Ingredients
For the sodium alginate solution
5 g Sodium alginate
1 liter (35 oz) Water, juice or flavored drink
For the the calcium chloride bath
5 g Calcium chloride
1 liter (35 oz) water
For the plain water bath
1 liter (35 oz) water
For most people, the easiest place to find these ingredients is probably on Amazon in your country.
Method
Introduction to Spherification
The technique for creating alginate hydrogels using calcium was developed by Unilever in the 1940s and 1950s. In 2003, the creative team at the iconic Spanish restaurant El Bulli built on this work to develop spherification techniques for culinary applications. Today, these ideas are being considered by a number of companies to make sustainable drink packaging, such as the edible water/drinks “bottles” I’m showing you in this video.
The spherification method we’re using here is known as “basic spherification”. You may see other methods elsewhere, such as “reverse spherification” or “frozen reverse spherification”. All the methods work in similar ways. That is, calcium ions react with alginate to form a calcium alginate hydrogel casing around your flavorsome liquid.
I’m giving you the basic spherification method here using a minimal number of ingredients which are easiest to find in most places in the world. I’m also giving you tips and tricks to get good results at home because the basic spherification method was not originally designed for making large “balloons” or “bottles”. Note, though, that all methods of spherification have pros and cons, so there’s no such thing as the “perfect method”.
The recipes for the sodium alginate and the calcium chloride solutions I’m giving you are both 0.5% w/v solutions. I’ve selected these concentrations to give you the best results.
For the sodium alginate solution
Make up the sodium alginate solution in a blender. Make sure to wash the blender well after this step. You may have lots of bubbles in your alginate solution due to incorporation of air. Let the solution stand in the fridge until it clears (this could happen either quite quickly, or take a long time, depending on how much air was incorporated).
You can use water or, preferably, a flavoured juice drink, so that the the balloons/bottles are delicious!
It’s important that you weigh out the sodium alginate precisely. That’s why I’ve given you a weight in grams. And also measure out the amount of water precisely.
Please note that it’s important that the drink is not too acidic, otherwise the gelling reaction won’t work well. There are ways to work around this issue (such as use of buffering agents to raise the pH, but this is starts to make the process more complicated).
Please also note that with this method, it’s important your drink doesn’t contain calcium. So, for example, you can’t use milk or yoghurt. Again, there are ways to work around this issue (such as use of calcium-sequestering agents, but as with the buffering agents above, this starts to make the process more complicated).
For the calcium chloride bath
Make up the calcium chloride solution using a blender.
It’s important that you weigh out the calcium chloride precisely. That’s why I’ve given you a weight in grams. And also measure out the amount of water precisely.
For the plain water bath
Use plain tap water
To make the edible balloons / bottles
After you’ve prepared your three solutions, you are ready to make the edible balloons / bottles.
Take a small scoop, and rinse it in the calcium chloride solution. Then, fill the scoop with your alginate solution (the juice). Gently, drop the scoop of alginate in the calcium chloride bath. Please see the video for details of the technique required to get a good result.
After the gel casing has formed (anywhere from 30 seconds to a few minutes, depending on the acidity of your juice), gently remove it from the calcium chloride bath, and rinse it in the plain water bath. The reason for rinsing the balloon / bottle in plain water is two-fold: first, to simply wash of the calcium chloride solution (it doesn’t taste good!); and secondly, to slow the gelling reaction.
Eat your edible balloons / bottles right away! These are great fun to make, and will give you a glimpse of the future of sustainable food and drink packaging!
Please note that edible balloons / bottles made using this method won’t keep for long. That’s because the gelling reaction will continue, even after you’ve removed the balloon from the calcium chloride bath, and rinsed off excess calcium chloride. Again, as with the issues of pH and and calcium containing drinks mentioned above, there are ways around this issue, but again, they make the process more complicated, so I’m not covering this here.
Please let me know if you’d like to see more food-science videos. I’d love to make them for you if you’re interested.
Frequently Asked Questions
Q: Can I make these with alcohol?
A: It’s best to use reverse spherification or frozen reverse spherification to make alcoholic versions of these.
Q: Can I make these with carbonated drinks?
A: You can make carbonated spheres, but not easily. You will need to use reverse spherification or frozen reverse spherification to make the the initial spheres. At this point, the spheres will not be carbonated. You will then need to force carbonate the spheres using carbon dioxide under pressure (the gel is permeable to carbon dioxide). This requires some special equipment.
