pectin

The longer you cook a cranberry sauce, the more pectin is released and liquid is evaporated, and the stiffer the result will be.

As the fruit ripens the pectase acts upon the pectose, which is insoluble in water, converting it into pectin, which is soluble.

If the pectin collects in two or three masses, use 2/3 to ¾ as much sugar as juice.

The pectin may be supplied by the addition of the juice of crab-apples or under-ripe grapes.

To be satisfactory, jelly must be made from fruit juice containing pectin and acid.

If the third extraction shows much pectin a fourth extraction may be made.