differing tempretures

[brydo]

hi guys, i have lager kit in my fv although the yeast said to ferment between 18oc and 24oc. during the day when im working the tempreture is lower, between 13oc to 16oc, but in the evening when im home and have the heating on the tempreture is up to 21oc. was gonna leane this one for 4 weeks before bottling, but now im worried what effect the fluctuating tempretures might have on the brew. the krausen has formed and fell away and so fermentation definately happened. am i worried about nothing ?

 

[stesmi]

I'm guessing you mean the room temp fluctuates? If this is the case then the beer temp won't fluctuate anything like that. The reality is, you are talking about a decent size thermal mass. If the temp of your room fluctuates a bit throughout the day, it will be difficult to move the temp of your fermenter (more so, the liquid inside it) with a small degree of ambient temp change. The other side of this argument is that while a 1c difference doesn't feel different to us (billions of cells), it can feel a hell of a lot different for a little yeastie boy (1 cell).

A temp change can cause yeast to drop out prematurely and leave a partially fermented beer, or stress the yeast and cause off flavors (acetaldehyde (green apple) and diacetyl (butter)) are the most common). But saying all that, it won't go 'bad' and probably just means it won't ferment to its max - hopefully be drinkable though :-)

Next time use a 'swamp cooler' to add to the thermal mass. They're great at maintaining temps. Google it