Quince jelly without added pectin

1. Presterilize about 4 clean 250 ml canning jars: stand upright on a rack in a deep pot, fill jars and pot with hot water, at least 25 mm above jar rims. Boil vigorously for 10 minutes up to 300 m elevation; above 300 m add 1 minute for each additional 300 m or part thereof. Keep jars in hot water until filling and drain individually immediately beforehand. Prepare new canning lids and screw bands according to the manufacturer.
2. Sort quinces, rub off fuzz, wash thoroughly and remove stems and blossom ends. Do not peel or remove cores. Slice thinly or cut into small pieces, bring to a covered boil with the 1656 ml water and simmer for 25 minutes at reduced heat.
3. Pour everything into a clean damp jelly bag and let drip over a container without pressing or squeezing. Measure exactly 887 ml clear juice for this batch. Use excess juice elsewhere; if short, extract more quinces the same way, never dilute with water.
4. Stir measured juice, the 60 ml lemon juice and 710 ml loosely measured sugar well in a large wide stainless-steel pot. Boil over high heat until the setting temperature is reached: about 4.4 °C above the local boiling point of water, about 104.4 °C at sea level. Alternatively test with a cool metal spoon: drops join and run off its edge as a broad sheet. Remove from heat and skim foam quickly.
5. Immediately pour hot jelly into hot presterilized jars, leaving 6 mm headspace; clean rims and close according to the manufacturer. Place on the rack in the hot water bath, at least 25 mm water above lids. Cover, bring to a vigorous boil and only then time: 5 minutes up to 300 m elevation; 10 minutes above 300 to 1800 m; 15 minutes above 1800 m. Maintain boiling; after any interruption restart the full time once boiling resumes.
6. Turn off heat, remove pot lid and wait 5 minutes. Lift jars upright and cool undisturbed for 12–24 hours; do not retighten or invert. Check seals, remove bands and date. Refrigerate correctly processed, freshly cooled jars that did not seal immediately at no more than 4 °C and use within 48 hours.