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Old 08-19-2012, 01:17 PM   #1
jsv1204
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Default Re-Pitching: The Saga Continues

Up to this point, I have pretty much stuck to starter-less pitching of liquid yeast (mostly WL, single vial). I have rarely enjoyed any of those two-day über-active primary ferments. Making a starter has always struck as a bit more work than it is worth, so I hunted around for options (besides buying and pitching more yeast).

After reading an article (BYO, I think) about repitching yeast, I made up a short series of English brews to give it a try. The article suggested brewing a series of beer with increasing alcohol contents. My series is:

1 - Mild Ale (1.040)
2 - Brown Ale (1.050)
3 - Oatmeal Stout (1.065)
4 - Barleywine (1.100)

I will be bottling the Mild this afternoon. I moved the Brown to secondary yesterday and brewed the Stout.

I am happy to report that all seems to be going famously so far.

Week 1: I started with a starter (naturally!) with the Mild. I was a bit disappointed with the fermentation rate - so much so that I gave it an extra week on the yeast bed. Used the "shake-the-crap-out-of-it" method to aerate, btw.

Week 2: Went to the beach...

Week 3: Brewed the Brown. On the same day, transferred the Mild to secondary. I pulled all of the yeast sediment out of the fermenter into a sanitized container and covered. I had about 200 ml of yeast slurry with no observable trub. I pitched all of this into 70 deg wort after aerating with the "stir-the-crap-out-of-it" method. Again, did not see a very aggressive ferment. Ferment hung up at 1.020 and no amount of rousing would budge it. Another two-week primary...

Week 4: golf... And ordered a oxygenation setup from the folks at Midwest.

Week 5 (this week, actually): Brewed the Stout an ended with something more like an Imperial at 1.070. Same process with the Brown - transferred to secondary, pulled 300 ml of yeast slurry and set aside. Pitched all into 75 deg wort that had been given 4 minutes of oxygenation from the new rig... Finally! Crazy fermentation action on this third gen yeast slurry. Without the blow-off tube, I am sure those happy little yeasties would have sent the fermenter lid for a ride.

Looking forward to seeing what kind of attenuation was achieved and pretty confident that the high-grav Barleywine has a happy ferment in its future.

Cheers!



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Old 08-19-2012, 03:48 PM   #2
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Pitching onto a whole yeast cake can lead to lower attenuation. If you use too much yeast it will not reproduce, and the beer will ferment with the old yeast rather than with fresh new yeast.

I generally use about a quarter of the cake to brew a beer of similar strength. Half a cake for a beer that is 2X the starting gravity (going from a 1.050 to 1.100).



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Old 08-19-2012, 04:33 PM   #3
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1/2 cake = what volume? Most "rules" I have seen had something slightly less that 200 ml for something in the 1.050 range. First yeast cake yielded about 200 ml (1 cup-ish), second was about 400 and I harvested 3/4 thinking the 1.070 wort deserved a little extra. I expect to use 400 ml for the barleywine (1.100). Does that line up with what you have found successful?

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Old 08-19-2012, 06:24 PM   #4
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The amount of yeast created during fermentation is roughly 6 times the amount that is recommended for proper pitching. It doesn't matter if you under or over pitch, the resultant yeast at the end of the brew is a similar amount.

This is why if you grossly over-pitch (pitch on a whole cake) you don't get much reproduction; it will only reproduce to replace the dead yeast.

Assuming the yeast in the trub = 6X, I like to take a quarter to account for yeast viability. Under a couple of feet of liquid for a couple of weeks you will loose a lot of yeast to the pressure.

The volume you end up with after racking will vary depending on peoples brewing methods: example, if you don't strain hops, you will get more trub. For a 7 gallon batch I usually end up with about 2 quarts of trub/yeast settled at the bottom of the fermenter. It is pretty consistent for me, so I now just swirl up the trub (with the small amount of liquid left in it), and fill 2 pint mason jars for future use and dump the rest.

I find one of those pint mason jars is good for a standard batch (usually 1.055 - 1.080) if stored in the fridge and used within a month. I usually get fermentation going within 12 hours.

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Old 08-19-2012, 11:19 PM   #5
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Great info. The 300 ml I pitched is about a pint jar. I was certainly not getting anywhere near two pint jars worth pitching one liquid vial, but it sounds like I am on the way. Let's see what I end up with next week!

Appreciate the input.



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