Roughly dice the apples, place in a large saucepan and mash with a pounder, add 1 liter of water, bring to the boil and simmer over a medium heat for 10 minutes. Pour through a large, fine hair sieve and collect the juice in a saucepan. Mix the juice and sugar, bring to the boil and skim. Mix with the preserving aid and pour into boiled bottles while hot. Close well.