A delicious fruity sweet tart jelly one of the best you will ever taste. It's good on toast and in my recipe for duck magret you will find on my blog.
Put crabapples in a large stainless steel casserole and enough cold water to cover them. Bring to boil, reduce heat and cook on medium heat 40 Minutes. Let cool 30 Minutes.
Put crabapples and juice in a jelly bag or a large piece of cotton cloth (I use a clean old pillowcase), tie with a cordon and let drip in a large bowl for 6 to 8 hours. For a clear jelly it is important not to press on the bag to extract juice.
Put jars in a large casserole, cover with water, bring to a boil and boil 10 Minutes. Leave jars in hot water while jelly is cooking. Put lids in hot water.
Put juice in a large deep casserole, bring to a boil, reduce heat and cook on medium-high 10 Minutes. Skim the white foam while jelly is cooking.
Add sugar( - 3 cups -750 ml for 4 cups (1 litre) of juice)) and cook on high heat until a thermometer reaches 220 °F (105 °C) - at 1000 feet altitude 219 °F (104 °C).
Immediately pour jelly into hot jars, leaving 1/2 inch (1 cm) headspace. To remove any residu pour jelly through a sieve placed on the canning funnel. Cap jars.
Place a rack in the large water filled casserole. Lower the filled jars into the casserole leaving allowing space for the boiling water to circulate. As needed, add hot water to cover jars by 1 inch (2 cm ), bring to boil and boil 5 Minutes. remove jars and let cool to room temperature before storing in a cool place.