Thank you Blake Leja and Aaron Fry for your responses last week on Barrel Toasting!
This week: Gravity Flow
What is gravity flow in reference to winemaking? Why is it used and how might it impact overall wine quality?
Gravity flow or Gravity Fed wine making is a process that has been around for years. It involves the use of gravity through hoses to move the juice/wine from one vessel during the wine making process to another without the use of mechanical pumps. There are generally four levels to gravity flow wine making: Crush pad level, fermentation level, aging level, bottling level. The use of gravity glow is supposed to eliminate the "harshness" of using pumps. This process is also a way of gently extracting flavor, color and tannin. I cannot give an honest answer as to how it truly effects the overall quality of the wine. I think it would be interesting to do a side by side tasting on wines using 100% gravity flow, and wines using other methods. Anyone else care to weigh in with more experience that I in this matter?
To jump in on this one too, I agree with Blake Leja on that I would like to taste side by side. Like a lot of things throughout the process of making wine, it is generally believed that the less impact the winemaker can have on the wine the better. And if that means not using pumps to perform simple tasks such as relocating juice from one vessel to another and allowing gravity to do it naturally that is better for the wine as it is more "natural" (oh sh*t) I think that it might have made a bigger difference in the wine 20, 30 or 40 years ago when technology was less sophisticated than it is now. Keep in mind that this is way it was done before there were pumps available as an option.
As far as tasting, I have no clue as to what would be an indicator that a wine was gravity fed or pumped. What elements of the wine do people think are lost when a wine is pumped? Or what elements does the wine take on? I get the reasons for not wanting to do this, but I'm curious if there are other reasons beyond the "Hands off" approach?
Gravity flow involves harnessing gravity anytime the winemaker needs to move grapes/must/wine from one place to another. Most people associate this term with ultra high-end wineries that are built with multiple levels -- grape receiving on the top level, press and/or fermenters on the next level down, barrel room on the next level down, and finally bottling line on the very bottom level -- in reality, gravity can be harnessed in other ways too... I worked at one small winery where the winemaker was eager to show me his version of gravity flow: using the forklift for pretty much everything. Forking up the fruit to tip into the fermenter. Forking up the 1-ton fermenters to drain the free run juice. Forking up the press pan (admittedly a small press pan) to drain the juice into the barrels. As he put it, gravity is the only free thing in the winery!
The idea, which is vey much up for debate, is that the must and/or wine is handled more gently, thus resulting in a more delicate, nuanced final product. Some winemakers feel strongly about avoiding pumps beginning right at the juice stage (in the case of white wine), whereas others feel it's only important once the juice becomes wine. Avoiding pumps also minimizes the juice or wine's exposure to oxygen, which can, of course, influence flavor. Oxidation can also be avoided, though, by using nitrogen or argon to push finished wine for racking and/or bottling, which is what many wineries use in the absence of, or in combination with, gravity flow. I can't really see, howvever, Blake Leja, how gravity flow has any way of affecting color or tannin. If anything, gravity flow would mean no pumpovers, which is inherently a more gentle way to handle a red fermentation, as opposed to punchdown. Hmmm, still thinking about that one.
My feeling is that the impact of gravity flow alone upon the final wine is probably very small. But really, what separates a great wine from a very good wine is the accumulation of nuance resulting from the tiniest details and decisions, so I understand why winemakers choose to avoid pumps if they can.
Best guess here is that using pumps may introduce more oxygen to the wine vs a gentler gravity flow. Best comparison I could think of was a gentle decant versus a splash decant. Or, there could be a degree of philosophy here outweighing actual impact. Wineries built for gravity flow certainly are pretty, though. :-)