The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Poppyseed crusted Tangzhong Purple Sweet Potato Sandwich Loaf

Benito's picture

Poppyseed crusted Tangzhong Purple Sweet Potato Sandwich Loaf

I’ve posted a previous purple sweet potato sandwich loaf which was enriched with brown sugar and butter. I wanted to try making a loaf with the sweet potato but without the animal fat enrichment of the butter and using honey instead of brown sugar. So based on the formula that Maurizio posted on I added mashed purple sweet potatoes to his formula and made adjustments to incorporate the sweet potato.

Total Dough Weight900 grams + sweet potato
Pre-fermented Flour11.00%
Levain in final dough25.96%
Yield1 x 900g Pullman loaf

For 9x4x4 Pullman Loaf Pan

Total Formula

Desired dough temperature: 77°F (25°C). See my post on the importance of dough temperature for more information on dough temperatures.

The rows marked pre-cooked below are the two ingredients cooked (in a water roux, or tangzhong) ahead of time, but they are still counted toward the formula’s overall percentages. In other words, the 8% whole wheat flour is still counted toward the total flour in the formula and is not an “extra” addition.

WeightIngredientBaker’s Percentage
37gPre-cooked (tangzhong): Whole wheat flour (Giusto’s Whole Wheat Flour)8.00%
148gPre-cooked (tangzhong): Whole milk32.00%
347gMedium-protein bread flour or All-purpose flour (~11% protein, Central Milling Artisan Baker’s Craft or King Arthur Baking All-Purpose)75.00%
79gWhole wheat flour (Giusto’s Whole Wheat)17.00%
33gOlive oil7.00%
5gSourdough starter1.10%

Total Yield: 194.90%, 900g

Sourdough Sandwich Bread With Pre-Cooked Flour Method

  1. Prepare Levain – Night before mixing, 9:00 p.m. (Day one)

Mix the following ingredients in a container and leave covered to ripen at about 78°F (25°C) for 12 hours overnight.

WeightIngredientBaker’s Percentage
25gMedium protein bread flour or all-purpose flour100.00%
25gWhole wheat flour 
10gRipe sourdough starter10.00%

Prepare Purple Sweet Potato

You can prepare your purple sweet potato several ways, but you want to have in the end a soft mashed sweet potato. Steaming works well and leaves you with a moist mash. You can also microwave pricking the sweet potato and placing it in a microwaveable dish but something this can be dry. You can also roast the sweet potato, pricking it rubbing it with olive oil and then wrapping it in foil and then baking it until soft.

  1. Pre-cook Flour (Tangzhong) – 8:00 a.m. (Day two)

Be sure to do this ahead of time to give the pre-cooked flour time to cool before mixing.

Milk alternative: If you want to avoid using milk in this recipe, substitute out the dairy milk in the roux, below, for water (or something like oat milk).

37gWhole wheat flour
148gWhole milk

To a medium saucepan, add the flour and milk listed above. Turn the heat to medium-low and cook, whisking continuously, until the mixture thickens and becomes like a paste, about 5-8 minutes. In the beginning, whisk vigorously to break up any flour clumps, and be diligent about this near the end to avoid burning. The mixture won’t seem to do anything until it reaches a critical heat point, be patient; it will thicken.

Once it transforms into a viscous paste (something like oatmeal porridge), remove the pan from the heat and spread it out on a small plate to expedite cooling. Set the tangzhong aside until called for when mixing.

  1. Mix – 9:00 a.m.

I used my KitchenAid stand mixer to mix this dough, but it’s possible to make this bread without a stand mixer by mixing everything together by hand in a mixing bowl. To do this, you’ll need to mix for around 10-15 minutes, depending on your technique (slap and fold will work really well!).

AllPre-cooked flour (see Pre-cook Flour, above)
320gMedium protein bread flour
54gWhole wheat flour
33gOlive oil
107gLevain (see Prepare Levain, above)

To the bowl of a stand mixer fitted with the dough hook attachment, add the pre-cooked flour, flour, water, ripe levain, honey, olive oil, and salt. Mix on low speed for approximately 2 minutes until the ingredients come together, and no dry bits remain. Increase the mixer speed to medium (2 on a KitchenAid) and mix for 8-10 minutes until the dough starts to clump up around the dough hook. It won’t completely remove from the bottom of the bowl, and it will still be shaggy.

