It's just something I have wondered since the first time I saw red juice buckets for sale.
How do the get the color in to juice buckets, and kits? Do they do some kind of cold soak with enzymes and then press?
Dont know about kits or juice buckets but with fresh red grapes after you crush and destem the grapes put the must into your fermentation bucket, I add yeast nutrient and pectic enzyme and of course yeast. Then nature does its thing as it is fermenting. Every day when you punch down the cap you can see the color changing. Hope this helps some.
At my local, there are those that purchase their grapes and have them crush/destem them. One large machine does both jobs. They dump the grapes into one end, then the compacted skins come out the side and the juice falls into a hopper at the bottom. Pretty cool to watch!
The resulting juice does have color (but nothing close to an extended maceration).
There must be enough contact with the skins through the crush/press machine otherwise there would be no color. I am not sure if the equipment they use has design considerations to maximize this. All I know is that the juice does have color.