Twelve-year-old Madison Checketts was named one of the 30 finalists in the 2022 Broadcom Masters Competition, the country’s premier science, technology, engineering and math competition for middle school students. Courtesy of Society for Science
For as long as she can remember, Madison Checketts has loved the beach. Yet when frequenting stretches of the coast around Escondido, California, on annual family vacations, she couldn’t help but notice all the plastic water bottles cluttering the sand and ocean.
“The beach is one of my favorite places to go, and seeing it all trashed up with plastic water bottles, I just felt like this needed to change,” Checketts says.
After learning more about plastic pollution and ways to reduce it, she designed what she calls the Eco-Hero. The gelatinous water bottle is actually edible.
The now 12-year-old student from Eagle Mountain, Utah, started working on the project in October 2021 as part of her elementary school’s science fair. After being selected as one of the students from her school to compete in the school district’s science fair, she won first place at a state science fair before advancing to a national competition. In September, Checketts was named one of the 30 finalists in the 2022 Broadcom Masters Competition, the country’s premier science, technology, engineering and math (STEM) competition for middle school students. There, she was surrounded by other young inventors who designed projects like a remote-controlled robotic hand that could be used in natural disaster situations and a foot-controlled welcome mat that can wirelessly unlock a door to help those with arthritis and other hand conditions.
In her early research, when Checketts asked herself what she could do to make the world a better place, she immediately thought about reducing plastic pollution. Plastic products like water bottles are designed as single-use items intended to be thrown out after use.
Americans consume more than 30 billion plastic water bottles annually, with the vast majority not being recycled. After being tossed away, plastic water bottles often end up in the ocean, where more than 5.25 trillion pieces of plastic trash circulate.
Checketts won first place at the Central Utah STEM Fair before advancing to the national competition. Courtesy of Society for Science
Checketts stumbled upon a website focused on reverse spherification—a method of enclosing a liquid in a gel membrane—and wondered if she could make an edible water bottle using this process. Reverse spherification was popularized by a team of chefs, creatives and researchers from the Spanish restaurant El Bulli in 2005. The process stems from another culinary technique pioneered in the 1940s called spherification—used to create culinary delights like the “popping boba” in bubble tea drinks—in which a liquid is turned into a semi-solid sphere. Compared to basic spherification, reverse spherification allows for the liquid encased in the membrane to remain a liquid for longer. The sphere itself can be bigger, too.
Checketts’ approach was based on further internet research about reverse spherification methods. She relied on a chemical reaction between two common food additives—a salt called calcium lactate and a natural polymer found in brown algae called sodium alginate. When mixed together, the chemicals form a cross link resulting in a gel membrane that traps liquid.
After some trial and error, Checketts made her final prototype by mixing calcium lactate, xanthan gum (another common food additive and thickening agent), lemon juice and water in a blender. She froze the calcium lactate solution in a rectangular mold and then placed the frozen rectangle in a sodium alginate solution, rotating it until a membrane began to form. Once the membrane was fully formed, after about seven minutes, Checketts removed the oval-shaped membrane from the sodium alginate solution and placed it in a bath of distilled water to stop the membrane from continuing to form. When she let the edible water bottle sit in the fridge submerged in a mixture of lemon juice and water, it lasted about three weeks before the membrane burst.
The Eco-Hero holds about three-quarters of a cup of water and costs about $1.20 to make. Basically, the consumer bites a hole at the top of the gelatinous membrane, drinks the water and then either eats the membrane or throws it away. In addition to being edible, the Eco-Hero is also biodegradable. Checketts says the drink tastes like water with a hint of lemon, and the edible membrane has the texture of a gummy bear and tastes slightly lemony but comes to have no taste as it’s chewed.