Purple Sweet Potato Sandwich Loaf

I have previously shared a recipe made with regular sweet potato. It was such a delicious sandwich loaf. Now, I’ve created a Purple Sweet Potato Sandwich Loaf.

Here is another delicious loaf made with addition of purple sweet potato. I have also added an egg to the dough, for extra softness. 

Here are the details.

Ingredients

Sourdough Starter

• 7g sourdough starter
• 35g water
• 35g bread flour

Dough

• 300g bread flour (100%)
• 120g roasted and mashed purple sweet potato
• 125g water
• 1 large egg
• 30g sugar (10%)
• 60g of levain (20%)
• 6g salt (2%)
• 30g soft or melted butter(10%)
• 0.5 g dry yeast (optional, to reduce the sourness, can be added with water)

Directions 

Day 1

Starter 

• 10 pm add starter to the water and whisk together, add flour, mix well, cover loosely, let it sit at a room temp 74-78F for about 8-10 hours until starter reaches its peak (at least triples in volume).
• Roast purple sweet potato and let it cool. Mash it.

Day 2

Dough

• 8 am mix water, flour, purple sweet potato, egg, sugar, sourdough starter (60g on its peak, the rest use for future feedings), let it autolyse for 1 hour. During the autolyse process the flour becomes fully hydrated. This activates gluten development.

• 9 am mix dough on low speed of your mixing machine for 2-3 minutes, or KitchenAid on speed 3 for 3-4 minutes until well incorporated.

• Add salt, mix for a couple more minutes. The dough should come up together.
• Add soft butter, increase the speed to medium and mix for 10 more minutes until the dough is well incorporated and comes up together.
• Perform a windowpane test. Wet your hands and stretch the dough. You should be able to stretch it very thin, that’s a sign of a well developed gluten, and that your final product will have a soft and light structure.

• Cover and let the dough proof for 3-4 hours at 76-80F/ 24-28C.

• During that time perform 2 stretches and folds.
• The dough should become slightly puffy.

• 1 pm transfer the dough to the fridge for cold fermentation till the evening (for 8-9 hours).
• 10 pm remove the dough from the fridge.
• Shape as desired. I rolled it into a roll half length of a baking/loaf pan.

• Put a sheet of parchment paper on the bottom of your loaf pan, or spread butter and sprinkle some flour, inside your loaf pan.
• Transfer the shaped loaf into the loaf pan.
• Cover the dough and let it proof overnight 72F /22C until it doubles or more in volume. About 7-9 hours. Usually it doubles or more in volume by morning (6-7 am).

Day 3

• 7 am preheat the oven to 375F.
• Bake bread for 35-40 minutes until golden brown.

Enjoy your purple sweet potato sandwich loaf  🙏

Purple Sweet Potato Sandwich Loaf

2071kcal

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Prep 45 minutes mins

Cook 40 minutes mins

Rise & Rest Time 23 hours hrs

Total 1 day d 25 minutes mins

This stunningly vibrant, naturally purple sandwich bread is exceptionally soft and pillowy. By incorporating mashed purple sweet potato and a whole egg into an enriched sourdough base, you achieve a beautifully moist interior crumb with a delicate sweetness and excellent shelf life, making it the ultimate showstopper for toast or sandwiches.

Cuisine Modern Artisan

Ingredients

Sourdough Starter Levain (Night Before)

• ▢ 10 g Sourdough starter culture
• ▢ 40 g Water
• ▢ 40 g Bread flour

The Enriched Purple Dough

• ▢ 350 g Bread flour (100%)
• ▢ 110 g Whole milk (31.4%)
• ▢ 120 g Purple sweet potato (Cooked, peeled, and completely mashed)
• ▢ 80 g Active sourdough starter levain (22.8% – From the stage above)
• ▢ Large egg
• ▢ 35 g Sugar (10%)
• ▢ 40 g Unsalted butter, softened (11.4%)
• ▢ 6 g Fine sea salt (1.7%)

The Golden Glaze

• ▢ 1 Egg
• ▢ 1 tbsp Water (Whisked smoothly for the egg wash)

Equipment

• ▢
  9×5 Inch Loaf Pan (Essential for framing the high vertical expansion of this enriched dough)
• ▢
  Stand Mixer (Crucial for handling the mechanical mixing required to properly emulsify the butter and dense sweet potato mash)
• ▢
  Rolling Pin (To cleanly deflate gas pockets and roll the dough into uniform sheets)
• ▢
  Pastry Brush (For smoothing on the final egg wash glaze)
• ▢
  Kitchen Scale

Method

Prevent Sleep ModePrevent Sleep Mode

Night Before – Levain Optimization & Potato Prep

1. 10:00 PM – Starter Build: In a small glass jar, add your 10g of starter culture to 40g of water and whisk together cleanly. Stir in 40g of bread flour. Mix thoroughly, cover loosely, and let it sit at room temperature 74–78°F (23–26°C) overnight for 8 to 10 hours until the starter reaches its peak and at least triples in volume.
2. Potato Preparation: Peel and dice your purple sweet potato. Steam or boil the pieces until they are completely fork-tender. Drain thoroughly and mash them using a fine potato ricer or fork until absolutely smooth, ensuring no lumps remain. Let the mash cool completely down to room temperature, cover tightly, and store in the fridge overnight.

