Strawberry jelly made with pectin results in a jelly that is more firm and thicker than one without it. However, it is important to note that strawberries have natural pectin in them, so just like raspberry and blueberry jam, if using fresh berries, you don't have to use pectin. Plus when you combine the strawberries with the jello, it firms up nicely as well. No pectin needed for this jam recipe!