Sourdough Discard Zucchini Bread

Name: Sourdough Discard Zucchini Bread
Prep time: 31 min
Cook time: 1 h 13 min
Total time: 1 h 44 min
Yield: 10 servings
Cuisine: American
Ingredients: 1 cup (100 g) walnut halves, coarsely chopped; 1 tbsp (14 g) unsalted butter, softened, for greasing the pan; 2 cups (300 g) zucchini, about 1 medium; trimmed and coarsely grated, then lightly squeezed in a towel (about 250 g after squeezing); 2 cups (240 g) all-purpose flour, spooned and leveled; 2 tsp (5 g) ground cinnamon; ¼ tsp (½ g) ground nutmeg (optional); 1 tsp (5 g) baking soda; ½ tsp (2 g) baking powder; ¾ tsp (4 g) fine sea salt; 2 whole (100 g) large eggs, at room temperature; ¾ cup (150 g) light brown sugar, firmly packed; ½ cup (100 g) granulated sugar; ½ cup (120 ml) neutral oil (such as canola or avocado); ⅔ cup (150 g) unfed sourdough discard (100% hydration), stirred; 2 tsp (10 ml) pure vanilla extract; 1 tbsp (12 g) turbinado or coarse sugar, for sprinkling on top (optional)

From the MyKitchenBank Kitchen

A moist, cinnamon-scented loaf with a subtle tang from unfed sourdough discard, tender shreds of zucchini and toasted walnuts in every slice. It's an easy way to use up discard and garden zucchini with no starter feeding or rising time.

Prep: 31 min
Cook: 1 hr 13 min
Wait: 1 hr 15 min
Total: 2 hr 59 min
Makes: 1 loaf (10 slices)

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Ingredients

10 servings

1 cup (100 g) walnut halves, coarsely chopped
1 tbsp (14 g) unsalted butter, softened, for greasing the pan
2 cups (300 g) zucchini, about 1 medium; trimmed and coarsely grated, then lightly squeezed in a towel (about 250 g after squeezing)
2 cups (240 g) all-purpose flour, spooned and leveled
2 tsp (5 g) ground cinnamon
¼ tsp (0.5 g) ground nutmeg (optional)
1 tsp (5 g) baking soda
½ tsp (2 g) baking powder
¾ tsp (4 g) fine sea salt
2 whole (100 g) large eggs, at room temperature
¾ cup (150 g) light brown sugar, firmly packed
½ cup (100 g) granulated sugar
½ cup (120 ml) neutral oil (such as canola or avocado)
⅔ cup (150 g) unfed sourdough discard (100% hydration), stirred
2 tsp (10 ml) pure vanilla extract
1 tbsp (12 g) turbinado or coarse sugar, for sprinkling on top (optional)

Equipment (8)

9×5-inch (23×13 cm) loaf pan
Rimmed baking sheet for toasting nuts
Box grater
Clean kitchen towel or several layers of paper towel
Large mixing bowl and medium mixing bowl
Whisk and rubber spatula
Wire cooling rack
Instant-read thermometer (optional)

Steps

Before you start

Use unfed sourdough discard at about 100% hydration (equal weights flour and water), straight from the fridge or at room temperature. Stir it before measuring.
Weigh the ingredients if you can. Zucchini and discard vary a lot by volume, and the batter's moisture matters.
Set eggs out 20 minutes ahead so they mix smoothly into the batter.
Plan about 75 minutes of cooling before slicing. Cutting the loaf warm makes it gummy and crumbly.

