Tate & Lyle
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A novel, effective way to keep produce fresh? Put an egg on it.

Researchers have found great preservation results for highly perishable fruit by coating them in a nanocomposite “egg wash”.

With so much global attention on the problem of food waste, many novel coatings to enhance shelf life are being investigated and developed, with this latest news documented in a recent article published in peer-reviewed journal, Advanced Materials.

The study’s authors were aiming to find a cheap, natural protein-based alternative to wax coatings that could keep produce just as fresh.

“Reducing food shortages is vital in this effort and is often addressed by the development of genetically modified produce or chemical additives and inedible coatings, which create additional health and environmental concerns,” the Rice University (Houston, Texas) researchers state.

“Herein, a multifunctional bio‐nanocomposite comprised largely of egg‐derived polymers and cellulose nanomaterials as a conformal coating onto fresh produce that slows down food decay by retarding ripening, dehydration, and microbial invasion is reported.

“The coating is edible, washable, and made from readily available inexpensive or waste materials, which makes it a promising economic alternative to commercially available fruit coatings and a solution to combat food wastage that is rampant in the world.”

The coating is a combination of egg white powder mixed with water, and the addition of trace amounts of egg yolk powder, glycerol for flexibility, cellulose for durability, and the turmeric extract curcumin for antibacterial purposes.

The scientists dipped strawberries, avocados, bananas, and papayas into a the mixture and monitored changes in shelf life over time.

Over the next two weeks, they monitored both the coated fruit and an uncoated control, comparing them visually, and checking for stiffness and weight over time. Uncoated produce ripened, and in some cases rotted to a point of being inedible, within a week. Coated fruit, on the other hand, faced minimal degradation, retained most of its water weight, and generally held up better.

Egg wash coating may prevent rotting of fruit
A side-by-side comparison on bananas, avocados, papayas, and strawberries that were coated with an egg wash, compared with ones that were not.

The coating was found to successfully reduce oxygen exposure and water loss — two conditions that contribute to ripening.

The study concludes: “The coating is mechanically robust, easy to produce, possesses extraordinary gas barrier properties, and could be sourced from waste biomaterials as well.

“Through the demonstration of four fruit models, we showed that the coating can retain freshness, appearance, and aroma for at least one week longer than uncoated samples, validating the universal effectiveness of the coating in preventing fruit rotting.

“Its edibility (biocompatibility) and washability (solubility) in water also reduce food safety concerns. We believe this work presents an innovative approach to addressing the global food waste problem as an environmentally friendly, highly scalable, and low‐cost freshness preserver.”

Journal Reference: https://onlinelibrary.wiley.com/doi/10.1002/adma.201908291

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