group of experienced winemakers and wine-tasters.

The volatile phenols guaiacol, 4-methylguaiacol, syringol, 4-methylsyringol, o-, m-, and p-cresol, as well as their glycoconjugates, have previously been shown to be present in elevated concentrations in smoke-tainted wine. Sensory descriptive analysis experiments, with addition of free volatile phenols in combination with their glycosidically bound forms, were used to mimic smoke taint in red wines. The addition of volatile phenols together with glycoconjugates gave the strongest off-flavor. The hydrolysis of glycosidically bound flavor compounds in-mouth was further investigated by in vitro and in vivo experiments. The results indicate that enzymes present in human saliva are able to release the volatile aglycones from their glycoconjugates even under low pH and elevated ethanol conditions, confirming that in-mouth breakdown of monosaccharide and disaccharide glycosides is an important mechanism for smoke flavor from smoke affected wines, and that this mechanism may play an important general role in the flavor and aftertaste of wine.

An analytical assay for glycosylated secondary metabolites of grapes, juices and wines, through quantification of glycosyl glucose (G-G), has been optimized and validated. The glycosides are isolated on C 18 reversed-phase silica gel and hydrolyzed with sulfuric acid at 100 o C; the released glucose is determined enzymatically. The accuracy and precision of the assay, determined from the gradients and coefficients of determination of linear regression curves for the recovery of a standard glycoside from wine, juice or homogenized fruit extract ranged, respectively, from 0.957 to 1.021 and from 0.991 to 0.997. Some examples of application of the assay are presented-the decrease of G-G in wines with aging, the range of G-G in Shiraz juices from different regions, and the development of G-G in ripening fruit

With increased prevalence of saline irrigation water applied to vines worldwide, the issue of appropriate nitrogen management is of concern. Different rates of nitrogen per vine as urea were applied to Shiraz vines on own roots over four seasons in a low-rainfall, saline growing environment.Application of nitrogen in the vineyard early in the season not only altered the vine nitrogen status but also increased some other elements in the petioles, notably chloride and sodium but also manganese and magnesium. In contrast, nitrogen application decreased petiole phosphorus. In comparison with the majority of nitrogen studies on non-saline sites, nitrogen-induced growth responses were restricted under the saline conditions in this study. While some changes in canopy density in response to nitrogen were observed, this did not affect light interception in the fruit zone. Yield responses were varied and could be related to the nutritional conditions under which bud development and flowering took place.This study demonstrated that current best practice guidelines, in terms of rate of nitrogen applied, for correcting a nitrogen deficiency on a non-saline site may not be appropriate for saline sites and that application of nitrogen can increase the potential for salt toxicity in vines.

Guaiacol and 4-methylguaiacol are well-known as contributors to the flavor of wines made from smoke-affected grapes, but there are other volatile phenols commonly found in smoke from forest fires that are also potentially important. The relationships between the concentration of a range of volatile phenols and their glycoconjugates with the sensory characteristics of wines and model wines were investigated. Modeling of the attribute ratings from a sensory descriptive analysis of smoke-affected wines with their chemical composition indicated the concentrations of guaiacol, o-cresol, m-cresol, and p-cresol were related to smoky attributes. The best-estimate odor thresholds of these compounds were determined in red wine, together with the flavor threshold of guaiacol. Guaiacol β-D-glucoside and m-cresol β-D-glucoside in model wine were found to give rise to a smoky/ashy flavor in-mouth, and the respective free volatiles were released. The study indicated that a combination of volatile phenols and their glycosides produces an undesirable smoke flavor in affected wines. The observation of flavor generation from nonvolatile glycoconjugates in-mouth has potentially important implications.

Free volatiles, and those hydrolytically released from glycosidic forms, were analyzed for Sauvignon Blanc juices from three successive vintages. Most of the 213 compounds identified were in one of the bio-genetic categories: norisoprenoids, benzene derivatives, monoterpenes or aliphatics. Several have not been previously reported as grape components. Monoterpenes were in lower concentration than normally found in floral grape varieties, but at higher levels than reported in Chardonnay juices. A notable proportion (40–50%) of the bound monoterpenes were monocyclic. Hydration of α-terpineol at pH 3 gave c-4-(1-hydroxy-1-methyIethyl)-1-methyl-r-1-cyclohexanol (cis-p-men-thane-1,8-diol) and t-4-(1-hydroxy-1-methylethyl)-1-methyl-r-1-cy-clohexanol (trans-p-menthane-1,8-diol) as the main products and a low yield of t-4-(1-methylethyl)-r-1-methylcyclohexane-1,4-diol (trans-p-menthane-1,4-diol). These were confirmed as major components of the acid hydrolysates of the bound fraction.

Consumer acceptance testing has been only recently applied in wine research, to assess wine sensory attributes that affect hedonic liking. The aim of this study was to investigate the effect of Saccharomyces yeast co-inoculations on wine volatile composition and sensory profiles, and to determine if differences were sufficient enough to affect consumer acceptance. Fermentations were conducted using two- and three-yeast co-inoculations, and single strains. Yeast inocula differed substantially in volatile thiols and other flavour compounds, and in their sensory properties. Wines from four yeast inocula which showed large sensory differences were subjected to consumer testing by 120 consumers, with differences in overall liking found. Four clusters of consumers were identified, with one group strongly preferring the two-yeast co-inoculated wine with an intermediate sensory profile, while another group favoured the wine made using the three-yeast co-inoculation. This study has demonstrated that the yeast inoculum used to conduct fermentation affects consumer acceptance. Refereed/Peer-reviewed

