late season shiraz berry dehydration alters composition and sensory

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Food and Beverage Chemistry/Biochemistry

LATE SEASON SHIRAZ BERRY DEHYDRATION ALTERS COMPOSITION AND SENSORY TRAITS OF WINE Hsiao-Chi Chou, Katja Suklje, Guillaume Antalick, Leigh M. Schmidtke, and John Blackman J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b01646 • Publication Date (Web): 02 Jul 2018 Downloaded from http://pubs.acs.org on July 8, 2018

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Journal of Agricultural and Food Chemistry

LATE SEASON SHIRAZ BERRY DEHYDRATION ALTERS COMPOSITION AND SENSORY TRAITS OF WINE

HSIAO-CHI CHOU1, KATJA ŠUKLJE1*, GUILLAUME ANTALICK1, LEIGH M. SCHMIDTKE1,2, 3 AND JOHN W. BLACKMAN1,2

1

National Wine and Grape Industry Centre, Charles Sturt University, Locked Bag 588,

Wagga Wagga, NSW 2678, Australia 2

School of Agricultural and Wine Science, Charles Sturt University, Locked Bag 588,

Wagga Wagga, NSW 2678, Australia 3

The Australian Research Council Training Centre for Innovative Wine Production, The

University of Adelaide, Glen Osmond, SA, Australia

*Corresponding author: Dr. Katja Šuklje Wine research Centre, University of Nova Gorica Glavni trg 8 5200 Vipava, Slovenia Email: [email protected]

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ABSTRACT

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Late season berry dehydration (LSD) is a common occurrence in Shiraz grapes,

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particularly those grown in hot climates. LSD results in significant yield reductions

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however the effects on wine composition and sensory characteristics are not well

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documented. Wines made of 100% non-shriveled clusters (control) were related to red fruit

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flavors by the sensory panel whereas wines made of 80% shriveled clusters (S-VCT) were

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perceived as more alcoholic and associated with dark fruit and dead/stewed fruit

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characters. The latter wines also resulted in higher concentrations of massoia lactone and

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γ-nonalactone, compounds known to contribute to prune and stewed fruit aromas. Wines

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made of shriveled grapes were also characterized by an increase in C6-alcohols, decrease

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in esters, whereas wine terpenoids were altered compound specific. An increase in orange

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pigments and wine chemical age in S-VCT wines indicated faster oxidative ageing

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compared to the control. LSD appeared to alter final wine composition directly, but also

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appeared to influence yeast metabolism, potentially due to an alteration of the composition

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of lipids in the grape juice. This study emphasized the relevance of sorting shriveled and

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non-shriveled berries for final wine chemical composition and wine style.

17 18 19

Key words: fermentation, late season berry dehydration, maturity, shriveling, wine aroma

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INTRODUCTION

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Grape berry water loss in late ripening, known as late season berry dehydration (LSD) is

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an irreversible decline in berry fresh weight. LSD occurs as a consequence of berry water

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depletion through the transpiration and a xylem back flow that exceeds the import of water

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and solutes into the berry.

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types of shrivel such as bunch stem necrosis (BSN), sugar accumulation disorder (SAD)

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and also sunburn in various cultivars.

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particularly accentuated in Shiraz (Vitis vinifera L.) and accelerated by hot and dry

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growing conditions.

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(temperature and precipitation) influence the severity of LSD through alteration of grape

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berry transpiration and hydraulic conductivity,

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yield.6, 8 LSD in Shiraz coincides with the onset of berry cell death, generally occurring

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around 90-100 days after the anthesis, at the maximum berry fresh weight and at a slow

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down or plateau of sugar accumulation into the berry. 7 Organized loss of cell vitality has

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been observed in grapes from premium Shiraz vineyards and has correlated with the

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enhancement of grape flavors, aromas and higher total soluble solids (TSS).

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also been reported that berry sensory scores were tightly coupled to the increased

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proportion of cell death in Shiraz.

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grape berry volatiles and total anthocyanins compared to non-shriveled control have also

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been observed.

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Cabernet Sauvignon berries.

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significantly alters Shiraz wine chemical composition. In particular, β-damascenone and γ-

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nonalactone were increased in wines made from shrivelled berries affected by

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predominantly bunch stem necrosis.

