Jeremy, I made some strawberry jam a couple of weeks ago ,replacing the sugar with dextrose. Tastes great but I found that a couple of days after opening the jar , the dextrose started to appear in the jam , almost like a mould(although it's not). I transfered it all to smaller jars as I
thought that it might be caused by air in the jar . The only solution I have found to this problem is to re-heat the remaining jar of jam in the microwave for 40secs to 1 min.to eliminate the white patches each time I notice them occuring. Tasted great and is better than vegemite and peanut butter all the time!
Roz. Young