Giant Popping Boba – with a floating filing

Giant popping boba is a sphere made of a clear juice filling and a transparent sodium alginate skin.

My giant popping boba has a special flowers and fruits filling floating in the clear juice. The boba will burst into juice when its delicate skin is poked or squeezed.

This recipe teaches us how to use the reverse spherification technique to make a snow-globe-like popping boba with a suspended flower or fruit filling.

If you want to make smaller size popping boba with the basic spherification technique, you can follow this strawberry popping boba recipe that I have posted last month.

What is Popping Boba?

Originated in Taiwan, popping boba is a fruit-flavor, colorful, beautiful, tasty, healthy, and fun-to-eat topping for bubble tea, ice cream, frozen yogurt, and a variety of desserts and beverages. Its gel-like skin will burst in your mouth when bitten. Then you will be able to taste the fruit juice center of the popping boba.

Both popping boba and tapioca boba are popular toppings to bubble tea and desserts. However, their tastes, textures, ingredients, and making processes are quite different.

Made from tapioca flour and brown sugar, tapioca boba is chewier but with less flavor than popping boba. See my classic brown sugar boba recipe here.

Popping boba can be made from all kinds of flavored drinks. The sodium alginate will form a thin and delicate skin to hold the juice. The bursting of popping boba will release an extra flavor to every sip of your drink.

How to Make Giant Popping Boba?

To make regular size small popping boba, the fruit juice is mixed with sodium alginate which will then be dropped into calcium chloride solution. This is what we called spherification technique. Each alginate droplet will form into a small ball in the calcium setting bath, causing the formation of a thin gel-like skin that can burst when squeezed.

However, when I tried to make larger-size popping bobas by using the spherification technique, I ended up getting something like this:

With the spherification technique, the large popping boba formed a thick, opaque, yet leaking skin. And the sodium alginate filling was gel-like, which made impossible for the flowers to floating freely inside the popping boba.

After that first failed attempt, I decided to use the reverse spherification method.

Reverse spherification is the process of adding a calcium-based ice ball to a sodium alginate setting bath. (We basically swapped the roles of calcium solution and alginate solution). Different from basic spherification technique, reverse spherification technique allows the use of alcohol, milk, and acidic liquids as the boba filling, while also creating more transparent, durable, yet thinner popping boba skin.

Although it will take us more time and efforts to use the reverse spherification technique, this method is more success-guaranteed and produces popping boba with a better taste and prettier appearance.

Tips for making popping boba using reverse spherification

1. Heat up the sodium alginate bath setting

With reverse spherification, we freeze the calcium lactate juice mixture into spheres, then defrost the ice balls in the alginate bath setting.

When the sodium alginate in the bath setting meets the calcium lactate on the surface of the sphere, it will form a thin yet durable membrane, like an egg yolk. As the frozen sphere melt, the membrane will hold the juice inside it, like a water balloon.

To speed up the defrosting process, we should heat up the alginate bath to 70°C/158°F. It will take the hot alginate bath about 5 minutes to completely thaw an ice sphere.

If we use room temperature alginate bath instead, the ice spheres will take hours to defrost. And if the reverse spherification process is too long, the boba will form a thick and uneven skin, instead of a thin and delicate membrane.

2. Use calcium lactate instead of calcium chloride 

Both calcium lactate and calcium chloride are often used with sodium alginate for making popping boba.

The difference is that calcium lactate has a neutral taste, while calcium chloride tastes salty and bitter. 

Calcium chloride can only be used to make the setting bath to activate the sodium alginate, as what we did in the strawberry popping boba recipe. When using calcium chloride in basic spherification, we need to rinse off the setting bath to get rid off the salty taste after the popping boba is made. 

Calcium lactate can be used for reverse spherification. In this recipe, we will dissolve the calcium lactate into juice and consume it. Therefore, calcium lactate, who has a better taste, would be a better choice than calcium chloride.