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Merlot wines made from LSD berries. β-damascenone and γ-nonalactone have been

11

6

1

Irreversible berry water loss is also a common trait to other

2-5

Development of LSD is cultivar specific,

Irrigation regime, grape sunlight exposure and vintage factors

10

6, 7

resulting in up to 25-30% reduction in

2, 3, 9

It has

In contrast, negative consequences of LSD on Shiraz

LSD has also significantly increased TSS and titratable acidity (TA) in 12

From our previous work, it is suggested that berry shrivel

5

γ-nonalactone was also reported as a marker of

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associated with the prune aromas in red wines subjected to pre-mature ageing.13

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Anecdotally, prune, stewed and dry fruit aromas are typical sensory descriptor of Shiraz

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wines made from berries affected by LSD.

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Despite the common occurrence of LSD in Shiraz and other cultivars such as Cabernet

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Sauvignon and Merlot across all warm grape growing regions of the world, limited

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research on the effect on wine chemical and sensory properties has been published. Due to

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the likelihood of global warming causing warmer seasons with longer and more

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accentuated heat waves, significant LSD is likely to occur more frequently, leading to a

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yield decrease and subsequent economic losses. For these reasons, the aim of this study

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was to investigate the effect of LSD in Shiraz on wine chemical and sensory properties.

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One novel aspect of this study was that we focused particularly on the evolution of wine

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volatiles directly affected by LSD or indirectly through modification of yeast metabolism.

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MATERIALS AND METHODS

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Chemicals. Analytical reagent grade solvents were used: ethanol was purchased from

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Chem-Supply (Adelaide, SA, Australia) and methanol was obtained from Merck

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(Bayswater, Australia). All of the reference compounds (purity of ≥ 97%) were purchased

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from Sigma-Aldrich (Castle Hill, NSW, Australia). Deuterated internal standards were

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obtained from C/D/N Isotopes (Point-Claire, QC, Canada).

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Vineyard. Shiraz (Vitis vinifera L.) grapes were sourced from a commercial vineyard

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located in Gundagai (New South Wales, Australia; -35°04’69”, 147°88’48”). The clone

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1654 Shiraz, was planted in 2001 with North to South row orientation and 3 m distance

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between both vines and rows. Vines were own rooted, spur pruned, trellised to an open

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sprawling canopy and drip irrigated with 1.8 ML/ha of water through the season with a

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yield around 8-10 t/ha. Climate in the selected vineyard was based on the 2989 calculated

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Huglin units classified as “warm” (i.e. 2400-3000 units).

14


Temperature data used for the

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calculation of Huglin index were obtained from SILO database (Queensland University,

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Australia,

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147°54’00’’.

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Grapes were harvested on the 25 February 2016, preceding commercial harvest date by

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approximately one week. Around 400 kg of Shiraz bunches were randomly collected

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across 10 rows from the both sides of the canopy. Bunches were harvested into 20 kg

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crates and immediately transported to the National Wine and Grape Industry Centre

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(NWGIC) experimental winery. Grapes were manually sorted in two groups, shriveled (S-

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VCT) and non-shriveled (NS-VCT), by visual and textural assessment. Berries with a

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turgid appearance and firmness that resisted finger pressure were considered as non-

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shriveled and those with visible shrivel (deformation on appearance) were considered as

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shriveled. To mimic common industry practice, whole bunches rather than individual

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berries were classified as either S-VCT or NS-VCT. Bunches with predominantly

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shriveled berry population were classified as S-VCT. A visual assessment of this treatment

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determined it consisted of approximately 80% of shriveled and very shriveled berries. For

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the 100% NS-VCT treatment, bunches that contained either zero or a few shriveled berries

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only were selected and any shriveled berries were manually removed.

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Shriveling index: Before crushing a 20 berries subsample was collected for a measure of

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the shriveling index. Berries were visually classified into 3 groups based on the severity of

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shriveling, i.e non-shriveled (NS), shriveled (S) and very shriveled (VS) (Figure 1).

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Berries with a turgid appearance and firmness that resisted finger pressure, were

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considered as NS; those with visible shrivel (deformation on appearance) were considered

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as S and berries with raisin-like appearance were classified as VS. The length and the

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diameter of the berries was measured using an electronic ruler and shriveling index was

http://www.longpaddock.qld.gov.au/silo)

for


location

-35°03’00’’

and


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calculated on a 0 to 1 scale, with 1 indicating maximum turgor and 0 maximum shrivel as

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described previously. 9

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Winemaking. Small scale fermentations were performed in triplicate for both treatments.

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25 kg replicates of the S-VCT and NS-VCT treatments were mechanically destemmed and

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crushed before transferring into 100 L variable capacity stainless steel tanks (VCT). 50

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mL of juice was collected in centrifuge tube for measures of basic maturity parameters.

