What is “yeastykaka?” This website was almost named “Yeastykaka.com” but limited market research among friends and family revealed that it had gynecological connotations – NOT my intention. Yeastykaka is a word I use to describe an unpleasant flavour in a brew that results from something going horribly wrong. It specifically relates to that yeasty taste that occurs for a variety of reasons that will be outlined here.
When brewing at home (or even at industrial scale), mistakes can be made that irreversibly taint the flavour of the product. Sometimes these mistakes are obvious (at least in hindsight) but some are subtle and counterintuitive to the novice brewer. The strain of yeast and how it is employed can have a huge impact on the palate of the beverage, both positive and negative.
Choosing the right yeast strain for the job at hand is a whole other article. Here, let’s discuss a few reasons why the perfect yeast can result in a yeastykaka drink.
The most obvious reason for a yeasty taste in your beer/wine/mead/etc. Is… the presence of yeast. Any homebrewer who bottles their beer knows that live yeast is required to ferment the priming sugar and carbonate the beer. When this sugar is consumed, the yeast go dormant and fall to the bottom of the bottle That’s why most people pour homebrew into a glass, leaving the yeasty sludge in the bottle. If you drink something that is still actively fermenting you could be drinking up to 100 million yeast cells per milliliter! It won’t hurt you but it can certainly influence taste. This is why we typically shut down the yeast with potassium sorbate and metabisulfite, and allow the yeast to fully settle before bottling. Crystal clear = no yeast.
Much like people, yeast have an optimum temperature range where they are happy and able to work comfortably. For yeast, this is typically 25-30C. Below this temperature, fermentation is slow and could stall with the yeast going dormant. Going above this range results in “heat shock” where the yeast pump out proteins and alcohols that can result in a yeastykaka flavour. If possible, do your brewing in a temperature-controlled environment or at least avoid starting a batch during the peak of summer.
Sitting on the lees
As yeast go through their life cycle, they inevitably die and sink to the bottom of the fermentation vessel. This graveyard of yeast is called the lees (in wine and mead) or trub (beer) and it’s perfectly normal but can impart flavour if left in contact with the brew for an extended time. In some white wines this done on purpose but for most fermentations, it is best avoided. This is one of the reasons for carefully racking to a secondary fermenter once the vigorous primary fermentation is done.
As always, good sanitizing and sterile technique are vital. If you are careful and pitch an appropriate amount of commercial yeast, it will be difficult for wild yeast to invade your brew. Many commercial brewing strains of yeast have been selected for an ability to out-compete other strains that could find their way into your fermenter but there’s always a chance of infection. The result of infection could be something glorious like an unplanned sour beer or you may have a yeastykaka batch that is fit only for the drain.