yeast loss from blow-off affecting attenuation

[andrewmaixner]

A few searches didn't really shed much light on this (answers ranged from "I heard.." to "won't matter", so:

I split a ~1.055 blonde batch between a 6.5gal and a 3gal fermenter, using WPL530(westmall)
The 6.5gal fermenter had 5.25 gal in it, and the 3gal was half empty.
Temperature was controlled (sensor taped and insulated to large carboy) at 66F.

The large, fuller, fermenter had a lot of blowoff, losing a lot of yeast. I did a cleanup and put everything back in the temperature chamber on day 3. After the first week, I raised temperature by about 1F per day, up to 77F.

At that point, I measured the gravity, and the no-yeast-loss batch was at 1.007, while the large fermenter was at 1.012. I'm continuing to keep it at 77F to see if it continues attenuating.

Anyone else had experience with this?

 

[m00ps]

I dont think it was due to the blowoff, but maybe due to the size difference. The 3 gal one has less thermal mass so it would warm up more. Taping the sensor to the large one also probably allowed the smaller one to get warmer. Also, since the smaller one had like 50% headspace, the yeast had access to more oxygen. Both of these factors could explain why they had better performance despite being int he same wort

 

[andrewmaixner]

I dont think it was due to the blowoff, but maybe due to the size difference. The 3 gal one has less thermal mass so it would warm up more. Taping the sensor to the large one also probably allowed the smaller one to get warmer. Also, since the smaller one had like 50% headspace, the yeast had access to more oxygen. Both of these factors could explain why they had better performance despite being int he same wort

I thought about the temperature issue.
Oxygen should not be a factor, as I oxygenate from a pure O2 bottle. The beginning level of yeast could have been different also, as I didn't measure exactly the ratio of yeast I pitched into each.

I'll see where they are in another week and post again.

 

[andrewmaixner]

I thought about the temperature issue.
Oxygen should not be a factor, as I oxygenate from a pure O2 bottle. The beginning level of yeast could have been different also, as I didn't measure exactly the ratio of yeast I pitched into each.

I'll see where they are in another week and post again.

Well, I need not have have worried. Both finished at about 1.003/4 despite my intentional high mash temp, and yeast losses. One just took longer. The body was supposed to be med-full, guess I have a true light blonde now. Keggeg/primed and bottled yesterday.

So in summary, at least with this yeast, yeast pitch volume may not matter, and it may vastly over-attenuate.

 

[m00ps]

yeah Belgian yeasts can be very finicky. I usually give them an extra week than I would for any American or British ale yeasts. Most of the bottle bombs Ive had have been from Bottling a Belgian before it was entirely finished fermenting