"Natural pectin" refers to a substance found in fruits that helps them thicken or gel when cooked. It is a type of fiber that adds texture and helps preserve the fruit's shape in jams and jellies. Full definition
Also working with fruit that has tons of natural pectin gives you an extra thick jam — blackberry jam could be used to make sculpture! (marksdailyapple.com)
As the cranberries cook, they release natural pectin which thickens the sauce, giving it its characteristic «gel.» (organicauthority.com)
These fruits / veggies contain natural pectin, which helps with binding and also adds moisture, while improving texture. (theheritagecook.com)