Effect of fermentation control (vs ambient temps) on fermentation time and intensity

[flyfishorbrew]

Hi all,

Firstly, I've been creeping and soaking up information from this forum for a year now and so I figured in the new year I would actually start posting and contributing. So here's a first post!

I recently acquired a Vissani 50-something wine bottle cooler and set it up with an Inkbird controller using a heating mat as the warming element (eventually I will follow the build instructions around these forums and the internet for bypassing the thermostat but for the time being I don't need to get to lager temps in it). It's been working better than I expected, especially compared to my prior fermentation "control" method which basically involved moving my buckets to different rooms in the house and adjusting proximity to heating vents throughout fermentation. When using yeasts like WLP001 I felt fairly confident I was maintaining decent but not great (+/- 2 degrees) consistency right around 70 degrees and then for a diacetyl rest I could bump it up a few degrees by moving it to a warmer room. Obviously it worked less well for other yeast strains.

For my first temp-controlled batch I did a 1.054 pale ale fermented in a Big Mouth Bubbler, used WLP001, and made a 1L starter as usual. I didn't actually want to ferment with the WLP001 at a much lower temperature than I normally use so I set it at 67 degrees. I was pretty amazed over three days at how much the krausen rose. Normally using 001 and a healthy starter, I see the yeast go to work within 12 hours, reach peak krausen around day 2-3, and generally have slowed quite a bit by day 4. After about 5 days I moved it for the rest (don't know if that's necessary with 001 but I tend to keg my beers fairly quickly so I figure it can't hurt).

I also only ever saw about 2-3 inches of krausen creep up in the Bubbler. With this fermentation, however, the yeast went wild. This is just a 5 gallon batch in the 6.5 gallon bubbler, so there's a ton of headspace, but I was about to pull off the airlock and put on a blowoff tube last night, the krausen was so high. The airlock also remains far more active than I would normally see on day 4-5. So, is this (apparent) increased activity a result of the tighter temperature control, or the slightly lower temperature? Or should I be expecting more or less the same attenuation as before, and the yeast has just done its work over a slightly longer period of time due to the lower temp? I'm not sure what the relationship between the level of krausen and the actual yeast activity is.

I plan to use WLP007 in my next batch and ferment at 64 and I'll probably use a blowoff tube, since at 70 degrees 007 really rips for me. Any thoughts on what to expect? In almost a year of brewing regularly, I've never been close to needing a blowoff tube.

 

[seatazzz]

I will try to answer part of the question; I've never used White Labs yeast and cannot comment knowledgably on it. Your fermentation in your new fermentation chamber finished out faster, because of the CONSISTENT temperature it was kept at; back when you were moving your fermenter room to room to get the "best" ambient temperature, a few factors were probably in play; namely, moving your fermenter, however carefully you do it, will cause whatever krausen you have to fumble around and fall out. Even if that didn't happen, the yeast were bouncing around in up & down temperatures, which can affect how they work. Leaving them alone to work in a stable temperature environment is much better for the finished product.

I will also comment on the "rest"; unless you are making a lager, a diacetyl rest is not really necessary, in my opinion. It's not even purely necessary for lagers, not with modern malts. I've done lagers with and without a diacetyl rest, and haven't noticed a significant difference.

 

[flyfishorbrew]

Thanks! That makes sense about moving the buckets around which I always worried about.

 

[Dland]

Try not to worry, but moving fermentor should be avoided. Anyway, the lower steady temp should translate in to slower, more stable fermentation. Usually for me, 1.054 at 64F w ale yeast, fermentation takes around 6-7 days. Attenuation at the lower temp (64 instead of 70F) should be similar, but flavor most likely better.

 

[flyfishorbrew]

Thanks! And those are all good points about not moving the fermenter - in a future set up, I'll have more dedicated space, hopefully, to reduce the need to always be moving things around.

Sounds like now that I have temperature control set up I should expect somewhat longer fermentation times and also sounds like I probably don't need to be worrying about a diacetyl rest. I often see people discussing fermentation plans and raising their temperatures either shortly after fermentation has begun or after a few days. For the time being I'll play around and see what seems to work best for me.

 

[Dland]

Yeah, as was mentioned before, the D rest is really only applicable to lagers, and only cool/cold fermented lagers at that.

I would not go too much by "what people are discussing" regarding moving their temps around. For the most part, with most yeasts, steady, even temp in mid to lower recommended range (for the yeast one is using) usually results in the best beer.

 

[marc1]

How are you measuring temperature with the probe? Attaching to the outside of the bucket and covering with bubble wrap/cloth works pretty well without getting too complicated.

 

[flyfishorbrew]

That's exactly what I'm doing at the moment. I've got the probe taped to the bucket and some leftover pipe insulation from insulating my mash tun attached around that and all taped down.