Egg Wash Keeps Fruits and Vegetables From Rotting Prematurely

A water-soluble coating made from eggs has a remarkable ability to preserve.

egg coating for fruits and vegetables
Eggs that would otherwise be wasted can be used as the base of an inexpensive coating to protect fruits and vegetables, according to Rice University researchers.

Jeff Fitlow/Rice University

 

Did you know that roughly one-third of food raised for human consumption goes to waste? Most of it is fresh fruit and vegetables that go bad in the time it takes to move from farm to store. The produce loses moisture, dries out, or grows moldy, which has led scientists to develop ways of coating, or sealing, the food to keep it fresher for longer. Typically carnauba wax is used, but now research at Rice University reveals that there might be a better way.

Scientists discovered that dipping produce – strawberries, papayas, avocados, and bananas – into an egg-based wash is remarkably good at preserving it. The coating is a mere micron thick, and made from a mixture of powdered egg whites and yolks (70 percent), some wood-sourced cellulose to act as a barrier preventing water loss, curcumin (a chemical sourced from turmeric that serves as an antimicrobial), and glycerol for elasticity.

What the scientists found was that the egg wash made a significant difference in helping produce to stay fresh over a two-week observation period. The appearance of the coated fruits and vegetables didn't change much, as they "faced minimal degradation, retained most water weight." The uncoated produce, by comparison, ripened and even rotted beyond edibility within the same time frame.

dipping apple in egg coating
Jeff Fitlow/Rice University

The Counter explains how a coating can prevent degradation. The goal is to minimize oxygen around fruit to slow the ripening process, and to halt water loss, which causes it to wilt. 

"Peels and skins and rinds can slow down the speed at which water leaves fruits and vegetables, while coatings — like wax or egg washes — can serve as additional reinforcement, keeping fruit fresh and juicy longer. The egg-based coating, as it turns out, did both: It limited each fruit’s oxygen exposure and prevented water from evaporating."

The non-toxic coating was found to be flexible and resistant to cracking; and tests "showed it to be just as tough as other products, including synthetic films used in produce packaging." For anyone with an egg allergy, the coating can be removed by thorough washing in water and is tasteless.

The scientists hope this could be a breakthrough in the fight against food waste. As materials scientists and study author Pulickel Ajayan said, "Reducing food shortages in ways that don’t involve genetic modification, inedible coatings or chemical additives is important for sustainable living." 

What's neat about this discovery is that it fights food waste in more than one way: even the coating was made from eggs that would otherwise have been discarded because they weren't fit for consumption. The researchers said that roughly 3 percent, or 200 million, of U.S.-produced eggs go to waste annually. So if this were scaled up, it could be a win-win situation all around.

It's exciting to see such research happening, as reducing food waste is one of the most effective things we can do to curb planetary warming and the climate crisis, not to mention stave off hunger and improve nutrition for over 10% of the world's population. The simpler and more straightforward the solution, the more likely it can be implemented by millions of farmers around the world.