To Airate The Wort Or Not?

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BEERBOY

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I have been reading a bit about what all u guys have been saying about airating the wort before pitching yeast. Why do we need to do this. I just dump & stir then fill with water from the tub tap.
My last brew was a Morgans Aust Old with 1.5Kg's Black Rock DME + hops and it took 10 days to go from 1042 down to 1015 & some have sugested that i could have speeded up the process by shaking the crap out of the fermenter after 1 or 2 days. Could someone please explain.
 

crackers

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without even knowing your aerating the wort.
splashing from the tap does a similar thing.
the more oxygen in the wort before the yeast is pitched the faster the yeast works.

hope this helps.
cheers
crackers
 
J

Jovial_Monk

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"10 days to go from 1042 down to 1015" and the target is 1010

Splash like the blazes before adding the yeast, aerate again 14-18 hours later.

When you pitch a packet of yeast from under the lid of a kit you are maybe pitching 5g active yeast. Recommended pitching rate for dry beer yeast is 1g/L, i.e. 23g for a 23L batch. However, we can get the yeast to make much more yeast. While there is oxygen in the wort the yeast will not ferment, instead they will spend their time budding off more yeast cells and this is how we can make up the deficit in yeast mass.

Now, all except the very last generation of yeast cells will have crater marks in their cell walls where they have budded off a new cell. The poor yeast cannot control what ions and molecules pass in or out of the cell though these crater marks, not good for the health of the yeast. Re-aerating 14-18 hours after pitching allows the cells to generate sterols and fatty acids and the like and they repair their cell walls with this.

Occasionally, with big beers or inadequate pitching rate etc, I will re-aerate twice a day for three days, and never fail to achieve the target attenuation level (FG) in five days.

If you are after the 3 day mark oxygenating the wort will cause the beer to stale very quickly and can do other harm. All you can do is either pitch a good new yeast (Nottingham Ale or champagne yeast) or stir the yeast from the bottom back up into the beer once or twice a day.

Forgetting about the inadequate packets of yeast stored under the lids of kits and buying some proper dried beer yeast from a HBS that keeps their yeasts under refrigeration 24/7, plus good aeration is the key to good strong complete ferments.

The stronger the ferment, the less chance the inevitable microbes in our worts have achance to multply and ruin our beer. There is also less chance of bottling beer not completely fermented out and so causing glass grenades

Jovial Monk
 

Linz

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Another reason for aeration is when you get around to boiling the wort, be it extract and adding hops or an AG batch, you are driving the oxygen from the wort that is vital to the yeast production; therefore it's necessary to aerate the wort in these conditions.
 

joecast

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JM,
how do you oxygenate after 12 hours or so? ive got plastic fermenters, so would the easiest way just be remove the lid and give it a stir? ok, now that i think about it, it seems a lot easier than reading it.
joe
 
J

Jovial_Monk

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Stirring schmirring

I pour wort from fermenter to cleaned & sanitised 20L food grade plastic bucket and back again, more than once when the beer is well over OG1050. I do not use the tap for this--I only use the tap for the final racking so as not to end up with extract in the tap that bugs have a feast on.

While it is easy to stir up some foam on top of the beer, I doubt significant aeration takes place


Jovial Monk
 

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