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The acidity of each ferment was adjusted to approximately pH 3.6 by the addition of

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tartaric acid. The must was inoculated with 30 g/hL Saccharomyces cerevisiae EC1118

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(Lallemand, Edwardstown, Australia). Fermentations in triplicates were carried in a

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temperature-controlled room to ensure a temperature range of 24-28°C. Cap management

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consisted of punch downs performed twice daily. Progress of fermentation was monitored

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after the punch-downs were performed using a hand-held density meter (DMA35N, Anton

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Paar, Graz, Austria) measuring total soluble solids (TSS) expressed as °Baumé.

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Malolactic fermentation was initiated by co-inoculation with Oenococcus oeni (0.01 g/L)

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(Lallemand, Enoferm, France), which was added the day after the onset of the alcoholic

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fermentation. After a 3° Baume decrease, diamonium phosphate (DAP) and Fermaid A

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(Lallemand, Australia) was added to each ferment to adjust yeast assimilable nitrogen

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(YAN) levels to a consistent level of 250 mg/L. After 7 days of fermentation, wines were

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pressed using a small basket press, with a maximum pressure of 1 bar applied. Pressed

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wine was maintained at 22 ± 1 ˚C to allow malolactic and alcoholic fermentation

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completion. When malic acid levels reached concentration of less than 0.1g/L, 80 mg/L of

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sulfur as potassium metabisulfite (PMS) was added. Wines were racked off lees, wine pH

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adjusted to an approximate pH of 3.6 using tartaric acid and molecular sulfur dioxide

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maintained at 0.5 to 0.8 mg/L before being held at between 0 and -2° C for 21 days for

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cold stabilization. Prior to bottling, wines were again racked and pH and molecular sulfur 6 ACS Paragon Plus Environment

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were readjusted to 3.6 and 0.5-0.8 mg/L, respectively. Wines were bottled in 375 mL

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screw cap bottles.

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Basic juice and wine parameters. The pH was measured and TA determined by sodium

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hydroxide titration to an end point of pH 8.2 with a Metrohm Fully Automated 59 Place

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Titrando System (Herisau, Switzerland). Glucose, fructose, ammonia, free amino nitrogen

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(FAN), malic and acetic acid were quantified using Thermo Fisher Scientific enzymatic

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kits (Waltham, MA, USA), with testing performed on an Arena Discrete Analyzer

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(Thermo Fisher Scientific). Free and total sulfur dioxide were measured with FOSS

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FIAstarTM 5000 (LMWI 40-14) (Höganäs, Sweden). Yeast assimilable nitrogen (YAN)

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was calculated from ammonia and free amino nitrogen according to methods

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published previously. 15

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Amino acids. Frozen juice stored at -20 °C was defrosted at ambient temperature and

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centrifuged (BeckmanCoulter, Microfuge 20 Series, Brea, USA) at 13000 rpm for 10.5

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min. The supernatant was collected and amino acids were derivatized and analyzed as

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previously described.

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with fluorenylmethyl chloroformate (FMOC). Metabolites were separated on a reverse

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phase column (Zorbax Eclipse Plus, Agilent Technologies, Mulgrave, Australia) at

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+40°C coupled to HPLC controller (Waters 600, Milford, U.S.A.) connected to an

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autosampler (Waters 717 Plus, U.S.A.). A fluorescene detector (Waters 2475, U.S.A.)

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was used for amino acids quantitation.

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standard in concentration 13.0 mg/L to samples prior to derivatization.

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Analyses of wine ethanol, glycerol, organic acids and sugars. Wine analyses of organic

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acids, carbohydrates and ethanol were performed in accordance with a previously

143

published method.18 Wine samples were filtered through 0.45µm filter (Merck, Frenchs

144

Forest, Australia) in a HPLC vial and injected into autosampler (Waters 717 Plus, U.S.A.)

16

In brief, primary and secondary amino acids were derivatized

17

L-hydroxyproline was added as an internal



145

coupled to PDA and RI detectors (Waters, U.S.A.) and controlled by HPLC controller

146

(Waters 600, Milford, U.S.A). Separation of carbohydrates, organic acids and ethanol was

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achieved on 300 x 7.8mm Aminex HPX-87H ion exclusion columns connected in series

148

(Bio-Rad Laboratories, Berkeley, U.S.A.) fitted with micro guard cation H+ column (Bio-

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Rad Laboratories, Berkeley, U.S.A.) at +65°C. 18

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Wine color parameters, polyphenols and tannins. Analysis of wine color parameters

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and polyphenols were carried out as previously outlined.

