Rhubarb jam - Mano Kitchen

Category	Details
Prep Time	15 minutes
Maceration Time	1 hour (inactive)
Cook Time	25–30 minutes
Cooling & Setting Time	4 hours
Total Time	1 hour 45 minutes (plus cooling)
Yield / Last of the Recipe	3 half-pint (8 oz / 240 ml) jars — approx. 48 tablespoons total
Storage Shelf Life	Up to 4 weeks refrigerated; up to 12 months sealed in a pantry

Table of Contents

Ingredients

2 pounds (900 g) fresh rhubarb stalks, trimmed, washed, and sliced into ½-inch (1.25 cm) pieces (about 6 to 7 cups chopped)
2 cups (400 g) granulated white sugar (gives a balanced tart-sweet profile; increase to 2 ½ cups if you prefer a sweeter jam)
3 tablespoons (45 ml) fresh lemon juice (about 1 large lemon; essential for brightness and helping the jam set)
1 teaspoon (5 ml) pure vanilla extract or ½ teaspoon ground cardamom (optional, for subtle warmth)
Pinch of fine sea salt (balances acidity and sharpens the fruit flavor)
½ teaspoon unsalted butter (optional, stirred in during boiling to reduce surface foam)

Large, heavy-bottomed, non-reactive saucepan or Dutch oven (stainless steel, enameled cast iron, or copper—avoid bare aluminum)
Wooden spoon or heatproof silicone spatula
Small ceramic plate placed in the freezer (for testing the gel set)
3 clean half-pint (8 oz) glass jars with sterilized lids
Canning funnel and ladle

Time: 15 minutes active + 1 hour resting | Heat Intensity: None (Room Temperature)

Trim the woody ends and remove any leaves from the rhubarb stalks—rhubarb leaves contain high levels of oxalic acid and should always be discarded. Wash the stalks thoroughly and pat them dry with a clean kitchen towel.
Slice the stalks crosswise into uniform ½-inch pieces so they break down at the exact same rate. If any stalks are especially thick, slice them lengthwise down the center before chopping.
Place the chopped rhubarb into your heavy-bottomed saucepan or a large mixing bowl. Pour the granulated sugar and fresh lemon juice over the fruit, add the pinch of salt, and toss thoroughly until every piece is coated in sugar.
Let the mixture sit undisturbed at room temperature for 1 hour. During this maceration phase, the sugar draws moisture out of the rhubarb fibers, creating a natural ruby-pink syrup. This prevents the fruit from scorching when heat is applied and preserves vibrant color.

Time: 5–7 minutes | Heat Intensity: Low to Medium-Low

Before turning on the stove, place a small ceramic plate into your freezer so it is ice-cold when you test the jam later.
Transfer the macerated rhubarb and all accumulated juices into your wide, heavy-bottomed pot over low to medium-low heat.
Stir gently and continuously with a wooden spoon until the sugar dissolves completely into the liquid. You should no longer feel gritty sugar crystals scraping against the bottom of the pot. Do not rush this stage on high heat, or undissolved sugar may crystallize later in the jars.

Time: 8–10 minutes | Heat Intensity: Medium

Once the sugar is fully dissolved, increase the burner to medium heat. Bring the mixture to a steady, gentle simmer.
Cook uncovered, stirring every minute or two to ensure the bottom does not catch. As the rhubarb heats through, the stalks will soften, release more juice, and begin to collapse into a chunky, glossy compote.
Use the back of your wooden spoon to mash any stubborn chunks against the side of the pot if you prefer a smoother spread, or leave them intact for a rustic, textured jam.

Time: 10–12 minutes | Heat Intensity: Medium-High to High

Increase the heat to medium-high (or high on a standard electric coil stove) to bring the jam to a full, vigorous rolling boil—a boil that cannot be stirred down. If foamy scum rises to the surface, stir in the ½ teaspoon of butter to disperse it.
Stir almost constantly, scraping the bottom and corners of the pot in a figure-eight motion so the thickening sugars do not burn.
As water evaporates, the bubbles will change from large, watery, fast-popping bubbles to smaller, thicker, glossy bubbles that pop slowly and heavily. If using a candy or instant-read thermometer, you are aiming for 220°F (104°C).

Time: 2 minutes | Heat Intensity: Off / Residual Heat

Remove the pot from the burner so the jam does not overcook while you test it.
Retrieve your chilled plate from the freezer and spoon ½ teaspoon of hot jam onto the center. Let it sit for 30 seconds, then push the edge of the puddle with your fingertip. If the surface wrinkles and holds a clear path without flooding back together, the jam has reached its setting point. If it remains runny, return the pot to medium-high heat for another 2 minutes and retest.
Once set, stir in the vanilla extract or ground cardamom off the heat. Skim off any remaining foam with a metal spoon for crystal-clear jars.

Time: 10 minutes active + 4 hours cooling | Heat Intensity: None

Ladle the hot jam into clean, warm glass jars, leaving ¼ inch of headspace at the top. Wipe the rims clean with a damp paper towel and screw on the lids until fingertip-tight.
Let the jars cool completely undisturbed at room temperature for 4 hours while the jam sets to its final spoonable consistency.

Total Recipe Yield: This batch produces 3 standard half-pint jars (24 ounces / 680 grams total), which equals roughly 48 one-tablespoon servings. For a household eating toast or yogurt daily, one batch typically lasts 2 to 3 weeks.
Refrigerator Storage (Quick Method): Once cooled, store the jars in the refrigerator. Unopened or opened, refrigerator rhubarb jam stays fresh, bright, and flavorful for up to 4 weeks.
Freezer Storage: Leave ½ inch of headspace in freezer-safe jars, cool completely, and freeze for up to 6 months. Thaw overnight in the fridge before using.
Pantry Canning (Long-Term Storage): If you process the filled jars in a boiling-water bath for 10 minutes (adjusting for altitude), sealed jars will keep in a cool, dark pantry for up to 12 months. Once opened, refrigerate and consume within 4 weeks.

Serving Size: 1 tablespoon (approx. 20 g)

Servings Per Recipe: 48

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