Controlling blow off with rigorous fermentation

[Tinpanharry]

So I brewed an American Brown but the OG came out to 1.065, so a little high. I pitched plenty of yeast (probably a little too much) at about 65 degrees. In about 6 hours I had a rigorous fermentation going and put on a blow off tube.

I then put a wet towel on the carboy to help cool the wort a little bit. All went well but I am wondering... without temperature control, was this a good method of controlling blow off?

Things progressed well after that but the beer is still in primary for about another week so its early to tell if there was any effect.

Thanks!
TPH.

 

[Remmy]

So I brewed an American Brown but the OG came out to 1.065, so a little high. I pitched plenty of yeast (probably a little too much) at about 65 degrees. In about 6 hours I had a rigorous fermentation going and put on a blow off tube.

I then put a wet towel on the carboy to help cool the wort a little bit. All went well but I am wondering... without temperature control, was this a good method of controlling blow off?

Things progressed well after that but the beer is still in primary for about another week so its early to tell if there was any effect.

Thanks!
TPH.

Not sure what the issue is here. Is your problem trying to contain the rigorous fermentation or temperature control?

Keep the carboy/bucket/primary somewhere a few degrees lower than you want for fermentation, hook-up the blow-off tube into some Starsan (or whatever you have) and leave it at that. An OG of 1.065 in a 7.9-gallon primary bucket (assuming that's what you have) shouldn't cause a stuck blow-off tube. So, I wouldn't worry too much about it.

 

[Tinpanharry]

Thanks Remmy,

In hindsight, my question was perhaps not as clear as it could be. I was thinking that perhaps the vigorous fermentation needing a blowoff would be settled by a cooler temperature, resulting in more happy yeast. So this made me think perhaps the right temperature for the wort helps to reduce blow off.

Or is blow off just a product of the amount of yeast and sugars? Perhaps temperature is not a factor at all?

Would the beer turn out the same if I had not placed a wet towel over the carboy?

 

[johngaltsmotor]

If I understand your question correctly yes. If you slow fermentation (by using a swamp cooler or wet towel to reduce the temperature) you will reduce the rate of CO2 production and decrease the need for a blowoff.
You will also keep the yeast closer to their ideal temperature range and reduce any undesirable flavor compounds you may experience from fermenting too warm.
Assuming you pitched too much because it was a re-used yeast cake, it was also likely immediately ready to create CO2 so you simply fast forwarded through the usual lag (so it might not have been too warm to start).

 

[Tinpanharry]

If I understand your question correctly yes. If you slow fermentation (by using a swamp cooler or wet towel to reduce the temperature) you will reduce the rate of CO2 production and decrease the need for a blowoff.
You will also keep the yeast closer to their ideal temperature range and reduce any undesirable flavor compounds you may experience from fermenting too warm.
Assuming you pitched too much because it was a re-used yeast cake, it was also likely immediately ready to create CO2 so you simply fast forwarded through the usual lag (so it might not have been too warm to start).

Perfect. Thanks John! You also read my mind. I did add a pint of yeast cake (London Ale 1028). I do realize that I don't want it so cool that it chills the yeast.

So here is the learning question. What exactly causes blow off? If I understand correctly, it is yeast that are immediately ready to create C02. Such as those who have already been through the lag phase in a previous batch, AND temperature can also have an impact. Is that correct?

Thanks
TPH

 

[Tinpanharry]

Not wanting to be lazy, I also did a search and found multiple factors can play a part.

https://www.homebrewtalk.com/f39/what-causes-blow-off-394860/

 

[johngaltsmotor]

As Tinpanharry's post above indicates there are a lot of factors. In the end it is how fast CO2 is generated and how much gets trapped in the krausen.
More proteins in the wort make it harder for bubbles to pop so you build more krausen height. (This is why Fermcap is effective, it reduces the surface tension and lets the bubbles pop instead of building to the point of blowoff)
More yeast cells means more CO2 generated per minute so more bubbles.
Hotter temperature means yeast are more active and each one is creating more CO2 per minute.

There are a lot of factors, but normally if you control pitch rate and temperature you'll be good. Unless you want to limit yourself to thin bodied beers you can't really avoid the protein content sometimes.