Hydration, Flour, and Time: How to Design Your Own Sourdough Recipe From Scratch

Moving Beyond Recipes: Designing Your Own Loaf

In this guide, we’ll slowly walk through the three main levers you control:

We’ll tie each to the microbiology in the dough, then build a custom loaf, step‑by‑step, from simple design decisions.

The Formula Foundation: Baker’s Percentages

To design a bread, we measure everything relative to total flour = 100%.

Example base formula:

• Flour: 100%
• Water: 70%
• Salt: 2%
• Starter (at 100% hydration): 20%

If total flour = 500 g, then:

• Water = 350 g
• Salt = 10 g
• Starter = 100 g (which itself contains 50 g flour + 50 g water)

This lets you scale up or down easily—and see exactly how wet, salty, or inoculated your dough is.

Lever 1: Hydration and Dough Behavior

Hydration controls:

• Dough feel (stiff vs slack)
• Fermentation speed
• Final crumb (tight vs open)

Rough Ranges

• 60–65%: Firmer dough, easier to shape, tighter crumb. Good for sandwiches.
• 65–75%: Versatile range, moderately open crumb, manageable handling.
• 75–85%+: Very open crumb potential but sticky and tricky to handle.

Microbiology Link

More water means:

• Easier movement for yeasts and LAB, so faster fermentation.
• Enzymes more active, more starch broken down into sugars.
• Potential for more acidity and enzyme activity if time is not adjusted.

Design question: What do you want from the crumb and handling?

Start with 68–72% for a balanced, beginner‑friendly artisan loaf.

Lever 2: Flour Choice and Microbial Food

Flour isn’t just structure—it’s food for your microbes.

White Bread Flour

• Higher protein (usually 11–13%) = stronger gluten network.
• Ferments predictably; flavor is mild.

Whole Wheat Flour

• Includes bran and germ: more minerals and vitamins, more enzyme activity.
• Feeds LAB and yeasts well; ferments faster and can increase acidity.

Rye Flour

• Very fermentation‑friendly: lots of sugars and enzymes.
• Weak gluten; best used in blends (10–40%) for flavor and activity.

Microbiology Link

• Whole grains provide more micronutrients that support LAB and yeast metabolism.
• Higher enzyme activity in bran/germ can break down starch and gluten faster, so timing needs adjustment.

Design question: How nutty or hearty do you want your bread?

For a first custom loaf, try:

• 80–90% white bread flour
• 10–20% whole wheat or rye for flavor and microbial vigor

Lever 3: Time, Temperature, and Flavor

Time and temperature dictate how your microbial community behaves.

Yeast vs LAB

• Yeasts: Produce CO₂ (rise) and some alcohol.
• LAB: Produce lactic (soft tang) and acetic (sharp) acids.

General Rules

• Warmer (24–27°C / 75–80°F) = faster fermentation, more lactic acid.
• Cooler (20–22°C / 68–72°F) + longer time = relatively more acetic acid.
• Longer total fermentation = more flavor, up to the point of gluten breakdown.

Design question: Do you want mild, medium, or pronounced sourness?

• Mild: Shorter bulk + short cold proof.
• Medium: Moderate bulk + 12–16 hr cold proof.
• Pronounced: Longer, cooler ferments (with care to avoid over‑proofing).

Putting It Together: Designing a Sample Loaf

Let’s design a medium‑hydration, mildly tangy, part whole‑grain loaf.

Step 1: Choose Flour Blend

Goal: Flavorful but easy to handle.

• 85% bread flour
• 15% whole wheat

If total flour = 500 g:

• Bread flour = 425 g
• Whole wheat = 75 g

Step 2: Pick Hydration

We’ll pick 70% for a balance of open crumb and manageable dough.

• Water = 70% of 500 g = 350 g

Step 3: Starter Percentage

Starter affects fermentation speed and flavor. We’ll use:

• 20% starter (100% hydration)

Starter contains:

• 50 g flour (10% of total flour)
• 50 g water

So we adjust:

• Flour you weigh: 450 g (since 50 g flour is in starter)
• Water you weigh: 300 g (since 50 g water is in starter)

Step 4: Salt

Standard: 2% of total flour.

