Introduction There is no single recipe to make wine. The techniques the winemaker chooses depends on what sort of wine is to be made – in terms of style, characteristics, and into what price category. The decision of how the wine is made is also influenced by the nature of the equipment available in the winery. Wineries have varying levels of equipment and sophistication and there are many types of equipment capable of performing the same task, but to different extents and degrees of efficiency. More care is needed to make a premium wine than commercial wine and different machinery, usually handling a smaller amount of fruit, is generally used to make premium wine. As suggested previously, the ultimate factor which determines the wine’s maximum potential quality is the fruit quality itself. MAKING WHITE WINE White wines are usually made by separating the juice from the skins as quickly as possible, for there is rarely need to extract phenolic compounds from grape skins into the juice. The major phenolic compounds in wine are the tannins and red anthocyanin molecules found in red grapes, which are used to give body and colour to red wine. These will be discussed shortly. In most cases the first operation after harvest is to crush the grapes, which usually have their stems removed at the same stage. Stems can contribute undesirable stalky-green flavours to wine. After crushing the mixture of juice, seeds, skins and the occasional stem is referred to as must, from the Greek word for grape juice, mustum. Then the must is put through a sieve, or drainer, to separate the juice which drains freely away, called free run, from that juice which remains bound up in the pulp of the grape skins. The skins must be pressed to extract this juice, which after the process is referred to as pressings juice. The free run juice is the most delicate and fragrant extract. The pressings are less delicate, darker in colour and more bitter. Both juice fractions are often kept separately after this stage, but may be re-blended before bottling. Next the must is chilled, a step that is repeated several times throughout the winemaking process to ensure that the must or wine is kept cool. Refrigeration helps to prevent the growth of undesirable microbiological organisms and also retains delicate wine flavours throughout fermentation and other process of production. After storage and a period of settling to clarify the juice, which is often aided by pectinase enzymes, the fermentation begins. It is important to use clear juice in the making of delicate, fragrant white wines such as riesling, but fully clarified juice may be not quite as advantageous for fuller, softer wines as chardonnay. Chardonnay may often be made after a short period of skin contact, which enhances is varietal flavour and extracts more body and richness. The juice may then not be fully clarified for the fermentation, which will again contribute depth and richness to the finished wine. The winemaker adds especially bred wine yeast cultures which, as they proliferate, convert the grape sugars into alcohol, with the additional production of carbon dioxide. As the level of sugar falls, the amount of alcohol in the fermenting must rises until all the sugar is used. The temperature of a white wine ferment is usually controlled to between 10 and 16 degrees Centigrade to prevent excessive loss of flavour compounds, which evaporate easily. By stopping the fermentation before it would naturally finish, through filtration, refrigeration or with an addition of sulphur dioxide, the winemaker may create a sweet wine. In any case, the rising alcoholic content of the must is toxic to yeast, which are killed by the alcohol they produce and through the deficiency of nutrition created when all the grape sugar is used. After fermentation further clarification is necessary to remove the clear wine from the grape and yeast debris, which after a period of time sinks to the bottom of the tank. This clarification is aided with fining agents such as Bentonite, an exceedingly fine clay, which is able to remove excess protein from the wine. After either neutral storage in stainless steel tanks or oak maturation, or a combination of the two, the wine is blended together. Prior to bottling it is also stabilised to remove excess acid, and other natural wine impurities which have the potential to ‘throw’ a crust or haze in the wine. MAKING RED WINE One of the most important differences between white and red wine production is that in making red wine the skins and the juice are not separated in the early stages. With only three rare exceptions, the colour in all red grapes comes only from the skins, and so to make a red wine it is necessary to extract this colour. After crushing and optional de-stemming, the mixture of juice, skins and the seeds, known as ‘must’, is fermented. The production of carbon dioxide during the fermentation creates an upward movement of gas out of the fermentation vessel, or tank, which pushes the grape