Hi Dazzling
The term "secondary fermentation" has evolved somewhat.
The original meaning was meant as a second fermentation period. ie. a second fermentable is introduced after primary fermentation. A good example is when bottling: sugar is added and the bottle is sealed. The suspended yeast then ferments a second time, feeding on the priming solution and because the bottle is sealed the CO2 dissolves into the beer causing carbonation. Another example of secondary fermentation is when brewing some types of beer that are required to be racked on to fresh fruit.
Glad we got that out the way
The more recent meaning and now generally accepted term means to rack the beer from one fermenter to another, either part way through fermentation or after fermentation has completed (more on this later) The beer is then held at the original fermentation temperature for two purposes.
1. To remove the beer from the yeast cake to reduce sediment and lower the (relatively low) risk of autolysis.
2. To rouse the suspended yeast into action to "clean up" any fermentables that may have escaped notice first time around.
The are arguments of whether to bother racking or not have been covered ad nauseam on just about every brewing forum I've seen so I won't go into that.
FWIW I was originally taught to rack part way through but after a nasty experience with a Kolsch yeast and two stuck ferments I changed tack. I now wait for "primary" fermentation to finish.
Cold Conditioning is where you rack either from primary or secondary to a vessel, seal it and store it in the fridge. The low temperature causes the yeast to "fall asleep", cease fermentation and drop to the bottom of the vessel.
So when you rack on to your priming solution you will leave even more yeast behind and end up with a clearer beer.
There is a belief that CCing will also speed up the maturation of beer. Whether or not this is true is another of "those" arguments. I believe that beers with extract in them do improve quicker if they have been CCed than those that haven't but I'm not convinced AG beers do. Mind you, I like my ales fresh :chug:
Again, FWIW my practice now is to ferment completely then rack into a jerry can for CCing. The time for CCing is until I have a vacant keg or for at least 4 days. Once I racked straight from primary into a keg and served. The beer never cleared up - still tasted nice and I don't mind cloudy beer but this was really murky! I've found that 4 days will drop enough yeast out that my kegged beer is clear enough. Not as clear as those cutting dip tubes and using gelatin but we all like to be different
Note: this info is meant as a general guide only. There are exceptions to everything in brewing.
Regards
Steve