Transfer your dough to a bulk fermentation container and cover.

  1. Bulk Fermentation – 9:15 a.m. to 12:45 p.m.

At room temperature, around 72-74°F (22-23°C), bulk should take about 3 1/2 hours.

After 30 mins of bulk do a lamination spreading the purple sweet potato over the laminated dough in thirds. Next slap and fold to combine.

Give this dough two sets of coil folds during bulk fermentation at 30-minute intervals.

After the second set of coil folds, let the dough rest for the remainder of bulk fermentation aim for almost double volume.

  1. Shape – 1:15 p.m.

Prepare a sling of parchment that you can lay your shaped dough onto and then lift to place in the pan. I usually also prepare a length of parchment that goes lengthwise to prevent sticking on the ends of the bread.

I shaped this dough in my typical method for shaping a pan loaf. Check out my guide to shaping pan loaves for detailed instruction.

Once the dough is shaped into a long tube, transfer each to their pan, seam-side-down.

Using either a brush or a spray bottle dampen the top of the dough. At this point, you can sprinkle on any toppings you’d like.

  1. Proof – 1:30 p.m. to 3:30 p.m. (2 hours room temperature)

Cover the pan with a large, reusable plastic bag and seal shut. Let the dough proof at room temperature, around 72-74°F (22-23°C), for 2 hours.

Overnight proof option: before the 2 hour counter proof, cover the pans with bags and place them in your home refrigerator to proof overnight. Bake them the next morning as indicated below. Expect a slightly more sour flavor.

  1. Bake – 3:30 p.m. (pre-heat oven at 3:00 p.m.)


Check on your dough: it should have risen just below the top of the Pullman pan and be very light and airy to the touch (see above). If it’s not quite there, give it another 15 minutes and check again.

I steamed the oven for this bake as described on my post on baking with steam in a home oven.

Preheat your oven, with rack at the bottom third to 400°F (205°C).

Place a pan with a Silvia towel filled with boiling water into the oven about 30 mins before the bread will be loaded.

Once your oven is preheated, remove your proofed loaf from its bag, score it and then slide it into the oven.

Take care to bake the loaf fully; if they are under-baked, the interior will be gummy.

Bake at 400°F (205°C) for 20 minutes with steam. After this time, vent the oven, remove the steaming pan(s), and close the oven door. Drop temperature to 350ºF and bake for an additional 30-40 minutes until the top is well-colored and the internal temp is around 205°F, watch the crust very closely as it might colour very quickly. Remove the pan and gently knock out the loaves onto a wire rack. Return the loaves to the oven to bake for an additional 5 minutes without their pans to add extra color to the bottom and sides.

Let the loaves cool for 2 hours before slicing to ensure the interior is fully set.

Waiting to let the loaf cool before slicing it and making myself a sandwich with it for dinner and I’m starving to it is taking a lot of willpower not to slice it early.




Benito's picture
Ilya Flyamer's picture
Ilya Flyamer

This is some tall sandwich bread! And beautiful crumb as usual, with the purple sweet potato. Looks really soft.

Benito's picture

Thank you Ilya.  That Pullman loaf pan creates some crazy height on loaves baked in it that’s for sure.  I do like that the metal has a silicone coating so nothing seems to stick.  I still use parchment just in case though.

isand66's picture

This came out perfect.   Great crust and crumb.  I love using the tangzhong method especially for this type of bread.  
Happy baking!


Benito's picture

Thanks Ian, I loved the first two I made with wanted to see how this would be without the butter and sugar.  It is hard to replace the flavour of butter, but this is good enough that I don’t really miss it too much.

Happy Holiday.


bottleny's picture

Couldn't find how much purple sweet potato was used in this recipe.

Or, just based on personal preference?

