Bar Man, by Jeff Hoyle, August 4, 2017

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If you want to make great beer, obviously the ingredients are important.

Your malt may come from Norfolk, with some local brewers using locally grown varieties such as Maris Otter as a selling point for their product, especially if it is malted at a nearby firm such as Crisps at Great Ryburgh.

Hops are also becoming more high profile, especially with the trend towards very heavily hopped American style IPA, and many beer lovers will be familiar with New World varieties such as Cascade as well as old English favourites such as Fuggles.

Water plays an important part and breweries will test and maybe treat their supply to ensure consistency, perhaps imitating the water that originally made IPA such a classic beer, a process known as Burtonisation. And then there is yeast.

Who knows anything about yeast? If you are a home brewer you may well purchase generic ‘Brewer’s Yeast’, perhaps marketed for the style of beer you wish to brew, and think no more about it. For a commercial brewer, this is not good enough.

The specific type of yeast used will contribute to the distinctive flavour the brewer wishes to create and it is an integral part of the process.

During fermentation, the yeast cells multiply and a portion can be retained for the next batch while the rest is converted to products such as Marmite. Given that the yeast collected is checked carefully for mutations, the same strain can be used for generations.

One of the most important brewing yeasts was called Saccharomyces carlsbergensis, formerly designated Carlsberg yeast no 1 in1884, and although reclassification has resulted in a name change, it continues to be used in lager production.

Clearly the loss or corruption of a brewery’s strain of yeast could be a disaster, so what should they do in case of fire or a flood such as that which affected Jennings in Cockermouth in 2009?

The answer is to call Norwich! Specifically, the NCYC or National Collection of Yeast Cultures. Situated on the Science Park, close to the university, the collection holds over 4,000 strains of yeast.

They operate open deposits, where they will accept donations from anyone, especially strains mentioned in scientific papers, new strains, those from unusual environments or those implicated in spoilage of foodstuffs.

For brewers prepared to pay an annual fee, they also have confidential safe deposits, where only the depositor is allowed access to the yeast. In this way, a brewer can store a back-up in a safe environment.

Samples are kept with on-site security, with a duplicate sample stored in a geographically-separate location, with only the depositor able to gain access. The yeast cells are both freeze dried and stored in liquid nitrogen and are available to be reactivated if necessary.

You can also purchase strains of yeast, some which may have been deposited here in the 1920’s. A sample may cost £175 for commercial use and the 521 varieties of brewer’s yeast available can be searched for characteristics such as head formation and clarity of final product. It is probably beyond the scope of a home brewer, but commercial producers wanting to recreate beer from historic recipes can take a step closer to being truly authentic.

Given that the nearby Sainsbury’s centre at UEA was used as a location for a recent Avengers film, maybe the next cinematic blockbuster could see masked characters breaking into the NCYC, to steal the yeast used in the legendary Crudgington’s Old Invincible.