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Using Stir Plate

dknutsen

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Do You use the Stir Plate continuously to maximize the yeast growth for the Starter? I am concerned about running the Stir Plate non-stop for the yeast growth period.
 
Well, My stir plate is under "construction" right now so i haven't used one myself so far. That said, for what I know, I don't think there is a problem if you let the stir plate open for a while, maybe just set a slower speed.
Beer geek nation have a good video of it on youtube. Might be clearer
 
Yes, or at least that is how I use my stir plate. Keeping the yeast suspended helps drive off CO2, and close to doubles the yield over not using a stir plate for the same size of starter.

At first I was wondering how to tell if the yeast had done its job, since you really don't see a krausen rise and fall. What you have to look at is for the rotating wort to slow down, and then speed up again.

-Dan
 
I'll let mine run continuously at a speed that creates a small vortex for 36 to 48 hours before crashing. As soon as the growth phase begins, the starter will turn "milky" and will stay that way until it flocculates at which point you should see flakes or chunks depending on the yeast strain.

Also depending on starter size and vessel size, I've had mine go volcanic many times so there is a krausen period with starters.
 
My SOP is to prepare a starter the night before brewing, leave it on the stir plate for up to 24 hours and pitch.  There's no benefit to leaving it on the stir plate after growth has completed. According to Wyeast microbiologist Greg Doss, growth is normally complete in 18-24 hours. 
 
Thank all of you for the information -
very helpful!!
 
I go continuous on the stir plate at whatever fermentation temp you are going to ferment beer at for 18 hours. I pitch vial into starter wort at 70-75 degrees and then drop temp. I am a die hard white labs customer and this is there web directions for starters. Try to stay at 1.030-1.040 on starter wort.
 
Don't think all yeast are the same, some are done at 18 hrs while others take 30 hrs, especially any of the English varieties. Yes, stir continuously on the stir plate. Ambient temperature has a lot to do with times. Some stirrers actually generate heat which is transferred to the flask. Since at higher temps the yeast can produce yukky flavors, that's why we decant the initial starter, and later add cooled pitching temp wort to restart it. If you built a DIY starter plate make sure there are cooling holes somewhere because some motors produce a lot of heat.
 
kcbeersnob said:
My SOP is to prepare a starter the night before brewing, leave it on the stir plate for up to 24 hours and pitch.  There's no benefit to leaving it on the stir plate after growth has completed. According to Wyeast microbiologist Greg Doss, growth is normally complete in 18-24 hours.
I have to agree with this
I have noticed that between 25 and 30 hours and I get a great start, any longer and it does not seem to improve. I do use a pinch of yeast nutrient in the starter
 
The timing of the starter will also depend on whether or not you're pitching the whole enchilada. I sometimes will do this if the starter is small enough or if time is short (I'll explain in a minute...) but lately I've been running the starters to completion and crashing for a day or two, pouring the spent wort off the slurry the morning of brew day, bringing the slurry to pitching temp and tossing it in.

By 36 hours my starters are done but they'll go 48 if my work schedule demands they sit another 12 hours. I've not seen any adverse effect from this extended stir-plate time.

By "short on time" I mean if I decide to brew something up within a few days and I hadn't started the yeast, I'll pitch at high-krausen which also has worked well for me. When I do this, I can pitch in 14-18 hours after making the starter and if I played my cards right, it'll be going volcanic come pitch time.
 
I always increase my batch size by 4 liters.(13 gallon batch size) When my boil hits about 200 F, I draw off 4 liters into 2-2000 ml flasks, cool them to pitching temp to add to my two decanted 3000 ml  flasks. By the time I am done boiling the yeast is ripping, slow stir on the plate or else you will really foam up the yeast. This technique adds time to your brew day, but it has never failed me.
 
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