Benito's picture

I typically will just use a single purple sweet potato for each loaf.  The one I used in this loaf was about 200 g and I think it would have been nice to have a bit larger one.

I hope you give it a try.


Bread1965's picture

Benny... an amazing looking bread! Well done. But it sure seems like you did a ton of work! Enjoy!

Benito's picture

Thanks Frank, but really it isn’t that much work.  The Tangzhong is simple, but I’d like to try a Yudane instead next because it is even faster and easier.  

Happy Holidays


texasbakerdad's picture

You take the most amazing photos.

Great Loaf!

I need to make myself a cool looking cutting board to put my bread on for photo ops.

Benito's picture

Thanks TBD, I try to get good photos.  I’m going to try this bread with a Yudane instead of Tangzhong next time.


Kristi's picture

Thank you so much for sharing this recipe. I actually joined The Fresh Loaf, because I saw your ube breads. Today, I just baked this bread!! I'm not a beginner with bread baking (probably made 15 loaves of bread in the past two years), but I was still a little intimidated. I don't have a pullman pan, so I cut the dough in half and used two smaller pans. 

For the levain, I used King Arthur Flour whole wheat. For the tangzhong and bread dough, I used King Arthur Flour white whole wheat. To make everything easier, the night before I did the tangzhong and put it in the fridge. The next day I just warmed it in the microwave. When it came to baking, I don't yet have a bread lame, so I left the steam pan in the oven, 

The bread came out very yummy!! 

This is the dough before baking...

Right before baking


Cut at an angle, because it wasn't very tall. I gave the pretty loaf away to the neighbor. 


I recreated a sandwich from Buccee's (a Texas, USA gas station); BBQ pastrami, sauerkraut, candied jalapenos, and mozzarella with thousand island. (It wasn't black, just the picture) My head is still freaked out by BBQ sauce pastrami. 



Can't wait to try this tomorrow toasted with jam (toast and jam are always my favorite)! 


Thank you again for sharing! I can't wait to make this again. 

Benito's picture

Hi Kristi, I’m honoured that you joined TFL seeing the Ube loaves I have baked and posted and even more so that you’ve baked this one.  I hope you enjoyed the bread and was happy with your bake.  What size pan do you have?  I have made this with my more standard 8.5x4.5” pan and used the same measurements not reducing.  The reason you may have gotten a relatively short loaf is that you didn’t make enough dough.

Aren’t the swirls of purple in the bread just beautiful, I find them to be and yours look wonderful.  The sandwich you made looks so delicious.  I have posted a few other Ube loaves in my blog if you’re interested in trying some other Ube breads of various sorts.

Welcome to the TFL.


Kristi's picture

Yes, I enjoyed the bread very much and I was very happy with the baking. I am so thankful you shared this. This morning I toasted the bread and used a little mountain blackberry jam, flavor was amazing! The bread is still moist and delicious today! I have two tiny slices left, I don't know they will make to dinner. I highly recommend everyone try this. Even if you can't get a purple sweet potato, I think red or even an orange-red mix would be beautiful and tasty too!!

I think the same about the amount of dough, next time I either need to get a pullman pan or maybe 1-1/2 recipes should do it. I don't know enough to make this determination before I start the project. It was a wing it thing! :D 

You had perfect timing on posting this! I saw the round sour dough loaf, and then the other sandwich bread post. While I was in progress of finding a nice purple sweet potato (the smaller ones can be very dry) and cooking it, you posted this one. :D I will be making the others, and this one again. 

This pic you can kinda see the tiny loaf in the back, but I didn't post this because you can see that I need a lame (badly!!). That's also why I didn't put poppy seeds, I was concerned I couldn't see the browning. I think they would be a fantastic addition! 


Thanks again, and I look forward to more of your posts! :) 


Benito's picture

Kristi I’m so pleased that you liked the bread so much, it warms my heart.

What is the size of your loaf pan(s).  If it is a standard loaf pan 8.5x4.5” then I’d use the same amount of dough as the original recipe.  You can calculate the volume of your loaf pan in relation to this standard and then guesstimate how much dough you need.