Grape Juice

A straightforward hot-extraction juice, sweetened heavily by the standards of the period. Two things decide the result: keeping the extraction below a boil, and sealing into jars that can actually be processed.

• The hinge: never boil the grapes"A slow fire until the juice runs freely" gives no temperature or time; modern practice for hot extraction is to hold the crushed fruit somewhere around 165-185F until the skins collapse and the color bleeds out. Hard boiling with seeds and skins present extracts bitter tannin and dulls the flavor.
• The five-minute boilBoiling the strained juice for five minutes after the sugar dissolves will darken it and cook off the fresh grape aroma. Current practice is to heat sweetened juice to about 190F, hold briefly, and fill hot.
• Sugar quantityA quart is 4 cups, so 1 1/2 cups of sugar per quart gives a distinctly syrupy juice, closer to a cordial to be diluted. Half that, or none at all, suits a juice meant to be drunk straight; Concord and other slip-skin grapes carry plenty of their own sugar.
• Pressing versus dripping"Pressing out all of the juice" forces through pulp and sediment. Letting the bag hang and drip gives a clearer juice; press only if yield matters more than clarity.
• "Bottle and seal"In a book of this period this meant corked or sealed bottles set aside in a cool cellar. Use clean canning jars with new two-piece lids, fill to a quarter inch of the rim, and process in a boiling water bath for 5 minutes for pints and quarts. Anything not processed and sealed should be treated as fresh juice and refrigerated for a few days.
• Tartrate crystalsGrape juice throws gritty crystals of potassium bitartrate as it stands. Letting the strained juice rest a day or two in the refrigerator and decanting off the clear liquid before heating cuts the deposit down, though some may still form later.
• YieldNo quantity of fruit is given. Reckon roughly 3 to 3 1/2 lb of grapes to a quart of juice, so a 20 lb lug produces something in the region of 6 quarts.