Rice University researchers say that eggs, that would otherwise be wasted, can be used as the base of an inexpensive coating to protect fruits and vegetables. The Brown School of Engineering lab of materials scientist Pulickel Ajayan and colleagues have developed a micron-thick coating that solves problems both for the produce and its consumers, as well as for the environment.
When the coating was applied to produce by spraying or dipping, it showed a remarkable ability to resist rotting for an extended period comparable to standard coatings like wax but without some of the inherent problems.
The work by Rice undergraduate students Seohui (Sylvia) Jung and Yufei (Nancy) Cui is detailed in Advanced Materials. The coating relies on eggs that never reach the market. As the United States produces more than 7 billion eggs a year and manufacturers reject 3% of them, the researchers estimate more than 200 million eggs end up in landfills.
Along with being edible, the multifunctional coating slows dehydration, provides antimicrobial protection, and is largely impermeable both to water vapor to slow dehydration and to gas to prevent premature ripening. The coating is all-natural and washes off with water.
Egg whites (aka albumen) and yolks account for nearly 70% of the coating. Most of the rest consists of nanoscale cellulose extracted from wood, which serves as a barrier to water and keeps produce from shrivelling, a small amount of curcumin for its antimicrobial powers, and a splash of glycerol to add elasticity.