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3.5 and measurements were conducted on a UV-1700 (Shimadzu, Kyoto, Japan)

153

spectrophotometer. Briefly, 20 µL 10% (w/v) acetaldehyde was added to 2 mL of wine for

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estimation of all the red and yellow/brown pigments at 420 and 520 nm. Red colored

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pigments resistant to bleaching were measured at 520 nm after the addition of 25% (w/v)

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sodium metabisulfite and total red pigments were measured at the same wavelength after

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the reaction with 1 M HCl. Under acidic condition all the anthocyanins and other

158

potentially red pigments are in the red colored form. Wine color density and wine color

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hue were calculated from absorbance measured in wines without any addition. Total red

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pigments, degree of red pigment coloration, SO2 resistant pigment and total phenolics

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were calculated as described. 19

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General wine volatile analyses. A previously developed head space solid-phase micro

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extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for

164

analyzing esters, higher alcohols, C6 compounds, and lactones5, 20 allowed the quantitation

165

or semi-quantitation of around 30 odorants. In brief, 5 mL wine sample was added to a 20

166

mL SPME vial with 3 g NaCl and 5 mL deionized water. Samples were spiked with an

167

internal standards solution (10 µL) containing mix of isotopically labeled esters at

168

concentration 20 mg/L [2H5]-ethyl butyrate, 20 mg/L [2H5]-ethyl hexanoate, [2H15]-ethyl

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octanoate, 5 mg/L [2H5]-ethyl cinnamate and 5 mg/L 2-octanol. A mixture of isotopically 8 ACS Paragon Plus Environment

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Wine pH was adjusted to pH

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labelled esters from CDN isotopes (Pointe-Claire, Canada) was used to quantitate esters5,20

171

whereas for C6 compounds, higher alcohols and lactones, octan-2-ol (Fluka, Castle Hill,

172

Australia) was used as internal standard. A PDMS-CAR-DVB fiber (Supelco, Bellefonte,

173

U.S.A.) was used for volatile absorption. Compounds were then released into Agilent 7890

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gas chromatography equipped with a DB-WAXetr capillary column (60 m, 0.25 mm, 0.25

175

µm film thickness, J&W Scientific, Folsom, CA) and coupled with a Gerstel MPX

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autosampler with a Peltier tray cooler set at +4 °C. The GC was connected to a 5975C

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mass spectrometer (Agilent Technologies) that can perform electron ionization mode by

178

SIM (selected ion monitoring) and scan modes simultaneously. Quantitation was

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performed using ions reported. 5,20

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Terpenoids and norisporenoids. Analyses of terpenoids and norisoprenoids in wines

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were performed as previously published

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above. In brief, 5 mL wine samples were placed in a HS vial containing 3 g of NaCl

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followed by 5 mL of deionized water (MilliQ) and 20 µL of internal standard solution

184

containing 2-octanol, [2H3]-linalool and [2H5]-ethyl cinnamate prepared in absolute

185

methanol at a concentration of 5 mg/L. Compounds additionally analyzed and tentatively

186

identified by comparison to spectral library NIST 2.0. were dimethyl sulphide (DMS),

187

vitispirane 1, vitispirane 2, hotrienol, safranal, and TDN, which were expressed as peak

188

area ratios. 5 The quantifiers were 62, 192, 192, 71, 121, 157 and qualifiers 47, 177, 121,

189

82, 150, 172 for DMS, vitispirane 1, vitispirane 2, hotrienol, safranal, and TDN,

190

respectively.

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Wine sensory analyses. Wines were evaluated approximately 2 months after harvest using

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sensory descriptive analyses (DA). A panel of 15 NWGIC staff members (5 females, 10

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males, aged 27−51 years) were trained prior to the tastings. Training sessions consisted of

194

selection, recognition and practice of ranking the intensity of sensory attributes using

5

using the same instrumentation as described



195

reference standards (Table S1). Samples (25 mL aliquots) were presented to panelists in

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ISO/INAO glasses labelled with a three-digit random number generated by Compusense®

197

5.0.49 software (Guleph, Canada). Tasting was performed in isolated booths at 22 ± 1 °C

198

under red lighting. Samples were presented in randomized orders as determined by the

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Compusense® program. The intensity of each descriptor was rated using an unstructured

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line scale anchored by ‘absent’ and ‘high intensity’. Results were recorded using the

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Compusense® five program.

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Statistical analyses. One-way analyses of variance (ANOVA) for variable shriveling, was

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applied to all measured chemical variables using GNU-PSPP version 3.0 (Free Software

204

Foundation Inc., MA, U.S.A.) and the means of three biological replicates were separated

205

by Tukey’s test at p

late season shiraz berry dehydration alters composition and sensory

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