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I'm trying to make this Chinese pastry called Shaobing. Some recipes I've found call for first adding boiling water then adding cold water. There's no yeast, just some salt and flour. FYI, these recipes are from pretty old cookbooks.

My question is, what does adding boiling water first, then cold water do to the flour?

Glorfindel
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daSn0wie
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1 Answers1

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Adding boiling water to flour causes the starch granules to swell and gelatinise, allowing the dough to absorb more water, resulting in a softer and/or fluffier finished product. However, a dough made entirely with boiling water lacks extensibility (i.e. can't be stretched) because some of the precursor proteins to gluten are denatured at such a high temperature. This may be desirable as less gluten means the dough is easier to roll out thin.

On the other hand, dough made entirely with cold water has high extensibility, especially when gluten is allowed to develop through time and kneading, giving the finished product more chewiness.

Your recipe uses a combination of both types of dough, balancing between both extremes so that the finished product is not too soft but not too chewy.

mbjb
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  • For more context, the method of cooking some of the dough to gelatinize the stach is called _tangzhong_ or [water roux](https://en.wikipedia.org/wiki/Water_roux). – Jacob Bundgaard Aug 16 '20 at 16:06
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    It sounds like the OP's recipe calls for adding _all_ of the flour to boiling water, and then all of it to cold water, though; wouldn't that denature the proteins in all the flour, something the later addition of cold water would not be able to reverse? – Vikki Aug 16 '20 at 19:54
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    When you add boiling water to room temperature flour, it cools down rapidly, and really only denatures the proteins that come in relatively close contact to the boiling water. Even dough where all the water is hot can be stretched a little bit, not all of the proteins can be denatured. – mbjb Aug 17 '20 at 00:14
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    @Vikki-formerlySean Usually you do not do that, so I doubt that's what the recipe calls for. If you do that, your dough turns translucent and extremely soft; this technique is used only in Cantonese dim sum for dishes like haar gow, where this is the intended effect. For shaobing, you generally mix two types of dough. – xuq01 May 13 '21 at 13:33
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    By the way, the much more common term for this technique is _tang mian_ 烫面, literally "hot flour/dough". – xuq01 May 13 '21 at 13:34