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Agitating Fermenting Mash - What are the benefits?


RyeWater

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I have been trying to decide if adding agitators to each ferminator is worth the added cost. Most things I read say not to agitate the mash during the fermenting process but I cant help but notice that a lot of people are using fermentation vessels with agitators. Are there any benefits to agitate the mash during the fermenting process like increased ABV, faster ferment, superior product, etc?

Thanks,

Tyler

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Agitating to keep sugars/fermentables suspended is great, but only in primary fermentation. You just don't want to break the surface and introduce oxygen to the mash once active fermentation starts. True beer specialists don't want to introduce oxygen into fresh wort until it cools. Realize if you boil water you are removing the oxygen, so introducing it back in when cooled down is do-able, until fermentation starts. Then just stir it up smoothly. Same holds true for wine/brandy makers during primary fermentation.

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Agitating to keep sugars/fermentables suspended is great, but only in primary fermentation. You just don't want to break the surface and introduce oxygen to the mash once active fermentation starts. True beer specialists don't want to introduce oxygen into fresh wort until it cools. Realize if you boil water you are removing the oxygen, so introducing it back in when cooled down is do-able, until fermentation starts. Then just stir it up smoothly. Same holds true for wine/brandy makers during primary fermentation.

Great answer thanks! I am a little confused on a couple things though and want to make sure I understand. So once I cool down the mash in the mashing vessel and pump it over to the fermenter it is beneficial to agitate the mash in the fermenter as long as I do not do it so vigorously that I disturb the surface and drawl O2 into the mash? Or are you saying that once fermentation begins it is best to not agitate it at all anymore for risk of drawling in O2, if so how long after I cool the mash down in the mashing vessel and pump it over to the ferm. does the fermentation process start?

thanks alot.

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"So once I cool down the mash in the mashing vessel and pump it over to the fermenter it is beneficial to agitate the mash in the fermenter as long as I do not do it so vigorously that I disturb the surface and drawl O2 into the mash?"

Pumping and splashing should inject enough oxygen back in. There's way's to measure O2 but I've never seen anyone bother other than to satisify curiosity. Don't splash while hot though. Get it below 85f to be safe.

"Or are you saying that once fermentation begins it is best to not agitate it at all anymore for risk of drawling in O2,"

Agitate from the bottom all you want, nice and smoothly. If it's a closed vessel it's going to have a Co2 blanket formed on top so don't worry. If it's open, then just don't break the surface or cause it to 'roll' the surface under.Rolling will take surface oxygen down with it.

For time, I've seen yeast start in 2 hours if all things are right.

Do some small 5-10 gallon batches if you're worried. Temp and variety of yeast are the 2 largest variables. Get the specs from the yeast supplier. For common yeasts 68-72 is perfect. Higher will give off flavors, colder just goes dormant or slows way down.

You'll get the best info from a wine/beer supply shop if you have one locally who knows what they are doing. They do the exact same thing, just smaller quantities.

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"So once I cool down the mash in the mashing vessel and pump it over to the fermenter it is beneficial to agitate the mash in the fermenter as long as I do not do it so vigorously that I disturb the surface and drawl O2 into the mash?"

Pumping and splashing should inject enough oxygen back in. There's way's to measure O2 but I've never seen anyone bother other than to satisify curiosity. Don't splash while hot though. Get it below 85f to be safe.

"Or are you saying that once fermentation begins it is best to not agitate it at all anymore for risk of drawling in O2,"

Agitate from the bottom all you want, nice and smoothly. If it's a closed vessel it's going to have a Co2 blanket formed on top so don't worry. If it's open, then just don't break the surface or cause it to 'roll' the surface under.Rolling will take surface oxygen down with it.

For time, I've seen yeast start in 2 hours if all things are right.

Do some small 5-10 gallon batches if you're worried. Temp and variety of yeast are the 2 largest variables. Get the specs from the yeast supplier. For common yeasts 68-72 is perfect. Higher will give off flavors, colder just goes dormant or slows way down.

You'll get the best info from a wine/beer supply shop if you have one locally who knows what they are doing. They do the exact same thing, just smaller quantities.

Thanks alot that clears things up for me. If you were fermenting a mash for like 4.5 days how often would you agitate it? IE like 3x a day for a hour each?

Thanks again everyone

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  • 4 weeks later...

I leave mine on the whole time. It's a closed tank and the fermentation creates a ton of co2, which is heavier than o2, so I don't worry about oxidation. As far as hot side aeration, I also agitate while cooling. My mash tun is my fermenter and stripping still and my mash will take days to cool down to fermentation temps, so I just turn in the agitator. Without a chiller I don't really have any other option

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