Step-by-Step Preparation

Step 1: Make the Watermelon Juice

1. Chop and blend about 1½ to 2 cups of fresh watermelon chunks until smooth.
2. Pour the puree through a fine mesh strainer into a bowl to remove pulp and seeds.
3. Measure 1 cup of the strained juice for your recipe.

💡 Tip: Choose sweet, ripe watermelon for the best natural flavor. Taste and adjust with sweetener if needed.

Step 2: Sweeten and Blend with Sodium Alginate

1. Add 1–2 tablespoons of sugar or agave syrup to the juice. Stir to dissolve.
2. Slowly whisk in ½ teaspoon sodium alginate — sprinkle it gradually to avoid clumping.
3. Use a blender or immersion mixer for 1–2 minutes to fully hydrate the alginate.
4. Let the mixture rest for 15–30 minutes to eliminate air bubbles.

🧪 Sodium alginate works best when blended into a low-calcium, smooth liquid. Resting helps remove trapped air for clearer boba.

Step 3: Prepare the Calcium Bath

1. In a separate bowl, mix 2 cups cold water with 1 teaspoon calcium lactate or calcium chloride.
2. Stir until the powder is fully dissolved.

⚠️ Calcium chloride has a stronger taste and reaction speed than calcium lactate. Use lactate for a milder experience or when flavor clarity is important.

Step 4: Form the Popping Boba

1. Transfer the rested watermelon mixture into a squeeze bottle, dropper, or use a small spoon.
2. Gently squeeze or drop the liquid one drop at a time into the calcium bath.
3. Watch as the drops instantly form into jelly-like spheres!

🔬 This works due to reverse spherification: the alginate in the juice reacts with calcium ions in the bath to form a thin gel shell.

Step 5: Let the Boba Set

1. Allow the pearls to sit in the calcium bath for 30–60 seconds, depending on your desired “pop.”
2. The longer they sit, the thicker the shell becomes.
3. Use a slotted spoon or mesh strainer to remove them carefully.

Step 6: Rinse and Store

1. Immediately transfer the boba pearls into a bowl of clean cold water to stop the reaction and rinse off the calcium.
2. Let them sit in the rinse water for 1–2 minutes.
3. Drain and use immediately or store in a simple syrup (1:1 sugar to water) for up to 24 hours in the refrigerator.