Background on the use of Concord grapes for wine production

Concord grapes are the most popularly planted native American grapes. Concord grapes are used to make wines, jellies, jams, and tarts. A variety of Vitis Labrusca, the Concord Grape is resistant to many of the diseases which destroy the European grape, Vitis Vinifera; they were the first onto which Vinifera cuttings were grafted to combat insects and disease and the first to be successfully cross-pollenated with European stock to produce hybrids. Most notable of these hybrids are French-American, but crossings were also made with German, Spanish, Portugese, Lowlands, and Baltic grapes. The resulting vines are hardy and produce good yields.

The Concord, however -- even its hybrids -- rarely contain the high amount of natural sugar that pure Vinifera varieties contain. They also contain more pectin and acid, and their wines may exude a musky aroma disagreeable to some. For these reasons their juice is always reinforced with added sugar, almost always diluted with water to balance the acid, treated with pectic enzyme to ensure that it clears, and may be flavored slightly with certain aromatic herbs or spices to counter the natural muskiness.

We have included three recipes below. The first produces a dry wine, so you may want to sweeten it slightly before bottling if you're not partial to dry wine. The second is diluted only slightly and requires a good many more grapes to produce, but results in a full-bodied, sweet dessert wine. Both wines should be stabilized before final sweetening and bottling, either with a commercial stabilizer (such as Sorbitol) or one crushed Campden tablet and 1/2 teaspoon of potassium sorbate per gallon. Final sweetening is always accomplished using two parts sugar dissolved in one part boiling water and allowed to cool. This syrup must be clear, so stir until every granule of sugar has dissolved. The third recipe is a "second wine," made by using the grape pulp from the first batch of wine. Grape concentrate is added to provide body and vinous quality.

If you wish to add an aromatic agent to your wine, any of the following will work: anise, bitter almond, camomile, cardamom, cinnamon, clove, corriander, juniper berries, whole nutmeg, fresh rosemary, saffron, sage, summer savory, thyme, tonka bean, woodruff, or vanilla bean. Do not use ground spices, but rather the leaf, seed, or -- in the case of cinnamon -- bark. Place an amount (one tablespoon per gallon for most, or two nutmegs, tonka beans or vanilla beans) in a finely meshed jelly bag, tied, and place it in the must during the primary fermentation only. Squeeze gently before discarding.

When adding sugar to raise specific gravity a tablespoon less than 8 ounces will raise the specific gravity of one gallon of must 0.010. For grape wines, the beginning specific gravity must always be at least 1.095 to achieve an alcohol content of 12.7%, while 12% is required to preserve the wine. This, however, presumes very little liquid will be lost during racking, which is a bad assumption. It is therefore wiser to begin with a starting specific gravity of 1.105, which under ideal circumstances will produce 14.1% alcohol by volume. Because you will lose liquid during racking, the finished figure will be closer to 12.7%.

Concord Grape wine must age two years in the bottle before being considered ready to drink. It always astounds the novice how greatly wine improves with age. A wine that is terrible after one year will be delightful one year later and wonderful in the third year. Therefore, the best plan for one to follow is to make a set amount (3-5 gallons) every year, set the bottles on their side in a cool, dark closet, and forget about drinking any until you begin the third year's winemaking. Even then, you may want to age them further. Just remember one thing: it takes five 750 ml wine bottles to store one gallon of wine; 25 bottles to store 5 gallons.

from https://www.homebrewit.com/pages/concord-grape-wine-recipes