There are some people who seek purity in wine. They want to taste something unique and well-defined rather than a blend of flavours but ultimately all wines are blends.
Even a single vineyard of the same grape variety is a blend of grapes from different bunches from different vines.
When I worked in New Zealand, there was a definite bias towards wines from a single grape variety, known as a “varietal” wine. I think this bias comes from the Scottish heritage and the connection with whisky where Single Malts are regarded as superior to blends.
However, many of the world’s most famous wines are blended from two or more varieties. Bordeaux nearly always contains Merlot and Cabernet Sauvignon with the possible addition of Cabernet Franc, Malbec and Petit Verdot. Rioja is blended from Grenache and Tempranillo and Châteauneuf-du-Pape can be a blend of up to 13 different grape varieties.
Those regions have a long history of growing different grape varieties to achieve their characters, which are now enshrined in Appellation rules.
Some grape varieties go well together and some do not. The Mediterranean trilogy of Syrah, Grenache and Mourvèdre evolved over centuries. Semillon and Sauvignon Blanc work perfectly together, especially in the Bordeaux climate.
Other French regions, notably Burgundy and Alsace, tend to make single variety wines.
Blending achieves a number of things. As I wrote two months ago, it can be used to achieve the consistency required for big brands and non-vintage Champagnes.
Négociants will buy from a number of producers in a region, each of whose wines may have a particular strength or weakness. A cheap batch from one producer can be bolstered by the addition of a percentage of a more alcoholic or richer wine from another.
Faults such as volatile acidity, which makes the wine smell vinegary, or aldehyde, which smells of nail-polish remover, or reduction, which smells like burnt rubber, can be hidden by blending the faulty wine into larger volumes of cleaner wine.
This allows wines which would otherwise be undrinkable to be sold, albeit at relatively low prices.
Blending can be used to balance wines in terms of acidity or tannin. A highly acidic white can be used to increase the acidity of a flabby one and a red with lots of tannins, such as the final pressings, can be used to add body to a thinner one.
The reverse is also true. Sometimes a small percentage of white wine is added to a red wine to reduce tannins and add a little fruitiness.
One famous example of this practice is in the Northern Rhône, where white Viognier is added to red Syrah, often during the fermentation. It helps to bind the colour as well as reduce the astringency of the tannins.
Under most Appellation and regionally-labelled wines, blending is only permitted within the rules of geography and grape variety.
AOP wines have much stricter rules on blending varieties than IGP wines.
However, in recent years, mainly to allow producers to compete with New World wines which have very few regulations on blending, some new AOPs have been introduced, such as AOP Languedoc which allows blends to be created from vineyards spreading from the Spanish border to the banks of the Rhône, and Coteaux Bourguignons, which stretches from Auxerre to Beaujolais and is used to sell all the poorer quality wines from the hilltops and plains that used to be called “Bourgogne-Grand-Ordinaire”.
There is also the new category of Vin de France, which as well as replacing the lowest quality level Vin de Table, allows innovative producers to experiment by blending wines (legally) from different regions Languedoc with Loire.
One form of blending that is prohibited in Europe is the blending of red and white wines to make rosé.
That is always made from lightly macerated and pressed red grapes, sometimes with the addition of white grapes, but never from finished red and white wine.
Blending is an art. Whether it is to create something drinkable from poor quality wines or to reach the heights of elegance of the haut-de-gamme of a prestigious estate. It is done by experts with heightened senses of taste and smell and thorough understanding of what is to be achieved.
Expert blending begins at harvest time when deciding when to pick a given vineyard or section of a vineyard, which grapes to ferment together and which combination of barrels to use to age the wine.
Sometimes a wine will be blended before going into barrel and sometimes it is done after the effects of ageing are more evident.
The final bottling blend will be decided by a combination of mathematics and tasting.
Working out what volumes of each component are available and how they can be combined to make the required quantities of various brands or cuvées requires a spreadsheet or dedicated program, or hours of pencilling in and rubbing out numbers.
Tasting involves taking samples from the various tanks and barrels, making notes on their characteristics in terms of acidity, tannin, strength, aroma, flavour and concentration and then figuring out what to blend with what, tasting each little combination, tweaking and comparing to achieve the goals.
Once the blends are agreed, the components are mixed together in large tanks ready to be bottled.
For large volume blends, several tanks will be required and these should also be homogenised to make sure all the bottles of that blend are roughly the same.
However, some wineries have been known to make a special blend in a small tank, which is better than the others, to send to critics and competitions.
Cellar masters are chosen for their ability to blend by taste or specialist consultants brought in to design wines that will meet the requirements of the chosen market, be that a supermarket chain, a bulk wine for restaurants, a prestigious estate wine designed to age beautifully over decades or a special cuvée that will win medals at competitions to raise the profile of the producer.
It is an interesting but challenging job and essential to get right. You cannot un-blend a wine if you make a mistake!
Jonathan Hesford has a Postgraduate Diploma in Viticulture and Oenology and is the winemaker of Domaine Treloar in the Roussillon – www.domainetreloar.com
If you have questions on this column, email him at firstname.lastname@example.org