1
Preheat and toast walnutsOven 350°F / 175°C
- Position a rack in the center of the oven and preheat to 350°F (175°C).
- Spread the chopped walnuts on a rimmed baking sheet in a single layer.
- Toast for 8 minutes, stirring once halfway, then slide them onto a plate to cool.
- Leave the oven on.
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Ready when: Walnuts smell nutty and look a shade darker
Tip: Nuts go from toasted to burnt quickly. Set a timer and check at 6 minutes if your oven runs hot.
2
Prepare the pan
- Use the softened butter to grease the bottom and sides of a 9×5-inch (23×13 cm) loaf pan thoroughly, including the corners.
- For easy removal, line the bottom and long sides with a strip of parchment, leaving a little overhang.
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Ready when: No bare spots remain in the pan
3
Grate and squeeze zucchini
- Coarsely grate the zucchini on a box grater (no need to peel).
- Gather the shreds in a clean kitchen towel and squeeze gently over the sink, just until the heavy dripping stops.
- You should have about 250 g (1¾ cups).
- Fluff the shreds with a fork.
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Ready when: Shreds are damp but not dripping when pressed
Tip: Don't wring the zucchini bone dry. Leaving some moisture keeps the loaf tender.
4
Whisk dry ingredients
- In a medium bowl, whisk together the flour, cinnamon, nutmeg (if using), baking soda, baking powder, and salt for about 30 seconds until evenly combined with no clumps of spice or soda.
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Ready when: Mixture is uniformly tan with no visible streaks
5
Whisk wet ingredients
- In a large bowl, whisk the eggs with the brown sugar and granulated sugar for about 1 minute until smooth and slightly lightened.
- Whisk in the oil, sourdough discard, and vanilla until fully blended and no streaks of discard remain.
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Ready when: Mixture is smooth, glossy, and uniformly golden-brown
Tip: Break up any brown sugar lumps now. They won't dissolve once the flour goes in.
6
Fold batter together
- Add the dry ingredients to the wet bowl and fold with a rubber spatula about 12 to 15 strokes, until only a few streaks of flour remain.
- Add the squeezed zucchini and cooled walnuts, reserving 2 tablespoons of walnuts for the top if you like.
- Fold just until no dry flour is visible.
- The batter will be thick and spoonable.
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Ready when: No dry flour pockets remain; batter is thick and evenly speckled
Tip: Stop mixing as soon as the flour disappears. Overmixing makes the loaf tough and rubbery.
7
Fill the pan
- Scrape the batter into the prepared pan and spread it evenly, pushing it into the corners.
- Smooth the top, scatter with the reserved walnuts, if using, and sprinkle with the turbinado sugar for a crunchy crust.
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Ready when: Batter fills the pan about two-thirds full with a level surface
8
Bake the loafOven 350°F / 175°C
- Bake on the center rack at 350°F (175°C) for 60 to 70 minutes.
- After 40 minutes, tent loosely with foil if the top is browning too fast.
- The loaf is done when it is deep golden, the center springs back lightly, and a toothpick inserted into the center comes out clean or with a few dry crumbs.
- An instant-read thermometer should register 205°F (96°C).
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Ready when: Toothpick comes out clean or with dry crumbs; center reads 205°F (96°C)
Tip: A toothpick with wet batter means it needs 5 more minutes. A zucchini streak is fine, but raw batter is not.
9
Cool in the pan
- Set the pan on a wire rack and let the loaf cool for 15 minutes.
- Run a thin knife around the edges, then lift the loaf out using the parchment overhang or by inverting it.
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Ready when: Loaf releases easily and feels sturdy to lift
10
Cool completely and slice
- Transfer the loaf to the wire rack, right side up, and cool for at least 60 minutes until room temperature.
- Slice into 10 slices with a serrated knife using a gentle sawing motion.
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Ready when: Loaf is no longer warm to the touch in the center
Tip: Slicing too early gives gummy, crumbly slices. The wait is worth it.

Good to know

Tips

Weigh the discard and zucchini. Too much discard or unsqueezed zucchini makes a gummy center.
Squeeze the zucchini gently. You want to remove excess water but keep it moist.
If the top browns before the center is done, tent the loaf with foil and keep baking.
Discard that is very old or has a strong alcohol smell will add sharper tang. Use fresher discard for a mellow loaf.

Make ahead

Bake the loaf up to 1 day ahead. The flavor deepens overnight. Wrap once completely cooled. You can also grate and squeeze the zucchini up to 1 day ahead and refrigerate it in an airtight container.

Storage & reheating

Room temperature: wrap tightly or store in an airtight container for up to 3 days. Fridge: up to 7 days, wrapped well. Freezer: wrap whole or sliced loaf in plastic and foil for up to 3 months. Thaw at room temperature for 2 to 3 hours, or warm a slice in a 300°F (150°C) oven or toaster oven for 5 to 8 minutes, or microwave for 15 to 20 seconds.

Substitutions

walnut halves → pecans, or omit. Pecans toast the same way. Omit nuts for a nut-free loaf, or use chocolate chips instead.
neutral oil (such as canola or avocado) → melted unsalted butter. Gives a buttery flavor, but the crumb is slightly firmer once cooled.
all-purpose flour → half whole wheat flour. Replace up to 120 g of the flour with whole wheat. The loaf will be denser and nuttier.
unfed sourdough discard (100% hydration) → plain whole-milk yogurt or buttermilk. Use the same weight if you have no discard. You'll lose the sourdough tang, but the texture is similar.