5kg (11lb) under-ripe tart apples
- Wash the apples and slice thinly, without peeling or coring. Put them into a large heavy pan and pour in water to cover.
- Cover the pan and bring to a boil, then reduce the heat, and simmer for 20-30 minutes, until softened. Line a large colander with a double thickness of cheesecloth (muslin) and place it in a large bowl.
- Tip the apple mixture into the colander and let drain for 24 hours without stirring or pressing, as this will make the juice cloudy.
- The next day, pour the strained juice into a pan, bring to a boil, and simmer until it has reduced by about half. Line a strainer with a double thickness of cheesecloth and strain the juice into a bowl.
- Let cool, then chill in the refrigerator until thickened. Pour into small, strong plastic bags, seal, and freeze. Alternatively, pour the pectin into sterilized small jars, cover, and heat-process them for 5 minutes.
- Either way, it keeps well up to a year. Add l cup (120 ml/ 4 fl oz) pectin to every 5 cups (1.2 litres/2 pints) low-pectin fruit juice to help it set.
- Pectin can be added to set jams, thus reducing the amount of sugar required. However, these jams must be consumed earlier than conventional jams as they become moldy quite quickly.