Getting big orange flavor in baking

Turn to the peel, not the juice.

On the left, bright white sugar has orange zest on top. On the right, the sugar is now uniformly yellow and a bit more damp.
Before and after of rubbing orange zest into granulated sugar.

When you want to have orange flavor in your baking, the way to get it is from the peel, not the juice. The peel of an orange holds oil that has a bunch of flavor compounds that give you that bright, distinctive orange flavor. The juice of an orange has a lovely, delicate flavor, but it's not concentrated enough to come through. You would need to add so much liquid, it would throw off your recipe (and still wouldn't be as orangey as the flavor from the peel).

You can also see this principle in action in the cocktail world. Orange juice is seldom used in cocktails, but orange peels show up all the time: the peel gets twisted over the top of the finished drink, to spray those oils into the air and liquid at the top, right where your nose is going to be as you sip.

When I say "peel," I'm actually only talking about the zest: the thin, orange, outermost layer of the peel. Just under that, you have the white pith, which is bitter, you don't want that. A microplane grater is an ideal tool for getting the zest off of an orange, without getting any of the pith.

I like to take it one step further. Instead of adding the orange zest toward the end of mixing a bake, along with other flavoring agents like vanilla, I combine it with the granulated sugar at the very beginning.

Using clean, dry hands, I use my fingers to rub the orange zest into the sugar. Granulated sugar crystals are sharp, like the teeniest little knives. They break up that zest and get the oils out. You can see the effect in my before and after photos at the top of this post; the oils turn the sugar bright yellow, and a little damp. The idea is to get more of the oils out of the zest and put those flavors compounds to work, so they spread throughout what you're baking.

This rubbing-into-sugar step is probably entirely unnecessary, to be honest. I've never done any A/B testing to see if it makes a noticeable difference. After all, if you add the zest the normal way, boom, you've added the oils, they're in there. Those oils probably come out on their own through the rest of mixing and baking. Maybe all I’m really doing is getting orange oil on my fingers instead of it going into the bake. (I have doubt!) So it might be silly.

But I like this little ritual. It's fun, it smells really good, and it definitely gives me, the baker, a more orangey experience.