Impact of Leaf Removal, Applied Before and After Flowering, on Anthocyanin, Tannin, and Methoxypyrazine Concentrations in ‘Merlot’ (Vitis viniferaL.) Grapes and Wines

7siThe development and accumulation of secondary metabolites in grapes determine wine color, taste, and aroma. This study aimed to investigate the effect of leaf removal before flowering, a practice recently introduced to reduce cluster compactness and Botrytis rot, on anthocyanin, tannin, and methoxypyrazine concentrations in Merlot' grapes and wines. Leaf removal before flowering was compared with leaf removal after flowering and an untreated control. No effects on tannin and anthocyanin concentrations in grapes were observed. Both treatments reduced levels of 3-isobutyl-2-methoxypyrazine (IBMP) in the grapes and the derived wines, although the after-flowering treatment did so to a greater degree in the fruit specifically. Leaf removal before flowering can be used to reduce cluster compactness, Botrytis rot, and grape and wine IBMP concentration and to improve wine color intensity but at the expense of cluster weight and vine yield. Leaf removal after flowering accomplishes essentially the same results without loss of yield. © 2016 American Chemical Society.reservedmixedSivilotti, Paolo; Herrera, Jose Carlos; Lisjak, Klemen; Baša Česnik, Helena; Sabbatini, Paolo; Peterlunger, Enrico; Castellarin, Simone DiegoSivilotti, Paolo; Herrera, Jose Carlos; Lisjak, Klemen; Baša Česnik, Helena; Sabbatini, Paolo; Peterlunger, Enrico; Castellarin, Simone Dieg

Pre-fermentation approaches to producing lower alcohol wines from Cabernet Sauvignon and Shiraz: implications for wine quality based on chemical and sensory analysis

Pre-fermentative juice substitution with water or early harvest wine has the potential to produce lower alcohol wines without critically modifying colour or tannin properties and only marginally changing volatile and sensory profiles. Whether this approach is suited to producing lower alcohol wines in the absence of excessive grape ripeness remained to be determined. The current study extends on pre-fermentative approaches to alcohol management under milder grape ripening conditions and builds on an existing study with McLaren Vale Cabernet Sauvignon fruit, allowing for a direct comparison under two distinct vintage conditions. Given its importance to Australia, Shiraz was also included and underwent the same consecutive harvest and juice substitution treatments. Cultivar-dependent implications on wine chemical properties were apparent and declines in wine colour and tannin were particularly evident in Shiraz wines, although impacts on overall wine quality and sensory parameters were minor when adjusting musts within the limit of 13.5 °Baumé.Olaf J. Schelezki, Guillaume Antalick, Katja Šuklje, David W. Jeffer

Comparison of consecutive harvests versus blending treatments to produce lower alcohol wines from Cabernet Sauvignon grapes: Impact on wine volatile composition and sensory properties

Available online 27 March 2018Abstract not availableOlaf J. Schelezki, Katja Šuklje, Paul K. Boss, David W. Jeffer

Cultivar, site or harvest date: the gordian knot of wine terroir

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

Unravelling the effect of harvest date on Shiraz wine volatile composition by two dimensional gas chromatography and wine sensory analyses

An investigation of Shiraz wine volatile composition from four vineyards located in the Riverina region of Australia was performed by accessing wines made from sequentially harvested grapes. Vines were drip irrigated with average yields from 10.2-18.5 kg/vine in the four vineyards. Shiraz wines were vinified from 60 kg grape triplicates. Following a berry ripening model [1], the first harvest (H1) was 12 days from the plateau of berry sugar accumulation and the second harvest (H2), 24 days after the plateau. Data acquired by HS-SPME-GC×GC-TOFMS were deconvoluted and aligned with LECO ChromaTOF Version 4.22 software at a signal to noise ratio of 100. A total of 1240 putative compounds were detected by HS-SPME-GC×GC-TOFMS in at least one of the samples. A comparison of vineyards revealed that approximately 200 of compounds were found to be at significantly different levels in at least one of the harvest dates. Principal component analyses illustrated a separation of samples based on harvest date. C5, C6 and C9 compounds, known as green leaf volatiles, were typically found in higher levels in H1 wines. Modifications of yeast metabolism of the sulfur-containing amino acid, methionine, were noticed. Methionol, methional and ethyl 3-(methylthio)-propionate were significantly lower in H2 wines whereas 2-(methylthio)-ethanol was increased. Several higher alcohol acetates were also measured at higher levels in H2 wines. Sensory evaluation revealed significant differences in wines based on the harvest date determined by berry ripening model. Wines from grapes harvested at H1 were perceived by panellists to be higher in red fruit attributes whereas wines from H2 were perceived higher in dark fruit and plum characters. These results indicate significant modulation of wine volatiles as a consequence of harvest dates, by altering lipoxygenase derived compounds and yeast metabolism, irrespective of vineyard cultural practices, within the same warm to hot climatic region. Acknowledgments We thank Australia’s grape growers and winemakers for their financial support through their investment body the Wine Australia (WA) and Australian Federal Government. The research was supported by the ADP 2015 Program funded by the Autonomous Province of Trento (Italy). References [1] Deloire, A. 15th Australian Wine Technical conference 2013, 47-50

