Destemming Whites before Pressing

I’ve only ever pressed whole cluster whites, what are the pros and cons of destemming?

I have destemmed whites that were fermented on the skins but never that went right into press.

Allows for a couple of things. You can wait a bit to get some maceration/breakdown. It also gives you a lot more room in the press. If I recall, Raytek was de-stemming his chard at Punchdown(or maybe it was Liocos). We probably will do it this year. The only issue is that you don’t have the stems to press against so you risk less juice unless you up the bar which can beak seeds, but then again that is why you would let it sit for a bit. I’d consider enzymes or chips to help with the press.

One other reason for destemming, and not crushing, is so that you can do a following berry sort for lots that might have some rot.

Interesting discussion. Ever since my first vintage when I asked the winemaker why we destem reds but not whites and he told me, “We need the stems to act as a press aid, otherwise the yield would be too low,” I took that as the gospel, and never questioned it again. I wonder what the difference in yield, and more importantly, juice quality, would be with destemmed vs. non destemmed whites. Maybe the thing that would worry me most would be an even lower phenolic level with destemmed whites, in the age of pre-mox.

Do you think there would be any pH change with pressed juice if comparing with and without stems?

Not sure about membrane presses as I always used whole cluster with them. In by basket press with Semillon I did not see any significant change in voice yields. I did destem some once to fit it all in the press. I use rice hulls with Semillon anyway as its a slimy varietal.

I was a little concerned about oxidation from destemming and that was the only vintage I have added so2 to the press juice.

I’ve only pressed destemmed whites once in 2011 as we de destemmed for potential rot. Went through a ton of rice hulls that year! I know a few houses in Burgundy destem all their chard.

I didn’t experience anything oxidation wise that made me concerned. You can throw dry ice in the press pan if you do get a little freaked out.

When I was at Charles Krug we destemmed the Sauv blanc, but we used lots of rice hulls and tons of dry ice in the press pan. But it was also a super young bottling, so we never had any oxidation issues.

I was thinking this would go the other way – more liberated juice, more “skin contact” and thus more phenolic extraction with destemmed fruit. No?

I love that, more liberated juice, not constrained by the prison bars of stems that restrict its flow out of the berries and through the press. I never thought of stems that way. I’ve always felt that in the few seconds the juice passes over the stems, it must pick up something in the way of phenolics. Maybe not the right ones though. Also, if you have to press harder to get the juice out of the berries without the help of stems, it’s possible you will pick up more of the favorable phenolics from the skins which could help with aging. You’ll probably also have to break up the press cake more often without stems, leading to more skin contact for the juice.

We find better yields with modest phenolics on destemed as long as we keep the rice hulls up and the bars down. On whole cluster it seems to get VERY low phenolics at low yield like 100 gal per ton. After that, phenolics hockey stick on you at a certain point as yield and bars go up. It takes patience, but destemed seems the way to go if gallons per ton matter. Our stemmed is an old slow soft edged machine. We used a different faster machine once an phenolics went through the roof.

Use rice hulls as a press aid.

pH tends to drift up a bit more through the press cycle with stems than with out. I agree with the phenolic benefits though.

For destemmed whites there are other options as a press aid. As noted rice hulls work well.

If I understand correctly, for aromatic whites, lower phenolics keeps the aromas stable and fresh longer. Something about aging phenols releasing hydrogen peroxide that reacts with aromatics. I real chemist might comment. So, the “benefits” of higher phenolics would depend on what style of wine is being made. We remove stems and add rice hull except for sparkling which is whole clusters and low pressures so VERY low phenolics.