Yeast Trivia

Yeast can be a rather dull topic, so here’s a bit more yeast trivia to finish off. Just little snippets of yeastie information which might hold something you’ve wondered about in the past or better yet help you to appear ever so clever. Below just may hold the answer to someone else’s muse offered up in conversation in front of an entire group of people you’d like to impress.

  • No matter how much fermentable sugar is available in the wort, yeast will only make up to a certain ABV% (alcohol by volume, expressed as a percentage of total beverage volume). Even if you throw in more yeast. This is because the solution’s alcohol level becomes toxic to yeast. Most beer yeasts have an alcohol tolerance between 8-12% ABV. Some, such as English ale, is as low as 7% and some, such as Belgian ale yeasts top out at 15%. This is why you will never find beer of higher ABV%, unless fortified with distilled spirit.

  • 99.9% of our genes are exactly the same in every human. 96% of our DNA is shared with our closest living evolutionary relative the chimpanzee. 85% of us is dog. 80% of us is cow. 60% of us is banana and 25% of us is DNA equivalent to yeast. Clearly this is how sports people can give 110%. We gross around 450%.

  • Yeast produce around 600 different flavour compounds in beer. They are very busy!

  • Comparatively speaking, yeast isn’t a big flavour producer in the common craft styles of Pale Ales and IPAs, which is why often a neutral yeast is deployed. These yeast strains are neutral in flavour, rather like the bakers’ yeast, and devoid of yeast flavours of other beer styles such as floral, funk, fruit, bubble gum, and citrus.

  • Yeast is environmentally friendly. A true greenie, it is used in the biofuel industry to make ethanol. It is also used for the degradation of oils, explosive material, hydrocarbons and fatty acids in polluted areas.

  • Normally yeast live for about a week, though on a calorie restricted diet that can increase 10 fold.

  • For the brewers amongst us and home dabblers pondering yeast propagation, interestingly, the first generation of yeast pitched straight from the yeast suppling laboratory will take 1 to 3 days longer than the same yeast strain of subsequent generation syphoned off the initial brew and repitched into a subsequent beer batch. This phenomena is owed to shorter lag time and faster fermentation, as the yeast has now acclimatised from lab conditions to its fermentation environment. The little buggers learn! They are amazing.

  • A trendy yeast in craft at the moment is the Norwegian Kviek with its super power to ferment beer over 30°C without throwing typical off flavours. A treasured gift for brewing in warmer climates.

  • Craft brewers have been known to dabble in Champagne yeast so as to effect a brut dry finish, such as “Hops on Pointe Champagne Pilsner” brewed by Garage Project for the Royal New Zealand Ballet. This yeast is also handy for drying out stronger styles too as it tops out at 15% ABV.

  • While yeasts are the only substance to create alcohol, it is possible for humans to create alcohol internally. Active yeast in the human gut can produce alcohol. There is a rare syndrome called auto-brewery where sufferers who eat carbohydrates have yeast inside their bodies convert the sugars into alcohol in the upper small bowel and cecum. This results in alcohol entering their blood stream without them having consumed alcohol. Research has suggested prolonged use of antibiotics may be a contributing factor.

Sally Cloake