Because of some health problems in my extended family, over the past year I’ve been trying to cut butter and lard out of my baking entirely. I even found a couple of canola oil piecrust recipes that work quite well. Fruitcake was the final frontier. Fruitcake is so important; it’s not just cake, but a weight of tradition and memory. (And as well, a great, expensive weight of nuts and dried and candied fruit and peel!) I couldn’t find much online about this experiment except what seemed to be devolving into practically religious arguments over whether canola oil was evil or not. Righteous oil … Well, use whatever cooking oil you like and can afford, I say. But since I found nothing saying either, “Yes, it works,” or, “Yes, it works but cut back the fat by X percent,” or “No, it all falls apart and is a disaster,” I decided the time had come to make the experiment myself, and to report on it. After all, I’d been using oil in every other cake I made for a year quite successfully.
Yesterday I made Dundee cake, and substituted canola oil for the butter, cup for cup. The cakes (three of them, a middle-sized round, a small round, and a large loaf) turned out very well. They have a bit more crust than a firm cake usually has, but my oven cooks bread in half the time yet adds twenty minutes to most large cakes, so it has — um, superficial, non-penetrating heat? a physicist should look into that — so the crust might be the oven rather than the oil. It’s been so long since I made a cake without oil that I can’t remember if my cakes were like that before the great oil shift or not! Possibly laying a sheet of tinfoil overtop once it is set would could slow the surface browning. The crumb is a bit coarser than than one expects in a Dundee cake, but I’m also an inveterate tinkerer and this particular batch of cakes had 1/5 rye flour, which probably accounts for that change in texture. (More of an inspirational alchemist than a proper experimental chemist, I guess — I know one ought to change only one variable at a time in an experiment.) Although a little coarser, it was neither crumbly nor greasy nor dry. It tastes as a Dundee cake ought, all citrus and almond, no canola overtone. [Update: The larger round cake, which was let rest wrapped up for a day, had quite a fine crumb as one would expect of Dundee cake, so the coarseness of the small one was not due to oil or rye flour, but to cutting and eating it hot from the oven! So, the only noticeable difference at all is the thicker crust, which could be due to the oven.] [Further update, January – I have finally bought an oven thermometer and discovered that if I lower the bottom rack as far as it will go and cook cakes near the front of the bottom, they do not get that very thick crust, so it was definitely the oven and not the oil. Yay!]
All in all, I’d say it was a very successful experiment and yes, Virginia, you can substitute canola oil for butter in fruitcake, and thereby lower the cholesterol and saturated fat a great deal. (Don’t worry about the ten eggs. The aim is lowering, while still having a proper fruitcake that tastes just like your mother’s/grandmother’s/great-grandmother’s, because that’s what you want at Christmas. And eggs have lutein and other good stuff in them. And those ten eggs were spread out over three cakes. And you shouldn’t eat it by the pound, after all, whatever the state of your health.)
Update: Dec. 2014. I’ve started using half canola, half olive oil for many cakes. It seems to give a better texture and a moister, better-keeping cake, than canola on its own. For things like muffins, though, just canola seems fine.