Despite the known ability of copper(II) to suppress sulfidic aromas, particularly the Cu fractions associated with organic acids and Cu(I) thiol species, the action of these copper fractions on the accumulation of light-induced sulfidic aromas in bottle-aged white wine is unknown. Chardonnay wine, containing different concentrations of riboflavin and copper(II), was exposed to fluorescent light for 6.5 months. The Cu fractions were measured by colorimetry, volatile sulfur compounds by gas chromatography-sulfur chemiluminescence detector (GC-SCD), and volatile aldehydes by gas chromatography-mass spectrometry (GC-MS). The protective Cu fractions inhibited light-induced sulfidic odor accumulation; however, light exposure accelerated the loss of these Cu fractions, and this loss was further accelerated with elevated riboflavin concentration. Upon depletion of the protective Cu fractions, the presence of copper sulfides led to an elevated hydrogen sulfide concentration with further light exposure. The results demonstrated that Cu(II) offers transient protection against the deleterious effects of short-term light exposure but can promote reductive characters with long-term light exposure.

Cu(II)-organic acid (fraction I) and Cu(I)-thiol (fraction II) complexes can suppress sulfhydryl off-aromas in wine. This study investigated the impact of light exposure on the protective fractions of Cu of bottled white wine. Fluorescent light-exposed Chardonnay with two initial concentrations of dissolved oxygen (0.5 and 10 mg/L) was stored in different coloured bottles and concentrations of Cu fractions and riboflavin, a photo-initiator at 370-440 nm, were measured during 110 days storage. Light-exposed wines with lower oxygen concentrations resulted in a 100-fold decrease in the Cu fraction I half-life, and a 60-fold decrease for Cu fractions I and II combined. The half-life for Cu fraction I decay during light exposure was extended 30-fold with the use of brown compared to flint glass. Light exposure can rapidly exhaust the protective Cu fractions in wine, and bottles with less light transmission below 440 nm can slow this loss.

Reproducible aromatic red wine styles can be predicted based upon the measurement of grape berry sugar accumulation (corresponding to the quantity of sugar that accumulates per berry; mg/berry/day) and berry fresh mass. Distinct maturity stages, “Fresh Fruit” reminiscent of fresh/red fruits notes and “Mature Fruit” associated with dark fruit and plum characters could be correlated to berry sugar accumulation (mg/berry) and berry fresh mass evolution without any direct relationship with berry sugar concentration. After berry sugar accumulation plateaued, wine aromatic and phenolic maturity were uncoupled from technological maturity.

The impact of ascorbic acid on the oxidative and reductive development of rose wine during bottle ageing has not been previously established. A rose wine that contained 0.25 mg/L of Cu was bottled with levels of 0, 50 or 500 mg/L of ascorbic acid and different total packaged oxygen concentrations (3 and 17 mg/L), and was stored for 15 months at 14 degrees C in darkness. Ascorbic acid increased the first-order oxygen consumption rate from 0.030 +/- 0.001 to 0.040 +/- 0.001 days (1), and decreased the mole ratio of total SO2 consumed to oxygen consumed from 1.0:1 to 0.7:1. Although ascorbic acid did accelerate the loss of a Cu form that can suppress reductive aromas, it did not induce reductive aromas. These results indicate that ascorbic acid can accelerate the removal of oxygen from bottled rose wine while maintaining higher concentrations of sulfur dioxide, however, it did not promote reductive development.

Cu in wine can suppress sulfidic-odours, but the active forms and duration of protection are uncertain. Additions of 0, 0.3 or 0.6 mg/L Cu(II) were made to Chardonnay and Pinot Grigio at bottling. Throughout a 12-or 14 month storage period, Cu fractions were determined by colorimetry, and sulfhydryl compounds by gas chromatography with sulfur chemiluminescence detection. After Cu(II) addition, the dominant Cu fractions were associated with Cu(II)-organic acids (fraction I) and Cu(I)-thiol complexes (fraction II), and over 8-months their concentrations gradually fell below 0.015 mg/L. During this time, a fraction of Cu, predominantly attributed to sulfide-bound Cu, increased in concentration. Suppression of free hydrogen sulfide was assured when the combined Cu fractions I and II concentrations were above 0.015 mg/L, while free methanethiol suppression required Cu fraction I concentration above 0.035 mg/L. Decay rates for Cu fractions demonstrated that the duration that Cu can actively suppress sulfidic odours is wine-dependent.

