I don't know why I never thought of it before, but you can go and buy egg whites in a carton at the store. How do they work when making meringues? Actually, they work really well!
Perhaps our favourite dessert is angel food cake. I had run out of frozen egg whites but we needed a cake. Someone mentioned store-bought egg whites, which I had never considered, so we tried an experiment. It turns out that the half-litre cartons are exactly 500 g, which is perfect for a single 10″ angel food cake.
There were just a couple of differences:
Despite being at room temperature, they didn't have the same volume. It didn't fill the pan the way the same amount of regular egg whites do.
Also, when I started whipping, it really foamed up. It took a minute to solidify as usual, which is why I was surprised at the reduced volume.
The cake cooked about 5 minutes faster than it usually does. Normally I bake at 350°F for 45 minutes and I check it at 40. When I checked it at 40, it had just crossed the "overdone" line. Another minute or two would have burnt it.
- The top didn't crisp up the way it usually does, which is arguably the best part of an angel food cake!
That said, the proof of the pudding is in the eating. The taste and texture were essentially identical. I will not hesitate to rely on store-bought egg whites in the future (though I will continue to save my egg whites and prefer them when available).