[ipaguy]

I've got a honey kolsch in primary at 62F right now.  This is my first time w/ 2565, and I was wondering if I need a diacetyl rest with this yeast.  I'm not currently planning on a secondary, just bottling with a little gelatin.

[bluesman]

Taste it...if you suspect diacetyl then warm it up to about 70 degrees for a couple days and try it again.
This yeast stays in suspension for a long time.  It should be fine with a d-rest.

[johnf]

Diacetyl precursor can be high before diacetyl is high so my preference is to warm a sample on the stovetop, which will rapidly convert any diacetyl precursor to diacetyl. If you detect diacetyl in the warmed sample, do a rest.

I increase the temperature of every ferment which has a number of benefits including preventing diacetyl when using strains prone to leaving some.

[ipaguy]

Diacetyl precursor can be high before diacetyl is high so my preference is to warm a sample on the stovetop, which will rapidly convert any diacetyl precursor to diacetyl. If you detect diacetyl in the warmed sample, do a rest.

I increase the temperature of every ferment which has a number of benefits including preventing diacetyl when using strains prone to leaving some.

Please elaborate on the additional benefits.

[majorvices]

I never heard of warming the beer before to test for diacetyl. IME diacetyl only pops up after a "clean" ferment due to infection or oxidation, which can cause the diacetyl to reform.

OP: Did you pitch enough yeast? You need to approximate closer to a lager pitch to brew a proper kolsch. Also, did you pitch cold or warm? If you underpitched or pitched warm there may be a chance you have diacetyl. but, frankly, I have never had any problems with any kolsch strain throwing diacetyl. YMMV.

[ipaguy]

I never heard of warming the beer before to test for diacetyl. IME diacetyl only pops up after a "clean" ferment due to infection or oxidation, which can cause the diacetyl to reform.

OP: Did you pitch enough yeast? You need to approximate closer to a lager pitch to brew a proper kolsch. Also, did you pitch cold or warm? If you underpitched or pitched warm there may be a chance you have diacetyl. but, frankly, I have never had any problems with any kolsch strain throwing diacetyl. YMMV.

I mostly asked because I haven't used this yeast and didn't known if it's prone to diacetyl.  I really don't anticipate any problems with this batch.  I always pitch pretty cool, I think around 68F this time.  Didn't do a starter, but pitched a fully swollen Activator smack pack, with I figure should do fine with this OG.  Airlock bubbles within a couple hours, with vigorous fermentation after 12 hr.  As far as I can tell, things are right on track.  Think I'll rdwhahb.

[majorvices]

Well ... 68 is a bit too warm to pitch a kolsch. I'd pitch no warmer than 58 and keep fermentation in the high 50s/low 60s. Like I said, you need to approximate closer to a lager pitch for these cool fermenting ales, if you want to brew them right. Also, if you don't pitch enough yeast it won't be quite as clean as it would be had you pitched an appropriate size starter (and a swollen smack pack is an adequate pitch for about a 1.040 ale, assuming the yeast is near 100% viability - which it never is. And underpitching can cause diacetyl.)

And, if you pitched at 68 and then forced the fermentation to cool down to the low 60s that very well could cause the yeast to throw diacetyl, as this is one of the classic causes of diacetyl.

Bottom like is, yeah, you might want to do a d-rest just to be sure. Next time I recommend making the right size starter (check the pitching calc at www.mrmalty.com and use the "hybrid" pull down menu) and pitch much cooler. The idea is to picth the yeast and let their metabolic activity raise the temp to the correct range, so for best bet pitch 4-6 degrees below your targeted fermentation temp. especially for beer like kolsch, which should have no yeasty off flavors.