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Unsweetened Grape Juice
To six quarts of grapes add one quart of water. Bring to boiling point and then strain through a jelly bag. Bring the juice again to the boiling point and pour into hot sterilized jars, and seal.
The method here is open-kettle canning: hot juice poured into hot jars and sealed with no further processing. That practice was abandoned by food-safety authorities long ago, and the recipe gives no processing time or temperature at all. The notes below explain the recipe on its own terms rather than repairing it.
- Why the sealing method failsPouring boiling juice into a jar and capping it does not reliably drive out enough air or heat the lid and headspace surfaces, so mould and yeast survive at the rim and the seal is unverified. Grape juice is acidic enough that botulism is not the concern; fermentation and mould spoilage are, and a jar that ferments can build pressure. Any grape juice you intend to store should follow a current tested canning procedure with a stated processing time.
- QuantitiesSix quarts of grapes means six quarts by volume of whole stemmed fruit, roughly 9-10 lb, yielding somewhere near three to four quarts of juice depending on the variety and how hard the bag is pressed.
- The grape assumedThis is probably a Concord-type slip-skin American grape, the usual juice grape in American books of the period, though the recipe does not say so. Its high acid and strong aroma are what make unsweetened juice palatable; seedless supermarket grapes give a thin, flat result.
- Bringing to the boiling pointThe first heating is only meant to break the skins and release juice, not to cook the fruit down, which is why the instruction stops at the boiling point rather than calling for a long simmer.
- The jelly bagA double layer of damp muslin or a fine nylon straining bag over a stand does the same work. Let it drip rather than squeezing if you want a clear juice; pressing forces through fine pulp that later settles as sediment.
- Tartrate sedimentUnsweetened Concord juice can throw crystals of potassium bitartrate as it stands cold. Commercial practice is to hold the juice cold and rack it off the deposit before packing; this recipe skips that step, so a jar may develop a gritty layer at the bottom.
- Unsweetened, deliberatelyNo sugar appears anywhere. The juice is meant to be diluted and sweetened at the table, or served plain in place of wine.
This appears to come from a Prohibition-era American drink book. Unfermented grape juice held a special place in the temperance campaign, since it offered the look and ceremony of wine without the alcohol, and it was promoted for both the table and the communion cup after pasteurized grape juice became commercially available in the later nineteenth century. The technique itself is older and simpler than the cause it served: heat the fruit just enough to loosen the juice, strain it through a jelly bag as one would for jelly, and reheat before packing. Recipes of this kind appeared in American household books through the 1910s as Prohibition approached, often printed alongside grape shrubs, ciders and "unfermented wines" that a hostess could serve without apology.