Is there something from the feet that helps wine ferment?!
Answers: I always wonder that when I see grape stomping activities.
LOL...no! Grape crushing by foot is a traditional way of pressing the juice out of the fruit from a time before machines were commonplace.
However, there are four points to be made.
1) Firstly, the process is generally customary so traditionally it has only been practiced in certain regions. There are grape crushing competitions these days but I am referring to the practice for wine making.
2) There are other means of pressing grapes and some have been around of for literally thousands of years. These grape presses do the same thing and be quite simple ancient devices or extremely complexed computer controlled machines.
3) Foot crushing has generally been used only for smaller harvests as opposed to at bigger wineries where the process is too inefficient.
4) Bare human feet are quite soft and as a result the seeds and stalks of grapes are not crushed when trodden on. This avoids the tannis in the seeds and stalks from being released into the grape juice (some tannins are required but not excessive amounts).
There is no element of human feet such as skin, sweat, bacteria or fungi that are desired for wine, only the pressure to extract the juice properly.
Much of what "Mustang" says in his answer is pretty accurate.
"Grape Stomping" -- that is, crushing grapes with the feet in order to make wine -- is illegal for any wine that will be sold in the USA, and also in most other countries.
The fermentation process has nothing to do with feet. It's caused by yeast. In most wineries, the winemaker selects a commercially available strain of yeast and innoculates the juice (in white wines) or the must (juice + skins in red wine) in order to begin fermentation.
The winemaker may also elect to use "wild yeast," that is, whatever yeast cells happen to be floating around in the air. Some of these will land in an open-top fermenter and begin the fermentation process.
It has nothing to do with the fermentation. It was originally done to get the juice out of the grapes. As you imagine, they have machines that do a better job today. There is a science on the best way to crush grapes.
I know some places do the foot stomping as a tradition, but not for the whole production.