Background and Aims Shiraz is the most widely planted winegrape cultivar in Australia. Sensory studies have indicated that different grapegrowing regions in Australia produce distinct styles of Shiraz wines that differ in flavour characteristics. The current project aimed to characterise the underlying volatile composition associated with regional Shiraz wine styles. Methods and Results Wines were selected from six geographically distinct regions and the volatile compounds were analysed using gas chromatography time-of-flight mass spectrometry to provide a comprehensive and holistic overview of the wine volatilome. A suite of R language based software enabled feature extraction and importance ranking, following an untargeted metabolomics approach. A classification model based on the random forests algorithm using the 80 most important compounds correctly associated all samples to regions. A range of these compounds, including terpenoids, benzenoids, esters, furan derivatives and aliphatic alcohols, has been associated with grape composition, winemaking influences and the ageing process. Conclusions The results suggest that the regional compositional differences in varietal wines may be influenced by all processes in the entire wine production chain. Significance of the Study The current study highlighted the chemical basis underlying the regional typicality of Australian Shiraz wines, and identified specific volatile compounds that may be associated with a region.

Background and Aims Regional characters or the 'terroir' aspects of Shiraz are not well understood. This study aimed to characterise the chemical composition of wines from sites within six important Australian regions, and the climate profiles of the sites, and to determine how they relate to sensory differences. Methods and Results For 22 commercially produced wines 70 chemical measures and 17 site- and season-specific climate indices were determined. Wines with stalky/cooked vegetal sensory properties had a higher concentration of cinnamate esters and dimethylsulfide, which through multivariate analyses was related to later budburst and time of harvest. Wines with a higher concentration of monoterpenes were associated with floral aroma. High radiation measures were linked to higher tannin, colour density, norisoprenoid compounds and phenylethyl acetate and to stronger dark fruit/dried fruit and tannin/colour attributes. High rainfall indices were generally related to low sensory attribute ratings and compositional measures. From cluster analysis of compositional data, wines were well grouped by region of origin. Conclusions Distinctive chemical fingerprints exist for the regions studied, and their climatic profiles were strongly associated with wine composition, with key compounds influencing sensory differences. Significance of the Study The approach of applying multiple site- and season-specific climate measures and relating these to chemical composition and the characteristic sensory attributes of regional Australian Shiraz wines can help producers better understand and influence the effect of place on their wines.

This study aimed to investigate the possible existence of reproducible aromatic red wine styles, focusing on fresh fruit aromas and mature fruit aromas (i.e., with dark, jammy fruit characteristics) and taking into account both vintage and vineyard. The study was performed on Australian Shiraz and Cabernet‑Sauvignon from three different meso-climate areas and two consecutive vintages. Sequential harvests were carried out based on the plateau of the physiological indicator berry sugar accumulation (mg/berry) in order to obtain fresh fruit and mature fruit wine sensory profiles. There was a predictable aromatic sequence during grape ripening at each of these two distinct maturity stages regardless of grape genotype (variety) and environment (vineyard and vintage). The post-plateau period of berry sugar accumulation was found to be crucial for the evolution of wine aromatic profiles. During this period, wine aromatic and phenolic maturity were uncoupled from technological maturity (i.e., berry sugar concentration). Dimethyl sulfide was found to be the most relevant wine aromatic marker for differentiating the fresh fruit and mature fruit stages irrespective of the variety. Specific cultivar markers with potential sensory contribution were also identified; for example, (Z)‐3‐hexenol, a possible contributor to the aromatic freshness of Shiraz wines from the fresh fruit stage. The evolution of terpenoids appeared to be separate from the dynamics of berry ripening post plateau of fruit sugar accumulation. On the other hand, ester composition was significantly altered during the same ripening period in Shiraz and Cabernet‑Sauvignon wines with a marked grape genotype effect. The results showed that yeast metabolism was also affected by berry ripening evolution from the plateau of berry sugar accumulation onwards.

This work investigated the influence of grape variety, vineyard location, and grape harvest maturity, combined with different oxygen availability treatments, on red wine composition during bottle aging. Chemometric analysis of wine compositional data (i.e., wine color parameters, SO2, metals, and volatile compounds) demonstrated that the wine samples could be differentiated according to the different viticultural or bottle-aging factors. Grape variety, vineyard location, and grape maturity showed greater influence on wine composition than bottle-aging conditions. For most measured wine compositional variables, the evolution patterns adopted from the viticultural factors were not altered by oxygen availability treatment. However, contrasting evolution patterns for some variables were observed according to specific viticultural factors, with examples including dimethyl sulfide, phenylacetaldehyde, maltol, and β-damascenone for vineyard locations, 2-methylbutanal, 1,4-cineole, and linalool for grape variety, and methanethiol, methional, and homofuraneol for grape maturity.

