Yes. Pectin is a natural starch that forms in the cell walls of fruits and vegetables, giving them structure. When combined with acid and sugar and heated to 220 ° F (104 ° C), it forms a gel that thickens fruit jam, jelly, and preserves. We don't have to add it. In most cases, the amount of pectin naturally present in fruit is sufficient. BUT, it's crucial to understand how to extract all that natural pectin from the fruit you're cooking so that the jam "sets," that is, it thickens into jam. In general, the firmer the fruit, the more pectin it contains. Apples, for example, have a high amount of pectin, unlike strawberries.