I’ve had four fermentations in the last year and a half where the krausen was not frothy white tipped with small brown bits of grains. The krausens would start out white but then turn into what seems to be a thick layer of yeast. This has happened with WY 3711, 3rd generation, and WY 1056, 6th generation.
I have been conservatively estimating 2 billion cells per milliliter for my harvested yeast. Could the cell size of these yeasts be much smaller in comparison to WY 1084 and WY 1332 which I also estimate at 2 billion cells per ml. Beers with WY 1084 and WY 1332 always have had a normal looking krausen.
The harvested WY 1056 has also consistently exhibited increased attenuation. Typical FG for an Amber Ale had been 1.010 to 1.011 three years ago and earlier. FG’s are now 1.006. Flavor of the beer seems to be the same, but mouthfeel is much less with the drier finish in the Amber Ale.
In your opinion should I be estimating up to 4 billion cells per ml? Have the properties of the harvested yeast changed and I should start over with fresh yeast?
Edit: The yeast being used is from fresh over build starters so the generation of use will remain the 3rd and 6th.
@flars I saw in another thread where you referenced an estimate of 2B cells/ml for your harvested yeast.
How do you arrive at this estimate? This is of particular interest to me because I feel like I’m making bigger and bigger starters all the time when maybe it’s not necessary. Any particular reading material you could refer me to?
I’ve harvested and reused 1272 the most and have noticed no increased attenuation but I seldom get past 3-4 generations.
My 2 billion cells per ml was basically taking a chance with an estimate that may be conservative or middle of the road. There is old data on the internet with cell counts, but the data has been criticized because of the testing procedure, but no evidence presented that the results were faulty. Pitch rate calculator sites have information, but also their data is reproduced from other sites. When I read through he post by @WoodlandBrew I thought it was reasonable and adopted the 2 B cells per ml.
I started rethinking this value after beginning to use the Brew United calculator and using the over build option. I would always end up with 25 ml of yeast in the jar with the recommended amount of starter slurry to pitch and the amount to save. If the calculator is accurate the saved starter slurry would have 4 billion cells per milliliter.
I started wondering if I was greatly over pitching by not estimating 4 billion cells per ml with the yeasty krausens I have gotten at times with a couple of yeasts.
Copied from a post in the HBT forum by @WoodlandBrew
Information can be found searching with Google on yeast harvesting. How much yeast is in these jars?
A safe estimate is normally 1.5 billion cells per ml of thick settled slurry. In the hundreds of cell counts I have done I have seen this range from 0.5 billion per ml up to 4 billion per ml.[6] It depends mostly on how the wort is prepared, but is also affected by the yeast strain.
I pump wort through a plate chiller and into the fermenter after whirlpooling for 15-20 minutes, most times, always for IPAs, usually for my lagers but I honestly don’t care if a bit of hot break/cold break, trub whatever gets in the fermenter. I don’t think it’s OK and may help the yeast. I also bag my hops so there’s very little if any hop material in the work.
I wouldn’t estimate for than 2. I’d rather be conservative in that regard and get a good result.
Are the beers too dry?
Maybe your over attenuation is coming from another sourse.
Maybe you’re producing more highly fermentable wort that previous. Are you mashing differently? Lower temp?
Have you changed your grain source?
Then again maybe this is a reason not to go beyond 3rd gen?
I was kind of mulling this over as I made the second stage of a starter. I began with a new smack pack of urquell yeast from wyeast, i think it’s 2001.
I did a 4 L starter with pilsner DME. So should be pretty clean right?
Result was 400ml of slurry which I’ll split in half to make 2 3L starters since a 6L starter really pushes the limits of a 2 gal jug.
Anyway back to the point. If I estimate 4B cells per ml and I have 400 ml of thick pack slurry…the result is 1600 Billion cells? Even if I estimate it at 2B/ml I have 800 Billion which is more than enough. So brewer’s friend calculater is only estimating 1B cells /ml from a starter? That seems harsh.
