To give jellies, jams and marmalades their semi-solid consistency, a thickening agent must be added alongside sugar. This calls for pectin.

Pectin can be found in the cell walls of plants, where it makes them firm and regulates the water balance. Pectin levels vary from fruit to fruit. In most cases, there is not enough to provide the desired level of gelling. Therefore, extra pectin is added when reducing the product.
For this, gelling sugar is available in a variety of gelling strengths. The job of the phosphates is to adjust the product to the right level of gelling.