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Rhubarb Jam

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Prep Time 15 minutes
Maceration Time 2 hours to 8 hours (passive)
Cook Time 20 to 25 minutes
Total Time ~2 hours 40 minutes
Recipe Intensity Medium (requires active stirring and temperature check)
Yield 3 half-pint jars (~24 oz total / 48 tablespoons)
Shelf Life Refrigerator: 3–4 weeks | Freezer: 6 months | Canned: 1 year

Safety Warning: Rhubarb leaves contain high concentrations of oxalic acid and are toxic. Always discard and compost the leafy tops completely, using only the crisp stalks for cooking.

Ingredients

To achieve the best balance of sweet and sour, choose stalks that are firm and crisp. Darker red stalks will give your jam a vibrant pink hue, though green-leaning stalks taste just as delicious!

  • 2 lbs (approx. 900g) Fresh Rhubarb, trimmed and chopped into 1/2-inch pieces (about 6 cups chopped)

  • 2 cups (400g) Granulated Sugar (adjust slightly based on sweetness preference)

  • 2 tbsp Fresh Lemon Juice (provides natural pectin and balances the sweet-tart ratio)

  • 1 tsp Fresh Lemon Zest (adds a bright aromatic lift)

  • 1/2 tsp Pure Vanilla Extract or 1 small cinnamon stick (optional, for depth)

  • Pinch of Sea Salt (enhances the fruit flavours)

Heat & Cook Intensities Explained

Understanding heat management during jamming is essential to prevent scorch marks or runny jam:

  1. Maceration (Zero Heat): Drawing out liquid naturally using sugar.

  2. Initial Simmer (Medium Heat): Dissolving sugar crystals and softening fibrous stalks without burning.

  3. Rapid Boil (Medium-High Heat): Evaporating moisture and raising the temperature to the gel point ($220^\circ\text{F}$ / $104^\circ\text{C}$).

  4. Cooling (Off Heat): Setting and thickening naturally as pectin bonds form.

Step-by-Step Instructions

1.Macerate the Rhubarb:15 min prep + 2 hr rest.

Combine the chopped rhubarb, granulated sugar, lemon juice, and lemon zest in a large non-reactive bowl (glass or stainless steel). Toss thoroughly until all the rhubarb pieces are coated in sugar. Cover and let sit at room temperature for at least 2 hours (or overnight in the fridge). The sugar will draw out the juices, creating a rich syrup and reducing cooking time.

2.Chill Your Test Plates:Parallel setup.

Place 2 small ceramic saucers or spoons in the freezer. You will use these frozen plates later to check if the jam has set without needing a candy thermometer.

3.Bring to a Simmer:10 minutes | Medium Heat.

Transfer the macerated rhubarb and all its juices into a wide, heavy-bottomed pot or Dutch oven. Add a pinch of sea salt (and the optional cinnamon stick, if using). Set heat to Medium. Stir continuously with a heatproof spatula until the sugar dissolves completely and the mixture begins to simmer gently.

4.Cook to Gel Point:12-15 minutes | Medium-High Heat.

Increase the heat to Medium-High to bring the jam to a rolling boil. Stir frequently, scraping the bottom and sides of the pot to prevent sticking. As the mixture boils, the rhubarb will break down into soft threads and the foam will subside. Continue boiling until the mixture thickens and reaches $220^\circ\text{F}$ ($104^\circ\text{C}$) on a digital thermometer.

5.Perform the Cold Plate Test:2 minutes | Off Heat.

Remove the pot from the heat source. Place a small spoonful of hot jam onto one of your chilled freezer plates. Let sit for 1 minute, then gently push the edge of the jam with your fingertip. If it wrinkles and holds its shape, it’s done! If it feels runny, return the pot to medium-high heat for another 2 to 3 minutes and retest.

6.Finish and Jar:5 minutes | Off Heat.

Stir in the vanilla extract if using. Skim off any surface foam with a spoon. Carefully ladle the hot jam into clean, warm glass jars, leaving 1/2-inch of space at the top. Seal with airtight lids.

 

Storage & Preservation Guidelines

How long your jam lasts depends on how you choose to store it:

  • Fresh Fridge Jam (Easiest): Allow jars to cool completely to room temperature, then place in the refrigerator. Use within 3 to 4 weeks.

  • Freezer Storage: Leave 3/4-inch headspace at the top of glass jars to allow room for expansion. Freeze for up to 6 months. Thaw in the fridge overnight before serving.

  • Water-Bath Canning (Long Term): Process sealed half-pint jars in a boiling water bath for 10 minutes. Properly canned jam can be stored in a cool, dark pantry for up to 1 year.

Nutrition Facts

Servings per recipe: 48 | Serving Size: 1 Tablespoon (approx. 20g)

Nutrient Amount per Serving % Daily Value*
Calories 35 kcal —
Total Fat 0g 0%
Saturated Fat 0g 0%
Trans Fat 0g —
Cholesterol 0mg 0%
Sodium 5mg 0%
Total Carbohydrate 9g 3%
Dietary Fiber 0.4g 1%
Total Sugars 8.5g —
Includes Added Sugars 8g 16%
Protein 0.2g 0%
Vitamin C 1.2mg 2%
Calcium 14mg 1%
Potassium 35mg 1%

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