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The culture club

Alice Whitehead explores the importance of yeast by taking a walk around the National Collection of Yeast Cultures.

If the whim should take you and, like Walt Disney, you decide to be cryogenically frozen, it’s quite probable when you wake in the year 21- something that your favourite beer from yesteryear can also be re-brewed – no doubt making life after death a much more harmonious experience.

Thanks to the National Collection of Yeast Cultures (NCYC), the yeast strains from hundreds of United Kingdom craft and commercial brews have been cryogenically frozen in perpetuity, since the 1940s.

Curator of this unusual library – one of the largest public brewing collections in the world – is Dr Ian Roberts, a trained botanist and scientist with a nose for yeast. “I guess you could say we’re the Kew Gardens of the yeast world,” says Roberts. “Brewers go to great lengths to look after their yeast and we’re often the only backup if it gets lost or destroyed.” During his 15 years at the yeast bank, based in Norwich, Roberts has lovingly cared for more than 500 brewing yeasts using surprisingly simple storage techniques.

Each yeast culture is covered in a special substance to protect it from the freezing process (-196°C in liquid nitrogen) and a droplet is then inserted into a children’s drinking straw.

“While the larger breweries have their own microbiological laboratories, smaller brewers don’t have access to this kind of technology so we’re a vital service for them,” says Roberts.

A FAMILY AFFAIR Ultimately, through his work, Roberts has become the final caretaker for many breweries’ microscopic – and often unique – beer ‘families’.

“All yeasts are natural living organisms and we go to some lengths to ensure their wellbeing,” says Derek Prentice, brewing manager at Fuller’s. “We monitor their viability and vitality, and ensure all the necessary requirements to keep them healthy are provided and controlled.” Ian Dixon, chairman of Brewing Research International (BRI), agrees: “The wise brewer babies his yeast – he feeds it, aerates it, and watches it grow over the generations. It’s real alchemy,” he says.

But rumours of brewers poaching yeasts from other breweries and attempting to ‘counterfeit’ rival beers abound in the industry.

In his book A History of Beer and Brewing, Dr Ian Spencer Hornsey, founder and ex-head brewer of the Nethergate Brewery, recounts the story of Gabriel Sedlmayr II, owner of the Spaten Brewery in Munich, who in 1833 – along with fellow-brewer Anton Dreher, visited a number of British breweries and stole yeast samples from them.

“Whilst they were warmly welcomed in some breweries, they were seldom left unsupervised in sensitive areas such as the fermentation room,” says Hornsey. “To overcome the lack of detailed information on offer, they resorted to what can only be described as industrial espionage… securing yeast, wort and beer samples in clandestine fashion, and analysing them when they returned to their rooms. Later, Sedlmayr wrote: ‘We always carry small flasks which we fill up furtively… without really allowing them to notice... Nevertheless, I feel daily a shiver running down my spine when we enter the brewery and I count myself fortunate to come out of it without getting a beating… We are now having walking sticks made of steel, lacquered, with a valve at the lower end, so that when the stick is dipped, it fills… In that way we can steal more safely’.” “Whether our travellers felt any remorse for their skullduggery is not known,” continues Hornsey. “But they made very good use of the information in their own breweries when they returned home. It is reported that Dreher subsequently wrote to one of his English hosts to apologise for the ‘unfair means’ that had been employed, and warned that other inquisitive brewers should not be given the same opportunity as he had been accorded!” Today, the protection of brewing yeasts remains just as important. The NCYC has dealt with more than 400 new customers in the last five years and, while some are happy for their yeasts to be stored in the ‘public’ library (where they can be purchased), other breweries are more secretive.

“I’ve heard that if a brewery is sold – once all the contracts are signed, the paperwork is out of the way and the keys are exchanged – the yeast is the last thing to be handed over,” says Roberts.

“Some are very protective,” adds colleague Dr Georgina Pope, the NCYC’s commercial manager. “Our ‘Safe Deposit’ service is confidential and secure, which is clearly important to depositors. There’s long-established procedures in place to ensure this information remains confidential between us and the brewery.” REIGN OF TERROIR So why all the fuss? In many ways, a yeast strain is to beer what terroir is to wine. In the same way the soil, the climate and the loving care of the grower imparts its own characteristics to the wine, yeast does the same.

While many microbreweries spend their spare time swapping yeast strains – the city of Portland (dubbed ‘Beervana’), in the American state of Oregon, has become famous for its 1,000 local beers and 70 or so craft breweries that share yeast ‘recipes’ – in the UK, at least, most yeasts are particular to one single brewery.

“Lots of breweries have had the same yeast for years, with some traditional breweries continue to serially repitch their yeast for generations,” says Prentice. “As a yeast adapts to the paramaters and methods within a brewery, it will almost develop into its own sub strain and breweries such as ours will select individual cells which exhibit the attributes we require. This is the yeast we’ll send away for expert storage and for use only by us.” Indeed, like many artisan products, provenance is all-important in brewing. To say you’ve used the same yeast as you did 10, 20 or 50-years-ago is invaluable to many breweries. “Yeast has a very significant part to play in the final flavour of a particular beer,” says master brewer Paul Buttrick, previously head brewer at Boddingtons and Stella Artois. “The yeast used to ferment a Bavarian wheat beer is completely different from that used for a lager or an ale.” In fact, the NCYC also offers a DNA fingerprinting service to check the identities of particular strains – and this yeast ‘line-up’ has proved very useful. “One Australian brewer contacted us because he felt the yeast he had been supplied was not the same as the one he had previously used,” says Roberts. “We were able to offer him genetic fingerprinting to see if the yeast in storage matched the new one.

In this case, it didn’t, and he was able to pursue the yeast supplier.” THE ROOT OF ALL WEEVIL While no breweries in the UK have chosen to go down the same route as enterprising university boffins in America – who brewed a wheat beer using a tiny colony of yeast trapped inside a 45-million-year-old Lebanese weevil – with the help of the NCYC’s ‘heritage collection’, it is possible to recreate a beer from the 1920s.

“Thanks to cryogenic freezing, we are able to save a little bit of history,” says Roberts. “Our heritage yeasts have been preserved in such a way that, if you were to use them to brew today (using the same conditions), you could be drinking a beer with the same characteristics as it had 90 years ago.” Something, Walt Disney (or at the very least, his frozen head) might approve of.