In my opinion yes, reader Bill. Yes, you can bake doughnut batter up in little savarin molds if you like, you’ll get a ring-shaped cake. It won’t be a doughnut as far as I’m concerned. The result you get from the two devices (fryer and oven) are simply too different. But what exactly causes that difference? Why does 365-degree oil produce such a very different product compared to a 365-degree oven?
A big part of the answer lies in the density of the cooking medium. Air is the cooking medium one finds in an oven, and it’s true you can get it pretty darned hot. Yet air is not especially dense stuff. Nowhere near as dense as say, water, which packs about 1000 times more molecules into the same space (cooking oils are actually a little less dense than water, which is why they float in it). If you heated an oven to 150 degrees and stuck your hand in, provided you didn’t touch any of the oven surfaces, it wouldn’t feel very hot. That has to do with the number of excited molecules that are colliding with your skin. Heat a pan of water to 150 degrees and put your hand in — which I do not recommend — and I guarantee it would feel a whole lot hotter. Oil, being nearly as dense as water, performs the same way, dumping huge amounts of heat energy into any object that’s immersed in it.
So why not just boil the doughnut batter then and avoid all that fat? Because of that delectable crunch, reader Bill. As most of us know, oil and water repel one another. Which means that unlike water, hot oil won’t invade the food to any great degree as it cooks. Which on the one hand means the food doesn’t get soggy, and on the other means the surface of the food gets nice and dried out. That dried surface — combined with the residual oil that gets left behind once the food is removed from the oil — is what gives fried food that one-of-a-kind rich and crunchy mouthfeel. A doughnut isn’t a doughnut without it.