How much does temperature affect fermentation?

[RedneckBrewer]

Does a lower temperature cause a beer to ferment slower? Reason I ask is that I've got a honey wheat in the fermenter, been there for 9 days. Took an SG reading today, and it isn't down to where it needs to be yet (it's at 1.020, needs to be about 1.010) , which isn't unusual, but there seemed to be a stronger alcohol smell to this one than my last 3 batches. It's been sitting right at about 64 for 8 days, but the first night we had a cold snap and it got down to somewhere between 59-60. There's quite a bit of junk floating on top, but it appears that the krausen has fallen so I'm hoping it hasn't contracted some cool new infection. :rockin::cross:

I'm not too concerned about it yet, but I don't want to mess with it if the yeasties are just cold and are taking their sweet time.

Any thoughts?

 

[midfielder5]

what yeast? Each strain has a preferred temp range.
If you brewed extract, your FG might never go below 1.020, although you should also calibrate your hydrometer.
good luck.

 

[RedneckBrewer]

I used Wyeast 3333. It was an extract brew with specialty grains and a pound of honey. I did calibrate my hydrometer when I got it, but it might not hurt to do it again. I did hit the OG on the brew at 1.060 which is what makes me think the cooler temp might be working against me. I may have to find a warmer place to put it.

 

[midfielder5]

WY website says 63-75F is the range. It could be done fermenting, or it could be a little cold- you can add a heating pad to the fermenter and gently rouse the yeast off the bottom.

 

[KevinW]

The temp range for Weast 333 is 63°-75° so you were running a little on the low end and the attenuation rate is 70-76%.

Under optimum conditions you probably would not hit the 1.010 which is about 83% attenuation (1.015 may be realistic) however you are at about 66% right now so warming up to the low 70's may help a bit.

One other issue with fermenting this yeast at the low end of the temp range is you will probably not get some of the esters like banana or clove that you could get by fermenting in the low to mid 70's.

Also, using a yeast starter and aerating/oxygenating the wort before pitching can make a huge difference in attenuation. If you do not make starters or aerate you may want to think about doing this!

My beers have improved dramatically since I started making starters and adding oxygen to my wort! Sometimes I just aerate very well and not use oxygen.

 

[bottlebomber]

You might not drop much lower than the 1.020 if it's extract

 

[RedneckBrewer]

Thanks for the help guys. I'll take another SG tonight and see if it's changed at all. Guess I'll have to move the fermentor during the winter from now on...

 

[Jayhem]

You might not drop much lower than the 1.020 if it's extract

I'm curious as to why using extract matters?

I've brewed an Extract Brown Ale that hit 1.013 FG.

 

[ChickenArise]

One reason is that extract has already been cooked/boiled, so if you are doing a 'normal' brew where you boil your extract, some of the sugars are going to cook into unfermentable sugars. There may be other reasons, too.

I'd say use a starter, late extract addition, and maybe try some other yeasts. For my IPA, I like it dry, and US05 has been a godsend for this.

 

[bottlebomber]

I'm curious as to why using extract matters?

I've brewed an Extract Brown Ale that hit 1.013 FG.

I can't explain the science behind it, but after 3 years of extract brewing and seeing dozens of beers stop there regardless of SG, there is something going on there.