It’s easy to make an edible water bottle using a natural, biodegradable product from algae. The result is a thin gel shell around a sphere of water. You can eat the bottle or drink the water and discard the shell. Here is is an easy spherification recipe to make a gel coating around liquid water. Once you master this simple molecular gastronomy technique, you can apply it to other liquids.
Edible Water Bottle Recipe
You only need a few simple ingredient to make an edible water bottle:
- 1 gram sodium alginate
- 5 grams of calcium lactate
- Large bowl
- Smaller bowl
- Hand mixer or whisk
- Spoon with a deep, rounded bottom
- Slotted spoon
The key ingredient for this project is sodium alginate, a natural gelling powder derived from algae. The sodium alginate gels or polymerizes when reacted with calcium. It’s a common alternative to gelatin, used in candies and other foods. Sodium alginate reacts with calcium to form a polymer. This recipes uses calcium lactate as the calcium source, but you can substitute calcium gluconate or food-grade calcium chloride. All of the ingredients are readily available online and at grocery stores that carry ingredients for molecular gastronomy.
The size of the spoon determines the size of your water bottle. Use a large spoon for big water blobs, such as a soup spoon or gravy ladle. Use a tiny spoon, like a measuring spoon, if you want little caviar-sized bubbles. Another option is to make water bottles using a kitchen baster.
Make an Edible Water Bottle
- In a small bowl, add 1 gram of sodium alginate to 1 cup of water.
- Use the hand mixer or whisk to combine the sodium alginate. Let the mixture rest about 15 minutes to remove any air bubbles. As air escapes, the mixture changes from white to transparent.
- In a large bowl, stir 5 grams of calcium lactate into 4 cups of water. Mix well to dissolve the calcium lactate.
- Use your rounded spoon to scoop up the sodium alginate solution. Or, use a baster to suck up the liquid.
- Gently drop the sodium alginate solution into the bowl containing the calcium lactate solution. It immediately forms a ball of water in the bowl. You can drop more spoonfuls of sodium alginate solution into the calcium lactate bath, but don’t let the water balls don’t touch each other because they’ll stick together. Let the water balls sit in the calcium lactate solution for 3 minutes. It’s okay to gently stir them around. The time determines the thickness of the polymer coating. Use less time for a thinner coating and more time for a thicker coating.
- Use a slotted spoon to gently remove each water ball. Place each ball in a bowl of clean water to stop any further reaction. Now you can remove the edible water bottles and drink them. The inside of each ball is water. The bottle is edible too—it’s an algae-based polymer.
Using Flavors and Others Liquids
You can color and flavor both the edible coating and the liquid inside the “bottle.” It’s okay to add food coloring to the liquid. You can use flavored beverages rather than water, but it’s best to avoid acidic drinks because they affect the polymerization reaction. There are special procedures for dealing with acidic beverages.
The basic spherification method works great for water, but what about fruit juices, soft drinks, alcohol, and milk? Make algae “bottles” for these liquids using reverse spherification. It’s the reverse of the standard technique because the liquid contains the calcium and gets added to the sodium alginate bath, rather than the other way around.
- Add a tiny amount of calcium lactate or calcium lactate gluconate to the liquid. Milk already contains calcium, so it may not need any more.
- Drip this liquid into a sodium alginate bath made using 1 gram sodium alginate to 1 cup water.
- Alternatively, freeze the liquid in round ice cube tray and then drop the frozen balls into the sodium alginate bath.
How Liquid Water Bottles Work
The edible, biodegradable capsule of a liquid water bottle is a polymer formed by reacting sodium alginate (a natural brown algae product) and calcium. Using calcium chloride as the calcium source, the chemical reaction is:
2NaAlg + CaCl2 → CaAlg2 + 2NaCl
The alginate coagulates, but most of the water is excluded. This reaction releases a small amount of salt into the water, but since only a small amount of calcium salt is needed, flavor isn’t unduly affected.
Safety and Biodegradation
Alginate gels are well-studied for human consumption and safety for release into the environment. When eaten, the shell of the liquid water bottle acts as dietary fiber and passes through the digestive tract. Undigested alginate and discarded liquid water bottles naturally decompose as calcium diffuses out of the gel matrix. The resulting alginate is broken into simple sugars by bacteria (using the enzyme alginate lyase), free radical oxidation, or exposure to acids or bases.
- Lee, Kuen Yong; Mooney, David J. (2012). “Alginate: Properties and biomedical applications.” Progress in Polymer Science. 37 (1): 106–126. doi:10.1016/j.progpolymsci.2011.06.003
- Potter, Jeff (2010). Cooking for Geeks: Real Science, Great Hacks, and Good Food. O’Reilly Media, Inc. ISBN 0-596-80588-8.
- Steinbüchel, Alexander (2005). Polysaccharides and Polyamides in the Food Industry. Wiley-Blackwell. ISBN 978-3-527-31345-7.
- his, Hervé (November 2006). “Food for tomorrow? How the scientific discipline of molecular gastronomy could change the way we eat.” EMBO Reports. 7 (11): 1062–6. doi:10.1038/sj.embor.7400850