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Old 04-20-2010, 04:03 PM   #11
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Originally Posted by pkeeler View Post
Yeast will multiply (i.e. asexual reproduction) when confronted by an abundance of sugar. When they multiply, they emit enzymes and chemicals and what not. If there is a huge amount of sugar and space relative to the amount of yeast, they will go a bit crazy. If temp. is controlled and given time, the yeast will go back and clean up most of these other chemicals they released, but not all. But, just because these chemicals are present doesn't mean you can taste them.

Using a starter is just a way of increasing yeast cells so that the yeast doesn't have to multiply so many times. While going from 100 million cells to even 250 million doesn't seem like a big deal; yeast cells grow geometrically. So, just that bit of a head start might mean the yeast only have to divide twice to ferment out the wort instead of three or four times.

On the flip side, it seems some growth is beneficial, which is why many experts advise not to pitch onto the entire dregs from a previous batch.

I think you can pitch a smack pack into 5 gal. of wort and get very good beer. However, at $7/pack, you should learn how to reuse the yeast using starters just to save some money.

Aren't they still multiplying the same number of times? That's what I dont get. I get how it can speed up fermentation, and how that could potentially affect flavors, I suppose. But I dont see how the yeast multiply less by having a starter, since your starter was made by multiplying te yeast.
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Old 04-20-2010, 04:35 PM   #12
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So would the outcome of the beer be better (in theory) if I pitch 2 packs of dry yeast (US-05) instead of one per 5 gallons of wort?
This depends on the gravity of the wort, but overpitching (using too much yeast) can be just as bad as underpitching.

Note that dry yeast has a lot more viable cells than liquid.

A typical 11.5g packet of dry yeast is optimal for an OG of 1.062; 2 packs is optimal at 1.124. So the underpitch/overpitch sweet spot is around 1.090; less than that, using 1 pack is closer to right. More than that, using 2 is closer.

Just go here:
http://www.mrmalty.com/calc/calc.html

Click the "liquid" tab or the "dry" tab. Enter your OG and the volume of your batch. Read the answer for how much yeast/how big a starter you need to be optimal.
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Old 04-20-2010, 04:40 PM   #13
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So would the outcome of the beer be better (in theory) if I pitch 2 packs of dry yeast (US-05) instead of one per 5 gallons of wort.
You don't need to make a starter with dry yeast, but you should rehydrate them prior to pitching. Edit: Correction - see SumnerH above... unless you're making really big beers, 1 packet of dry should suffice.

There's another viable alternate to making a starter - pitching more yeast. I'll admit to often being lazy and double pitching vials of White Labs as opposed to making a starter. Yes, it ads $7 to my material costs, but I've decided the hour of my life that I'd spend messing with the starter is worth more than $7 to me.
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Old 04-20-2010, 05:11 PM   #14
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Aren't they still multiplying the same number of times? That's what I dont get. I get how it can speed up fermentation, and how that could potentially affect flavors, I suppose. But I dont see how the yeast multiply less by having a starter, since your starter was made by multiplying te yeast.
For the yeast to multiply, they need to take in oxygen to make new cell walls. When making a starter, you shake/stir to help oxygenate a small amount of liquid boosting cell count. Then you pitch that into your full batch and oxygenate again. The yeast will multiply less if you pitch the vial into 5 gallons because oxygen is a limiting factor. If you put a ton of oxygen into your full batch you will end up with a hot alcohol off flavor.

Starters get you to a point where the yeast grows a little, then ferments a lot. They will also be healthy enough at the end of fermentation to clean up the fusel alcohols and other off flavors.

At least that is my understanding of the aerobic/anaerobic workings of the yeast.
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Old 04-20-2010, 10:32 PM   #15
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This depends on the gravity of the wort, but overpitching (using too much yeast) can be just as bad as underpitching.

Note that dry yeast has a lot more viable cells than liquid.

A typical 11.5g packet of dry yeast is optimal for an OG of 1.062; 2 packs is optimal at 1.124. So the underpitch/overpitch sweet spot is around 1.090; less than that, using 1 pack is closer to right. More than that, using 2 is closer.

Just go here:
http://www.mrmalty.com/calc/calc.html

Click the "liquid" tab or the "dry" tab. Enter your OG and the volume of your batch. Read the answer for how much yeast/how big a starter you need to be optimal.
Wow! According to that site I need to start adding more than one packet at about 1.045 OG.
http://www.mrmalty.com/calc/calc.html
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Old 04-20-2010, 11:48 PM   #16
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From what I understand, it's purely a subjective thing.

Some people always make starters, some people never make starters; both groups of people report that they have stellar results. Obviously, up to this point not making it hasn't been a problem for you. If it hasn't, then I see no reason to change up your technique.

Even though some people dont make starters and some do, the evidence that some people post about making starters influenced me to do them myself. Basically, a smack pack contains somewhere from 25-100 billion cells depending on if you got the propagator or the activator pack. Wort needs about 200 billion for a standard gravity beer (correct me if I'm wrong). Obviously, there's about half as much in one of those packs. Making a starter just allows you to make some (presumably) foul tasting beer that your yeast can grow in number in initially, so you can pitch the enlarged amount of yeast into your wort and they can get going making that delicious, delicious ethanol.

Apparently, when you allow your yeast to grow separately (and if you decant the starter liquid) then you can avoid having some of the off flavors in your beer that they may produce while propagating.

Again, not everyone makes starters and if this works for you, I would suggest continuing to do it.
I happen to have one of each. Can you tell me what the difference is?
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Old 04-21-2010, 12:23 AM   #17
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http://www.homebrewtalk.com/f163/propagator-vs-activator-question-144499/

propagator to grow more yeast. activator is pitchable as is.

propagator pack will be your first "starter" growing the culture up to a pitchable amount.

hope this helps.
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Old 04-21-2010, 12:52 AM   #18
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Very much, thanks. So to clarify, my activator (Pacman) I can just smack, wait on it to swell, then pitch and the propagator needs a standard 2l starter. Correct?

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Old 04-21-2010, 01:04 AM   #19
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that's the idea!

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Old 04-21-2010, 01:06 AM   #20
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Very much, thanks. So to clarify, my activator (Pacman) I can just smack, wait on it to swell, then pitch and the propagator needs a standard 2l starter. Correct?
Er, no. Again, it depends on several factors. Look at mrmalty.com's yeast pitching calculator. Put in the age of the yeast, the OG of the batch, and if it's an ale or lager. It should tell you how many yeast cells are optimal. For some batches 100 billion is barely adequate (one smackpack (activator) pack).

A propagator is NEVER adequate, but sometimes an activator is. But not usually.
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