Agitation during ferment

[fruitfreak]

As I understand it's good to agitate all the ingredients when you're setting up your mash, but my question is it right agitate the mash after you pitch the yeast?

I've read on several forums (beer topics with grains) where ntroducing oxygen will oxidize the grains and cause off flavors and things like that. I've also read that yeast needs oxygen to reproduce ( I assume that's at the start), I have also read that CO2 can suppress yeast production.

I don't know if it's a good idea to stir the mash, and if so whats the best way is it to agitate your mash. I've read don't break surface tension, so use some sort of motorised wand that passes thru the fermentaion vessel but under the surface?

I've read only stir stalled ferments, and I've read stir every couple of days?

What's to the best practice for ferments? I have to assume that once you pitch the yeast, you want to maintain a consistent temp and let the yeast do it's work. Let the yeast eat and fall to the bottom then rack off the top.

I know it's a newb question, I just wanted to hear from the pros here so I can finally make up my mind on what's the proper thing to do .

[Birrofilo]

The best option to oxygenate your wort is to use an aerator, of the kind that homebrewers use. This is composed by a simple air pump and a "stone", of the kind which is used in fish tanks, better if it is a stainless steel "stone" because they are more durable (just don't touch them with your hands, because the natural grease on the hand will obstruct the micropores). The kit normally includes an air filter which fileters out unwanted bacteria.

You find this thigs in homebrewing shops, they are relatively inexpensive:
https://www.mr-malt.it/ossigenatore-mos ... pleto.html

First you turn the pump on and then you submerge it in the wort. 30 minutes for a typical 23 litres is enough.

Other methods (violent agitation) mix ambient air with the wort, with the result that the wort will enrich in oxygen AND in unwanted bacteria or molds or yeasts.

If you make a whisky wort (a "beer") from dried malt extract you don't need oxygenation because you don't boil the wort, and therefore you don't lower the amount of oxygen which is dissolved in the water which you used in making wort (unless for some reason you used boiled water: in that case, you should oxygenate).

If instead you do cooking-mashing-gelatinization you warm up the wort and the wort will release the dissolved oxygen. When you pitch the yeast, the wort will be poor in oxygen. That's why you want to increase the dissolved oxygen.

Oxygen is needed by the yeast to multiply itself, which happens in the first one or two days of the fermentation. The normal anaerobic activity (production of alcohol and CO2 from sugars) does not need oxygen.

If the fermentation is stuck, and you oxygenated the wort properly, the reason is probably wrong temperature, pH which went too much down, or too high wort density. You can try to gently stir the yeast so as to put it again "in motion" in the wort, but I wouldn't aereate the wort again by agitation. If you want to aereate again, use the oxygenator.

[Expat]

What's to the best practice for ferments? I have to assume that once you pitch the yeast, you want to maintain a consistent temp and let the yeast do it's work. Let the yeast eat and fall to the bottom then rack off the top.

Yes.

After the mash is set to working, best to leave it alone; Reduces the risk of undesirable infections. If you've done the setup properly there really isn't anything mixing accomplishes.

[fruitfreak]

Thanks for the confirmation fellas. I thought of using an air stone and fish pump, never heard of the stainless steel stones. Take care and again thanks.

[DetroitDIY]

On fruit washes, solid fruit will often rise and produce a cap. This will trap CO2 and raise the temperature of the ferment. For wine makers, that's an issue as people generally like to control the ferment temperature carefully to minimize fermentation byproducts and get repeatable ferments. So, they push down the fruit cap 1-3 times a day for the first few-several days. But it's not exactly meant to be agitation.

I do this when making meads with fruit, not for distillation, just drinking mead. It'a a good thing to do for strictly fermented drinks. I recently did this with watermelon that I planned to run as a brandy, and furthermore agitated briefly with a power mixer (don't know what possessed me). That was a mistake. The agitation, oxygenation, and subsequent gas release seemed to vent out all the good delicate flavors during the fermentation, and my distillate was quite wanting.

[NZChris]

I push the cap down for any ferment that needs it, but not mead. I leave mead closed until bottling day.

[fruitfreak]

Thanks, great information.

[Utes Kid]

I’ve been making wine for a while and on my second run now. I’ve noticed the ferment has taken me longer. Everything takes longer with my mash. To your question though, I always give my mash several stirs, especially with my last two. Even temps into the 70s is key as well. I like to taste my mash as well after I stir. Gives me a wine flat that I love and I’m pretty foot at telling if my alcohol content is getting there.
Good luck.