Yeast Pitching Question

Hey Guys,

So I tried my hand at brewing wine last night. I didn't read up on the techniques involved and only followed the directions in the kit I bought at the LHBS. Anyway it included a packet of dry yeast and the directions said not to stir the wine after pouring the yeast in. Is this correct? Why? I'm used to aerating the wort after pitching yeast to give the yeast oxygen that it requires. Thanks.

wanagohueco said:

Hey Guys,

So I tried my hand at brewing wine last night. I didn't read up on the techniques involved and only followed the directions in the kit I bought at the LHBS. Anyway it included a packet of dry yeast and the directions said not to stir the wine after pouring the yeast in. Is this correct? Why? I'm used to aerating the wort after pitching yeast to give the yeast oxygen that it requires. Thanks.

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I believe it would have to do with oxidization. Basically, you don't want oxygen to be in contact with the wine, as it will make vinegar. The reason it doesn't need to be aerated is because the fermentation takes so long anyways, boosting the yeast won't cut down the time considerably without risking oxidization.

Others will answer to confirm or defer this.

Oxidation isn't an issue with primary fermentation at all- you actually want plenty of o2 in there. If you didn't rehydrate the yeast, and just sprinkled it in, that's fine. I believe the directions for that have something to do with the cells of the yeast. That is, if it's rehydrated, it's ready to start reproducing and fermenting. If it's sprinkled it, it'll rehydrate a bit at a time and then start reproducing and fermenting. Either way is fine. You won't actually hurt it if you stir, but it's best to follow the directions.

Even when you rehydrate yeast, you sprinkle it on the water and wait until its dissolved on its own before you stir it. It allows the yeast to gradually get ready to do its thing.

Oxidation doesn't cause vinegar- acetero bacteri do. If you keep fruit flies and the like away, no worries about vinegar.

So now that the yeast has sat overnight and is dissolved into the wine... should I shake the carboy to oxygenate the juice or no? There's also a large separation between the grape juice on top and ~ 1/4 gallon of water that was mixed with something (can't remember) during the first step. Should all this be homogenous?

If you are doing a kit, it's always best to follow their instructions as each one is a bit different. But if the instructions don't say to mix, there isn't really any need to. My last kit instructions instructed me to stir twice a day for 5 days, or something like that. Don't worry about not looking mixed- the yeast will find the sugars and that'll mix it up.

Awesome... thanks for the info. If only Charlie had written a wine making book I could just "relax and have a homebrew"!

Not a book, but this is my winemaking "Bible": http://winemaking.jackkeller.net/basics.asp