The best fruit for jam-making contains a high level of pectin, a substance under the skin which, when the fruit is cooked with sugar, helps it to set. Apples, apricots, black and red currants, plums and damsons and sharp gooseberries are ideal. Among fruits low in pectin are strawberries, grapes, pears, rhubarb and cherries. To make a successful set with these, add a fruit rich in pectin: blackberry and apple jam, for example, or strawberry with red currants. Alternatively, add lemon juice, apple, red currant or gooseberry juice, or a commercial pectin. Follow your recipe.
There is a test to find out if there is enough pectin: pour a little cooked juice into a glass containing methylated spirits and swill it around to see if a large clot forms from the juice, in which case, there is sufficient pectin for a firm set.
Sugar Use granulated or the more expensive preserving sugar. Warm in a low oven for about 20 minutes before adding to the cooked fruit for a fast set.
While you make the jam, put your storage jars into a very low oven to warm.
Prepare the fruit; cut away any bruised parts, rinse, stone or hull. Measure out an equal quantity of sugar to fruit but, if the fruit is sour, you can increase the amount to taste. For low pectin fruit, use also commercially bottled pectin, following the manufacturer’s instructions for quantities. Simmer the fruit (and pectin) in a pan, stirring, until it becomes soft and pulpy. Stir in the warmed sugar and bring to the boil, stirring all the time, until the sugar dissolves. Keep at a fast boil until the jam sets, after about 15-20 minutes.
Checking the setting point The easiest method is to use a cold saucer test. Put a saucer in the refrigerator. After the jam has been boiling for about 10 minutes, spoon a little on to the saucer. Push it with your finger. If it wrinkles, it is set. Alternatively, spoon out a little of the jam, and allow it to cool for a few seconds. Drop the jam from the edge of the spoon. If the drops form into flakes which break away clearly and sharply, the jam is ready. You can also use a sugar thermometer: it should register 110°C (230°F).
Skimming, potting and covering If there is any scum on the surface of the jam, skim it off with a metal spoon.
Take the warm jars out of the oven, and pour in the jam, using a small jug or a funnel. Cover immediately. Label, including the date the jam was made, and store in a cool, dark, dry place.
Jellies are made from the juice of cooked fruit, strained through a jelly bag, then brought to the boil and cooked with sugar to a set. Because only the juice is used, the yield is much smaller than that of jams. This explains, in part, why wild and damaged fruit is often used. Traditionally, jellies
made from wild fruits complement different meats and game.
MARMALADES Marmalades are made from citrus fruit. Use Seville oranges for a fine, bitter flavour; or use a mix of sweet oranges, grapefruit, lemon or lime.
COMMON FAULTS IN PRESERVE MAKING
Poor set is usually due to insufficient boiling after the sugar has been added; insufficient acid; overripe fruit or excess sugar in relation to pectin and acid.
Poor colour may be caused by over-boiling after adding the sugar, overripe fruit or insufficient acid.
Sugar crystals are usually due to over-boiling but excess acid could also be the cause.
Air bubbles appear if the jam is left to cool for too long before pouring it into the jars.
Mould on the surface is usually because of insufficient sugar or low sugar concentration. The remedy is to remove the mould, reboil and use for cooking.
Fermentation is caused for the same reasons as mould or because of warm storage.
Cloudy jelly appears if the bag has been squeezed when the juice is pressed through.
Layer of syrup is because of too much acid.