- 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.
- 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.
- 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.
- Warm the sugar before adding it to the fruit. Spread it on a baking tray and put in a low-temperature 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.
- Typically, a jam contains as much sugar as it contains fruit, making it a perfect 50/50 split.
Reprinted with permission from The Little Book of Jam Tips (2017), by Andrew Langley and published by Absolute Press.
