Tangzhong, or Water Roux

Tangzhong is a paste of flour and water that has been cooked to fully gelatinize the present starches (then cooled before addition to your bread).

The effects of water roux can be two fold. The supplementary gelatinized starches further bind water in your bread, creating loaves or buns that stay “fresh” and soft for longer, and in binding that same water, lightly restrict gluten formation. This mild restriction means that while enough gluten forms to create good structure around the new excess of gelatinized starches, there is less of a hard protein structure to exacerbate stiffness as the bread ages.

Tangzhong is generally recommended to be mixed from a 1:5 ratio of flour to water, taken from already present total weights much in the same way one could cover a recipe to include a levain. This mixture is cooked, stirring, until it reaches 65ºC/150ºF. This slurry, cooled, is then added to your mix with your flour and liquid.

On Pastry Chef Online, Jennifer Field integrates tangzhong into a pain au lait. Having previously tested tangzhong use, she deviates slightly from the typical methodology. She uses milk in place of water (perfectly sensible in a pain au lait) and decreases the ratio difference between liquid and flour to create a thicker slurry. She integrates several bread techniques, such as autolyse making this a complex, but rewarding recipe.

Tangzhong Water Roux Pain au Lait
Recipe from Pastry Chef Online
(some steps modified for readability)

What You Need
For the tangzhong
* 6 oz whole milk
* 1.2 oz bread flour
For the Dough
* All the tangzhong
* 6 oz. whole milk
* 15.8 oz bread flour
* 4 teaspoons granulated sugar
* 1¼ teaspoons active dry yeast (from a batch of yeast you know is alive and kicking)
* 1⅛ teaspoon (7 grams) kosher salt (picky, but there you have it)
* 3.25 oz butter, cut into small pieces and allowed to get very soft

What To Do
For the tangzhong
1. Whisk together the flour and milk.
2. Once there are no lumps remaining, cook over medium heat, whisking constantly, until the mixture has evenly thickened and is nice and smooth.
3. Remove from the heat and…
For the Bread
1. Pour the 6 oz of milk into the tangzhong, whisking until smooth. (This will lower the temperature so you don’t have to wait before continuing.)
2. To your mixing bowl, add all the tangzhong/milk mixture and all the rest of the ingredients except for the butter.
3. With the dough hook, mix on low speed for one minute, or until the dough just comes together. There might be some loose flour in the bowl, but don’t worry about it. It will get incorporated in the next step when you add the butter.
4. Cover the mixer bowl with a lint-free towel (you can leave the bowl on the mixer) and let rest for 30 minutes. This rest (autolyse) allows some gluten to form before you even start kneading.
5. After the rest, turn the mixer on medium-low speed and add the butter in several additions over the course of about three minutes. The dough will be a wreck–sticky, buttery, messy. Worry not.
6. Turn the mixer on medium speed and knead for 7 minutes.
7. Cover the bowl again and let rest for 20 minutes.
8. Remove the towel and knead on medium speed for 7 more minutes.
9. Test the dough. It should be somewhat tacky, very extensible (you can stretch it out really easily) and smooth. Check the dough with the windowpane test. If you can stretch out a wee piece of the dough until it is taught and translucent like bubble gum, you’re good to go.
10. Put the covered dough in the warm and moist microwave–leave the mug of water in there–and let double in size, 45 minutes-an hour.
11. Once the dough has doubled, turn it out onto a clean work surface–no flour. Lightly press the dough into a rough 9″ square.
12. Fold the dough into thirds like a letter. Then, fold it in half–it will seem an impossible task, but just start at one side and sort of push the dough down in the center of your letter fold and pinch the top and bottom edges together. Keep doing this all the way down the length of your dough. Now you will have a fat cylinder of dough about a foot long.
13. Roll the dough over (smooth side up) and hold it like a bowed up slinky.
14. Fit the dough into a pan-sprayed 9″x5″ loaf pan so the slinky’s ends are down in the bottom of the pan. Then press the dough down a bit to even it out and allow it to sit snugly in the pan.
15. Heat the mug of water for another minute or so, and spray the top of the loaf with pan spray.
16. Cover with plastic wrap and place back in the cozy microwave with its little mug friend.
17. Go ahead and set a rack in the center of the oven and preheat to 350ºF.
18. Let the rise until it has not quite doubled in size–it will probably rise about an inch or so above the lip of the loaf pan. This will take about 30-45 minutes.
19. Once the dough has risen nicely, place in the preheated oven and bake until the loaf is a deep golden brown. It doesn’t need any egg wash or anything. The loaf should sound hollow when tapped and the internal temperature will be between 205ºF and 210ºF.
20. Tip the bread out of the pan and onto a wire rack to cool. Let cool at least an hour.
21. Store at room temperature in an airtight container for 3-4 days. For longer storage, pre-slice, wrap well and freeze. Pull out slices as needed and leave the rest frozen.

The scientific basis of tangzhong’s successful use is fairly straight forward to the educated baker; staling is caused by the migration of moisture out of the starch, resulting in it’s degelatinization. Use fully gelatinized starch in greater amounts, hold on to more water for longer, have less degelatinization. Simple stuff. Even the reduction in gluten formation, while it may not spring immediately to mind, is easily confirmable by any book detailing the science of gluten formation. However, The science behind tangzhong is fairly difficult to find authoritative confirmation for.

Said to originally be from Japan, it was proliferated throughout south-east asia in the 1990s via the book 65º Bread Doctor by Yvonne Chen. (cited in Cookipedia) This history seems to be generally accepted in the majority of descriptions found of tangzhong, which is indeed found in such popular japanese bread products as Hokkaido milk bread. My attempts to get the information straight from the horses mouth (or at least the book the horse wrote) was waylaid by the fact that 65º Bread Doctor is in Chinese. I can find no other mention of tangzhong anywhere that does not either cite Chen’s book as the source, or is entirely uncorroborated. Tangzhong works through basic, well known mechanisms, but short Yvonne Chen’s contributions might not be so readily available through the internet to the home or novice baker.

(If you know of any further books that mention tangzhong please comment! I would love to learn more about this fascinating medium.)

Interesting ways to experiment in the future: how would a tangzhong work in tandem with a levain? Tangzhong can be made from a variety of non gluten alternatives suggested on Pastry Chef Online (which seems very successful in Gluten Free on a Shoestring.) What difference is there between such alternatives?

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