HOW TO REHYDRATE DRIED YEAST AND KEEP IT HAPPY?
So, you finished brewing is finished? Now it’s time to inoculate your wort with your yeast to kick-start the fermentation and transform your malt liquor into beer.
What is yeast?
Yeast, our faithful brewing companion, is a single-cell micro-organism that performs a simple, but essential part of the brewing process: fermentation. When yeast divides and multiplies, it produces CO2 and alcohol – the two things that make beer fizzy and, er, alcoholic.
Dry or liquid yeast?
Yeast is sold in freeze-dried or liquid form. They’re both good, but if you’re buying it dried, then you’ll need rehydrate it for optimum results. Sure, you can use sprinkle it straight from the sachet into your fermenter, but it’ll take longer to produce your perfect homebrew beer.
How do I rehydrate beer yeast?
There are two options for rehydrating yeast. The first option is to rehydrate it before pitching the yeast into the fermenter, for a more professional result.
What is a yeast starter?
Yeasts starters are a kind of yeast soup that lets the dried yeast multiply before you add it to the brew. The advantage of easts starters is that the yeast is already active and beginning to multiply, giving your fermentation a head-start.
How do I make a yeast starter?
In a clean, sterile vessel – conical flask, beaker, Erlenmeyer) place the yeast in 10 times its weight of water or wort (1ml of water weighs 1g, so for an 11g yeast sachet, you’ll need 110ml of water) at a temperature of +/-27°C.
Let it rest for 30 minutes then stir gently with a clean spoon. Leave it for another 30 minutes and then pour your special yeasty potion into the wort that’s waiting in your fermenter. Make sure the wort is properly cooled, otherwise you’ll kill the yeast before it can start fermenting. The advantage of this method is it avoids shocking your yeast by getting it used to its new home before you pitch it.
For beers over 9% ABV, rehydrate your yeast in a 2% sugar solution with a rehydration time of up to 90 minutes. Finally, adjust the temperature to that of the beer and inoculate immediately.
What about pitching the yeast directly?
If that all sounds like too much, you can add your yeast directly to the fermentation vessel, making sure beforehand that the temperature of the wort is +/- 20°C. Sprinkle it over the surface of your wort, avoiding the formation of lumps. Let it stand for 30 minutes and then mix and aerate your wort. Your fermentation may take a little longer to get going with this method, and your gravity will decrease more slowly.
Advantages of Yeast starters vs direct pitching
One advantage of pitching the yeast directly into the fermenter is that you avoid the risk of infections associated with yeast starters (first method). Fermentis yeasts are now produced to be sown directly in the must, without the need for rehydration, which makes the process a whole lot easier.
How do I make my yeast happy?
Happy yeast means healthy fermentation. You can make your yeast happy too by paying attention to two things: storage and shelf-life.
Dry or liquid yeast can be kept at room temperature without risk as long as this period does not exceed 3 months. However, yeast is always happiest if you store it in a cool, dry place at less than 10°C, but never below 0°C. Yeast like to play it cool, but snow days are a definite no-no!
Like any dried food (yup, it’s actually classed as a food), yeast has a best-before date. It won’t go bad if you don’t use it before the date marked on the sachet, but it might not be the best it can. The shelf-life of yeast is 2 years from the date of manufacture so check the use-by DLUO date on the pack. An open yeast sachet can be stored closed at 1-4°C in sterile conditions, but needs to be used within 7 days of opening.