Wine makers have a huge range of tools, to manipulate wine. Blending is an often under recognised method that has a profound effect on the wine.
The two parts are
Why do winemakers blend? Is it for Quality? Price? Style? Volume? These are all true, but behind them all is Synergy, the magic ingredient of blending. Synergy is the idea that the sum of the whole is greater than the sum of the parts. For example humans are synergy. We are much more than a collection of atoms.
Blending allows winemakers to make a better wine than the grapes would normally make. For example, blending Cabernet Sauvignon, which often has a strong acidic and tannin structure, with a softer more rounded Merlot, creates a full rounded wine. The combination is more pleasurable than both wines by themselves.
Other classic combinations include Semillon with Sauvignon Blanc, where the Sauvignon Blanc gives an acidic backbone to complement the Semillon's fullness.
Some blends are purely for economic reasons. For example if a variety is particularly fashionable and another unfashionable you may want to blend the two together. Like all food labelling the order of the grape is in order of volume in the wine. So a Sauvignon Blanc Semillon has more Sauvignon Blanc than Semillon. But if say the Semillon was less than 15% it does not even have to appear on the label in the UK and most countries around the world.
Some wines are simply at their best as blending Wine Makingpartners. For example Grenache is a high-yielding grape that can achieve high sugar levels but at the cost of a lack of colour and low tannins. So in Australia and the Rhone Valley it is blended with Shiraz/Syrah. Here the Syrah provides colour and tannins, filling the gap that Grenache needs. Mourvedre is another blending component with Grenache. With all three combine to create the classic Rhone blend known in Australia as GSM (Grenache Syrah/Shiraz Mourvedre). In Spain Grenache is often partnered with Tempranillo to give the wine structure.
Something of interest to note is Chateauneuf-du-Pape where up to 13 grape varieties are authorised by the appellation for making the powerful and richly coloured red wine. Not all are red grapes. Similarly Chianti, the famous Tuscan wine, is a red wine made up of Sangiovese blended with the white Trebbiano.
Blending before fermentation
Complementing one variety with another is one of the huge benefits of blending. The blender knows what they have and can trial blend the wines and know what they are going to get. This gives flexibility and certainty to the blender. But another type of blending is to add the grapes together before fermentation. This was how wines where traditionally made and blended. Different grapes varieties in the vineyard were grown together and picked and fermented together.
In mixed vineyards the speed of ripeness is important. For slower ripening varieties these can add acidity and even green flavours. Selecting the grapes and the proportion of each was essential. But the same frost and wind can affect grapes at different times in their cycle. The resulting blend and quality can vary. However in more temperate and consistent climates, such as parts of Italy, this is still practised.
A more common reason for co-fermenting grapes is to create a unique wine. Here molecules from one grape combine with molecules from another to create a flavour or style that would not occur if the grapes where fermented first then combined. Perhaps the most common of these is blending. Shiraz with a dash of Viognier then ferment the two. This creates a wine that is rich but with delicate flora top notes, which can’t be achieved by blending two finished wines.
Non Vintage Wines
The last form of blending is blending across different years, or Non Vintage wines. All Non Vintage wines are made up of at least two vintages. This is to give consistency to the wines, smoothing out the variability of vintages to give a more consistent quality. The most successful is NV Champagne, but there are other types such as non vintage fino sherry and many types of port. It is uncommon to find still white and red wines from more than one vintage, except at the very cheapest end of the market.
Blending for Insurance
One important element of blending is not to improve so much the quality but to improve the finances of the producer through insurance varieties. Because different grape varieties go through their life cycle at different speeds, having a range of varieties provides some protection against the weather. The key weather patterns are frost, wind and rain.
A late frost can wipe out many early budding varieties. Here the frost destroys the young tender buds. Varieties that bust forth at a later time will not succumb to damage that may have burnt off earlier varieties. This can mean the difference between having a drop and not having one.
The next big risk is flowering. Some varieties do not flower and fertilise well in windy conditions, while others do. Different varieties can give better results and different flowering times can protect the vineyard against losing the crop.
Finally, rain can create problems. Wet conditions can cause the outbreak of moulds and mildew on the vine, with some varieties such as Pinot Noir being very susceptible and others such as Cabernet Sauvignon being better adapted. While no grapes like their roots being wet, different rootstocks are better adapted to sodden soils. As a result vineyards use a range of rootstock in the vineyard to manage rain and vigour.
As well as different root stocks grape varieties can have different clones, thus a vineyard planted with Chardonnay may contain a number of different Chardonnay clones. Each clone has its own characteristics, flavours and life cycle. Often when planting a vineyard you might have a range of rootstock and clones to meet the needs of the different soil and climatic conditions. Often these different clones are harvested separately and then blended, each providing their own personality to the final blend.
Alcoholic fermentation is not the only fermentation to be used for wine making. Malolatic fermentation is another significant change in the wine. Here, wines with crisper malo acids, are softened to lactic (milk) acids. Blending the two wines allows control of the perceived acidity in the wine.
Malolactic Fermentation (MLF) is the conversion of sharper, stronger citrus/green apple like Malic acid into the softer creamier, lower acidic milk-like Lactic acid. A further bi product is carbon dioxide. It naturally occurs during or after normal alcoholic fermentation unless the winemaker stops it by adding sulphur dioxide to the wine. Most reds undergo malolactic fermentation but not all white wines. Wines with sharp racy acidity such as New Zealand Sauvignon Blancs often do not have malolactic fermentation. Typically if you are in a cool climate with high acidity you will carry out MLF to soften the wine, while in hot climates where acidity can be a problem MLF is often avoided to preserve the fresh nature of the wine.
Many Chardonnays have a buttery creamy taste, the buttery flavour is associated with MLF and is the reason that many Chardonnays have MLF , particularly if the wine is to be aged in oak barrels. Caramel flavours are not uncommon but not all flavours are desirable - some wines can develop a rancid butter, sweaty and mousy taint. Off flavours can be managed by the inoculation of lactic bacteria that is responsible for process.
Occasionally some winemakers give wines partial malolactic fermentation. That is, some of the wine is separated out and allowed to go through malolactic fermentation. When added back in, the wine has a blend of the racy Malic acid and the fatter, softer Lactic acid. In this way the winemaker can control the mouthfeel of the wine. Lactic bacteria are sensitive to temperature, alcohol sulphur dioxide and acidity. Sulphur dioxide is the easiest and most reliable way to stop it occurring. Sometimes wines have a slight spritz to them and taste off - this is most likely associated with MLF after bottling.