The aroma properties of hydrolysed glycosidic precursors from Semillon, Sauvignon Blanc and Chardonnay grape juices were investigated in a neutral wine medium using sensory descriptive analysis. The glycosidic fractions were hydrolysed by acid catalysis in the presence or absence of ethanol, by glycosidase enzyme action, or by a sequence of glycosidase and acid treatments. Wines made from the Chardonnay and Semillon juices were also assessed. Sensory difference tests showed that samples from each variety for each treatment were distinct, except the hydrolysates prepared enzymically from Semillon and Chardonnay. The aroma of each acid hydrolysate was distinguishable from the neutral wine by enhanced intensity of the attributes honey, tea, lime and floral. Enzyme treatment of the glycosides from Sauvignon Blanc gave a hydrolysate with aroma properties similar to those of the corresponding acid hydrolysate, but with less intense tea, oak and honey attributes. The treatment consisting of enzyme followed by acid hydrolysis produced an artefact, apparently due to degradation of the added enzyme. Aroma attributes that characterise Chardonnay and Semillon wines were also aromas perceived in the hydrolysed precursor samples, indicating that grape precursors on hydrolysis contribute to and enhance these key aromas in the wines.

Alcoholic fermentation using Saccharomyces wine yeast is an effective means of modulating wine aroma. This study investigated the impact of coinoculating commercial yeast strains (Vin7, QA23, Vin13) on the volatile composition and sensory profile of Sauvignon Blanc wines. Small-scale replicated fermentations were conducted using single-strain and coinoculations of Vin7 with QA23 and with Vin13. The results showed that the chemical and sensory profiles of the coinoculated wines were different from both the single-strain wines and equal blends of the single-strain wines. Volatile thiol analysis indicated that the Vin7/QA23 coinoculated wines were highest in 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), although this pattern was not observed for the Vin7/Vin13 yeast combination. The negative white vinegar aroma and high volatile acidity measured in the Vin7 single-strain wines were not present in the coinoculated wines. This study demonstrates that coinoculations can modify the aroma profile of wines, when complementary yeasts are used.

'Black pepper' aroma and flavor is important to some Australian Shiraz red wine styles but the aroma compounds involved have yet to be identified, and no objective analytical method to assess 'pepper' grape aromas is available to date. Samples of potentially 'spicy'/'peppery' grapes were obtained from vineyards in South Australia and Victoria over two vintages. The important sensory attributes of the grapes, including the aroma descriptor 'pepper', were rated by a sensory panel. The sensory study revealed a strong correlation between the intensity of 'pepper' aroma and the intensity of 'pepper' flavor perceived on the palate. The grape homogenates were analyzed by static headspace GC-MS using a cool inlet system. Vectors obtained by analysis of over 13 000 individual mass spectra per grape sample were then subjected to multivariate analyses. Both principal component analysis and partial least-squares regression were used to develop multivariate models based on mass spectra and aroma descriptors to explain the intensity of the rating of the 'pepper' character. Corresponding differences in mass spectra and aroma were observed among vineyards and from the same vineyards in different years. Additional optimization of the methodology enabled selection of a single region of the GC-MS chromatogram that allowed prediction of 'pepper' aroma intensity with a correlation coefficient0.98 and led to the identification of alpha-ylangene, a tricyclic sesquiterpene. To assess the potential of alpha-ylangene as a marker for this sensory characteristic, a method for alpha-ylangene analysis of grapes and wine using HS-SPME-GC-MS was developed. Although not a significant aroma compound by itself, alpha-ylangene was a satisfactory marker for the 'pepper' aroma in grapes and wine, and its concentration showed similar discrimination between 'peppery' vineyards and vintages as that obtained using the multivariate models. Despite its presence in grapes, we could not detect alpha-ylangene in wine.

Volatile thiols, such as 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), are among the most potent aroma compounds found in wine and can have a significant effect on wine quality and consumer preferences. At optimal concentrations in wine, these compounds impart flavours of passionfruit, grapefruit, gooseberry, blackcurrant, lychee, guava and box hedge. The enzymatic release of aromatic thiols from grape-derived, non-volatile cysteinylated precursors (Cys-4MMP and Cys-3MH) and the further modification thereof (conversion of 3MH into 3MHA) during fermentation, enhance the varietal characters of wines such as Sauvignon Blanc. Wine yeast strains have limited and varying capacities to produce aroma-enhancing thiols from their non-volatile counterparts in grape juice. Even under optimal fermentation conditions, the most efficient thiol-releasing Saccharomyces cerevisiae wine strain known realizes less than 5% of the thiol-related flavour potential of grape juice. The objective of this study was to develop a wine yeast able to unleash the untapped thiol aromas in grape juice during winemaking. To achieve this goal, the Escherichia coli tnaA gene, encoding a tryptophanase with strong cysteine-beta-lyase activity, was cloned and overexpressed in a commercial wine yeast strain under the control of the regulatory sequences of the yeast phosphoglycerate kinase I gene (PGK1). This modified strain expressing carbon-sulphur lyase activity released up to 25 times more 4MMP and 3MH in model ferments than the control host strain. Wines produced with the engineered strain displayed an intense passionfruit aroma. This yeast offers the potential to enhance the varietal aromas of wines to predetermined market specifications.

Powdery mildew, caused by the fungus Uncinula necator, is a widespread and economically important disease of grapevines. The fungus grows superficially on green tissues of grapevines and other members of the Vitaceae. Powdery mildew costs the Australian grape and wine industry approximately A$30 million per year in terms of lost yield, reduced quality and disease management.