krausen

[Morganrich2]

I just put a cream ale in the fermenter and just bottled a belgian white. The belgian formed krausen for about 12 hours and the cream ale has formed none at all, though both bubbled away nicely for about 24 hours at about 75 degrees.

Is this cause for alarm, is krausen always so short lived? Does this indicate any issues I should be aware of?

 

[devilishprune]

All fermentations are different. I made a beer the other day and the krausen lasted for 3 days. I made a beer a few months ago and the krausen was thick and full for about 3 full weeks.

Krausen or lack thereof doesn't indicate anything strange about fermentation. It's usually beer/strain specific. The temperature is a little high, so they probably both finished pretty quickly. Just let it ride.

 

[Morganrich2]

Great, thanks a lot for your help.

On another note since you mentioned fermentation temp, the packet indicated temps between 65 and 75 as ideal. Does fermenting on the lower side, 65 – 70, produce a longer, slower fermentation? If so, what effects might this have? Conversely, what effects does a warmer, faster fermentation have? Thanks in advance!!

 

[devilishprune]

Yeah, you're right. Lower temperature=less active yeast=longer fermentation times, and vice versa.

As a general rule of thumb, lower fermentation temperatures with a given strain of yeast will produce less esters and less fusel alcohols. These are the two things that most people are concerned with, and raising the temperature will increase the concentration of these compounds in your beer.

Esters usually have a fruity flavor, like isoamyl acetate (banana) or isbutyl acetate (berries). Fusel alcohols are higher alcohols, meaning that they have more carbon molecules than Ethanol (the alcohol we want) which has 2. These higher alcohols contribute to a hot alcohol taste/smell and can also be associated with hangovers.

 

[Morganrich2]

Thank you very much for that explanation. As a rule of thumb, should I be shooting for the lower side of recommended temperature ranges to avoid esters and fusel alcohols? Is there any potential downside to lower fermentation temps?

 

[devilishprune]

This is really style and yeast strain dependent. Some styles you want more esters, some you don't. The tradeoff comes from fusels, which I would say are universally unwanted.

Generally if you're fermenting with an american ale yeast like 1056, you want to ferment lower to keep the clean profile. However, if you're using a Belgian strain, then most people like to start those low, and then ramp up to increase ester production while minimizing fusels.

Generally, I like to use the lower side of fermentation temps because I make a lot of american ales which don't usually have a lot of yeast character.

The potential downside to lower temperatures is that the yeast may stall out on you a bit early, which is why some people choose to raise the temperature a bit towards the tail end of fermentation.

 

[Morganrich2]

This has been really helpful, thanks a lot.

-Morgan