Hi from South Africa! The Chilli Jam is so delicious, have had some set problems but think it is because we struggle to get liquid pectin here so use powder. My question is, if I want to make 20 jars to give away for Fathers' Day gifts, do I double or treble the recipe?
Jars of Nigella's Chilli Jam (from NIGELLA CHRISTMAS) is a popular gift item. We have made the jam ourselves with powdered pectin and the jam should be fairly soft set, though not liquid. As there is no pectin at all present in the chillies you may like to try using a little extra powdered pectin to improve the set.
If you are making larger quantities we would suggest actually making 3 separate batches of the Chilli Jam. You could use slightly smaller jars (approx 200ml each) to get a total of 20 jars. The main problem with making large quantities of preserves in a domestic environment is that it can be difficult to get the mixture to the correct temperature without affecting the pectin. To activate the pectin's gelling qualities it needs to cook at above 105°C (220°F) for about 1 minute and this can be difficult to do on a domestic hob with large volumes without parts of the mixture burning. Also with very large quantities you can get uneven heating and this can cause the pectin to break down without gelling.