Breads (Yeast) - Loaves

Purple Sweet Potato Loaf (Straight Dough Method)

August 15, 2017 | Recipe by Bake with Paws
Japanese Purple Sweet Potato Bread

Japanese Purple Sweet Potato Bread


I made this Japanese Purple Sweet Potato Loaf for my step-daughter when she was back for summer holidays recently.  

I have made her few different breads but this is her favourite and she always requests this particular bread.  This recipe is straight dough method.  If you prefer old dough method, please click Japanese Purple Sweet Potato Buns .

If you have any questions regarding this recipe or any other post, please leave me a comment in the “LEAVE A COMMENT” link and I will reply you as soon as possible.

Recipe - Japanese Purple Sweet Potato Loaf (Straight Dough Method)

Yields : 1 loaf in 25cm X 12 cm X 11 cm  loaf pan

INGREDIENT:

400g bread flour (I used Japan High Gluten Flour)
250g mashed japanese purple sweet potato (about 300 - 350g potato - peeled, sliced, steamed and mashed)
30g brown sugar
1 ½ tsp instant active yeast
1 tsp salt
40g whisked egg (from 1 large egg, whisked and keep the balance for egg wash)
120g - 150g fresh milk
60g butter

Egg wash:  Balance of whisked egg from the above + 1 tsp water
Some sesame seeds for topping (optional)

Utensil:  25cm X 12 cm X 11 cm  loaf pan

*  This recipe is not suitable for 450g Loaf Pan.  Please use this recipe for 450g Loaf Pan

METHOD:
  1. Put all ingredients (except butter) into the bowl of stand mixer. Using the dough hook, knead for 5 minutes (Chef Kenwood mixer, speed 2.5) until the dough comes together. Add in butter and continue kneading for another 10 - 12 minutes until the dough comes together, become elastic and reaches window pane stage.  Start with 120g of fresh milk first then slowly add in if the dough is too dry.  
  2. Form the dough into a round ball and let it rise in a warm place for 1 hour or until double in size in a large greased bowl, covered with cling film or kitchen towel.  I normally leave the dough in the stand mixer’s bowl and cover with kitchen towel.
  3. Punch down the bread dough to release the air.
  4. Transfer the dough to a clean floured surface then divide into 2 equal portions. Roll out each dough with a rolling pin into rectangle shape. Roll up like swiss roll until a short log is formed.  Place bun onto the baking pans lined with non-stick baking paper. Let it rise for another 45-60 mins or until double in size.
  5. Preheat oven at 190 C (top and bottom heat) or 170C (fan-forced) for 10 - 15 minutes. 
  6. Brush the dough with egg wash and sprinkle with some sesame seeds on top.
  7. Bake in a preheated oven for about 30 minutes or until golden brown.
  8. Remove bread to cool on rack completely.

Notes:
  1. Please cut down mashed sweet potato to about 200g - 220g if you find the texture too moist for you.
  2. Add 120g of fresh milk first, then slowly add in the rest if dough is too dry.
  3. If fresh milk is not available, you may use 120g - 150g water + 2 tablespoons (20g) of full cream milk powder

GENERAL NOTES:

GLUTEN DEVELOPMENT & WINDOWPANE TEST
Gluten forms when flour comes in contact with water.  Hydration of the flour causes the sticky and stretchy protein to form, giving structure to the bread.  This makes your bread trap air and rise. 

Gluten in dough can be developed by autolyse, resting, kneading or folding.

The windowpane test is used to determine whether the dough has been sufficiently kneaded.  By gently pulling the dough (or you may pinch off some dough) and trying to stretch it into a thin membrane.  If you are able to stretch the dough paper thin and translucent  without tearing, then the gluten is fully developed.  However, if you can stretch it without tearing but the membrane is not transparent, then the gluten is not yet fully developed.  

However, from my experience not all the recipe can achieve a thin and translucent window pane stage easily.   For example low hydration and low fat dough.  For such recipes, a reasonable window pane is good enough and it can be left to rest. Gluten will continue to develop while resting.  Exercising restraint to not over-knead the dough prevents the gluten from being overworked and broken.   Some of you may have experienced the dough breaking during the second proofing.  It is because the dough is over kneaded. 

The total kneading time for me is usually 15 minutes at low speeds except brioche dough with high fat percentage or dough using liquid fat which usually takes a little longer (maybe 18-20 mins).

From my experience, I found that high hydration dough with high percentage of fat will be easy to stretch and achieve a paper thin windowpane stage.


KNEADING TIME
For kneading, please regard the timing provided as an indication only. It is only meant as a guide.  Timing may differ depending on the brand of flour and electric mixer used. The protein content may vary from one brand of flour to another.

