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Wood aging

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Wood aging isn’t new. But is has been rediscovered by a generation of brewers more used to shiny, sanitised stainless steel. In a previous era, wood was used to ferment, age and transport beer before there was anything better. One of the characteristics of today’s creative craft brewers is not just reviving old beer styles and brewing techniques but seeing how far they can develop beer taste and profile using wood.

Not content with simply “wood-ageing” beer, craft breweries are experimenting with new creations. And the brewer has choices to make – what type of wood to use? Typically, French or American oak. Should the wood be charred? Just charred or toasted? And what was in the barrel before it came to the brewer?

Whiskey barrels the most popular choice for ageing. With the right beer in them, they can balance flavours and make a whole greater than the sum of its part especially if higher alcohol, malt-forward beer being used. It also helps if the brewer understands how to blend beers from different barrels.

The brewer need also decide if they want to make sour or non-sour beers. Non-sour, are usually aged in barrels to extract the oak and/or the character of whatever liquid was stored. It could be whisky, wine or even sherry, but other barrels are available. In the US tequila and rum barrels have been trialled. However, some brewers are looking to create a sour beer, ones which are inoculated or infected with a yeast such as Brettanomyces. In these cases, the porous wood is home to the microbes.

But oak-aged beers do not all come from wooden barrels. In some cases, such as Innis & Gunn, oak chips from the staves of barrels are put into steel tanks and the beer poured over it. The results can be stunning.

Duchesse de Bourgogne is a beer from West Flanders, Belgium, which is produced by a mixed fermentation of yeast and lactobacilli and then a long, gentle maturation in oak.  The tannins in the oak give the beer its fruity character. Could this beer be the bridge, between grain and grape? After two fermentations, the beer goes for maturation into the oak barrels for 18 months. The final product is a blend of younger eight months old beer with 18 months old beer. The average age of the Duchesse de Bourgogne before being bottled is one year. The result is a complex, blend of acidic tartness and sherry flavours. It is with good reason that worldwide, other brewers from the US to Japan, Italy and beyond are trying to recreate the style. Worldwide, sour red beers are one of the hottest styles there is.

The beer was recently showcased at the British Guild of Beer Writers awards dinner and paired with a dish comprising smoke venison, goats’ cheese and a terrine of fig and apple. According to the menu notes: “The venison dish is über-complex with apple juice, fig sweetness, beetroot and red wine vinegar, smoke and cheese fattiness to deal with. An immediate flavour hook of acidity is needed to tie in, cut through and contrast. The Duchesse achieves this with its intensely fruity sourness balanced by aged oaky and malty flavours and spiciness.”

One of the greatest sights in the beer world has to be the large storage room in the Brabandere brewery in Bavikhove, in the heart of one of Belgium’s best-known brewing regions, Flanders. Here stand the large 220 hectolitre French oak foeders, which quietly go about their business of ageing and souring beer. The large wooden storage vessels are often known as tuns, and it is in these where the aged, pale beer used in the blend that makes up a Petrus Oude Bruin slowly matures.

The family-owned brewery, whose surname gives the brewery its name, was founded in 1894. Like many Belgian brewing families, the Brabandere’s began as farmers and used their own grains to make beer.

Its beer Petrus Oud Bruin is a classic blend of one third Petrus Aged Pale, pure foeder beer and two-thirds of a young brown beer. This beer is liquid heritage and the brewery is rightly proud of its motto “never compromise on taste”.

Possibly all beers were once made in this way and it’s a tradition to the brewery is proud to have revitalised, the blending of beers old and new. Both in Belgium and the United Kingdom there is a tradition of making beers in this way. The ageing on beer in wood allows a lactic fermentation to take place and some additional conditioning from the slow working brewing yeasts, which often reveals characteristics not present when the beer first ferments. The ageing turns the beer slightly sour, like an oak-aged wine. And similar to a wine which needs blending to bring out its true character, the flavour spikes will be softened by the addition of a younger beer.

