Recently Forbes Magazine reported that global production of plastic bottles had reached 1 million bottles per minute! That is a staggering figure. They went on to report that 91% of those bottles are never recycled. Imagine the ecological impact of all that plastic ending up in landfills, along the roadsides, or the oceans.
Science and industry have made several attempts to develop more environmentally friendly plastics and bottles but none have had much of an impact. The most intriguing step in the direction of making "bottles" that are more eco-friendly is a recipe that anybody can try at home! And, while these bottles are not going to replace current bottles, it is an interesting step in developing a bottle or container that can hold liquid and is completely biodegradable and, if you are brave, completely edible! Maybe with a little more experimentation, these "water bottles" can help make a big impact on the world!
This method was developed by three young scientists who they were awarded the Lexus Design Award for their spherification process called "Ooho". They went on to start a lab called Skipping Rocks Lab to improve upon their design.
How to make edible water bottles
(Click for a printable version of the instructions)
Sodium Alginate solution
Measure 1 cup of water
Add 1 gram (or 1/4 teaspoon) of Sodium Alginate
Blend until dissolved
Pour into a bowl
Be sure to clean blender before moving to the next steps
Calcium Lactate solution
Measure 5 cups water and pour in a large bowl
Add 5 grams (or 1 heaping teaspoon) of Calcium Lactate
Blend until dissolved
Alternate Method for a smaller batch of Calcium Lactate Solution
(We use this method with classes and large groups)
1. Measure 2 cups water and pour into a bowl
2. Add 2.5 grams (or 1/2 teaspoon) of Calcium Lactate
3. Blend until dissolved
Making the "water bottles"
I would encourage you to experiment with these steps to see how the "water bottles" turn out as you change the time, amount of solutions used and the flavor (when you add flavored liquids).
Measure one tablespoon of Sodium Alginate solution
Gently set the spoon with the solution into the large bowl of Calcium Lactate solution being sure to keep the solution in the measuring cup from pouring out. Allow the spoon to become completely immersed before tipping it over to pour the solution out. It may be difficult to see the ball forming - this is normal.
You may add more than one "ball" of sodium alginate to the calcium lactate bath at a time.
Set a timer for 10 minutes (minimum) and remove the "water bottles" with a slotted spoon.
We experimented with several measuring spoon sizes and found that a tablespoon was a good place to start but that a 1/4 cup spoonful of sodium alginate produced the best sized "bottle"
Increasing the time gives a more rigid outer layer. We left a few batches in for 1 hour and others for 2 hours and got good results.
Experimenting with edible water bottles
As a chemistry teacher, I always adapt all of my science experiments into activities I can do with my students. After I had experimented with making the water bottles I challenged my students to improve upon the design by focusing on the shortcomings of this design with the goal of improving these water bottles. Here is what we learned through their experimentation:
Suggestion 1: Concentrated water flavoring
The best results for improving the flavor came from using concentrated flavoring liquids like Mia and Crystal Light. We experimented with adding them to one solution and both solutions with the best taste results coming when we added flavoring to both solutions.
Suggestion 2: Powdered water flavoring
Adding powdered Crystal Light or sugar free Gatorade to the water before adding the sodium alginate or calcium lactate produced similar results to the concentrated liquids used above but the shell didn't seem to be as strong in many cases. We did try sprinkling the powdered flavoring on the outside of a normal shell and it gave the shell a zesty, sour, fruity flavor!
We tried soda, pop, fruit drinks, and many more but found that most drinks with sugar (sucrose or high fructose corn syrup) did not form with a very strong shell. There appears to be an interaction with sugar and this method which is why we started to experiment with artificially sweetened flavor enhancers (see above).
Improving Outer Shell Strength:
We altered the concentration of every solution in this experiment. The greater the concentration of sodium alginate led to a thicker shell but we found that the shell eventually becomes so thick that it is not longer very practical. Keeping the concentrations the same as the instructions and altering the amount of time it is left in the 'bath' proved to be the best method of changing the consistency of the shell.
How do edible water bottles work?
Spherification is the process of creating a gel around a liquid. This process has been used by gourmet chefs to create unique food dishes for quite some time. Sodium alginate is derived from brown algae in seaweed and is responsible for giving seaweed that gelatinous feeling when you try to squish it in your fingers; it has been used as a thickening agent for many years.
When the sodium alginate encounters the the calcium lactate it coagulates (turns to a gel) and form calcium alginate. The solution that does not interact with the calcium lactate does not coagulate thus leaving the center in liquid form.
Are edible water bottles safe?
Yes. Sodium alginate is used in many food and drug applications and is completely digested by human enzymes in the stomach. Alginates are classified as a dietary fiber. Calcium lactate is used as a calcium supplement to treat calcium deficiencies and as a food additive. So, eat and drink up! These water bottles are going to be much better on your body than eating the traditional plastic ones!
Are you making edible water bottles? Leave us a message and let us know how they turn out! Or, maybe you will improve on this recipe as you experiment - if so, let us know. And, definitely show us your best pictures:
Keep on Learning!