Stuck Fermentation from Partigyle?

[jamesdawsey]

I've got a question for some of you experienced partigylers out there. I did my first partigyle a month ago. Got 3 fermenters full of 5 gallons of the same beer (a stout) progressively lighter:

1st runnings = 1.090 OG (fermented with Wyeast Irish ale + White labs tennessee whiskey yeast)
2nd runnings = 1.060 OG (Irish ale yeast)
3rd runnings = 1.030 OG (Irish ale yeast)

This past weekend I went ahead and kegged my 3rd runnings, with a FG of 1.018... I'm ok with this because it tastes like an imperial stout, which I love, with the abv of a near beer, which means I can drink more in a go. However, I'm curious. I used a fresh smack pack of Wyeast's Irish ale yeast, which I've used before with great success. My fermentation temps were between 68-73F. And I checked my readings a couple of days in a row to be sure fermentation was actually finished.

This being my 3rd runnings from a pretty large partigyle, I'm wondering if maybe the first 2 batches got all the minerals and nutrients from the barley that the yeast needs and maybe the third batch was starved for those? That's my only guess so far.

Has anybody else experienced this with a partigyle? Any thoughts, stories and suggestions are greatly appreciated. Thanks!

 

[Yooper]

It sounds like you have sufficient yeast (and the nutrients don't go away), so I'm wondering if the reason you stopped at 1.018 was because of a high mash temperature.

 

[jamesdawsey]

That's a fair point. Here's my mash schedule that I used for this partigyle:

1) mashed whole grain bill - 1.25 qts. water/lb. grain at 156F for 1 hour.
2) vorlaugh and drain into first boiling kettle.
3) add 1.25 qts water/lb. grain at 175F; stirred and gave 20 minutes to settle before vorlaughing and draining into second boiling kettle.
4) 3rd boil was a freebie, not part of the plan, so we just rinsed the grain with the same amount of water again at tap temp (~75F), stirred and gave 20 minutes for grain to settle before vorlaughing and draining into third kettle
5) 2nd and 3rd runnings got a 60 minute boil. (the first one got a 90 minute boil.)

Maybe that sparge for the second boil was premature / unnecessary? Would that make a difference after the enzymes do what they do in the mash? Maybe the mash was incomplete? I don't test for starches to check mash completion. I've always just stuck with a full hour mash to great success, but this partigyle thing is new. I'm not really sure when/if to sparge, or if that would make any real difference?

Thanks Yooper!

 

[Yooper]

Mashing at 156 makes a less fermentable wort. By mashing out, the enzymes were denatured so the mash profile was set. Doing another sparge simply rinsed off some sugars, along with the water added.