Keeping Fruit Fresh Longer with a Nanocellulose Film

David Palenski
9th January, 2024

Keeping Fruit Fresh Longer with a Nanocellulose Film

A photograph of fresh fruit.

Photographer: Miomir Magdevski / CC BY SA (Source)
Bananas are a globally consumed fruit, but their short shelf life presents significant challenges for storage and transportation, leading to substantial food waste. Bananas rapidly ripen and deteriorate after harvest due to high respiration rates and ethylene production – a natural plant hormone that triggers ripening[2]. Extending the time bananas remain fresh is therefore a key goal for researchers and the food industry. A recent study from Seoul National University[1] investigated a novel approach to preserving bananas using an edible coating made from carboxymethylcellulose nanofibers (CM-CNFs) and red cabbage extract (RCE). The study focused on creating a protective layer around the bananas to slow down the ripening process. CM-CNFs are derived from cellulose, a natural component of plant cell walls, and are processed to create very fine fibers. These fibers are chemically modified and mechanically ground to form a suspension that can be applied as a coating. The resulting film is transparent and forms a dense layer when it dries, effectively reducing respiration and water loss from the fruit. The addition of red cabbage extract (RCE) provides antioxidant properties, preventing discoloration of the banana peel. The researchers found that the CM-CNF coating significantly extended the shelf life of bananas. The coating works by creating a barrier that reduces the rate at which the fruit loses moisture and releases carbon dioxide – both indicators of ripening. The RCE component combats oxidation, preventing the development of black spots on the peel, a common sign of deterioration. This dual action – reducing respiration and preventing oxidation – slows down the overall aging process of the bananas. This approach builds upon previous research into edible coatings for fruit preservation[3]. Like the CM-CNF coating used for strawberries, the banana coating relies on forming a protective barrier around the fruit. However, the addition of RCE distinguishes this study, addressing a specific problem of banana deterioration – peel browning. This is particularly relevant as the appearance of fruit significantly impacts consumer acceptance. The study also connects to broader efforts to improve banana preservation through modified atmosphere packaging[2]. While that research focused on altering the gases surrounding the fruit, this study focuses on directly modifying the fruit’s surface. Both approaches aim to control respiration and delay ripening, but the CM-CNF/RCE coating offers a simpler, potentially more cost-effective solution. Interestingly, the findings align with observations regarding the importance of the banana fruit cuticle in responding to stress[4]. The banana cuticle, the waxy outer layer, plays a crucial role in limiting water loss. While the CM-CNF coating doesn’t replicate the cuticle’s exact composition, it functionally mimics its barrier properties, reducing water loss and protecting the fruit from external factors. The study[4] also highlighted changes in the cuticle’s chemical composition during chilling injury, suggesting that maintaining cuticle integrity is vital for banana quality. The CM-CNF coating could be seen as a way to reinforce this natural protective layer. The CM-CNF coating is created through a relatively straightforward process. Cellulose is chemically modified to become carboxymethylcellulose, then processed into nanofibers through mechanical grinding. This results in a suspension with a high ‘aspect ratio’ – meaning the fibers are long and thin – which is essential for forming a uniform, transparent film. The coating is applied by dipping the bananas into the suspension, allowing the water to evaporate and leaving behind a dense, protective layer. The RCE is simply added to the CM-CNF suspension before application.

FruitsSustainabilityBiotech

References

Main Study

1) Enhanced Preservation of Climacteric Fruit with a Cellulose Nanofiber-Based Film Coating.

Published 9th January, 2024

https://doi.org/10.1021/acsomega.3c07273

Related Studies

2) Development and Application of Poly (Lactic Acid)/Poly (Butylene Adipate-Co-Terephthalate)/Thermoplastic Starch Film Containing Salicylic Acid for Banana Preservation.

https://doi.org/10.3390/foods12183397

3) Protective coating of strawberries with cellulose nanofibers.

https://doi.org/10.1016/j.carbpol.2021.117688

4) Changes of Morphology, Chemical Compositions, and the Biosynthesis Regulations of Cuticle in Response to Chilling Injury of Banana Fruit During Storage.

https://doi.org/10.3389/fpls.2021.792384


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