Discovering the English Yeast
In this article we want to introduce English yeasts. Used to produce the most varied types of beer, these yeast strains are known for some characteristics that make them unique. Let's find out together!
The yeasts that are classified as "English" are Saccharomyces cerevisiae strains, isolated and identified in British breweries. It is a group of high fermentation yeasts, united by medium-high to high flocculation levels, medium-low attenuation levels (mostly between 70% and 75%), and an average production of esters. Yorkshire's yeasts tend to be very flocculating, with a pronounced fruity profile, low attenuation (around 70%), and high diacetyl production. The production of esters is one of their most interesting characteristics because it makes them able to give an interesting and unique profile to very “simple” beers, perfectly matching the aromas of malts and hops. The high flocculation allows obtaining clean beers in a short time, while the medium-low attenuation give the beers a round body, even at low alcohol levels (3-4% alc). Other yeast strains, on the other hand, tend to be faster in fermentation, drier (apparent attenuation around 75%) and slightly harsh/earthy, and less flocculation. They are less "demanding" yeasts that carry out fermentation more easily.
Some English yeast strains are finding interesting results in the production of modern hopped beers, the NEIPA. These yeasts are very well suited to this style and their medium attenuation guarantees beers with a softer finish. In addition, it seems that some English yeasts have a good capacity for bioconversion of the aromatic oils of hops (the set of biochemical reactions where the yeast is able to modify the aromatic molecules of hops). Most brewers nowadays prefer to use American yeast strains which are more reliable and controllable. In fact, it is known that English yeasts are the cause of problems such as too low attenuation, blocked fermentations, unpleasant aromatic profiles and uncontrolled re-fermentations, with gushing and off-flavors.
In fact, the extreme flocculation of some British strains ensures that they are deposited quickly and compactly on the bottom of the fermenter at the end of the tumultuous phase. This feature allows the production of clear beers without filtration, fining or cold-crash. At the same time, it is possible that the yeast settles on the bottom before the end of fermentation, thus leaving the beer under-attenuated, and with possible fermentative off-flavors (diacetyl in particular). How can we avoid this? One of the most popular tips is to raise the temperature of the beer a few degrees at the end of the tumultuous phase, to help the yeast run out of remaining sugars and reabsorb the diacetyl. Another more effective but unusual practice is to bring the yeast deposited on the bottom back into suspension. If at home this can be done by shaking the fermenter or with a paddle, at the commercial level it is done with recirculating pumps or blowing carbon dioxide from the bottom. This operation must be done about 24-48 hours after the start of fermentation, to put back into suspension very vital cells that have deposited early. For some strains, periodic agitation is beneficial during the tumultuous fermentation, up to 72-96 hours from the start of fermentation.
So we can say that is possible to produce excellent beers using English yeasts but with various tricks and a lot of effort. A great tip is to try blending different strains of yeast to get the best result. We know that to brew a good Bitter Ale or an English Barleywine, using British yeasts is a must.