I recently tried to make jelly-topped cookies (specific recipe was from home, but here's an example recipe) using an assortment of flavors, including maple syrup, homemade sumac syrup, homemade elderflower syrup, vanilla flavoring, and a pandan flavoring that I bought at my local Asian market. I thought I could just make a dent in the cookies and fill them directly with the flavorings; I was wrong. I sort of expected the liquids to cook off (which happened), but I thought they would at least leave flavor residues behind (that did not happen).
My goal is to be able to make small amounts of a bunch of different flavors and then use them to bake a single batch of cookies with a diversity of different jelly toppings. I already make homemade syrups for pancakes and marinades and the like; I'm not going to go through all the effort of making and storing dozens of different types of jellies too, not for just the occasional baking day.
So what is it about jelly that makes the flavors last better through the baking process? What would I have to do to a liquid flavoring to make it last through the baking process? If I made a paste out of flour and liquid flavoring, would that hold the flavor? Is gelatin important/useful in order to retain moisture? Any and all help appreciated!
Best Answer
Fruit preserves have a lot going on. They have a lot of sugar and pectin and sometimes fiber from the fruit. They have already been boiled for a while and the fruit flavors that are left are there to stay.
Liquid flavorings are mostly alcohol with volatile flavoring compounds. They are added late to a recipe because they boil off easily- at a lower temperature than water boiling.
I don't know of a way to prepare liquid flavoring so that it will be less volatile. I can't think of a time that I've seen that done. Perhaps if you mixed it into another jelly that would buffer the heat during baking. Perhaps an apple jelly with your flavoring mixed in. I suspect most of the flavor would still boil out unless you added the jelly right at the end of baking.
I think you would have more success with making a topping that you can add after the cookies are baked. It would be a different texture without the candied edges but it would still be good. Pectin NH glazes are used commercially for this kind of thing.