underpitching for esters

I'm going to be brewing a Best Bitter (1.040) this weekend and want to slightly under pitch my London ESB yeast for a good amount of ester production. The last time I brewed an English Bitter I made a good starter, and as a result, the esters just weren't there. Mr Malty says to add 1.8 smack packs or 1 smack pack per liter starter for this gravity. If I pitch just one smack pack to the wort without starter is that sufficient for under pitching or would that not be enough? I don't want to cause any off flavors or under attenuation from under pitching. My other idea was to do one smack pack in 1/2 liter starter. Figured that would be under pitching as well, just not as extreme. Thoughts?

 

I like underpitching to bring out esters too, but you have to be careful about it. If your fermentation temp control isn't good, you can easily overdo it.

How fresh is your yeast? If it's less than a month old, for that gravity and 5 gallons, I'd say you should be fine. It'll be a little lower than I'd ideally want (I usually pitch my English beers around 0.5-0.6 million cells per ml per °P, and this will probably be closer to 0.4 mil cells/ml/°P). I often prefer to use YeastCalc instead of Mr. Malty for starters since you can sort of ballpark a custom pitching rate. If your yeast is super fresh (90%+ viability), that's right about where I would want to be without the starter and I'd say a starter will hurt more than help in this case. Assuming again your yeast is about a month old (just because that's what I usually get), I'd go about a 0.5-0.75 liter starter, no starter aeration (and aerate the main batch properly), and pitch it at high krausen, which would put you at about the 100 billion viable cells that I would target. But personally, I'd rather just aerate a little bit more and pitch without the starter in this case.

Of course, others will disagree with me, and again if you don't have spot on temp control and a good aeration practice, you may be better suited but pitching at the suggested Mr. Malty rate, and just raising the fermentation temperature instead.

 

I've done it with burton ale, and boy did I get esters!. Way too estery for me. I'd like to do some more experiments though. I do like subtle esters in my uk ales.

 

I just legged a bitter I did with White Labs Irish Ale yeast. Didn't under pitch but still very fruity. My wife and I agree it taste like figs. Is that a a common ester flavor?

 

You can get the dark fruits from the yeast, or from the malt. In your case given the style and the yeast I'd say it's a combo of both, but probably more from the malt.

 

How do you oxygenate your wort?
Reducing the amount of oxygen available to your yeast can produce esters as well. I haven't done any experiments with this but it might be worth a try.
Maybe split a batch?

 

You're using 1968 London ESB yeast, right? I'd strongly recommend against underpitching that strain. I really like 1968, but it is notorious for dropping out of suspension fast, resulting in incomplete fermentation unless it's handled properly with proper temperature control, etc. If you underpitch, you're asking for an underattenuated beer.

If you want it estery, ferment it warm, like above 66. To avoid underattenuation, warm it up as fermentation slows (which can be as little as 12-18 hours - seriously, this yeast works FAST.)

 

+1

I'm not familiar with this strain, but if I were looking to increase esters, fermenting on the warm side would be how I would go about it.

 

Resurrecting an old thread here... but I would agree to not underpitch a high flocculator such as 1968.

I had a recent 1st experience with 1968 on a 1.081 OG imperial stout and it did not attenuate well, only 50%. I believe I under pitched @ 2 packs in a 3L starter, but this is what BeerSmith calculated for me. Admittedly was heavy on caramel malts ~14%, 9% dark malts, and 7% lactose, so I was expecting FG to be in the 20's. Fermentation was started low, around 62F and SG dropped to 1.041 in 3 days where it stopped. Once the yeast flocculates it is done. I've managed to revive fermentation by aerating again and pitching with 1 pack of 1056 in 2.5L dropped in at high krausen. As of this morning things have started and gravity is beginning to drop.