Influence of yield and harvest date on Shiraz wine volatile and non-volatile composition

Targeted and untargeted metabolomics was applied to wine samples in order to determine the effect of yield and harvest date on Shiraz wine volatile and non-volatile composition within the same warm-hot Australian mesoclimate. Vines were drip irrigated and trellised to open sprawling canopy with an average yield from 10.2-18.5 kg/vine/vineyard. Shiraz wines were made in triplicates from grapes harvested at two occasions 10 to 12 days apart (harvest 1; H1 and harvest 2; H2, respectively) commencing 12 days from the plateau of berry sugar accumulation. Wine volatiles were acquired by HS-SPME-GC×GC-TOFMS. A total of 1,276 putative compounds were detected in at least one of the wine samples and 175 compounds showed significant trends related to grape maturity. The first two dimensions of the PCA accounted for 57% of the variation and separated the samples according to the harvest date, irrespective of the yield. Trained tasting panels were able to perceive differences between wines from H1 and H2. Wine polyphenols and wine pigments were quantified by LC-MS/MS. Vineyard yield had a predominant effect on wine color related pigments, whereas harvest date was of lesser importance. More than 50 quantified polyphenols in wines were poorly correlated with either harvest date or yield. In conclusion, common evolution of wine volatiles, irrespective of site particularities was noticed for Shiraz, whereas it seems that wine non-volatile composition (colour related compounds and polyphenols) is at bigger influence of site rather than harvest date in the late ripenin

Unravelling the effect of harvest date on Shiraz wine volatile composition by two dimensional gas chromatography and wine sensory analyses

An investigation of Shiraz wine volatile composition from four vineyards located in the Riverina region of Australia was performed by accessing wines made from sequentially harvested grapes. Vines were drip irrigated with average yields from 10.2-18.5 kg/vine in the four vineyards. Shiraz wines were vinified from 60 kg grape triplicates. Following a berry ripening model [1], the first harvest (H1) was 12 days from the plateau of berry sugar accumulation and the second harvest (H2), 24 days after the plateau. Data acquired by HS-SPME-GC×GC-TOFMS were deconvoluted and aligned with LECO ChromaTOF Version 4.22 software at a signal to noise ratio of 100. A total of 1240 putative compounds were detected by HS-SPME-GC×GC-TOFMS in at least one of the samples. A comparison of vineyards revealed that approximately 200 of compounds were found to be at significantly different levels in at least one of the harvest dates. Principal component analyses illustrated a separation of samples based on harvest date. C5, C6 and C9 compounds, known as green leaf volatiles, were typically found in higher levels in H1 wines. Modifications of yeast metabolism of the sulfur-containing amino acid, methionine, were noticed. Methionol, methional and ethyl 3-(methylthio)-propionate were significantly lower in H2 wines whereas 2-(methylthio)-ethanol was increased. Several higher alcohol acetates were also measured at higher levels in H2 wines. Sensory evaluation revealed significant differences in wines based on the harvest date determined by berry ripening model. Wines from grapes harvested at H1 were perceived by panellists to be higher in red fruit attributes whereas wines from H2 were perceived higher in dark fruit and plum characters. These results indicate significant modulation of wine volatiles as a consequence of harvest dates, by altering lipoxygenase derived compounds and yeast metabolism, irrespective of vineyard cultural practices, within the same warm to hot climatic region

Unravelling wine volatile evolution during shiraz grape ripening by untargeted hs-spme-GC×GC-tofms

The influence of grape maturity on wine volatome was investigated using HS-SPME-GC×GC-TOFMS. Shiraz wines were made from grapes harvested from four different vineyards from two berry maturity levels. A total of 1,276 putative compounds were detected in at least one of the wine samples and 175 showed significant trends related to grape maturity. The first two dimensions of the Principal component analysis accounted for 57% of the variation and separated the samples according to the harvest date. Wines from the first harvest date were characterised by an abundance of lipoxygenase derived compounds, norisoprenoids and sulfur-containing compounds whereas a significant increase in some acetate esters was observed in wines produced from the more mature grapes. This study demonstrated a common evolution of grape volatiles for Shiraz inside the same mesoclimate. During the late ripening stage of the grape, a direct nexus between sugar concentration and wine volatile evolution was not observed