Just started making some "Big Beers"... questions about pitching yeast and o2
So I'm on my 6 batch in i guess just over a month (I went a little crazy I know). The first two have been a real hit (Classic Stout, Coffee Oatmeal Stout)... I started saving the yeast cakes on the bottom in sterilized mason jars, and pitched my next brews with the original yeast cakes (Probably about 24 oz of yeast cake per batch). Anyway my next 2 brews fermented away so not to much to worry about although after 2 weeks my 'lite" beer went from 1060-1020 (and didn't really get down below to 1010 which seems to be what everyone wants to get it down too, but I bottled it anyway. (I haven't actually been able to taste the results of drinking repitched yeast cake beer yet....still conditioning)
Anyway, I just made 2 imperials OG 1080 and 1086 respectively. And rather then repitched old yeast cakes I just pitched a fresh bottle of white labs into each.
Everything went off without a hitch. But I have a few questions after the fact.
1) As i have been reading more it seems that I really need to start making yeast starters...But shouldn't the yeast do its thing in the carboy anyway? And just take say an extra day or two to reach optimal population size? Am I going to get stuck fermentations because I didn't use a yeast started... I don't see why I would I only see that it would take longer.
2) Also what is everyone's take on just saving the yeast cake in sterile mason jars and pitching 24 oz of it in subsequent batches? IT seemed to work ok. Do you think my lite beer stalled at 1020 because it wasn't an adequate technique? Or maybe my hydrometer reading was off or I unsettled trub on the bottom when I moved the carboy to where I was going to siphon it off for bottling?
1) You should make a starter when using liquid yeast for a couple fo reasons. A starter proofs the yeast is alive and viable. There is only so much oxygen in your wort, and it will be used by the yeast during the growth phase. With a starter the yeast will use the o2 and then start fermenting beer. Without a starter the yeast will run out of o2 before the population has grown to size. This can stress the yeast and impact the flavor.
2) Pitching from mason jars is completely fine. Your stuck fermentation possible had other issues that caused the fermentation to stop.
For big beers, Pitch big and use lot's of o2. Making a starter is a very good practice. With the starter, your taking advantage of the lower gravity beer with lots of o2 to grow the yeast.
By pitching to little yeast can stress the yeast and it may caue a stuck fermentation. It can also stress the yeast to the point t simply doesn't clean up the flavors behind itself.
Look up Jamil's Yeast Pitching Calculator... (sorry on work machine no favs here).
The online pitching rate calculator from MrMalty.com says that you should have had a 4.5 liter starter with your 1.080 batches. Far from the amount you pitched from the vials. The fermentation will probably take longer and may putter out before reaching the proposed FG. Also, because the yeast need to replicate quite substancially with that size of a beer, you may also be looking at some subtle off flavors.
It is a good habit to ALWAYS make a starter. Regardless of how strong the beer is, make a starter. Check this site: Mr Malty Pitching Rate Calculator for more information regarding how big of a starter you need for future batches.
+1 for Mr Malty
Also, aeration, aeration, aeration. Big beers need larger amounts of yeast to reach terminal gravity. The more oxygen they have available the more time they will spend in the aerobic state and reproduce resulting in the larger yeast population to finish the fermentation. With the increased amount of oxygen you may see a longer lag time, as the yeast take more time to finish reproducing before fermentation begins.
As the consensus shows here, proper pitch rates from the use of a starter, and adequate aeration are going to be the 2 greatest determining factors (other than temp control) in reaching your FG when it comes to "big" beers.:mug:
How to approach yeast starters thoughtfully
This is a really common question and it's an important issue. I am going to spell this out one last time. I am going link this post in my sig, and I am not going to bang my head on this wall anymore.
Starters do three things.
1. They prove your yeast is alive. This is important.
2. They increase the number of yeast cells you can pitch. This is problematic.
One of the beautiful things about the Wyeast smack pack is you know your yeast is living. With the White Labs vials, a small starter, even a quart of water with some DME is adequate to prove you have viable yeast. OTOH with the White labs you get a reusable vial, not the point of this post.
So we are in the beginner's forum here. What do you really want? I think you want to make the best beer you can.
My thesis: To end up with the best possible final product, controlling fermentation temperature is more important than pitching rate.
I just hate it when I see folks tell beginners to pitch 5 liters of active yeast without asking about ferment temp control.
We got plenty of folks out there pitching on 1.080 without a starter and bringing home good beer a few months later, with no chiller other than the central A/C in the house.
Let's look at the other extreme. Imagine you got a sanitized 55 gallon drum with 50 gallons of active #56 American (Chico) Ale yeast in it. You pour in five gallons of 1.080 wort. Active ferment is going to take about three minutes.
I'll make two wagers.
1. You can't tell me how high the ferment temperature got, and
2. The beers sucks because it fermented above 70°F.
Not only do I collect two dead presidents on folding money, but the brewer is going to have to wait at least a week to siphon the beer off the yeast cake anyway.
If you can get a permit you could put a tank of liquid nitrogen in your driveway and run some two inch pipe, but the pump is gonna be serious coin.
Following logically on my thesis, my conclusion is the brewer's max pitching rate (to end up with the best possible beer) has to trail a little behind the cooling capacity of the fermentation cooler.
Higher heat capacity fermentation temp controller = higher max pitch rate.
With a water bath that reaches 3/4 up my wort and room for three quarts of ice in the water bath I am struggling to keep my ales under 65°F in 95°F ambients, but I am doing it. All I am using for a starter is a well swollen smack pack. If I pitch anymore than that my ferment temps are going to exceed 70°F, I am going to end up with off flavors and that will piss me off.
If I get a 1.080 stalled from too small a pitch I can always re pitch and wait some more. If I got a 1.080 running at 82°F I got five gallons of crap I will never serve to a friend.
OPn00b, get your ale ferment temperatures under 65°F, and then see how much yeast you can pitch while keeping your max ale ferment temp under 70°F.
As soon as I remember what that third thing was I'll edit it in.
Mr.Malty also has a pitching from slurry tab that will tell you exactly how many ml of yeast to repitch. 24 ounces is probably way more than you need (I’d rather over pitch than under pitch though). I just repitched to a 1.080 OG and after I converted ml to ounces it only called for about 14 ounces and I assumed the worst case scenarios regarding slurry thickness and non yeast material.
Poindexter does use a bit of logic.
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