Jams and jellies are basically the same type of preserve, as both are made from cooked fruit to which sugar is added. It is the high concentration of sugar, combined with a high temperature, that enables the fruit to be preserved. The sugar also affects the fruits’ setting quality, and the exact amount that is needed depends on the pectin strength of the fruit. These preserves will only set if there are sufficient quantities of sugar, acid and pectin present.
Fruits high in pectin include cooking apples, crab apples, red and blackcurrants, gooseberries, quinces and Seville oranges. Fruits containing a moderate amount of pectin include cranberries, eating apples, loganberries, apricots and raspberries. Fruits low in pectin include bananas, cherries, elderberries, figs, japonica, melons, nectarines, peaches, pineapple, rhubarb, medlars and straw berries. For low-pectin fruits a mixture of half pectin sugar and half granulated sugar gives good results. Soft fruits such as raspberries have a wonderfully fresh flavour if only boiled for a few minutes — using pectin sugar it is now possible to make successful jams this way which actually set.
The best type of sugar to use is granulated sugar. Although it is not necessary to use the more expensive preserving sugar, it does produce less scum. Caster and brown sugar produce a lot of scum.
© 1991 All rights reserved. Published by Websters International.