skins up with it to form a solid cap. If left unchecked this cap, which heats up very quickly, could create the presence in wine of off-flavours, thanks to a proliferation of unwanted thermophilic (heat-loving) bacteria. While the fermentation is in progress the winemaker helps the juice to extract colour from the skins by various mechanical means which also serve to prevent a cap from forming. The most primitive is simply to plunge the cap with a pole with a square metallic plate attached to one end. Other techniques involve pumping juice from the bottom of the tank out and over the top of the cap, back into the vessel. As the concentration of alcohol rises, so does the ability of the must to extract colour and tannin. Tannin is an agglomerate of the molecules which give wine its red and purple colours, the anthocyanins. Therefore, as the colour is extracted, so is tannin. When the winemaker feels that enough colour and tannin have been extracted in the fermenting must, the must and the skins and seeds are separated by draining and pressing, and each fraction of the fermentation, the free run and the pressings, is left to continue, as with a white wine. The Malo-Lactic Fermentation The winemaker may let the wine ferment again, this time by bacteria. This secondary or malo-lactic fermentation converts malic acid (think of green apples) to lactic acid (try yoghurt this time), which is less acidic and ‘softens out’ many wines. All fermentations produce carbon dioxide gas (C02) and this is no exception. Red wines usually have a secondary fermentation before bottling, to avoid it taking place accidentally inside the bottle, by strange and unwelcome microbes. Oak Maturation Often before bottling, many wines, especially reds, are given a period of maturation in oak casks. All are made from imported wood, and different oaks from different countries have their own distinct flavours and properties. While in wood wines undergo a slow and controlled oxidation, which with the natural flavour pick-up from the wood, adds greatly to their complexity. Oak contributes a variety of flavours and characters, which usually gives more depth and weight to the wine. Frequently the flavours bear no resemblance to oak at all. Biscuity, buttery, lemony, vanillin, toasty, coconut-like and even herbaceous flavours can be the result of oak maturation, all of which can ultimately contribute to wine’s complexity and quality, provided they don’t take it over and dominate the fruit. Young barrels impart more character than older ones, small more than large, and the longer a wine is in barrel the more ‘oaked’ it gets. The whole affair is very expensive, for small new casks from overseas cost many hundreds of dollars. It has become common to cut this cost by tossing oak shavings and chips into stainless steel tanks holding the wine. This is rapid and infinitely cheaper. Although it cannot imitate the true wood-ageing of oak casks completely, it’s very difficult to pick and some premium wines have indeed been ‘oaked’ in this fashion. Carbonic Maceration Carbonic maceration is a red winemaking technique which involves fermenting whole berries of grapes, without crushing. The grapes are best placed in sealed shallow containers, so that the weight of those on top does not crush the ones on the bottom. Oxygen is displaced by carbon dioxide which is pumped in, and the berries begin to auto-metabolise, taking them along the biochemical pathway that leads to alcohol production. After a few days they are gently pressed, and yeast is introduced to complete the process of fermentation. The wines are soft, jammy and fruity, and contain an almost negligible degree of tannin. MAKING SPARKLING WINE The Methode Champenoise The Methode Champenoise procedure as we know it today is the result of two very different French personages, a Benedictine monk called Dom Perignon and a venerable old widow, Madame Veuve Clicquot, the uncrowned Queen of Champagne, who quite separately contributed the two most important aspects of making Champagne – how to get the bubbles in there and how to get the dead yeast out. The first step is to make a still dry white wine, bottle, add yeast and sugar and re-seal. Because you’ve set the wine up for a second fermentation, to take place inside the bottle, to produce the CO2 and more alcohol. This addition is known as the tirage, and the wine in which the sugar and yeast are added is called the liqueur de tirage. After the second fermentation the liquid will have turned quite cloudy, thanks to all the yeast cells and debris inside. Between the time of Dom Perignon’s discovery of the second fermentation and the successful work sponsored by Madame Veuve Clicquot, all the Champagne drunk had to be stood upright for several hours and decanted slowly from the bottle to minimize the haze poured into the glass. Veuve Clicquot’s discovery was that by gradually twisting and turning the bottles over a period of time, so that they finished by sitting virtually upside-down in