The Basics of Fermentation

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The Basics of Fermentation

Post by BIABrewer » 7 years ago

[Like all, "The Basics," in the General Brewing Skills, Equipment etc, section, the following is not a definitive guide. It is simply a guide that will get a new brewer under way safely and with confidence. Please advise BIABrewer of any errors. Please justify, in full, any contrary topics that you may choose to start in this forum. If well-written and justified, they will be, "promoted," as best as we are able.]
All brewers, new and experienced, are encouraged to start new topics in this section provided they have read the below.
The Basics of Fermentation
Fermentaton begins the moment that we add yeast to a chilled wort. See ???? for a description of how wort is created and here for how it can be chilled????.

This is the first time we see yeast in the beer-making process. Yeast eats the sugar from our sweet tasting wort and turns it into a drier tasting liquid whilst simultaneously increasing it's alcohol content and accentuating desirable flavours. The end result of fermentation could be generally thought of as, "flat beer."

There are many different ways of handling yeasts, many different strains of yeast, there are also dried yeasts and liquid yeasts. There are even ways of fermenting these strains to produce different flavours. It is yet another area of brewing that has a thousand or more answers that the new brewer should not become concerned with. Following the below will give the new brewer a good, often great beer but it is also an area that the new brewer should explore more as soon as they feel comfortable.

Should I use Dried or Liquid Yeast?

Two types of yeast are available to home brewers - dried and liquid. Liquid yeasts are specialist yeasts that for the home brewer to make economic require re-generation techniques. This requires advanced brewing skills and knowledge and should not be considered by the new BIABrewer. Re-generation and management of, "living," liquid yeast may however be an area that provides considerable enjoyment for the advanced brewer. Re-visit the question of liquid yeasts once you have a few brews under your belt. Many styles of beer can be brewed with dried yeasts so it is possible for a new brewer to avoid the use of liquid yeasts for a considerable period of time if desired.

Due to the above, the new brewer is best advised to use dried yeast.

For Kit Brewers, this will be supplied under the lid and is always in dried form. This yeast will often produce a great result over a bewildering range of temperatures but often not. See how you go ;

All other brewers will have to buy their yeast.

Ale, Lager or Hybrid Yeast?

When deciding on what dried yeast to buy, first consider whether you are brewing an ale, lager or hybrid beer such as a kolsch or wheat beer.

BIABrewer recommends the following dried yeasts to the new brewer as they are reliable and non-intrusive. For your first brews, consider using recipes that are suited to the following yeasts.

1.) Ales - Use Safale US-05 and allow to ferment for two weeks at 18 degrees celsius/
2.) Lagers - Use Saflager W34/70 and allow to ferment for 3 weeks at 11 degrees celsius/
3.) Kolschs - Use Safale K97 and allow to ferment for 3 weeks at 16? degrees celsius/
4.) Wheat Beers - Use Safbrew WB-06and allow to ferment for 2 weeks at ? degrees celsius/

The above time recommendations allow for fermentation and settling of the beer if fermented at the correct temperature. There are many ways in which the above can be modified.

How do I Pitch the Yeast and Start Fermentation?

There are many different ways of pitching dried yeast. The following is a very simple, reliable and trouble-free method for the beginner and one that is also used by many experienced brewers...

Step 1: Make sure your wort is within a degree or two of the fermentation temperature using a suitable chilling method. Ensure that your thermometer is accurate at the fermentation temperature. For lagers, pitching at two degrees below fermentation temperature will avoid the necessity of a, "diacetyl rest." The sooner you pitch your yeast the sooner it can outnumber and nullify the effect of other microbes that all worts contain. Pitching the yeast at too high a temperature can create off-flavours, sometimes serious ones. So, if your equipment cannot chill your wort to pitching temperature within say 16 hours, consider using the, "no-chill," method.

Step 2: Use a clean pair of scissors to cut open the yeast packet. Make sure there that both are clean first. Spraying the pack and scissors first with your no-rinse sanitiser prior to cutting the pack is good practice.

Step 3: Remove your fermenter lid and sprinkle the yeast over the top of the wort. Re-seal the fermenter. (The fermenter does not need to be perfectly air-tight and it is, in fact, quite difficult to do so with many fermenters.)

Step 4: Maintain the temperature of your wort as best as you can to within two degrees of the fermentation temperature. The wort tends to get a bit hotter one to three days after pitching so a little more attention may be required during this period.

Do I Have to Rack my Wort?

The practice of transferring the fermenting beer from the first (primary) fermenter to a secondary one is not considered a necessary step for the beginner. There are many good reasons to rack and many not to and they depend on a number of factors. The purpose of racking is to give a clearer beer and/or to reduce the chances of some usually subtle off-flavours. These things can be achieved in other ways. As many outstanding brewers do not rack, BIABrewer recommends that beginners keep things simple and skip this practice. It is also recommended that after a few brews, the new brewer becomes informed about and then experiments with racking as it may become a valuable tool depending on your individual situation.

How Do I Determine When Fermentation is Complete?

A simple way of knowing when your fermentation is complete is by using the yeasts, temperatures and times mentioned above in, "Ale, Lager or Hybrid Yeast?" These times have allowed for fermentation to complete and for the beer to settle. In the unlikeley event that you managed to seal your fermenter well and your airlock was bubbling, after fermentation is complete you will notice little if any activity in the airlock once fermenation is complete. Another method is to use a hydrometer to determine when the yeast has, "eaten," all the sugars. Please read, Hydrometer Calibration and Readings

If, as recommended in that article, you have purchased two hydrometers and accompanying wide, "jars," three days after pitching, you can fill a jar from your fermenter tap and leave it sitting beside your fermenter. This way, on a daily basis, you can watch the gravity drop. It is a worthwhile exercise for new brewers.

With your second hydrometer or, if you only have one, you should take a reading from time to time. (The wide hydrometer jars that are recommended use a lot of wort, about 200mls, so don't overdo this.) After any reading, taste the wort and concentrate on its, "sweetness." You should always take a reading prior to or just after pitching. Consider taking another three readings after that, at most. Take the first, a week prior to when you expect your beer to be ready. The second should be taken two days before you expect your beer to be ready and the last on the day that you expect it to be ready. So for example, with our ales using SO-5 we would take three readings. One at 7 days, one at 12 days and another on the 14th day.

The readings on the last two measurements should be quite close or identical. They will also not have the sweet taste that you would have experienced when tasting your wort at or around pitching.

Once Fermentation and Settling is Completed.

Your wort has now been turned into beer and is ready for packaging. So, now proceed to either, Bottling - The Basics or Kegging - The Basics

Summary

The above is a very simple guide to the very complex subject of fermentation. The above could seem contradictory for brewers who have fermented several beers (kit or AG) and not detailed enough for the virgin brewer. Experienced brewers will understand and have knowledge of the myriad of variations that exist but also realise that the above is a safe and simple method for new brewers to get under way.

Virgin brewers should not feel, "dumb," asking any question on fermentation as long as they have read the above. You'll need to ask questions on your first few brews.

Brewers with more experience should likewise not hesitate to ask questions, discuss and/or educate other brewers about fermentation.
All brewers, new and experienced, are encouraged to start new topics in this section provided they have read the above.
Last edited by BIABrewer on 02 Mar 2010, 21:23, edited 18 times in total.

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