葡萄酒酿造科学英文资料：L5, Sue Blackmore.pptx

Options inWhite Wine ProcessingSauvignon Blanc focus,References,Wine Science - Jackson Chapter 7,8 and 9 Making Good Wine Rankine Chapter 4 Ewart, A. White Wine,. From Fermented Beverage Production. Eds Lea minimization of extraction of phenols lower extraction of aroma compounds; decreased SO2 requirement (as less oxidation),Serious about quality whites? Consider whole bunch pressing. G Baldwin - Australian & New Zealand Grapegrower & Winemaker, Nov 2005 (Moodle),More subtle, less fruit forward wine, more textural and aging potential,Contrast,Crush + Maceration,Whole bunch,Lower juice yield Less 1aroma cpds/ phenolics Less SO2 required Wine.More subtle, less fruit forward wine, more textural and aging potential, Phenols 1fruit aroma & flavours Higher juice yield More solids More susceptible to oxidation Wine.More fruit forward Drink when young,Options In the winery,Crushing or not try to destem first get less phenolics from stalks and seed. OPTIONS Whole bunch press by dumping straight into the press. Less acid less fruit flavour extraction ONLY destem- no crush and retain high % whole berries Destem and crush most common whites Then possible skin contact more phenolics overt fruit good for fuller bodied. Temperature effects extraction. Lower temp less phenolics,Sauvignon blanc,Possibilities pre press Machine harvested - most common in NZ. Gives flavour extraction from the time of picking but also causes oxidation. SO2 added to counteract (20-60ppm) Hand harvested higher quality, QC in field, less oxidation Whole bunch pressing part or all (requires hand harvest) Less overt fruity characters. Stylistic choice- More body/weight mid palate Maceration in tanks Montana (or less time just in press- Wither hills). No maceration St Clair (many others),Or,Or,Tipping Tanks,http:/,Skin contact (maceration) drain free run tilt and dump fruit into press,Pressing,Membrane or bag press. An air bag squeezes juice out of the must Sulphur dioxide (SO2) can be added at this stage. Protection from oxidation and bacteria Juice yields 550-600 l free run, 50-100 l press per tonne Tasting off press fraction often kept separate What is left?. Marc or Pomace,Marc,Back on vineyard Stock food Compost Seeds oil byproduct,Possible problem wet year - Botrytis,Breaks skins down allows infection by bacteria (add extra SO2) Mouldy flavours , loss of fruit flavour (no skin contact!) Excretes an enzyme laccase - speeds oxidation of the juice (acts as a catalyst) Converts phenolic compounds to quinones and they are polymerized in O2.bForm brown pigments Resistant to SO2! (More later!) Also excretes glucans- high molecular weight carbohydrates. Can cause wine clarification and filtration problems.,Botrytis infected juice -options,Laccase Pasteurise to denature laccase produced by botrytis Higher SO2 rates also deactivates Fine with carbon (0.5-1.0 g/l). Care as strips flavour and aroma -Glucan enzyme addition Use of -Glucanases (enzymes) to break down polysaccharides. Filtration difficulty if remains. Ferment health Use of vigorous yeast. Addition of thiamine reduces binding of sulphites. Feed ferment.,Pasturisation,Removes microrganisms, oxidase enzymes (PPO and laccase) and heat-unstable protein. At Montana, the wine is heated to a maximum of 83C for 30 seconds, then cooled. They can process 35,000 litres an hour. Potential effect on quality?,Must /Juice chilling,Heat exchanger Why use ? 2 stages Rapid cooling of the juice for settling. Can be used later to heat up juice for innoculation.,Heat exchanger,Free run and press combined,Heat exchanger,Free run,Combined Press Tank may be filled over several days,550-600 l/tonne,50-100 l/t,Settling to Clarify,Settling For fresh fruity wines need to remove grape solids (0.5%) Cold settle 5-10 - 24-36hrs Disadvantage . ?,Other methods of rapid clarification,Filtration- rapid but has an effect on flavour/aroma Centrifuge - Creates a centrifugal force of up to 15,000 times gravity Operating capacity up to 30,000 litres per hour,http:/,Addition of Pectolytic enzymes from Aspergillus niger Enzymes added to juice to break down pectic polysaccharides in cell walls. (cement) Increases juices yields, eases pressing and speeds settling. (tiny amounts 15ml /tonne!) E.g. pectin-lyase, pectin-methyl esterase and polygalacturonase,http:/www.wynboer.co.za/recentarticles/0411enzymes.php3,Clarification,Flotation method of wine clarification involving the introduction of inert gas under pressure at the bottom of a vat of must causing suspended solids to be carried to the surface where they can be easily removed. Advantages speed and control over degree of clarification- new in NZ http:/www.armourtech.co.nz/juiceflotation,a.html,Bentonite (clay) Commonly added after initial spontaneous settling to avoid high volumes of soft lees. But does fatty acids (e.g. oleic, linoleic) that contribute to complexity of finished wine bouquet. Involved in reactions that form esters.,Sauvignon blanc,Possibilities press and settle Pres。