Purple Sweet Potato Sourdough – Crust & Crumb Academy

Crust & Crumb Academy

Purple Sweet Potato Sourdough

⏱

Prep

30 min

🔥

Bake

45-50 min

🕐

Total

18-24 hrs

🍞

Yield

1 loaf

🌡

Temp

500°F / 260°C

💧

Hydration

75%

Ingredients

Naturally purple sourdough made with purple sweet potato puree or powder. Soft, moist crumb with a nutty sweetness and stunning color throughout. A lean dough — no butter, no eggs.

The Dough

Metric	Volume	Ingredient
405g	3¼ cups	Bread flour
45g	6 tbsp	Whole wheat flour
290g	1¼ cups	Water (75°F / 24°C)
90g	6 tbsp	Active sourdough starter (at peak)
150g	½ cup	Purple sweet potato puree (OR 30g / 3 tbsp powder)
9g	1½ tsp	Fine sea salt

Loaf Pan Version (optional)

Metric	Volume	Ingredient
15g	1 tbsp	Honey
20g	1½ tbsp	Olive oil

Instructions

🍠 Day Before — Prepare the Sweet Potato

Cook, peel, and mash 25 min

Steam one medium purple sweet potato (about 200g) for 20-25 minutes until completely tender. Peel and mash until completely smooth — no lumps. Weigh out 150g. Cool completely before using.

🎨 Why Steam, Not Boil?

Boiling leaches anthocyanins (the purple pigment) into the water, leaving paler flesh. Steaming keeps the color locked in the potato where you need it.

🧪 Morning Of — Check Your Starter

Float test

Drop a spoonful of starter into water. If it floats or hovers, it's ready. If it sinks, feed it and wait 1-2 hours.

🥣 Morning Of — Mix and Autolyse

Combine flours, water, and puree

Mix bread flour, whole wheat flour, and water until no dry flour remains. Add the cooled purple sweet potato puree and mix until incorporated. The dough will turn a striking purple-grey.

Autolyse rest 45-60 min

Cover and rest at room temperature. The flour hydrates, gluten begins forming, and the color deepens throughout the dough.

💧 Add Starter and Salt

Incorporate starter and salt 5-7 min

Add the active starter. Squish and fold until fully incorporated (3-4 min). Sprinkle salt evenly and mix another 2-3 minutes. For the loaf pan version, add honey and olive oil now. Rest 30 minutes covered.

⏰ Bulk Fermentation

Stretch and fold series 30 min apart × 3

Perform three sets of stretch and folds at 30-minute intervals. Four folds per set. After the third set, optionally do one lamination pass to distribute color and add strength.

Rest undisturbed 5-8 hrs total

After all folds, let rest until 75-80% volume increase at 75-78°F (24-26°C). The dough should feel noticeably lighter and more airy. Watch the dough, not the clock.

🧪 Sweet Potato and Fermentation

The natural sugars speed up yeast activity while the starch slightly thickens the dough. Don't rely on the jiggle test — volume increase and dough feel are more reliable here. The purple will also deepen toward blue-purple as the pH drops during fermentation.

🤲 Preshape and Shape

Preshape and bench rest 20-30 min

Turn out onto a lightly floured surface. Shape into a rough ball using bench scraper. Rest uncovered 20-30 minutes.

Final shape

Boule: fold in thirds, flip, drag with bench scraper to build tension. Place seam up in well-floured banneton (rice flour is not optional). Loaf pan: pat to rectangle, fold sides in, roll into log, place seam down in greased 9x5 pan.

Cold proof overnight 10-14 hrs

Cover and refrigerate overnight. Cold dough holds its shape better when scored and gives a cleaner ear.

🔥 Day 2 — Bake

Preheat with Dutch oven 45-60 min

Dutch oven (lid on) in cold oven. Preheat to 500°F (260°C) for at least 45-60 minutes. The Dutch oven needs to be genuinely hot all the way through.

Score and bake covered 20 min

Score cold dough with a lame at 30-45° angle. Lower into Dutch oven on parchment. Lid on. 500°F (260°C) for 20 minutes.

Bake uncovered 20-25 min

Remove lid. Reduce to 450°F (232°C). Bake until internal temperature reads 205-210°F (96-99°C). The crust will look darker than a plain sourdough — that's the anthocyanins browning, not burning.

Cool completely 2 hrs minimum

Wire rack. Do not cut for at least 2 hours. The sweet potato starch holds moisture and needs the full cooling period to set. Cutting early = gummy interior.

💡 Pro Tip

This loaf actually improves on day 2. The flavors meld and the crumb firms to a better texture for slicing.

Baker's Math

Bread Flour

90%

Whole Wheat

10%

Water

64%

Sweet Potato

33%

Starter

20%

Salt

Total hydration: 75% (incl. potato moisture) · Inoculation: 20%

Storage

Room temp: 3-5 days. Stales very slowly due to potato starch.

Frozen: Up to 3 months. Slice before freezing. Color holds well.

Refresh: Toast from frozen or warm at 350°F (175°C) for 10-12 min.

Nutrition

Per slice (~75g): 185 cal · 37g carbs · 6g protein · 1g fat · 0g sat fat · 2g fiber · 230mg sodium

Classroom Resources

🎓 Learn the Techniques

✂️

Scoring TechniquesYouTube Tutorial

🎬

Shaping BasicsYouTube Tutorial

🌀

Sourdough FundamentalsCrust & Crumb Academy

Equipment

Challenger Breadware · Baking Scale · Bench Scraper · Wire Monkey Lame · SourHouse Goldie (HBK23) · Banneton · Thermometer

Related Recipes

Love natural color in bread? Try the Marbled Bread (Sourdough) — same dramatic crumb reveal with cocoa, matcha, or beet powder.

Color Science

🎨 Anthocyanin pH Shift

The purple color shifts with acidity. A milder loaf stays blue-purple. A more sour loaf shifts toward pink-magenta. Both are correct — it's chemistry, not a mistake.