Can anyone suggest a pitching rate for Weiss please?

[jat147]

Howdy friends,
Just got myself an antique microscope and haemocytometer so I can count yeast cells and then stop blaming the yeast for messing up my brews from time to time I've had WLP300 on a stir plate for a while and have counted the cells and reckon on 59M/ml @ 850ml = 50.15 Billion cells - that maths look ok?

Chris White in 'Yeast' says a pitching rate of 0.5 to 0.75 Million cells/ml for Ales or Weiss per degree P is a good rate.
So at the lower end of that scale: 0.5 x 19,000 (19L of wort) x 12 (roughly 1.048)= 114 Billion cells needed.
He then goes on to say that yeast grown from slants with good aeration could use 50% less than the above figure, which was based on repitching anyway?

If so, then the ideal pitching rate could be 114 / 2 = 57 Billion cells, which is a little more than my 50 Billion - but close.

Can anyone please confirm or rubbish my calculations?
Or anyone who has experience of optimum pitching rates for Weiss, as the range of 0.5 to 0.75 leaves an enormous difference in yeast numbers.
Grateful for any knowledge I could acquire.

 

[ReverseApacheMaster]

There's disagreement between very smart people over the right pitching rate for weiss strains. Some believe you need to pitch as normal, some believe you need to underpitch to get more flavor out of it. If you're having problems with your beers it makes more sense to pitch standard numbers until you have a good beer and then you can adjust up or down for your flavor needs on subsequent batches.

Are you growing from a fresh, clean slant? If not, definitely disregard the 50% statement by White. Again I think since you're saying you have problems with the quality of your beer, pitching the optimum amount makes more sense than hoping you have 50% of the needed yeast in very good condition.

 

[LLBeanJ]

For traditional hefeweizens, I subscribe to the camp that says you underpitch for clove and ferment high for banana.

Your final numbers look a little low to me. According to yeastcalc.com, the total cell count should be around 169B. For a hefe, that is probably too much, but your number of ~50B seems to be woefully inadequate. I'd be aiming for a cell count around 100-120B for this style.

On my last hefe batch, I used yeastcalc to get the starting number of cells needed (It was a 4 gallon batch @ 1.049, and yeastcalc said I needed 138B cells total. I used Wyeast 3068). To my understanding, in order to get the signature banana/clove notes of a traditional hefe, the yeast need to be stressed and ferm temp needs to be relatively high. Based on this, I created a starter with a cell count of 70% of the yeastcalc number (~97B cells) and fermented at 68°F ambient. I also oxygenated the wort half as much as I usually do. The fermentation took about 48 hours to get going and produced a lot of sulphur, which dissapated fully after about 2 weeks into a 3 week fermentation. Final product yielded a hint of clove and banana, so I think I was on the right track. Overall, it's a great tasting hefe. However, I would like the clove and banana to be just a little bit more pronounced, so next time I plan to go with 60% of yeastcalc's cell count and ferment at 70°F ambient. I don't think I'd go much lower on the cell count than that, though.

Of course, your mileage may vary. As ReverseApacheMaster said, there's a lot of disagreement on pitch rates for hefe's and I know a lot of homebrewers try and fail to find that somewhat elusive sweet spot for clove/banana. I do feel that my process has gotten me pretty close, though.

 

[jat147]

There's disagreement between very smart people over the right pitching rate for weiss strains. Some believe you need to pitch as normal, some believe you need to underpitch to get more flavor out of it. If you're having problems with your beers it makes more sense to pitch standard numbers until you have a good beer and then you can adjust up or down for your flavor needs on subsequent batches.

Are you growing from a fresh, clean slant? If not, definitely disregard the 50% statement by White. Again I think since you're saying you have problems with the quality of your beer, pitching the optimum amount makes more sense than hoping you have 50% of the needed yeast in very good condition.

Yes it is a clean, fresh slant - but I do think that the 50% rule is best parked at the moment. You're right about pitching the correct amount if faced with problems. The last batch was way too phenolic .... but started nice and fruity for the last 2 weeks. This is when I decided to start counting cells.

Thanks for the tips LLBeanJ, I'm grateful for the percentage numbers and will try to pitch nearer to 100B next time around. The positive that can be gained from counting is that my viabilty was 98%! Really happy with that given the slant has been in the fridge for 4 months, and was my first effort at storing long term cultures.