Equipment
Ingredients
Fruit Base
- 1000 g blueberries, fresh or thawed frozen, rinsed and picked over
- 120 ml lime juice, freshly squeezed
- 10 g lime zest, finely grated
Sugars and Seasonings
- 600 g granulated sugar
- 1 g kosher salt
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 61 kcal
- Protein
- 0 g
- Carbohydrates
- 16 g
- Fat
- 0 g
- Fiber
- 1 g
- Sugar
- 15 g
- Sodium
- 8 mg
- Saturated Fat
- 0 g
- Monounsaturated Fat
- 0 g
- Polyunsaturated Fat
- 0 g
- Potassium
- 20 mg
- Calcium
- 2 mg
- Iron
- 0.1 mg
- Magnesium
- 1 mg
- Phosphorus
- 3 mg
- Zinc
- 0.0 mg
- Vitamin A
- 1 mcg
- Vitamin C
- 3 mg
- Vitamin E
- 0.1 mg
- Vitamin K
- 4 mcg
- Vitamin B6
- 0.0 mg
- Thiamin
- 0.01 mg
- Riboflavin
- 0.01 mg
- Niacin
- 0.1 mg
- Folate
- 2 mcg
- Water
- 20 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
In a large heavy-bottomed pot, combine the blueberries, lime juice, lime zest, granulated sugar, and kosher salt. Stir gently to coat the fruit in the sugar and let sit at room temperature for 30 minutes to macerate.
Place the pot over medium-high heat and bring the fruit mixture to a rolling boil, stirring frequently with a silicone spatula to prevent the sugars from scorching at the bottom.
Clip a candy thermometer to the side of the pot. Continue to cook at a rapid boil, stirring occasionally, until the temperature of the jam reaches exactly 105 degrees Celsius (220 degrees Fahrenheit).
Remove the pot from the heat immediately. Let the jam rest for 5 minutes, skimming off any foam that rises to the surface with a spoon.
Carefully ladle the hot jam into sterilized glass preserving jars, leaving exactly 1 centimeter (about half an inch) of headspace at the top of each jar.
Wipe the rims of the jars clean with a damp paper towel to ensure a proper seal. Secure the lids tightly, then allow the jars to cool completely undisturbed at room temperature for at least 12 hours before storing.
Chef's Notes
- If you do not own a candy thermometer, use the wrinkle test: place a small plate in the freezer before you begin. Once the jam thickens, drop a small spoonful onto the chilled plate. If it wrinkles when pushed with your finger, it is ready.
- Do not attempt to double this recipe in a single pot. Jam relies on rapid surface evaporation to reach the setting point quickly. Too much volume will result in overcooking the fruit before the water evaporates.
- A tiny pinch of kosher salt is a pastry chef secret; it acts as a flavor enhancer that cuts through the sweetness and highlights the tart, floral notes of the lime.
Storage
Refrigerator: 3 months — Duration applies after opening. Unopened jars processed in a boiling water bath are shelf-stable for up to 1 year.
Troubleshooting
Jam is too runny after resting for 12 hours
Cause: The mixture did not reach the proper setting temperature due to thermometer inaccuracy or removing from heat too soon
Fix: Pour the jam back into a pot, return to a boil, and cook for an additional 3 to 5 minutes until the correct temperature is reached, then re-jar
Prevention: Calibrate your candy thermometer in boiling water before starting, ensuring it reads exactly 100 degrees Celsius
Jam is rubbery and extremely stiff
Cause: Overcooked past the setting point or boiled for too long
Fix: Cannot be fixed to perfect jam texture, but can be gently warmed and thinned with a little hot water to serve over pancakes or ice cream
Prevention: Monitor the temperature closely as it approaches 105 degrees Celsius, as it rises rapidly at the end of the cook time
Cultural Context
Preserving summer berries is a centuries-old culinary tradition born out of the necessity to extend the harvest through harsh winters. The addition of lime to a classic blueberry preserve represents a modern, bright evolution of the technique, elevating a rustic staple with tropical citrus notes that transform it from a simple breakfast spread into a versatile culinary condiment.
