Stirring in the primary fermenter

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I've read you should stir daily and also read not to stir. Which is it or is it different for different types of wine? TIA James
 
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jgmillr1

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If you are working with fruit must, then it should be punched down 2-3 times per day (I do only twice). If it is just juice you are fermenting, then leave it be and rack once it's done
 

bernardsmith

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I think the answer is (always).. It depends. One reason for stirring is to remove CO2 and the reason for removing CO2 is two-fold: A) the gas itself can build enough in solution to create pressure on the yeast cells and that pressure stresses the yeast and B) the CO2 breaks down and creates carbonic acid and that acid adds to the acidity of the wine/mead. If the must was already at a low pH before pitching the yeast you might find that the pH drops low enough to stall the fermentation. That drop in pH is a typical concern when making mead because honey has no chemical buffers that can mitigate a drop in pH so you can find the pH falling precipitously unless you remove the CO2.
Another reason that some wine makers invoke is that stirring helps ensure the yeast does not flocculate too soon. Stirring keeps the yeast more fully in suspension and depending on the height of your fermenter, that action (apparently) helps inhibit the dead yeast cells from being damaged by the weight of other cells and sediment piling up on them and so releasing all manner of compounds into the primary too early in the fermentation process (autolysis). This last rationale I am simply reporting as I have no knowledge about when the time is right for autolysis.
 

hamiltonkiler

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Even in fruit with the bucket full of fruit and sugar mixed in what water it will hold. Once I pitch the yeast, sprinkle on top I cover it and it doesn’t get stirred or messed with for 7 days. It bubbles and the yeast grows and sinks it self. When I rack it off the fruit and top carboy with water it gets mixed then.
IMO no need to stir into the must.

Here’s my reason. Don’t have to keep a big spoon sterile. Don’t have to mix and maybe contaminate. Keeping it covered makes me feel better.
 

GeneDaniels1963

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I always stir in the primary to oxigenate and to punch down the fruit. But I also stir after I pull the fruit (usually 3 days to avoid bitterness). As for keeping a "sterile" spoon, just rinse with water before and after use is enough. Clean is important, sterile is just that, "devoid of life."
 

bmd2k1

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Curious.....as I'm making my first welch's vino -- how is wine different than cider - which I've Never stirred. Always trying to learn & improve [emoji111]

Cheers!
 

GeneDaniels1963

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I have read that early in fermentation yeast need oxygen, so stirring is for that, even if you don't have any fruit must to keep submerged. The goal is happy yeast, b/c happy ones don't make off flavors due to stress.
 

bmd2k1

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Seems like the concern is a must with excessive pulp that forms a cap & chokes off O2.

https://blog.eckraus.com/stirring-the-wine-must

I'm Not gonna stir my Welch's vino & will report back -- fermentation seems to be chugging away in a very healthy fashion currently. [emoji111]
 
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bernardsmith

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I have read that early in fermentation yeast need oxygen, so stirring is for that, even if you don't have any fruit must to keep submerged. The goal is happy yeast, b/c happy ones don't make off flavors due to stress.
Not sure that you can provide anything like the amount of O2 yeast need simply by stirring. Not a biologist so I may have this very wrong but I think yeast need the O2 when they are budding during the lag stage. When the yeast begin fermenting (producing alcohol) the yeast really need to be anaerobic otherwise they will use up the sugar but not produce ethanol - which is why brewers only oxygenate before pitching the yeast and they don't add O2 during fermentation... or do I have that wrong?
 

GeneDaniels1963

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Not sure that you can provide anything like the amount of O2 yeast need simply by stirring. Not a biologist so I may have this very wrong but I think yeast need the O2 when they are budding during the lag stage. When the yeast begin fermenting (producing alcohol) the yeast really need to be anaerobic otherwise they will use up the sugar but not produce ethanol - which is why brewers only oxygenate before pitching the yeast and they don't add O2 during fermentation... or do I have that wrong?
I am not sure the reasons and the cycles of when yeast need O2. But most of what I have read, esp. work on wild brewing, says to do it. It seem that best practice is to stir vigoriously for 1-2 min each day in the primary, then when the SG has dropped about 3/4 of expected total, put under airlock and leave along. Or at least that has been my practice, except when I do "all juice" batches, those go straight into a jug, thus are not stirred.
 
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