Written by Ray Jordan,
Winemaking – An Art And Science
If you’ve ever read those back labels of wine bottles and wondered what really goes on behind that wine you are about to drink, then this blog will help you understand.
It’s a simple guide to making wine, touching on the very basics. But of course, winemaking is a lot more than a step-by-step guide to be read from a book. The best winemakers have to understand a lot more to turn grapes into wine. They need to understand and have a feel for the grapes, the sites, the region and a myriad of other things that go on from harvest to harvest to achieve the best results from the fruit.
Sometimes when they have all the science and all the technology they can get their hands on, the real art is in knowing when to hold back and let the whole thing just happen in a hands-off minimalist way. That is often what sets the great winemakers apart from the solid plodders.
Hopefully, after reading this, you will have some idea of what goes into making wine, which will contribute to your understanding and appreciation of that next bottle of wine you are about to drink.
Wine can be made from all manner of different fruits but in this case, we are talking about wines made from grapes. The fruit is harvested once a year – called a vintage – generally from late summer into early autumn, which means of course, vintages vary by six months between the northern hemisphere and the southern hemisphere. In general, a later harvesting is more conducive to better quality fruit with better flavour and acid balance, especially for certain table wines requiring more subtlety and delicacy.
After grapes are harvested, they are placed in a clean container and crushed. Yeasts, which are the catalyst for converting the natural grape sugar into alcohol, then take over. Yeasts occur naturally and some winemakers prefer to let the fermentation begin on its own with these natural yeasts, while others prefer to use cultivated yeasts which give greater certainty to the finished wine, with precise impact on the aromas and flavours.
The interaction of the yeasts on the grape sugars is called fermentation. Fermentation time varies depending on the style of wine the winemaker is trying to produce. The winemaker must also decide which type of container to ferment the wine in. Oak and stainless steel barrels are the choices and it varies from variety to variety. For instance, red wines mostly go into oak for fermentation, while aromatic whites such as Sauvignon blanc and Riesling mostly go into stainless steel.
While stainless steel is consistent and impacts no character to the wine, the many different types of oak – French, American, Russian for example – and the different forests and coopers, impart significantly different characters to the wine. And then the question of the balance between new and old oak is an important consideration for the winemaker.
There are two types of grapes: red (or black as they are often referred to in Europe) and white. There are many parts to the grape, and the winemaker must decide which parts to use. Even the stems are used in some instances for specific styles and varieties of wine such as pinot noir for example. Stems contain a high amount of tannins and are sometimes kept with the grape juice in order to transfer those tannins to the juice.
The number and shape of seeds will vary from grape to grape. Seeds also contain a high amount of tannins and are often removed in the process of crushing the grapes.
Within the grape, the pulp is the liquid centre that is made up of mostly water as well as sugars and acids. The pulp of most grapes is actually colourless. Almost no grapes have red pulp and the colour comes from the skins so that even red grapes such as pinot noir can produce white wine as in the case of champagne.
The skin of a red grape is important, with the tannins and colour compounds of the skin necessary to give red wine its colour. The pigment is transferred into the wine when the skins are left with the juice during fermentation. This process is called maceration.
Types Of Wine
Wines can be grouped into six categories: white wines, red wines, rosé wines, sparkling wines, dessert wines and fortified wines.
White wines are wines that contain little or no red pigmentation. These wines are almost always made from white grapes but can be made from red grapes as well, from Cabernet Sauvignon through to Pinot noir for instance. White wines can be sweet or dry, or somewhere in between.
Red wines are made from red grapes with the colour actually coming from the skins. Tannins are also found in the grape skins and are transferred into the wine while the skins are in contact with the juice. Besides the colour, the main difference between red and white wines are tannins. There are almost no tannins in white wines but in reds, they produce the dry, grippy sensation in the mouth and in the back of the throat. They also help preserve wine, allowing most (but not all) red wines to be aged longer than white wines.
Rosé wines are pink in colour and can be referred to as rosé, pink or blush wines. Rosés are made from red grapes but don’t fully turn red because the grape skins are removed from the juice soon after contact. This brief contact with the grape skins gives the wine a pink colour from the slight transference of red pigments from the skins. Rosés only have a small amount of tannin. Australian roses have tended to be a little fruitier and sometimes sweeter than the bone-dry wines of Europe. That is changing and in some cases, a small amount of older oak is used to build texture into the wines.
Sparkling wines, made from many different varieties, but the greatest, the wines of Champagne, are made solely from Pinot noir, Pinot Meunier and Chardonnay. There are a number of different techniques for making champagne and Champagne-style wines but the most famous and the one that creates the most complex is the methode champenois, a process of secondary fermentation.
Many Australian sparkling wines are made in the method champenois tradition, while others use simpler less costly methods to introduce carbon dioxide into the wines. In addition to Champagne, famous names in sparkling wines are Cava from Spain and Prosecco and Asti Spumante from Italy.
Dessert wines have high sugar content, making them a popular choice with or as dessert. They can be made sweet from many different ways, such as harvesting the grapes very late when sugar levels are high, drying the grapes on mats or handing in cellars, or simply cutting the cordon on the vine, all to concentrate the sugars.