FLOUR
The right flour plays a very important role in bread making.   To achieve fluffy, soft and light bread, I used Japan High Gluten Flour in most of my bread baking.  The protein content is around  12 - 13%.

HYDRATION
The liquid measurement given is also a guide.  It is advisable to always reserve some liquid and not add it all in one go.  This would give you the opportunity to adjust if necessary. If dough is too dry, add the reserve liquid one tablespoon at a time until the right consistency.  This is because each flour absorbs water and hydrates differently. 

PROOFING
Please note that the proofing timing may also vary depending on your climate and environment. The humidity and temperature at your place will influence how dough rises.  
If you are unable to judge by just looking at the dough, you can do the finger poke test:
  1. First Proofing:
    • Lightly flour or oil your finger or knuckle, gently poke in the centre of the dough then remove your finger.  If it bounces back immediately without any indentation then it needs more time.
    • If the indentation stays and it doesn’t bounce back or if the dough collapses, then the it is over proved.  
    • If it bounces back just a little, then the dough is ready to be punched down and shaping.
  2. Second Proofing:
    • Lightly press the side of the proved dough with your finger.  If it bounces back immediately without any indentation, it means the dough is under proved and needs more time before baking.
    • If the indentation stays and it doesn’t bounce back, it means it has been over proved.
    • If the indentation slowly bounces back and leave a small indentation, it is ready to bake. 
    • There will be a final burst of rising once the bread is placed to bake in the oven and it is called oven spring. 
WRINKLE TOP OR SHRINKING
If your bread collapses or gets wrinkled on top after removing from oven, it could be because your dough over proved during the second proofing. Please proof until it rises 80 - 90% in size or is slightly below the rim of the pan.

BAKING TEMPERATURE & TIME
Do also note that the baking temperature and timing provided are what works for my oven and should also be regarded as a guide only. Every oven behaves a little differently, so please adjust accordingly for your oven.

Comments

  1. Hi,
    Does it matter if i put in all the ingredients including the milk together?

    ReplyDelete
    Replies
    1. Hi Irene,

      Thank you for dropping by. It is ok to put all the ingredients together. But, please don't put salt and yeast together. Please follow the sequence in Step 1.

      Cheers & happy baking:)

      Delete
  2. Hi Yeanley,
    Thanks for the info.
    Just curious why salt n yeast cannot put together. I hv tried your sweet corn loaf it turned out very pretty n nice. But nt for this sweet potatoes loaf. Im mt sure wht goes wrong.:-(. The dough didnt rise at all.:-(

    ReplyDelete
    Replies
    1. Hi Irene,

      From my understanding, the salt will kill the yeast if they contact directly. Sorry to hear that your sweet potatoes loaf not successful. It could be many reasons, yeast expired or too much salt or not warm enough? I normally leave my dough to rise inside the oven (door close and off) with a bowl of hot water beside.

      I hope it helps.

      Cheers:)

      Delete
  3. This comment has been removed by a blog administrator.

    ReplyDelete
  4. Hi Yeanley,

    Thanks for yr advise, i will try making one more time. Hope this round it is successful.:-)

    Have a nice week end!

    ReplyDelete
    Replies
    1. Thank you, Irene.. Good luck and let me know ya..
      Cheers:)

      Delete
  5. Hi Yeanley,

    May i know what type of butter and milk (low fat/full cream)you used?

    ReplyDelete
    Replies
    1. Hi there,

      Sorry for late response. I used Lurpak butter and full cream milk or fresh milk.

      Cheers :)

      Delete
  6. Hi Yeanley

    May i know what type of butter and milk(full cream/low fat) you used?

    ReplyDelete
  7. Can i use 450g loaf tin for this recipe?

    ReplyDelete
    Replies
    1. Hi, I afraid the bread will over flow. I have not tried this recipe in 450g loaf pan. You may want to try reduce the flour to 320g and reduce the rest of ingredients accordingly by multiply 0.8.
      I hope it helps.
      Cheers :)

      Delete
  8. May i know where you bought your loaf pan for this recipe?
    Tqvm.

    ReplyDelete
    Replies
    1. Hi, thank you for asking. I got this pan from "Bake with Yen" in KL many years ago. But it is not a non-stick pan.
      Cheers :)

      Delete
  9. Hi Yeanley,
    I cooked purple potatoes in microwave for 10 mins instead of steaming as you said. As the result the dough was far too dry and I ended up doubling the milk in the recipe. So it took me over 15 mins to get the window pane stage. I used 450 g loaf tin and had leftover for a few rolls. They came out beautifully so soft and fluffy, a bit sweet with fragrance.
    Thank you for the lovely recipe. Next time I won’t be too lazy to steam the potatoes.

