Towards the prediction of wine outcomes from grape compositional measures. Bob Dambergs, Paul Smith WS42 18 July 2012

Transcription

1 Towards the prediction of wine outcomes from grape compositional measures Bob Dambergs, Paul Smith WS42 18 July 2012

2 The Australian Wine Research Institute AWRI technology along the value chain Working on the Value Chain from vineyard soil to point of sale, and beyond

3 Some basic wine parameters The Australian Wine Research Institute F/T SO 2 Heat and cold stability ph TA Alcohol Sugar VA

4 Classes of quality measures, based on process The Australian Wine Research Institute Grape metabolites directly extracted into wine Grape metabolites converted by mechanical processing Grape metabolites converted by yeast processing Grape metabolites converted by a combination of mechanical and yeast processing

5 Grape metabolites directly extracted into wine The Australian Wine Research Institute Rotundone Methoxypyrazine C13 norisoprenoids Beta-ionone

6 (-)-Rotundone O By GC-MS-O, rotundone was established as the principal aroma impact compound for pepper aroma in grapes and wine % of people can t smell it Wood, C.; Siebert, T. E.; Parker, M. et al. J. Agric. Food Chem. 2008, 56, Siebert, T. E. et al. J. Agric. Food Chem. 2008, 56,

7 Adelaide Hills Clarendon Hills Coonawarra Geelong Grampians Macedon Ranges McLaren Vale Yarra Valley Adelaide Hills/Yarra Mornington Peninsula Tasmania Yarra Valley Barossa Valley Goulburn Valley Rutherglen Canberra District Frankland River Rotundone (ng/l) Rotundone in Australian wines We can now start to look at what influences rotundone levels A large survey of commercial wines was undertaken to guide us AWRI TR #180 (June 2009) Region/Variety

8 Impact of viticulture on Rotundone? Fruit exposure? Leaf removal time? Crop load? Vine vegetative vigour? found in grape skins, leaves and stalks Increases during grape ripening rotundone not detected not detected

9 Methoxypyrazines The Australian Wine Research Institute Concentration in wines depend on berry maturity climate fruit exposure skin contact during winemaking, pressing Green bean, capsicum, asparagus IBMP easily extractable concentration in free-run wine is principally determined by that in the grapes, while it is relatively unaffected by vatting conditions. Cabernet sauvignon, merlot, sauvignon blanc, semillon (not in pinot grapes, shiraz, chard, riesling)

10 Wine aromas that are released or created from grape compounds (but a little help from yeast...) The Australian Wine Research Institute Terpenes; geraniol (skin), Linalool (throughout berry), Nerol (skin), alpha-terpineol Wine lactone C13 norisoprenoids Beta-Damascenone C-6 alcohols

11 Free Terpenes The Australian Wine Research Institute Geraniol (skin) & Nerol (skin) young wines Linalool (throughout berry) & alpha-terpineol older wines Rose, geranium, floral Enzyme and acid releases the glycosylated precursor from grapes

12 Polyhydroxylated terpenes The Australian Wine Research Institute the polyhydoxylated monoterpenes make no direct contribution to the aroma although some of them are reactive and can easily rearrange during ferment to give pleasant and potent aromas; cis rose oxide lychee, rose Wine lactone coconut, lime

13 C13 Norisoprenoids The Australian Wine Research Institute Grape berry metabolism Carotenoid degradation Bound to sugars: released from glycoside precursors Diverse aroma properties as a class damascenone sweet, fruity, cooked apple, ionone raspberry, berry, violets

14 C13 Norisoprenoids during grape maturation The Australian Wine Research Institute

15 C6-alcohols 1-hexanol cis-3-hexenol Fresh cut grassy aroma in wine enzymatic oxidation of grape fatty acids by lipoxygenases, solids in ferment Role in green flavour unclear

16 Wine aromas created by metabolic action of yeast The Australian Wine Research Institute Esters Alcohols 4-EP VA

17 Esters The Australian Wine Research Institute fatty acid ethyl esters, acetate esters fruity aromas isoamyl acetate (3-methyl butyl acetate) banana ethyl hexanoate pineapple slower rate of fermentation, increase in esters ie lower temp yeast strain juice composition: amino acid pattern undergo chemical hydrolysis/reaching chemical equilibrium with storage varietal differences can be significant Very significant in defining sensory profile of the wine Fatty acid derivatives role in esters

18 Higher Alcohols The Australian Wine Research Institute Yeast metabolism of amino acids and sugars. For e.g. Phenyl ethyl alcohol from phenylalanine, (rose-like aroma) lsobutanol Solvent, harsh Isoamyl alcohol whiskey, malt, burnt 2-Phenylethyl alcohol rose, lilac

19 Grape metabolites influenced by mechanical and yeast effects The Australian Wine Research Institute Varietal thiols for Sauv Blanc (some riesling/chard) Tannin Colour Polysaccharides Fatty acids (short and medium chain)