Day 2 – The Enriched Autolyse & High-Speed Mixing

1. 8:00 AM – The Enriched Autolyse: In your stand mixer bowl, combine all 110g of whole milk, 120g of your smooth purple sweet potato mash, 35g of sugar, 1 large egg, 80g of your active overnight starter peak, and all 350g of bread flour. Mix everything together with a spoon just until a rough, shaggy purple mass forms. Cover and let rest for 1 full hour to completely hydrate the flour proteins.
2. 9:00 AM – Developing Gluten: Attach your dough hook. Mix the autolysed dough on low speed for 2 to 3 minutes (or use a KitchenAid mixer on speed 3 for 3 to 4 minutes) until well incorporated. Add the 6g of fine sea salt and continue mixing for a couple of minutes until the dough gathers tightly together.
3. Butter Emulsification: With the mixing machine running, gradually drop in the 40g of soft unsalted butter piece by piece. Once introduced, increase the speed to medium-high and mix continuously for 10 to 15 minutes until the fat is completely incorporated, the dough cleans the sides of the bowl, and it passes a clear windowpane test.
4. Bulk Proof with Intervals: Cover the container tightly and let it proof for 3 to 4 hours at a warm 76–80°F (24–28°C). During this window, perform 2 gentle rounds of stretches and folds to build structural tension. The dough should look visibly lighter, smooth, and slightly puffy.
5. 1:00 PM – Cold Fermentation Retard: Slide the entire covered proofing container directly into the refrigerator to rise slowly for 7 to 8 hours of cold fermentation retard until evening.

Day 2 (Night) – Rolling the Loaf & Overnight Proof

1. 9:00 PM – Sandwich Loaf Shaping: Remove the chilled violet dough from your refrigerator. Tip it onto a lightly floured work surface. Using a rolling pin, roll the chilled dough out cleanly into a long, flat rectangle roughly 1/4-inch thick, ensuring the width matches the length of your loaf pan.
2. The Overnight Counter Rise: Starting from the edge closest to you, roll the dough up tightly away from you into a tight, uniform cylinder. Pinch the final seam firmly to seal the log closed. Grease your loaf pan with butter or line it with parchment paper, and place the log inside, seam-side down. Cover loosely and let it proof overnight on your counter for 8 to 10 hours at a stable room temperature of 70–72°F (20–22°C) until the next morning. The dough must completely double in volume, rising cleanly past the rim of the pan.

Day 3 – The Golden Purple Bake

1. Next Morning – Baking: Preheat your home oven to 375°F (190°C). Brush the towering top crown of your beautifully risen loaf lightly with your prepared egg wash mixture for a glossy finish. Slide the pan onto the middle oven rack and bake for 35 to 40 minutes until the top turns a deep, uniform golden bronze.
2. Cooling: Remove the pan from the oven, slide the soft loaf out carefully onto a wire cooling rack, and allow it to cool completely down to room temperature before slicing to reveal the vibrant, striking purple interior!

Nutrition

Calories2071kcalCarbohydrates349gProtein58gFat47gSaturated Fat25gPolyunsaturated Fat5gMonounsaturated Fat11gTrans Fat1gCholesterol263mgSodium2511mgPotassium1031mgFiber13gSugar47gVitamin A18448IUVitamin C3mgCalcium267mgIron5mg

Notes

• The Starch Secret Behind Ultra-Soft Sandwich Loaves: Incorporating mashed potatoes into bread dough is an old-world baking secret for creating a cloud-like texture. Potatoes are packed with gelatinized starches that disrupt the wheat gluten network just enough to prevent the crumb from turning tough or rubbery. Furthermore, these starches hold onto moisture significantly longer than wheat flour alone, keeping your sandwich slices soft and fresh for days without stale staling.
• Why the Final Pan Rise Happens Overnight on the Counter: Enriched doughs packed with dense potato flesh, eggs, sugar, and butter ferment significantly slower than standard lean flour-and-water artisan loaves. Giving the shaped pan loaf a slow, 9-hour room temperature proof on your kitchen counter overnight allows the wild yeasts to work steadily over many hours, ensuring a gorgeous, towering oven spring by the time you wake up.
• Achieving an Ultra-Smooth Potato Mash: To avoid unappealing pockets of unmixed potato throughout your beautiful purple crumb, ensure your sweet potato is boiled until completely falling apart. Running the hot potato chunks through a fine mechanical potato ricer or a mesh sieve yields a silky, velvety paste that incorporates seamlessly into the milk and flour matrix during the autolyse stage.

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