A tart solution for sweet crumb cake
Grapefruit’s acidity and bitterness keeps sugar in check
With easy-to-peel satsumas, seedless clementines and scarlet blood oranges all available to satisfy citrus yearnings, it can be hard to remember to give grapefruits their due.
Even when I do think to buy them, they often languish. Their vast size requires you either to commit or to share, and they’re not the kind of thing you’d casually toss into your bag on the way out the door. Grapefruits can also be somewhat bitter, which may turn off people accustomed to honey-sweet tangerines.
But dessert is different. That’s when the acidity and bitterness of grapefruit is precisely what makes it so appealing, especially in confections that lean cloying. Like crumb cake.
With its mound of brown sugar nuggets blanketing a moist, sour cream-enriched cake, crumb cake often walks the line between luxury and overkill. But adding grapefruit segments on top of the batter pulls it back from the sugary abyss, each bite releasing a burst of bracing, tangy juice.
Before adding the fruit segments, you have to remove the membranes that surround them, which interfere with flavour and texture. (This technique is known as supreming the fruit.) Once the membranes are removed, the segments will fall apart, and that’s perfectly fine. You’re aiming for a scattering of the pulp, each tiny juice vesicle remaining distinct until it hits your teeth.
I also sprinkle a few grains of sea salt on top of the grapefruit. It does wonders to mitigate the fruit’s inherent bitterness. But be restrained: you don’t want it to go the way of salted caramel. Here,
the salt is a more subtle contribution.
The cinnamon in the topping is de rigueur, but I also add cardamom because I like the vaguely Scandinavian way it tastes with almonds. Ginger works wonderfully with the grapefruit, so feel free to substitute that if you like it better.
You can also substitute other sweet citrus fruit, trading oranges or tangerines for grapefruit.
Really, any tangy fruit will work. Pineapple, raspberries, nectarines and sour cherries all have enough acidity to zip up the heavy molasses flavour and texture of brown sugar. Just skip the salt sprinkle, which isn’t necessary without the bitterness of grapefruit to subdue. And stay away from the likes of blueberries, sweet cherries, peaches and pears, which are too sweet for this supremely sugary dessert.
After all, balancing bitter, sweet, salty and acidic is the key to all good cooking — and, in this case, baking.