Simmer your fruit, stalks and all, with a little water. Make sure it's well and truly cooked down. It just needs to simmer gently for around an hour. Get some muslin from the hardware or fabric shop and pour the fruit into 2 layers of it. Do have a bowl underneath or it all goes down the plughole.... Tie the muslin up, not squeezing the fruit but you need to contain it. Then find a way to suspend the bag over the bowl so it can hang there for several hours or overnight.
In the morning throw away the fruit (don't squeeze it first) and measure the juice into a pot. For every 600ml add something like 1- 1 1/2 cups sugar (slightly less for tart apples). Add the sugar before you heat the juice for better results. Bring to the boil while stirring to dissolve the sugar then boil it rapidly for about 10-15 minutes.
Do you know how to test for setting? Drop a small amount onto a cold saucer and push it with your finger - if it's ready little wrinkles will form. (On the jelly not your finger dummy..)
Now bottle it in sterilised jars. I usually have mine heating in the oven while I'm making the jelly.
(See sugar amounts and setting guides below)
Fruits with enough pectin to jell easily when cooked are blackberry, plum, gooseberry, apple, raspberry and grape. (Wild grapes jell better than tame ones). Pectin levels drop as fruit ripens so try to gather mid-ripe fruit. But don't let it stop you!
To achieve proper proportions of pectin and acidity and to add flavour to the jelly, different fruits can be mixed. Some good combinations are crab apple with grape, currant with raspberry, gooseberry with raspberry, tart apple with plum and tart apple with quince. You can add 1 tablespoon of orange, lime or lemon juice per cup of juice to make it jell better.
The amount of sugar you add does depend on the pectin level and the way to test is to add 2 tsp methylated spirits to 1 tsp juice. If low in pectin, the mixture will clump in little blobs. If medium, 2 or 3 blobs, and if high then you'll have one big jelly blob. The higher the pectin content, the more sugar you need.
