Homebrewers Association | AHA Forum

General Category => Yeast and Fermentation => Topic started by: DW on February 06, 2013, 06:28:36 PM

Title: yeast starter temperature and gravity
Post by: DW on February 06, 2013, 06:28:36 PM
In "How to Brew" Palmer states that you should make your starter to match the conditions of your intended batch fermentation (gravity and temperature), but in "Brewing Classic Styles" the authors state that the OG of the starter should be 1.03-1.04, and temperature for lagers should be a little less than 70 degrees.  How to make sense of this?
Title: Re: yeast starter temperature and gravity
Post by: davidgzach on February 06, 2013, 06:37:54 PM
IME, when you make a starter, you are making yeast, not beer.  Room temperature is fine for lager yeast as well.  Most starters are in the 1.035-1.040 range.  What version of HTB do you have?

Dave
Title: Re: yeast starter temperature and gravity
Post by: jackhorzempa on February 06, 2013, 07:06:01 PM
Below is from Jamil Zainasheff’s article Making a Starter (Zymurgy March/April 2007).

Q: IF I’M MAKING A HIGH GRAVITY BEER, SHOULDN’T I MAKE A HIGH GRAVITY STARTER SO THE YEAST BECOME ACCLIMATED?

No. In general, starter wort should be between 1.020 and 1.040 (5–10 °P). Lower gravity starters are easier on the yeast, but result in less growth. High gravity starters result in more growth, but are more stressful for the yeast. Logsdon says, “Generally, you’d use the lower end of that range [1.020 SG, 5 °P] for coming off a plate or slant or very old yeast. Yeast don’t get used to a high gravity environment, and the high osmotic pressure can really stress the yeast.”


I would recommend that you download the article; lots of good information in there.


Cheers!
Title: Re: yeast starter temperature and gravity
Post by: Jimmy K on February 06, 2013, 07:09:50 PM
I'd say the BCS info is the more current method.
Title: Re: yeast starter temperature and gravity
Post by: kylekohlmorgen on February 06, 2013, 10:08:34 PM
I'd say the BCS info is the more current method.

+1

This method is echoed in "Yeast"
Title: Re: yeast starter temperature and gravity
Post by: DW on February 06, 2013, 11:13:58 PM
Below is from Jamil Zainasheff’s article Making a Starter (Zymurgy March/April 2007).

Q: IF I’M MAKING A HIGH GRAVITY BEER, SHOULDN’T I MAKE A HIGH GRAVITY STARTER SO THE YEAST BECOME ACCLIMATED?

No. In general, starter wort should be between 1.020 and 1.040 (5–10 °P). Lower gravity starters are easier on the yeast, but result in less growth. High gravity starters result in more growth, but are more stressful for the yeast. Logsdon says, “Generally, you’d use the lower end of that range [1.020 SG, 5 °P] for coming off a plate or slant or very old yeast. Yeast don’t get used to a high gravity environment, and the high osmotic pressure can really stress the yeast.”


I would recommend that you download the article; lots of good information in there.


Cheers!

Brilliant!  Thanks!
Title: Re: yeast starter temperature and gravity
Post by: DW on February 06, 2013, 11:45:57 PM
I read Jamil's article from 2007 in Zymurgy.  The only thing that I was left a little confused on was the goal temperatures.  He said 65-75 is the ideal range, and 70 is ideal.  Little lower for lagers and a little higher for ales.  But then he says right after that that when you pitch the yeast starter to the main wort that if there is a large temperature shift the yeast can be stunned.  So do I need to cool the starter down before I pitch (particularly for lagers)? 
Title: Re: yeast starter temperature and gravity
Post by: erockrph on February 07, 2013, 12:24:37 AM
I read Jamil's article from 2007 in Zymurgy.  The only thing that I was left a little confused on was the goal temperatures.  He said 65-75 is the ideal range, and 70 is ideal.  Little lower for lagers and a little higher for ales.  But then he says right after that that when you pitch the yeast starter to the main wort that if there is a large temperature shift the yeast can be stunned.  So do I need to cool the starter down before I pitch (particularly for lagers)?

For bigger starters (lagers, for instance), I'm already cold-crashing the starter to decant the spent wort. I generally just pitch it right from the fridge. I really wouldn't want to pitch 3+ liters of oxidized starter beer into my lager.
Title: Re: yeast starter temperature and gravity
Post by: jackhorzempa on February 07, 2013, 01:50:26 AM
I read Jamil's article from 2007 in Zymurgy.  The only thing that I was left a little confused on was the goal temperatures.  He said 65-75 is the ideal range, and 70 is ideal.  Little lower for lagers and a little higher for ales.  But then he says right after that that when you pitch the yeast starter to the main wort that if there is a large temperature shift the yeast can be stunned.  So do I need to cool the starter down before I pitch (particularly for lagers)?
You bring up a good point. You should bring your yeast starter down to a temperature similar to the wort within the primary fermenter. From the online book How to Brew by John Palmer:

“In addition, the pitching temperature should be the same as the fermentation temperature to prevent thermally shocking the yeast. In other words, you will need to chill the wort down to 45 - 55 °F before pitching the yeast. The yeast starter should also have been brought down to this temperature range while it was fermenting.”

So, for example for a lager you could bring your starter down to around 55°F and your wort to that same temperature of 55°F and the pitch the yeast. Or equivalently you could do everything in the previous sentence except replace 55°F with 45°F.

Cheers!
Title: Re: yeast starter temperature and gravity
Post by: davidgzach on February 07, 2013, 12:55:55 PM
It sounds like two processes are being confused. 

For lagers:

If you make a starter at room temperature, you need to crash cool and decant the ester, sulphur and diacetyl laden "wort" before pitching in to your main wort for primary fermentation.  You hopefully made a lot more yeast but you also made some really bad beer.

However, if you make a starter at primary fermentation temperatures, you can pitch the entire starter in to your wort if you desire.  The starter will take much longer to ferment so timing the brew will be harder to determine.

For ales, you have the choice to pitch the starter directly in to your wort if made at room temps.  Just be sure to calculate it in to your recipe.

Dave
Title: Re: yeast starter temperature and gravity
Post by: Jimmy K on February 07, 2013, 01:37:03 PM
I'd say the BCS info is the more current method.

+1

This method is echoed in "Yeast"
In Yeast, they also say that healthy yeast should be the primary goal, then multiplying cells. Lower gravity starters help keep yeast healthy. 
Title: Re: yeast starter temperature and gravity
Post by: a10t2 on February 07, 2013, 04:02:53 PM
For ales, you have the choice to pitch the starter directly in to your wort if made at room temps.

If you're using a stir plate or otherwise aerating, I'd say you should always decant.

Actually, I'd say you should always decant, period.
Title: Re: yeast starter temperature and gravity
Post by: davidgzach on February 07, 2013, 05:16:27 PM
For ales, you have the choice to pitch the starter directly in to your wort if made at room temps.

If you're using a stir plate or otherwise aerating, I'd say you should always decant.

Actually, I'd say you should always decant, period.

I actually had that there and took it out as I know it's done by some.  I agree with you 100%....