Jams, Jellies, Marmalades and Conserves are made by boiling together fruit and sugar to give a high solids product. The sugar content ranges from 50 % to as high as 65 % and this helps suppresses microbial growth, sweetens the product, helps set the pectin and makes the product glisten.
Some sugar comes from the fruit, most from added sugar (common sugar is sucrose).
The acid ‘cuts’ the sweetness of the sugar and achieves the pH necessary to set the pectin.
Sugar is essential in the gelling process of jams to obtain the desired consistency and firmness. This gel-forming process is called gelation where the fruit juices are enmeshed in a network of fibers.
For some people, cutting down on the sugar in a jam recipe is just asking for failure. The challenge is in obtaining the desired texture and taste. Sugar helps in the development of flavour and texture in jams and it is essential that the right sugar substitute with similar characteristics as sugar is chosen to obtain the best technological properties.