Old Yeast, Starters, And Mr Malty's Pitching Calculator

[len]

I was rummaging through the bottom of the vege drawer in my fridge on the weekend, and I found a packet of Wyeast Belgian Wit yeast manufactured on 16/11/06. I was planning on a bohemian pilsner for my next batch, but this yeast needs to be used ASAP, so I warmed it up and smacked it. It's gradually swelling after 40 hours or so, so it seems like the yeast is still alive.

I plugged these details into Mr Malty's pitching calculator and it tells me the yeast is only 10% viable. Fair enough, I think. I'll just need to be more careful with sanitising the bottles used to ferment the starter. BUT - the calculator tells me that I'll need 4 yeast packs and a 3.8L starter, even at the maximum yeast growth factor of six times. I've only got one yeast pack so that's not going to happen.

Would I be right in thinking that the calculator assumes a single-step-up process? Surely if I pitch yeast into a 1L starter I'm going to end up with the same amount of yeast no matter how many cells I pitched to begin with. There's the same amount of nutrient, sugar and oxygen.

I was planning on stepping up the 100mL smack pack to 500mL or so of 1.040 wort, waiting 48 hours, then stepping up to 3L. If I currently have 10^9 viable cells and a growth factor of 6, I'll have 10^9 * 6 * 6 = 360 billion cells which is more than enough to pitch plus put a test tube aside for next time. Does that sound reasonable?

If that all fails, they tell me wheat beers can be underpitched, right?

cheers,
Len

 

[Stuster]

Your plan sounds fine to me. I often start yeasts up from vials in the fridge that have very small amounts of yeast and do the same as you are suggesting. There seems to be no problems with flavour, attenuation or lag time.

 

[JSB]

Len,

I had a 3068 lying around, cranked it up last Thursday nite, pitched Monday morning - climbing out of the fermentor Monday night, stepped it up plenty and o2'd the wort prior to pitching. Smells awesome.!!

Cheers
JSB

 

[blackbock]

Aeration..aeration...aeration! Some nutrient wouldn't hurt either.

 

[Kai]

Bugger the calculator, get stuck in.

 

[len]

Bugger the calculator, get stuck in.

hehe .

Thanks for all the comments. I'll try a couple of step-ups and I'm sure it'll get there eventually.

cheers,
Len

 

[lucas]

looks to be one of those situations where mr malty isnt so much help. I'd just treat it as though you were culturing the dregs from a stubbie; start small, step up ~2x each time, she'll be right

 

[Weizguy]

for my 2c worth, I'd advise you not to underpitch a Belgian beer.

Yes, it's OK to underpitch a wheat beer, but only a German wheat beer, not a Belgian, nor a Yankee wheat for that matter. It's just different...

I recommend pitching the Belgian like a lager, with about 3 litres of yeast starter and pitch coolish, say about 16C.

Try to keep the witbier cool or you'll end up with too much phenolics, and I don't think you'll enjoy that.

Seth out

 

[len]

I recommend pitching the Belgian like a lager, with about 3 litres of yeast starter and pitch coolish, say about 16C.

Try to keep the witbier cool or you'll end up with too much phenolics, and I don't think you'll enjoy that.

That I did not know. I like my hefeweizens fermented cool to keep the banana down so it makes sense that 3944 would be the same. I'm aiming for a Hoegaarden-style as much as possible.

Thanks,
Len