Background and Aims Wines that exhibit regional characters are often the most sought after and the highest valued wines available in the marketplace. This study evaluated the sensory properties that were regionally distinctive for Australian Shiraz wines. Methods and Results Sets of wines (22-28 wines) from six prominent Australian Shiraz-producing regions were initially evaluated by groups of local winemakers using a rapid sensory method called Pivot Profile (PP) to obtain maps of their sensory characteristics. Three or four wines from each region were then selected using cluster analysis of the PP data and were evaluated using sensory descriptive analysis. The regional PP assessments provided a sensory fingerprint of the variability of each of the regions studied and identified sensory characteristics that typified the largest groups of wines of each region. The descriptive analysis highlighted sensory characteristics that distinguished the wines from the different regions, including mint, cooked vegetal, viscosity, dark fruit and savoury attributes. Conclusions This work has provided detailed quantitative data on the sensory properties associated with each of the regions and demonstrated that there are distinctive, region-specific sensory characteristics. Significance of the Study Sensory fingerprints that differentiate one region from another will aid producers and the trade in appreciating what can be expected from different regions; they allow targeting of production decisions to enhance distinctive sensory attributes and will assist in improved communication between marketers and consumers.

Background and Aims The threshold for Botrytis contamination of winegrapes is not fully known. Using a measurement of the fungal sterol, ergosterol, we aimed to understand how much grey mould of grapes can be tolerated before there is a perceivable impact on wine sensory characteristics. Methods and Results Chardonnay grape bunches hand-harvested in January 2016 from the Hunter Valley, NSW, were divided into one of five groups based on the visual assessment of the severity of grey mould using a scale of 0-4. Ergosterol analysis indicated that the fungal biomass of the five batches of grapes was 0.06, 0.28, 0.87, 1.50 and 4.25 g dry mass of fungus per kg wet mass. Grey mould infection resulted in an elevated concentration of benzaldehyde, 2-pentyl furan, ethyl linoleate, (E)-3-hexenol, 3-octanol, 1,5-dimethyl-naphthalene, 1,5-dimethyl tetralin 1-octen-3-ol, 1-octen-3-one and 3-octanone in the juice. 1-Octen-3-ol, and 3-octanone, ethyl-3-hydroxydodecanoate and isoamyl acetamide were elevated in wine made with Botrytis-affected grapes. Sensory discrimination tests identified a difference between wine made from grapes with >= 0.87 g of dry mass of fungus/kg wet mass of grapes (equivalent to >= 2.57 mg ergosterol/kg grapes) and wine made from asymptomatic grapes. Conclusions Ergosterol correlated with the degree of grey mould contamination and the threshold in Chardonnay grapes was 0.28-0.87 g dry mass fungus/kg fresh mass of grapes. Significance of the Study Measurement of ergosterol has been evaluated as a quantitative estimate of the threshold for Botrytis contamination of winegrapes.

INTRODUCTION:The complex interactions of vine cultivars, and localised regional climate associated with specific vineyard sites are important attributes to the concept of terroir and significant contributors to grape maturity and wine sensory profiles. An improved understanding of the influence of each factor and their interactions is a challenging conundrum, and will enable more efficient production targeting specific wine styles.OBJECTIVES:To characterise the metabolic flux of grape berries and resulting wines to characterise the relative impact of site specific climate, cultivar, and grape maturity based upon berry sugar accumulation models that consistently target specific wine styles.METHODS:A spatial and temporal study of grape and wine composition was undertaken for two important cultivars in two distinct regions of New South Wales. Measures of composition and wine sensory ratings were simultaneously analysed using a multiblock algorithm taking advantage of the ANOVA framework to identify important contributions to wine style arising from grape maturity, vineyard site and cultivar.RESULTS:A consistent flux of grape and wine constituents is evident for wine made from sequentially harvested grapes from the same vineyard with increasing levels of grape maturity. Contributions of region and vineyard site to wine style could also be elucidated. Differences in metabolite flux in grapes and resulting wines between cultivars growing in similar conditions are evident.CONCLUSIONS:The combination of a metabolomics and multiblock data decomposition approach may be successfully used to profile and elucidate the contribution of abiotic factors to grape and wine composition and provide improved understanding of the terroir concept.

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.

This study validates a new methodology which allows the direct quantification of 13 volatile aldehyde compounds related to oxidative off-flavours in wine. The compounds investigated were four (E)-2-alkenals ((E)-2-heptenal, (E)-2-hexenal, (E)-2-octenal and (E)-2-nonenal), four Strecker aldehydes (2-methylpropanal, 3-methylbutanal, methional and 2-phenylacetaldehyde) and five general aldehydes (hexanal, furfural, 5-methylfurfural, benzaldehyde and nonanal). This methodology involved the addition of p-benzoquinone to release the aldehydes bound to hydrogen sulfite, collection via solid phase extraction, derivatisation by o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride and quantification by gas chromatography triple-quadrupole mass spectrometer in multiple reaction monitoring mode. Overall, the limit of detection, limit of quantification, accuracy (recovery, 98–103%) and precision (repeatability and reproducibility, RSD ≤ 15%) are sufficient to enable routine measurement of the 13 aldehyde compounds in wine. Sixteen commercial white and red wines of varied varieties and vintages were analysed with this methodology. White wines trended to have higher concentrations of the aldehyde compounds in comparison with the red wines.