Wort + Yeast = Wash

Wort + Yeast = Wash

The importance of fermentation

Production | 29 Jan 2016 | Issue 133 | By Ted Bruning

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It all started, as we know, back in 1495 with James IV of Scotland's grant of eight bolls of malt to Friar John Cor to make aqua vitae with. Whisky lovers get very excited about that entry in the Scottish Exchequer Rolls: what was Friar John's whisky like? Was it really whisky? Was it even a beverage, or was it just a solvent for herbal alkaloids? And how long had people been distilling malt liquor, as opposed to wine, before this mention?

All good questions. But we rarely stop to think about the ale that had to be brewed first. And it would have been quite a lot of ale, since eight bolls or 48 bushels of malt weighs 740kg; enough (if it was efficiently malted and mashed) to brew 13 - 15 hectolitres of ale at 7 - 8% ABV. There's no way of knowing, at this distance, whether the ale Friar John intended to distil was the same ale that he and his fellow-monks enjoyed every day; but there's no reason to suppose that it wasn't.

Today, though - well, a pint of wash wouldn't be so enjoyable. For just as Cognac is distilled from weak, acidic wines you certainly wouldn't want to drink, so malt whiskies derive from ales so well-attenuated that even tasting them is more of a chore than a pleasure. Scott Ferguson at the Eden Mill craft brewery and distillery in St Andrew's describes the wash from which his new make was created as, frankly, "thin and weedy".

"We want as much conversion in the mash as possible, and the distiller's yeast we use in the washback is very efficient," he says. "So although we get a wash of 9 - 10% ABV and sometimes more, the beer isn't something you'd drink - the final gravity can get right down to 1000°, so the wash is very thin and sometimes it's even a bit sour."

The yeast Scott and other distillers use today was developed some 50 years ago to work fast, to ferment every last grain of sugar, and to tolerate the levels of heat and alcohol it itself created. At the time there was a boom on and new distilleries were popping up everywhere; but the Scotch Whisky Regulations forbade the use of almost all process aids, so the only way to make efficiency gains was to beef up the yeast. More recently the environmental benefits distiller's yeasts bring - less waste, and reduced water and energy inputs - have driven further R&D, and only a handful of distillers still use old-school brewer's yeasts.

But alongside the cutting-edge biochemistry, malt distillers still use some pretty ancient techniques. Just like a medieval alewife, most whisky distillers mash their malt three times, getting progressively weaker worts. The worts are usually blended before fermentation, but practices vary: at Glenfarclas, for instance, the wort from the third mash becomes the liquor for the first mash of the next batch.

An equally ancient practice that has recently made a comeback, albeit on a tiny scale, explains the story of the drunken duck. The mythical bird that appears on countless British pub signs owes its inebriation to an accident that would be impossible today: the brewer's wife threw out the spent grains; the duck ate them; they were still saturated in beer; the duck therefore got plastered with, of course, hilarious consequences. This is only possible if you ferment your wort without running it off your goods first, which might not have been a universal habit in the days when the duck got drunk, but is today.

The exception is at Loch Ewe in far-flung Wester Ross where distiller John Clotworthy has reinvented the 18th Century way of brewing, dispensing with the refinement of separate mash tun and washback. Like his forebears, John simply waits until his wort is cool enough and then stirs in the yeast.

"A lot of Bourbon distillers still do it this way and it produces fantastic results," he says. "With the malt still in the wort the yeast can digest all the sugar, and we get low wines that aren't 18 - 25% ABV but 45 - 50%!" Not to mention a fermentation that creates so much heat that on a cold day you can warm your hands on it.

John's revivalist experiments - of which this is but one - betray a playfulness which is largely absent from an industry where you have to wait three years before you know whether your experiment has worked. A craft brewer or a small-batch gin rectifier can afford the occasional ill-advised innovation; a whisky distiller can't. Still, Scott at Eden Mill has dared to try out various brewing malts - 50kg of chocolate malt added to 800kg of the usual Golden Promise left a lingering mocha in the new-make, while 25kg each of brown and crystal created warm flavours of toast and shortbread.

"I was surprised by how well the flavours carried through," he says. "And I'm also surprised that more distillers haven't tried out different malts. Glenmorangie did it with chocolate malt and it worked brilliantly."

Playing with malt, yes. But hops? Wash isn't hopped, we know that; but eau de vie de bière distilled from hopped beer is an established tipple in Alsace; Het Anker of Mechelen near Brussels distils its Gouden Carolus; and Adnams has a beer eau-de-vie, Spirit of Broadside, made from its eponymous strong ale.

"In the early days we still had downtime, so we thought: 'let's play'," says head distiller John McCarthy. "Our regular wash is 6.7% ABV, and so is Broadside before it's bottled, so we distilled some, aged it in oak for a year - and it was good! Unusual, but good. So now we're going to play a bit more - we're planning a rye and a wheat whisky and we'll just see if they work too."
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