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Earth Notes: Cactus Juice Plastic Bags

Sandra Pascoe Ortiz

Fans of the prickly pear cactus might be familiar with recipes for cactus jelly, cactus candy, and fried cactus pads or nopalitos. But how about a recipe for a biodegradable plastic bag?

Sandra Pascoe Ortiz, a scientist at the University of the Valley of Atemajac in Mexico, came up with one after seeing students experiment with cactus juice at the university’s science fair. Prickly pears grow abundantly in Mexico and the United States, and thrive in dry climates. The pads can be plucked without killing the plant, leaving it free to grow more. Ortiz peels the pads and squishes them in a juicer to create a thick, slimy, neon green liquid. Then she adds other non-toxic, plant-based ingredients to create a sticky substance that can be rolled out flat and dried. It can be made into different thicknesses, shapes that look and act a lot like plastic.

The process takes about 10 days. Right now it’s only done in the laboratory, and is not being manufactured yet on an industrial scale. While ordinary plastic bags take decades to break down in a landfill, cactus juice bags take only a month or two … sooner if they’re composted.

The U.S. generates more than 35 million tons of plastic trash annually, and that number has been growing in recent years. Researchers estimate rivers carry roughly 2 million tons of plastic waste into the sea every year. So one day, the desert-dwelling cactus plant might help protect the oceans.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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