The Little Book of Jam Tips (Absolute Press, 2017) by Andrew Langley covers every aspect of making jams at home, with short snippets of wisdom to guide you through the process. The following excerpt is a list of his top tips for making jams.
1. It is vital to wash and sterilize all jars and bottles before filling them. This wipes out harmful microbes inside. The simplest method is to put them (with their lids off) on a baking tray, put the tray in a cold oven and heat to about 110 degrees Celsius for 20 minutes. More wastefully, you can put them in a dishwasher on its hottest setting.
2. How do you ensure there’s enough pectin in your jam mixture? One way, of course, is to mix high- and low-pectin fruits together. Another is to add citric acid (try lemon juice or lemon slices). The acid helps to release the pectin from the fruit during cooking.
3. What kind of sugar should you use? Ordinary granulated is fine, though you may prefer what is classified as ‘preserving sugar’, which has bigger granules and gives a clearer color to the jam. Steer clear of ‘jam sugar’, which has artificial pectin incorporated. The fewer factory chemicals the better.
4. Warm the sugar before adding it to the fruit. Spread it on a baking tray and put in a low oven for 10 minutes or so. Warm sugar will dissolve more quickly in the fruit mush and help it get back to the boil more quickly. This gives a fresher tasting jam.
5. If your jam won’t set, take affirmative action. Refrain from simply boiling it to death – the sugar will darken and the jam will end up dull in both looks and flavor. Instead, add the juice of a small lemon and stir this in to perk up the pectin levels.
6. Jam with sugar crystals at the top is usually the result of not stirring enough to dissolve it all before the mixture starts boiling. To get rid of sugar crystals, stand the jar in a saucepan of cold water and very slowly heat (without boiling). This should get rid of the offending crystals.
7. Find a cool, dry and dark place to store your jars of jam and jelly. Constant warmth is not good for preserves. Coupled with damp, it can encourage molds and worse. Frequent sunlight is almost as bad as it oxidizes the contents of the clear jars, spoiling both the flavor and color.
8. Always clearly label your jars of jams and preserves. Fruits can look indistinguishable after a while and it’s nice to know what you’re eating. So write the main ingredients on the label, plus the date you potted it. That way you will know how long a jar has been on the shelf.
Reprinted with permission from The Little Book of Jam Tips (2017), by Andrew Langley and published by Absolute Press.