20 Fruity thiols 4-methyl mercaptopentanone 4-MMP 3-mercaptohexanol 3-MH 3-mercaptohexyl acetate 3-MHA Aroma threshold 0.8 ng/l 60 ng/l 4 ng/l Cysteine, glutathione conjugates, released by yeast metabolism Sauvignon Blanc, Riesling, Chardonnay, Cabernet Sauvignon

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26 Factors affecting fruity thiols The Australian Wine Research Institute Ripening - Low levels of precursors until commercial harvest Processing/transportation precursors are sensitive to oxidation a combination of both SO 2 and Ascorbic acid optimum BUT very high SO 2 suppresses conjugate formation Yeast choice turn a Chardonnay into Sauvignon Blanc!! 26

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28 Grape colour correlates with wine colour 4 Wine colour (AU) Grape colour (mg/g) Riverland Shiraz trial

29 Value But grape colour does not equal wine colour M3G Anthocyanins are not the final stable colour in wine they react with tannin to produce pigmented tannins (or pigmented polymers ) 100 Pigmented Tannins DAY The concentration of M3G increases during fermentation until taken off skins, then it rapidly declines, while pigmented tannins increase

30 Predicting wine pigmented tannin potential [PP] = 0.06 [ M3G ] [ T ] R 2 = 0.92 PP: pigmented polymers M3G: malvidin 3-glucoside T: tannins If we know the tannin and anthocyanin concentrations we can predict final, stable wine colour

31 Tannin correlates with commercial quality grading Tannin (g/l epicat) Hardy Shiraz - but also applied to Fosters and Orlando wines 0 A B C D E F G H I Quality grade Mercurio, M.D., Dambergs, R.G., Cozzolino, D., Herderich, M.J, Smith, P. A. (2010) Relationship between red wine grades and phenolics 1. tannin and total phenolics concentrations. J. Agric. Food Chem., 58:

32 The Australian Wine Research Institute Wine Tannin varies with region 6 5 Cabernet sauvignon Shiraz Pinot noir Tannin (g/l) Tannin (g/l) 3 2 Tannin (g/l) Adel BarCan Clare Coona Lang MDar Marg Mud Mvale Pad Pyren Rland Ruth Swan Wrat Yarra Region 0 Adel BarCan Clare Coona Lang MDar Marg Mvale Pad Pyren Rland Ruth SwanWrat Region 0 Adel Morn Pad Tas Yarra Region

33 Tannin and pigment in context with commercial wine styles The Pinot Shop...Avancé is a very charming pinot. The fruit has a sweet suppleness. It is quite delicate but there s nice liveliness and freshness with florals and red berries.. $29.50 Tannin 1.31 g/l Pigmented tannin 1.14 AU Total Pigment 8.11 AU The Pinot Shop Reveur ( dreamer ) Pinot Noir is a pure but weighty wine with distinct charry-cherry characters. That s from some good oak wrapped around vintage 2008 s ripe Coal Valley fruit. The tannins are round and chewy I suspect that the ripe tannins will smooth out into silky, luscious pinot.. $46 Tannin 1.84 g/l Pigmented tannin 1.56 AU Total Pigment AU i.e. Pinot tannin is worth $42,000/Kg

34 Tannin (epicat. eq. g/l) Tannin (epicat. eq. g/l) Correlation of tannin and wine colour density: cool season 5 4 R= 0.47 Cabernet 3 R= 0.42 Shiraz Colour density (AU) Colour density (AU)

35 Tannin (epicat. eq. g/l) Correlation of tannin and wine colour density: hot season Cabernet Shiraz 3 R = R = Colour density (AU) Colour density (AU)

36 A model of tannin extraction, desorption and adsorption during fermentation

37 Polysaccharides in Australian Shiraz across quality grades PA1 PA2 PA3 PA4/5 low MW polys low MW polys Medium MW polys grape derived High MW polys yeast derived Quality grade Astringency modulation Hotness suppression? Texture/viscosity? Roles in white vs red?

38 environment The Australian Wine Research Institute 1,8-cineol (Eucalyptol) Smoke taint Regionality other aromas from plants?

39 1,8 cineole - Eucalyptol The Australian Wine Research Institute Terpenoid Eucalyptus, mint, camphor Can be both grape-derived and from eucalyptus trees near vineyards Cineole levels increase during skin contact

40 The Australian Wine Research Institute Out of 146 commercially available red wines of various varieties we analysed, 40% of them contained 1,8-cineole above reported detection threshold.

41 mysteries The Australian Wine Research Institute Benzyl mercaptan (struck flint) Low molecular weight sulphur compounds DMS Red wine character Partly grapes, partly yeast Blackcurrant, dark fruit at moderate levels Undesirable cooked veg at higher

42 A tool to characterise and communicate Pinot Grigio and Pinot Gris wine style 42

43 and there is now a Grape and Wine Tannin Portal

44 BUT...

45 Acknowledgments Our industry collaborators Our funding bodies