3. Choice of juice filling for popping boba

Unlike basic spherification which will not work if the juice filling is too acidic or contains too much calcium, reverse spherification allows you to use almost any type of drinks you like, such as soda, fruit juice, milk, tea, coffee, or alcoholic drink.

You can use any type of juice to make giant popping bobas, as long as the juice is transparent. For example, you can use Sprite, green tea, lemonade, fruit juice, or alcoholic drink.

But for this specific recipe, I’d suggest you to use a transparent drink, such as Sprite, as the filling. Otherwise, you won’t be able to see the fruit or flower filling floating inside the popping boba, if the drink is too dark.

4. Decarbonate the juice filling

If you choose to use carbonated drink (for example, I used Sprite), make sure you decarbonate it before freezing it into ice balls. Otherwise there will be too many tiny bubbles in your popping boba, then you won’t be able to see the flower or fruit fillings very well.

To decarbonate a fizzy drink, you can pour the soda into a pot and warm it up (no need to boil), keep stirring until the soda becomes flat. 

5. Use a blender to mix sodium alginate

Sodium alginate is hard to be dissolved if you stir the mixture with a whisk. A simple method is adding the sodium alginate directly into the blender. Blend the sodium alginate with water for 1 minute, you will be able to get a well-combined sodium alginate solution.

If you don’t have a blender, make sure you whisk the mixture for 5 to 10 minutes until the sodium alginate is fully dissolved.

6. Use a kitchen scale with at least 1/10th of a gram precision

Small variations in the quantities can drastically change your results. The process of making popping boba is like a chemical experiment. Eyeballing it or using a measuring teaspoon will not work.

EQUIPMENT you will need:

• Kitchen scale (with at least 1/10th of a gram precision)
• Blender (optional)
• Sphere Ice Mold with Lid
• Food thermometer (optional)

INGREDIENTS list

• 6 small strawberries (For the floating filling, you can also use edible flowers, cranberries, orange pulps, pomegranate pulps, or anything else that’s colorful and can float.)
• 6 g calcium lactate 
• 600 g Sprite (or any other drink of your choice: green tea, lemonade, fruit juice, or alcoholic drink)
• 5 g sodium alginate
• 1 liter clean water

Step-by-step INSTRUCTIONS:

1. Place fruits or edible flowers of your choice into the sphere ice mold. (Do not overfill the ice mold. In each tray, I’d put only 1 small strawberry, or 3 edible sakura flowers, or other fruits in similar size of a small strawberry. You can add some sweet fermented rice or edible glitter to make the popping boba look prettier, like a snow globe.)

2. Add 6g calcium lactate and 600g juice of your choice (I used Sprite)to a large bowl, whisk until fully dissolved. Pour the calcium lactate solution into the bottom piece of the ice cube tray, snap the top part on, then pour or inject the rest of the solution through the hole on the top until each ice cube tray is full.

3. Keep the sphere ice mold in the freezer for at least 4 hours (or overnight) until the solution is solid.

4. Add 5g sodium alginate and 1 liter of clean water to a blender. Blend on high speed until the sodium alginate is fully dissolved. (You can also whisk by hand. But the sodium alginate could be hard to dissolve. You may need to keep whisking for about 10 minutes.)

5. Pour the sodium alginate solution into a pot, warm it up to about 70°C/158°F. (You can use a food thermometer, or tell the water temperature by observing: Once tiny bubbles start to form on the bottom of the pot, the water is around 70°C/158°F.)

6. Turn off the heat, pour the warm sodium alginate solution to a large cup. Gently drop a calcium lactate ice ball into the warm solution. Let the ice ball sit, uninterrupted in the warm bath, for about 5 minutes or until the ice is completely thawed. (At the beginning, the ice ball will float on the surface. You don’t need to press it into the water. It will gradually be submerged under the water as it gets thawed.)ts thawed.)

7. Use a slotted spoon to transfer the popping boba to a serving plate.

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