Sunday, May 15, 2011

Yeast - Dry or Liquid?

When it comes to making beer, it has been said a million times before, but is worth reiterating; yeast makes beer, not brewers. The importance of this statement is not just to explain the part that yeast plays in turning your sweet wort into alcoholic beer, but rather to emphasize the fact that if you want to make good, or even great beer, then yeast should be one of your focus areas. There are lots of yeast strains to choose from but one of the first decisions to be made is whether to use dry or liquid yeast.

Dry Yeast

Dry yeast is probably where most homebrewers will start. If you begin with kit brewing you would normally get a sachet of dried yeast included with your kit. Once you move onto extract or all-grain brewing you then have the option to continue using dried yeast.

Varieties: There are a limited number of yeast strains available in dry form and that is due to the fact that not all yeast strains can be freeze dried successfully. Popular dry yeasts include US05, US04 and Nottingham.

How to Use it: The optimal way to use dried yeast is to rehydrate it prior to pitching. To do this simply get a plastic bottle and fill with 100ml of boiled water and let it cool to 20-25c. Then pour the sachet of yeast into the bottle, but do not shake. Cover the top with some foil and then let it sit for 10-15 minutes, then you can gently swirl the bottle and allow to sit for another 10-15 minutes. Once you wort has cooled to roughly 20c you can then pour in the contents of the bottle and stir it in.

Pro's: There are a number of advantages of dry yeast. It is relatively cheap compared to other forms of yeast and it is also very easy to use.

Con's: The main downside of dried yeast is the limited variety of yeast strains. Also as with any food stuff that has been dried it certainly loses some of the flavours and freshness that you would get with a liquid yeast.

Summary: An easy to use dependable form of yeast that is particularly good for beginner homebrewers who wants to focus more of their attention on other elements of the brewing process.

Liquid Yeast:

Liquid yeast is the choice for more advanced homebrewers. Due to the wide choice of yeast strains it allows you to brew a beer with the specific strain that is traditionally used.

Varieties: Yeast strains available in liquid form number in the hundreds and style specific strains allow for a much more authentic brew to be made. 

How to Use it: Liquid yeast normally comes in two distinct forms. Either pitchable yeast which can be used straight from the vial or alternatively the yeast may require a starter wort to be made. The simple instructions on creating a starter wort are detailed on the packaging, and although time consuming is very straight forward.

Pro's: The advantages of liquid yeast really lie in two main areas, firstly the variety of strains allows for much greater choice. Secondly, once prepared correctly, it can offer a much healthier yeast as it is much fresher. Another option is to reuse the yeast slurry from a batch of beer and so it can be used through a number of batches.
Pitchable yeast allows you to pitch
directly into a 5 gallon batch.

Con's: The disadvantages of liquid yeast are that it is more expensive that the dried version and also if you use a form that requires a starter wort to be made this can be quite time consuming.

Summary: When choosing which type of yeast to be used I would recommend that beginners use dried yeast. This is due to the fact that when beginning to brew there is quite a lot of processes to get your head around and the added complication of having to prepare a yeast starter is probably something the beginner can do without. For more advanced brewers I would suggest it is a matter of 'horses for courses'. If you are brewing a simple sessionable pale ale you can do no wrong going with the dry yeast strain US05. However if you are brewing a beer that requires more of an input from the yeast to create its flavour and profile I would certainly look at liquid yeast options.

Further Reading: Wiki - Yeast
How to Brew, John Palmer - Chapter 6: Yeast (online edition)

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