• Salt = 2% of 500 g = 10 g

Final Formula

• Bread flour: 425 g
• Whole wheat flour: 75 g
• Water: 300 g (plus 50 g in starter)
• Starter (100% hydration): 100 g
• Salt: 10 g

Designing the Fermentation Schedule

Let’s assume your starter doubles in 6–8 hours at room temp.

Example Room Conditions

• Kitchen temp: ~23–24°C (73–75°F)

Target Profile

• Mild‑to‑medium sour
• Manageable, daytime schedule

Proposed Timeline

1. Morning: Feed starter so it peaks around midday.
2. Midday: Mix, autolyse, and start bulk.
3. Afternoon: 3–4 hour bulk with 2–3 folds.
4. Late afternoon: Shape and move to fridge.
5. Next morning: Bake straight from fridge.

Total fermentation from mix to bake: ~18–24 hours (including cold time).

Step‑by‑Step Process for Our Designed Loaf

1. Prepare Starter

Feed your starter at a ratio that lets it peak at your planned mix time.

Example: 1:3:3 at 8:00 AM to be ready by ~1:00 PM.

2. Autolyse (1:00 PM)

In a bowl, mix:

• 425 g bread flour
• 75 g whole wheat flour
• 300 g water

Stir until no dry bits. Cover and rest 30–60 minutes.

Science: Autolyse allows enzymes to start converting starch to sugars, and gluten strands begin lining up, improving extensibility with minimal kneading.

3. Mix Final Dough (1:45 PM)

Add:

• 100 g active starter
• 10 g salt

Pinch and fold until evenly incorporated.

4. Bulk Fermentation (2:00–5:30 PM)

Keep dough at 23–25°C (73–77°F).

• 2:30 PM: First set of folds
• 3:15 PM: Second set of folds
• 4:00 PM (optional): Third set, if dough still feels slack

By 5:00–5:30 PM, look for:

• ~50–75% volume increase
• Small bubbles on surface and sides
• Dough that jiggles when the bowl is shaken

5. Shape and Cold Proof (5:30 PM Onward)

1. Preshape into a round, rest 15–20 minutes.
2. Final shape into a boule or batard.
3. Place in a floured proofing basket, seam‑side up.
4. Cover and refrigerate at 3–5°C (37–41°F) for 12–16 hours.

Microbiology: Yeast slow down but don’t stop. LAB keep producing acids, increasing flavor and slightly tightening gluten.

6. Bake (Next Morning)

1. Preheat oven + Dutch oven to 250°C (480–500°F) for 30–45 minutes.
2. Turn dough out from basket onto parchment, score decisively.
3. Bake covered 20 minutes, then uncovered 20–25 minutes at 230–240°C (445–465°F).

Tweaking the Design: Cause and Effect

Once you’ve tried this baseline loaf, you can adjust one variable at a time:

To Make It More Open‑Crumbed

• Raise hydration from 70% to 72–74%.
• Add one or two more folds during bulk.
• Ensure you don’t over‑proof; open crumb needs strength + correct fermentation.

To Increase Sourness

• Extend cold proof to 18–24 hours, tasting results.
• Ferment bulk slightly cooler and longer.
• Use a slightly stiffer starter (lower hydration) to encourage acetic acid.

To Reduce Sourness

• Shorten cold proof to 8–10 hours.
• Do an earlier bake (same‑day proof at room temp for 2–3 hours instead of fridge).
• Refresh starter 2–3 times before baking to reduce its acidity.

To Add Hearty Flavor

• Increase whole wheat from 15% to 25–30%.
• Watch fermentation: whole grains ferment faster, so reduce bulk or proof slightly.

Reading the Microbial Signals

As you adjust hydration, flour, and time, pay attention to:

• Smell: Sweet, yogurty, fruity, or sharp? More sharpness means more acetic acid.
• Feel: Dough gaining strength over bulk indicates LAB and gluten alignment working together.
• Rise pattern: How fast does the dough rise at your ambient temperature? That’s your personal baseline.

Designing sourdough recipes is like tuning a small biological machine. Hydration, flour, and time are the dials; the microbes are the engine.

With this framework, any recipe you see becomes less a set of rules and more a set of choices you can interpret—and confidently change—to suit your taste and kitchen.