    ReplyDelete
    Replies
    1. Hi, thank you for trying this recipe and your kind feedback. Yes, steaming method will yield more moist potato. Happy to hear that you like the bread. Hope will hear from you for your next baking.
      Cheers and happy baking :)

      Delete
  10. The recipe turned out great. Fragrant bread, and my kitchen smelled like a HK bakery. Only a bit too sweet for my family, so in future I might try with %50 less sugar. Thank you!

    ReplyDelete
    Replies
    1. Hi, thanks for trying this recipe and your feedback. Yes, please cut down the sugar if it is too sweet for you.

      You are most welcome and happy baking :)

      Delete
  11. can i ask if this recipe is for 2 loafs? as the recipe did say divide into 2 and place in baking tinS. Also do we need to melt the butter or add solid butter? thank u.

    ReplyDelete
    Replies
    1. Hi, thanks for reading this recipe. The recipe is for 25cm X 12 cm X 11 cm loaf pan. You can shape into one loaf or 2 loaves in one pan. I shaped into 2 loaves and baked in in pan.

      Cheers :)

      Delete
  12. Wondering how I can make this using tangzhong or yundane? If you have a suggestion, let me know!!! Takes me a long time to eat a loaf of bread so I'd love for it to stay fresh for longer :)

    ReplyDelete
    Replies
    1. Hi, thanks for reading this recipe.

      I don't encourage using Yudane or Tangzhong Method for sweet potato bread it is because it will make the texture too moist. Potato starch also absorbs more water than wheat starch and this makes the bread texture more moist and have better shelf live. So, it does not need yudane dough. However, I think old dough method will work better.

      Please use this recipe link and bake in 450g loaf pan.https://www.bakewithpaws.com/2017/07/japanese-purple-sweet-potato-bun.html

      Cheers :)

      Delete
  13. How to apply tangzhong in this recipe? I understand tangzhong requires 1:5 ratio flour to milk. how much flour to make the tangzhong?

    ReplyDelete
    Replies
    1. Hi, thanks for reading this post. I would not recommend this bread to use Tangzhong or Yudane method. I afraid the bread texture going to be too moist. However, you can see my old dough method on this bread as below link if you like:

      https://www.bakewithpaws.com/2017/07/japanese-purple-sweet-potato-bun.html

      You may also refer to the Bread Baking Method Bar on the above to read more about Tangzhong Method.

      Cheers :)

      Delete
  14. Hi dear. Can I check the size of the loaf pan, it’s different from the usual 450g that we are using right? Thanks

    ReplyDelete
    Replies
    1. Hi dear, Thanks for reading this recipe. Yes, it is not the 450g loaf pan. This bread was made many years back before I have the 450g loaf pan. If you want to bake in 450g loaf pan, please search for Purple Sweet Potato Buns (Old Dough Method) in this website. This recipe is suitable for 450g loaf pan.

      Here is the link if you can't find:
      https://www.bakewithpaws.com/2017/07/japanese-purple-sweet-potato-bun.html

      By the way, the old dough method yields even fine and soft better texture.

      Cheers :)

      Delete
  15. Hi, what is the difference between using instant yeast and starter/levain? is using instant yeast really bad for health tho I see that sweet levain recipe calls for more sugar. Appreciate your advice. Thank you.

    ReplyDelete
    Replies
    1. Hi, Thank you for visiting this post.

      Sourdough starter is natural yeast. Sugar used in the sweet stiff starter is to prevent the bread from sour. The natural yeast eat the sugar, so by the time when we use the starter the sugar already gone.

      To be honest, I am not sure about the instant yeast really bad for healthy.

      Cheers :)

      Delete
  16. Hi I made this but when I sliced it, the bread was gummy. Is it because it is too moist? Or something wrong with the proofing?

    ReplyDelete
  17. Hi, my bread turned out gummy after cutting. I ended up adding 160ml milk because the dough was dry when mixing and baked for 30 mins on 190. Could it be because it was too moist or I did not bake it enough?

    ReplyDelete
    Replies
    1. Hi, thank you for trying and sorry to hear that your bread turned out gummy. Possible too much moisture in the dough. It could be the different flour and potatoes that we used.

      Usually 30 mins at 190C should be enough. However, it is very much depend on your oven too.

      I have been using this recipe for many years and so far no issue. Sometimes I need to use less or more liquid. However, the bread still turned out very soft.

      The percentage of sweet potatoes I used is around 60%. However, you may want to cut down the potatoes to 150g, around 37%.
      I find when I cut down the sweet potatoes the bread turned dry/stale very fast.

      You may want to try old dough method in my blog too which the bread is even softer. Just search for Purple Sweet Potato Buns (Old Dough Method).

      I hope this will help.

      Cheers :)

      Delete

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