Further to the query you already have about damson jam, I made a big batch of it last night and it has not set. Could it be that I spent too long sifting out the stones while it was bubbling away and it has gone past the setting point? Is there anything I can do now please??
There are a few reasons why a jam may not have set. Quite frequently it is due to the low levels of pectin in certain fruits but damsons have a high level of pectin so this is unlikely to be the reason. Unfortunately pectin's setting properties will diminish if the fruit is cooked for too long and this could be a reason. We would suggest simmering the damsons just until they are soft then drawing the pan off the heat and picking out the stones (pits) before adding the sugar.
The other main reason for jam not setting is that it wasn't boiled for long enough once the sugar has dissolved, so did not reach setting point. Setting point is when the boiling mixture reaches 105c/220F and a sugar/jam/candy thermometer is useful as you can put it in the pan of bubbling jam and check the temperature. However we like the "plate test" to see if jam has set, even when using a jam thermometer. When you start cooking the jam you need to put 3 or 4 plates in the freezer (make sure they are suitable for changes in temperature) to chill. Once the jam gets close to setting point take the pan off the heat and put a teaspoonful of the hot liquid on to one of the chilled plates. Let it stand for a minute or two then push the jam blob with your finger. If the jam has a skin on it which wrinkles slightly when you push it then it has reached setting point. If the jam is still quite liquid then put the pan back on the heat, bring it back up to a rolling boil and cook for a couple more minutes before testing again. You may have to repeat this a few times before you find that your jam has set.
You can try to rescue the jam by putting it back into a saucepan with the juice of 1 or 2 lemons then boiling again, and testing for a set as described above. However we would not advise this unless the jam jars were properly sterilized and sealed when you made the jam and we would like to emphasise that the jars need to be washed and re-sterilized before the jam is put back into them.
If this also fails then we would suggest using the jam as a sauce for ice cream and panckaes instead.