Talking with some fellow harvest interns today, a few questions came up and I thought I’d consult the wisdom of the board here.
When doing pumpovers is there a difference in results if you use a rotating head (like a lotus, which we use) vs just “firehosing” the wine back over the cap? The theory posited was the 2nd option would have more direct force and may increase extraction.
In a similar vein, when doing punchdowns is there a significant difference between just breaking up/wetting the cap and punching down all the way to the bottom of the tank and bin?
I’d imagine you’d get more extraction with a forceful firehouse rather than a gentle sprinkler and with an aggressive punch down rather than a gentle cap wetting.
A difference is that when punching down to near the bottom of your bin or tank, you’re introducing more oxygen to all parts of the must than if you just punch through the cap and don’t go much farther down. We generally don’t punch quite all the way to the bottom to avoid breaking up seeds though.
Oxygen is a nutrient the yeast needs. Punching down introduces that in a controlled manner. Without it you might notice some worrying smells.
Depending on the grape variety and your winemaking goals, you might want to be anywhere from extremely gentle to quite brutal in your methodology. A good winemaker might be treating musts from different blocks of the same vineyard differently. Some grapes don’t handle rough treatment well. Also, think of things like skin thickness. A thin skinned grape likely won’t need help with extraction, so roughing things up might be releasing harshness from the seeds out of proportion to everything else in the wine. With very thick skins, they might need help breaking up. That also means there may be a lot of trapped sugary pulp, so your forceful macerating works as a sort of time release of new sugar nutrients.
To go deeper, is anyone aware of any research that shows rates of extraction during pumpovers/punchdowns at varying intensity and/or for different varieties? And what exactly is being extracted?
Firehosing creates enough turbulence to turn over the top layer of the cap a little. I have worked in wineries that just did sprinkler pumpovers day after day, and the same layer of grapes took the impact (big tanks and a long fall) and turned to mush. I do like the aeration of an early pumpover, and it’s easier than punchdowns on whole cluster lots early on, but I don’t like to do more than 1 or 2 without churning the cap more thoroughly by treading or punchdown.