Fortified wines have brandy or other spirits added to the juice during fermentation. The brandy prematurely stops the fermentation process, thus leaving a high amount of sugar in the wine. Some fortified wines, including Port and Sherry, were originally designed to ensure the wine survived long voyages on 17th century ships. Australia makes some of the world’s greatest fortifieds especially the liqueur Muscat and tokay styles of Rutherglen and the Swan Valley.
In this segment, we will look at the making of the basic wines, without too much of the tweaking that winemakers might use to get that little something extra in the wines.
After the primary fermentation of red grapes, the free-run wine is pumped into tanks and the skins are pressed to extract the remaining juice and wine. The press wine is blended with the free-run wine in varying amounts.
The next phase is the secondary fermentation to convert the harsh malic acid to the softer and richer lactic acid, a process which lowers to acid in the wine and creates more texture and softness into the palate. After this, the red wine is transferred into oak for a period which can be a few months to a few years – longer in some extreme wines. This imparts important characters from the oak into the wine and increases complexity.
During the maturing phase, winemakers check the barrel regularly to determine the take-up of oak and ensure the wine is not left too long in oak. Once satisfied the winemaker will take the wine out of the barrel for filtering and then bottling.
White wines are mostly processed without destemming or crushing and are transferred from picking bins directly to the press. This is to avoid any extraction of tannin from either the skins or grapeseeds.
With white wine, the liquid is separated from the must before fermentation. The primary, or alcoholic fermentation, can be done with natural yeast, but since this can give unpredictable results depending on the exact types of yeast present, cultured yeast is often added to the must. This also eliminates the problem of the wine not going to complete fermentation during this important phase.
After the alcoholic fermentation winemakers might want to introduce malolactic fermentation. There are differing schools of thought on this, especially with chardonnay with winemakers choosing between complete malolactic fermentation, partial or none at all. A lot of this has to do with the style of wine being sought.
Winemakers take different approaches with white wines. For instance, aromatic varieties such as Riesling or Sauvignon blanc are generally fermented in stainless steel and prepared for bottling as young fresh wines without the influence of oak.
But other varieties such as Chardonnay will spend a number of months in oak of varying ages to import further complexity and texture into the wine. During this period winemakers may wish to stir the dead yeast cells which are still in the barrels with the wine – a process called battonage.
In the main, these are made in much the same way as white wines, although in Australia the difference more recently has been to introduce a small amount of older oak to build texture and contribute towards the drier leaner style.
The juice of the grapes is left on skins for a short time to pick up colour and an ever so slight amount of tannin. Some winemakers are tweaking things even more with wild yeasts to further enhance the complexity and texture of what are still light-bodied wines.
There are a myriad of ways desserts wines are made. The varieties vary from Riesling through to Semillon and Sauvignon blanc from the great dessert wines of Bordeaux. They are generally made in much the same way as white wines with winemakers choosing to keep them away from oak and rely totally on the sweetness of the grapes or putting them into oak to build structure and complexity and prepare them for extended ageing.
The key is the grapes which must be picked riper than normal white wines so that the sugar content is much higher. The greatest of these are also infected by botrytis cinerea, a greyish fungus, which attacks the grapes in the right conditions to concentrate the sugars and influences the flavours.
There are a number of different processes for making sparkling wine, from the simple addition of carbon dioxide by adding gas to the wine, to the more complex methode champenois, the process adopted by the Champagne Houses of France and better quality New World producers.
In this process, winemakers choose the grape varieties they want, to produce a number of different wines from different sites which are then blended into a base wine which will form the basis of the sparkling wine. It is then bottled and a small amount of yeast and sugar is added to kick-start the secondary fermentation is added. Because the bottle is sealed the gas generated from the fermentation remains in the bottle giving it the gas and bubbles we all know.
The wine is then left on the dead yeast cells caused by the process to pick up further character. These wines can age for many years in this way in a stage that is called tirage.
After a period of time generally more than three years, the wine is prepared for bottling when either by hand or mechanically the bottles are turned to draw the yeast cells into the neck of the bottle.
The wine is then disgorged – the seal broken – then immediately topped with a sweet expedition liqueur – called dosage – to balance the dry acidity of the wine, before being resealed under cork and wire.
There are many different styles of fortified wines, including the various sherries, ports, and liqueur styles. Australian winemakers make a whole range of different fortified styles with the rich liqueur muscats and tokays the most famous and individual.
Liqueur style fortified is made by picking grape very ripe and then putting them through normal fermentation as far as possible before stopping the fermentation with spirit and storing the wine in oak. The wines remain in oak for many years in some cases. New vintages are used to top up the barrels which lose volume due to evaporation and in this process the wine gains complexity and richness. Older wines with decades of ageing are some of the world’s great wines.
There are basically two types of ports – vintage port which is from a single vintage or tawny port which is a blend of vintages. Vintage port is made as red wine with the spirit added to boost the alcohol and then after a couple of years bottled so that it can continue to age without oxygen in the bottle, sometimes for 100 years or more. Tawny port has the spirit added but the wine is put into oak where slow oxidation develops the wine so that when it is bottled it will not age any further.