special racks or Champagne tables, the sediment would gather together behind the cork of the bottle. This process is called the remuage, and is carried out by teams of highly-skilled craftsmen known as remeurs, who deftly go about the business of turning and tilting Champagne bottles at remarkable speed. The next step is to remove the yeast plug, in the process of disgorging. Both cork (or more commonly today, the crown-seal) and plug are expelled from the bottle, an operation made easier today by first snap-freezing the neck of the bottle in liquid nitrogen, making the plug more solid and less likely to break up. In modern wineries, the remuage and the disgorgement are handled mechanically. Next, the expedition or dosage. All the bottles are by now standing upright, a little low in level and exceptionally dry, seeing they have been fermented twice. This final step before the second and final corking can determine the style of the Champagne in a single step. Even the very driest of Champagnes, labelled brut, receive a portion of sugar before they are released, except for a very rare few called natur brut. A sweeter, or demi-sec style is made by adding more sugar in the champagne used to top up the bottles, which is called the liqueur d’expedition. The wine may be converted to a rose by the tache (stain) method with addition of a portion of red wine into the liqueur. The quality of methode champenoise wines is almost invariably affected by the time that the wine spends inside the bottle between the second fermentation and disgorging, while in contact with the decaying yeast cells, which make a deposit inside the bottle called lees. The longer this period, the more yeast character in the wine, up to a point. Yeastiness is often likened to Vegemite and bready, doughy flavours, but in spite of this it is extremely pleasant and is the hallmark of great Champagne. French Vintage Champagnes spend a minimum of three years before disgorgement, the Non-Vintage Champagnes one year. Other Sparkling Wines Variations on the methode champenoise are basically short-cuts to save on cost and inevitably reduce quality. ‘Bottle Fermented’ means that the second fermentation did in fact take place inside a bottle, but not the one you buy, as with methode champenoise. This transfer method then involves the movement of wine from one bottle to another, via a tank, with loss of effervescence and flavour. ‘Naturally fermented’ is the next step down. This implies that the effervescence resulted from a yeast fermentation, which didn’t happen inside a bottle at all, but inside a sealed stainless steel tank. This technique is occasionally referred to as the Charmat method, and it is readily forgettable and does not produce much in the way of yeast character or quality wine. The very cheapest sparkling wines are little more than carbonated wines, and the end result is little better than the standard of wine used to begin with. One would not expect them to show much in the way of developed yeast character. Fortified Wines Fortifieds are sold with the names of sherry, port and muscat. They must contain at least 17 percent alcohol by volume and many contain much more, making them appreciably stronger than table wines, the name given to non-fortified styles. The alcohol is added either during or after the fermentation, depending on whether the wine is to finish sweet or dry. Adding concentrated alcohol of around 90 percent by volume will kill any yeast and therefore stop a fermentation. Sweet fortified wines, some ports for example, are made by adding the alcohol, as naturally-flavoured grape-spirit, or brandy in more expensive cases, to the wine when it has fermented to the desired level of sweetness. Dry fortifieds are made by adding the spirit to wines after they have fermented dry. The solera Most fortified wines are blends of several years. These are made by a complex fractional blending system known as a solera, or a derivation of it. A solera is a huge stack of barrels in carefully-ordered layers with the oldest wine in the barrels at the bottom. About a third of each cask is drawn off for bottling, leaving room for wine from the next layer to be moved down. This initiates a flow-like effect in which wine is moved from each barrel to the layer below all the way up the stack, so that there is ultimately room in the top layer for the new year’s wine. The space left in the youngest cask is filled with ‘new’ wine. The solera will continue to produce a final product identical to superior old wine that it began with. Inside the solera the fortified wine undergoes a most controlled oxidation, resulting from the imperceptible passage of oxygen through the pores of the wood and into the wine. Ageing in this fashions mellows and softens the flavour, increasing wine complexity and concentration. A solera clearly takes a great expense to manage, for it is very labour-intensive. Most wineries today modify the system, but continue to use the principles of gradual blending involved.
