Every year, millions of eggs are rejected for sale in supermarkets, while millions of fruits and vegetables spoil before being eaten. Scientists are now addressing both problems, utilizing rejected eggs to create a coating that keeps produce fresh longer.
The micron-thick, inexpensive, edible coating was developed at Rice University in Houston, Texas by undergrad students Seohui (Sylvia) Jung and Yufei (Nancy) Cui. They are working in the lab of materials scientist Prof. Pulickel Ajayan.
Approximately 70 percent of the coating consists of a biopolymer made from egg whites and yolks. The rest is composed of nanoscale cellulose fibers harvested from wood, a bit of curcumin derived from turmeric spice, and a small amount of glycerol – the cellulose forms a barrier that keeps water from evaporating from the produce, the curcumin has an antimicrobial effect, and the glycerol gives the coating some elasticity.
After strawberries, avocados, bananas and other fruits were dip-coated with the liquid, they were found to resist spoilage much longer than uncoated samples. More specifically, they ripened slower and resisted infiltration by bacteria, staying stiff and firm for a longer period of time.
Additionally, when free-standing films of the material were tested on their own, they proved to be highly flexible, resistant to cracking, and to exhibit a toughness similar to that of synthetic food-wrap films. And even though the coating is non-toxic, it can still be rinsed off of produce within a couple of minutes using tap water.
The scientists are now looking into replacing the egg content with plant-derived proteins, for vegans or people with egg allergies.
A paper on the research was recently published in the journal Advanced Materials.
Source: Rice University
