Jam Sugar (With Added Pectin) for Chilli Jam

Our answer

Pectin is the natural substance, found in some fruits, which will thicken and set when heated with sugar, water and acid. Chillis don't conatain any pectin, so it needs to be added to the chilli jam to help it to set. In the UK sugar with added pectin, also known as jam sugar, is fairly readily available.

Lemons, and other sour citrus fruits, contain fairly high amounts of pectin. However the pectin is found mainly in the skin and membranes of the fruit rather than in the juice. Consequently adding lemon juice to regular sugar for the chilli jam will not help it to set. The acid in lemon juice can help pectin to gel which is why it is often added to lower pectin fruits in jam-making, but it is not a straight replacement for pectin. As the recipe contains (apple) cider vinegar there is already a reasonable amount of acid in the chilli jam and extra lemon juice shoud not be needed.

We would suggest that if you cannot get jam sugar then it would be better to buy a commercially produced pectin, unless you want to go through the fairly time-consuming process of extracting pectin from whole lemons. Pectin is available in some supermarkets and also on-line. Unfortunately each brand of pectin will vary in terms of amount needed and when to add the pectin. The packaging of the pectin should give guidelines as to how much to use, based on the amount of sugar in the recipe. Powdered pectin is usually added at the beginning of the recipe, along with the sugar, but liquid pectin is often added towards the end of the recipe and boiled for just a couple of minutes - again, the instructions on the package should give directions for use.

Please note that the chilli jelly in Nigella's recipe is a fairly soft set version. Also in the UK jam sugar should not be confused with preserving sugar. Preserving sugar is sugar which has larger crystals than regular sugar which dissolve slowly - preserving sugar does not contain added pectin.