The addition of the young, dark beer not only softens the beer’s sourness but gives it its characteristic reddish-brown colour. Even though, the aged beer is in the barrel for 24 months the brewer doesn’t want the beer to taste of oak. Instead, the foeder is a container which provides a fertile breeding ground for various microorganisms that convert the remaining sugars in the beer from the prime fermentation into acids, higher alcohols and esters. The wood is also semi-permeable and allows air to come in contact with the beer. Over the two years, the beer slowly oxidises, which after two years becomes a refreshing, palate-cleansing fruity sour, aromatic beer.

The sweet and sour style was once very common across Flanders – in the east of the region they are often called browns or bruin, head west and they usually become known as red., but Oude Bruin is an exception to this rule.

A blended old ale with a long heritage can be found in England, Strong Suffolk which is made by Greene King. Moreover, many of the country’s new wave of brewers are rediscovering the art of storing beer in wood and then blending them. One such is Burning Sky, where the brewers are experimenting with making a Sussex version of a Flanders beer. The aim is a deeper, more complex taste. The brewer must be careful, though, as excess wood tannins can also be introduced to the beer, affecting it in a negative way. Barrel ageing is especially suitable for the amber brown beers of Flanders., which rely for grain and malt for flavour and not aromatic hops.

The Petrus Oude Bruin has a deep, almost a rusted Burgundy colour. The taste is light and refreshing, wheat and a blend of pale ale and crystal malts are used in the grist that cocktail of grains adds to the beer’s refreshing qualities. Ruby red to the eye and it is easy to see why it is known as the Burgundy of Flanders. Its aroma swirls with red fruit flavours. It a complex harmony of sweet and sour, which feels sensuous on the tongue. There are tart flavours of plum, prune, raisin and black sherry. Who needs a glass of red wine when one can drink a beer like this.

A lot of bikes stand outside the New Belgium Brewery on Fort Collins, Colorado. And many cycling references feature in the names of brewery’s beers including Slow Ride, Shift and Fat Tire. They seem appropriate as the founder of the New Belgium brewery Jeff Lebesch was inspired to open his own brewery in 1991 following a cycle tour of Belgium. La Folie, French for “the folly” is a beer steeped in New Belgium brewing tradition. The beer created quite a storm when it won gold at the Great American Beer Festival in 1997. There wasn’t even a class for this style of beer. But the judges were wowed.

Now, New Belgium brewmaster Peter Bouckaert, a native Belgian who used to work at Rodenbach says there must be seven classes for sour beers at the Great American Beer Festival. And he is dismissive of any craft brewer who doesn’t have a programme for ageing beer in wood. “Who are you,” he challenges.

He believes that New Belgium is at the forefront of rediscovering, the classic tastes of beers before it was refined by industrial production a hundred or so years ago which encouraged most producers to move to single cultured yeasts.

Now he is a curator for a “zoo” of hundreds of lactobacillus, pediococcus and other bacteria. Latcobacillus can ferment with or without oxygen and produce lactic, instead of alcohol, and carbon dioxide. Unwanted by most brewers, who shun the off flavours which can include butterscotch or buttery flavour known as diacetyl, they are an important component of sour beers.

The pediococcus, which is the bug that helps turn cabbage into saurkraut, ferments glucose into lactic acid but doesn’t produce carbon dioxide. It adds rich complexity to a beer. Different barrels will progress in a different way. The skill of the sour beer brewers and blenders is to take the characteristics of different base beers to create the acid profile they are looking for.

Beneath the Fort Collins brewery there now 64 large French oak foeders, large barrels, making it one of the most comprehensive wood beer programme in the world. Here matures the beer which will be used for blending each the beer. The staff call the room the foeder forest.

Wineries retire their foeders for a variety of reasons, but usually, it is because the tannin flavours in the wood have been exhausted. Tannin is regarded as an essential flavour component of many wines. However, tannin is not a flavour, brewers are usually looking for, so they are happy to take on the second-hand barrels, which as well as being perfect for storing beer, they are also excellent homes for microbes and wild yeasts.

The wood-aged La Folie spends from one to three years in oaken barrels. Many American brewers of craft beers, refer to their bacteria as critters and relish the opportunity of getting to know their barrel characteristics before blending with it. La Folie needs to be sharp and sour. It should have notes of fresh Granny Smith apples, cheery and plum skins. It will pour a dark mahogany into the glass, and on tasting it is a curious harmony of smooth and puckering.

A new wooden age has begun.

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