What’s With All the Alkalinity?

Reader T wants to know why the mooncake crust recipe below calls for baking soda AND Chinese lye water. It’s an excellent question and I believe the answer is twofold. First, an extremely alkaline dough will brown up more readily. I mentioned Maillard reactions in a post a few days ago. One aspect of these mysterious browning reactions that I failed to mention is that they happen faster in an alkaline environment. It’s one of the reasons breads like pretzels and bagels are dipped in a lye solution before they’re baked. Chinese mooncakes don’t spend much time in the oven, so to get even a mildly browned appearance the pH needs to be fairly high. I don’t know what the pH of Chinese lye water is, but it’s must be higher than that of baking soda (9). Otherwise, why use it?

The other reason an alkaline dough is advantageous here is because alkalinity undercuts gluten development. That’s a good thing in this instance since as I mentioned earlier any significant rising will “erase” the delicate patterns on the top of the cakes as they heat up.

7 thoughts on “What’s With All the Alkalinity?”

  1. This raises the question of where you expect to get Chinese lye water from or how you will replicate it.

  2. You are forever a fountain of new knowledge. I never knew about pH affecting the Maillard reaction. Does this apply equally to meat as to dough? I.e. would meat with an acidic marinade take more time, or heat, to sear?

    1. Hey Hellyweg!

      That’s a good question and one I’m not sure how to answer. So much affects browning reactions: heat, time, pH…however from what I’ve seen heat is the dominant factor where something like meat is concerned. It seems to me that while marinated strips of meat for a stir fry might take a bit longer, they eventually brown up without much problem. Meat is always at least slightly acidic but the longer it ages the less acidic it becomes. I wonder how that might affect steaks on a grill? It might be fun to run an experiment. Thanks for the question!

      – Joe

  3. You know you are moving dangerously close to national treasure territory don’t you? I had no idea that alkali would aid browning. Next time I make bagels I am going to try this with the water . THANKS – for like the thousandth time

    1. Ha! My pleasure, Frankly! I was thinking the same thing about my next bagel attempt. My assumption is that Chinese lye water has a higher pH than water with dissolved baking soda in it. I’ll need a fair amount, but it might be worth a shot!

      Cheers — and national treasure my foot! 😉

      – Joe

  4. An alternative to lye water, if that is difficult for some to find, is to bake baking soda at 300 degrees for about an hour. The baking soda decomposes, releasing carbon dioxide, and leaving sodium carbonate behind. In solution, sodium carbonate is can have a pH of about 10.

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