We are fast approaching the half way point in the journey of discovery that is 52 brews in a year. So far I have made stars of the hop (50 hop and DUSI) special malt (25-grain Chechen Imperial Porter), Herbs and Spices (Gruit Ale and Cardamom wheat), bacteria, shellfish and even animal organs (Heston’s Offal Ale). It is now time to turn to the Cinderella of brewing, Saccharomyces cerevisiae (brewer’s yeast).
I once read an article in the Brewer’s Guardian by a very well regarded brewing academic which basically said the yeast strain is largely incidental to beer character. At the time being newly graduated I took this as gospel and assumed that the brewhouse and process stages along with control of fermentation were where the true key to flavour control lay. Quite a few years on I can only assume that the eminent professor was talking about strain of yeast within a style of yeast because I have found the contribution of yeast to be absolutely pivotal to a number of defining beer attributes. If he wasn’t then he should have spent longer brewing and less time studying barley beta glucans.
At a few times in my career I have had run ins with yeast. Yeast can be a dream come true or a nightmare made reality. Once a few years back I was at a brewery, (name withheld), where the yeast just started to do stupid things. We looked at changing the yeast and got in samples of commercial yeast strains which had similar flavour characteristics. We did small scale trials on the same wort pitched with different yeast. All were significantly different from the brewery strain and each other. I was stunned at the degree of variation within a group of yeasts which were all described as top fermenting British ale yeast with a fruity and dry flavour. Fortunately the brewery in question’s yeast started behaving again.
Battle of the yeasts isn’t just about what flavours a yeast strain can produce, it’s also about how much and how quickly. I am creating an even field by ensure that the cell number, viability and condition of all the yeast are equal. The contribution of the yeast to the flavour will depend on which compounds it produces as well as how well it competes for nutrients in the wort. The yeast may be able to produce pronounced, characteristic aromas like bananas and cloves but if it is last to the oxygen and sugar feeding trough, it isn’t going to be able to ferment strongly enough to contribute to the overall flavour. Conversely Sharp’s yeast may compete well for the available nutrients but its naturally clean and gently fruity contribution may be drowned out by the more expressive Belgian and German yeast.
In the words of Harry Hill, there’s only one way to find out. FIGHT!!!!