We made our first jam of the year last night from our first redcurrant harvest of the year. Jane had previously juiced the redcurrants and we cooked the extracted juice with sugar (so, technically, a jelly rather than a jam).
Waiting to reach the setting point took a long time. The book I was using suggested that setting would occur at 105°C (and the Internet concurs) but my measurements, alongside using a cool china dish (where a sample will rapidly cool allowing you to see the way it sets) suggested closer to 110°C. I’ve just confirmed that the thermapen is accurate with a pot of boiling water so I wonder if the lower number really means the point at which you need to start conducting tests?
Trying the results this morning, I think I got the balance about right. We are having a good year for fruit in the garden so it looks like I will get some more chances to practise and experiment.