Make delicious homemade jam, jelly or marmalade every time by following these foolproof tips.
Always use undamaged fruit. Fruit with too much damage will spoil the result, and the jam is likely to deteriorate quickly.
Fruit freshness affects how the finished product sets. Jam, jelly and marmalade set because of pectin. Pectin occurs naturally in fruit and, when cooked with sugar and the naturally occurring acid in the fruit, thickens and sets the preserve. Citrus fruit, blackberries, apples and red currants have high pectin levels. Soft fruits, such as peaches, have lower levels. If fruits are low in pectin, then fruits with a higher level need to be added. Alternatively, a few squeezes of lemon juice will help them to set. When possible, use slightly underripe fruit when pectin levels will be at the highest.
Use granulated or preserving sugar. Granulated is fine for high-pectin fruits. Preserving sugar is more expensive, but will help set low-pectin fruits without the need to add lemon juice. Always make sure the sugar is completely dissolved before bringing to a boil. If not, the result will be grainy.
Ensure all equipment you use is sparkling clean. For jelly making, always boil-wash the jelly bag or tea towel before using.
Don’t make too large a quantity at one time. Large volumes of fruit and sugar will take a long time to reach setting point, causing the fruit to break up and eventually dissolve in the jam.
Place a small plate or saucer into the fridge for 15 minutes to test for setting. Pour a spoonful of the hot jam, jelly or marmalade onto the plate and return to the fridge for 5 minutes. Push the edges of the jam with your index finger–it's set when it's all wrinkly and crinkly. Always test for setting point at the time the recipe suggests. If not set, continue to cook, checking every 5 minutes. Don’t overcook. It is tempting to keep cooking to achieve a firmer set. A slightly looser jam is preferable to one that tastes scorched or where the fruit has dissolved.
Skim any scum that rises to the surface, only when setting point is reached. Skim with a ladle or add a tiny piece of butter and stir. This will dissolve the scum almost instantly.
Always leave the jam to settle off the heat for 15 minutes once setting point is reached to prevent the fruit rising to the surface when poured into the jars.
Always use clean, sterilized jars. To sterilize, wash in hot soapy water, rinse well and place upsidedown in a cool oven for at least half an hour.
Cover the surface of the jam in the jar with a wax disc. This helps prevent mold forming during storage. Seal the jar with a tight-fitting lid or cellophane disc secured with an elastic band. Store in a cool, preferably dark place. Only store in the refrigerator once opened.