The wine label often tells the tale. If the label is "Estate Bottled" all of the grapes and the wine making process must be on the winery's property. If the label names a region, or a county, then the grapes may have come from outside the winery.
Large screw-shaped mechanisms act like a conveyor to move the grapes through different processes.
The first stop (except those grapes designated for Chardonnay at Simi) is the "distemper".
The destemmer has a paddle that mashes the grapes against a screen. This is a distemmer we could see at Deerfield winery.
The hard stems get caught by the screen and the grapes and skin fall through where they are carried into a large vat for initial fermentation. The stems are carried by another conveyor and dumped into a truck. This winery uses the stems to enrich their soil and help break down the clay in the soil.
Another interesting aspect of this process is that this winery uses a gravity feed. The initial crushing and storage is higher up a hill than this area, so once the wine has gone through processes in the larger tanks, it moves without the use of pumps to this area.
I found it interesting to learn that barrels used for white wine could later be used for red, but not the other way around. The winery now uses bar code labels with all of the information about the contents encoded.