A lot has been bandied about over the years regarding Concord for winemaking. There are a few things to keep in mind -- to reduce the "foxy" nature of Concords, limit contact time on the skins. gregbathurst mentions treating like a white wine, i.e., press the grapes immediately and ferment without the skins, and that is certainly one way to do it better. My experience is to put all the crushed grapes into a poly or nylon mesh bag (check out Williams Brewing, ECKraus, all the other supply houses and especially your local suppliers), and begin fermentation, but taking the pulp/bag out after only about 18-24 hours max. There's a LOT of good flavor, fair to excellent tannins, and amazing color in those skins and I like to treat it like paint on a canvas, except that the canvas is the wine. It can be useful, but too much and it's not good. Anyways, use pectic enzyme (follow Yooper's recipe schedule for this type wine for campden, pectic, etc, and yeast additions). I don't always add sugar, but I do always have to adjust for acids. If you're going to add water to dilute the acid content, you'll have to add sugar afterward to get to the desired sugar level. What I'm doing more and more (and based on the results, I think I'll do from now on) is this: Take out a portion of the juice/must, once I know what the titratable acid level is, and use calcium carbonate to reduce that portion to well below what I'm looking for and then add it back to the whole. For example, if I'm shooting for 6-8 or even as much as 10 or so g/l, and the must/juice is over 20g/l (some years, even more - a LOT more!), I'll bring the portion to be adjusted down to almost nothing and then add it back, wait awhile for it to stabilize, take another reading, keep this up until it's right. So far, to me, it's trial and error. Eventually it gets right. I hope that I learn along the way just what works and that I can make it repeatable and predictable. I don't adjust the whole batch at once for the reason that it seems harder to manage getting to and keeping the right acid level with a larger amount all at once. Also, it's important to keep an eye on pH; you don't want it going too high or too low. And, adjusting it this way, at the beginning before ferment, seems to give better long-term results than trying to adjust the finished wine's acid levels with potassium bicarb - although there's nothing wrong with doing it at the end, it just seems to suit Concords better this way.
Doing it this way, FOR ME, seems to give a better finished wine. Sometimes the sugar is low, and sometimes I'll add sugar to bring it up, sometimes I don't and I just let it finish to dry and have a lower ABV. It won't keep as long, but having a lower ABV makes it drinkable sooner anyhow. Other than adjusting the acids, the fewer things done to it, the more of its better features come through and the fewer of its not so desirable features ever make it into the wine.
Here are a couple of links that I've posted before, they're not "the answer" but they are helpful in understanding better what Concords can and do offer --
http://www.winemakermag.com/stories...rietalswine-styles/218-concord-varietal-focus
http://fastgrowtheweeds.com/2008/02/05/a-drinkable-concord-grape-wine/
Best wishes to you, you've got a lot of grapes and hopefully a lot of years ahead to make a lot of wine. Experiment, have fun, and enjoy! Along the way you'll likely branch (pun intended) out into wine grapes, but Concord is something that'll always stick with you, especially when you find the best way for YOUR vines to be made into pretty darn good wines.
- Tim
I'd like to keep it "easy" and get the right stuff so we can do this year after year and get better. There are a lot of grapes and next year there will be more.
