Red vs White Fermentation

justinb · Aug 22, 2019

I have made a few batches of Cab from frozen grape must through Brehm. I want to try their frozen Chard juice. My question relates to primary fermentation. With the Cab, I fermented in a Brute garbage can and did not worry about oxygen since Co2 was being released. I thought I could do the same thing for the Chard, but according to Brehm's instructions I need to conduct primary fermentation in a carboy with airlock. I don't have a problem doing this. I just can't figure out why it's necessary. Won't there still be Co2 given off enough to keep it from oxidizing?

Johnd · Aug 22, 2019

justinb said:
I have made a few batches of Cab from frozen grape must through Brehm. I want to try their frozen Chard juice. My question relates to primary fermentation. With the Cab, I fermented in a Brute garbage can and did not worry about oxygen since Co2 was being released. I thought I could do the same thing for the Chard, but according to Brehm's instructions I need to conduct primary fermentation in a carboy with airlock. I don't have a problem doing this. I just can't figure out why it's necessary. Won't there still be Co2 given off enough to keep it from oxidizing?

Technically, yes, but juice can oxidize as well before fermentation starts, they're probably just trying to help you limit it. I ferment all of my whites from grapes in this manner, and do them in the wine room at 55F to prevent blowing off delicate aromas and flavors with warm, vigorous fermentations. You can certainly do it in a pail as well, but it's just as easy in a carboy, and a little more fun to watch..........

Ct Winemaker · Aug 23, 2019

Some other thoughts. Reds need to be punched down so you need access in order to do this (large opening on top of fermenter). Whites are not fermented on skins, so no punch down access required. The cap formed on the reds also helps to protect the wine somewhat from oxygen during ferment, again whites don’t have this. Whites are generally fermented in a “closed” fermentation, as Johnd stated to attempt to retain as much of the fine aroma as possible. Closed meaning under air lock or similar air access restriction.

I have fermented small batches of white in a 7 gallon glass wide mouth fermenter (with screw top and air lock). It’s a nice way to do small batches because you can see all of the activity. A carboy should work for this as well.

mainshipfred · Aug 23, 2019

Not sure what Brehm recommends if anything about the fermentation temperature of white wines. From what I gather and do myself is ferment them for a longer time period at lower temperatures. By doing this the amount of CO2 given off to protect the wine is in far less concentrations. I have always fermented in buckets but I can see the advantage of using a carboy. In the commercial world I believe whites are fermented in stainless steel tanks so O2 exposure would be limited.