AsianScientist (Aug. 17, 2017) – In a study published in Scientific Reports, scientists in Korea have invented an edible nanocoating that extends the shelf-life of perishable goods.
The coating of agricultural products in an edible, protective layer of material has drawn a great deal of attention in the food and agricultural industry. It could not only prolong the postharvest shelf life of produce against external changes in the environment, but also provide additional nutrients that enhance human health.
However, most versions of coatings have had intrinsic limitations in their practical application. Highly specific interactions between coating materials and target surfaces are required for a stable and durable coating. At the same time, the coating of bulk substrates such as fruits is time consuming or is not achievable using the conventional solution-based method. In this respect, material-independent and rapid coating strategies are highly demanded.
Polyphenols are metabolites of photosynthesis and possess several hydroxyl groups. They are found in a large number of plants and display excellent antioxidant properties. They have been widely used as a nontoxic food additive and are known to exhibit antibacterial as well as potential anti-carcinogenic capabilities. Polyphenols can also be used with iron ions, which are naturally found in the body, to form an adhesive complex that has been used in leather tanning and ink, among other applications.
In this study, the research team led by Professor Choi Insung of the Department of Chemistry at the Korea Advanced Institute of Science and Technology combined the chemical properties of polyphenol-iron complexes with spray techniques to develop a sprayable nanocoating technique that can be applied to any surface. This new nanocoating process forms nanometer-thick films, allowing for the coating of commodity goods such as shoe insoles and fruits in a controlled fashion.
Compared to conventional immersion coating methods, which dip substrates in specialized coating solutions, this spray technique can coat the select areas more quickly. The spray also prevents cross contamination, which is a big concern for immersion methods.
The research team has showcased the spray’s ability to coat a variety of different materials, including metals, plastics, glass, as well as textile fabrics. The polyphenol complex has been used to form antifogging films on corrective lenses, as well as antifungal treatments for shoe soles, demonstrating the versatility of their technique.
Furthermore, the spray has been used to coat produce with a naturally antibacterial, edible film. The coatings significantly improved the shelf life of tangerines and strawberries, preserving freshness beyond 28 days and 58 hours, respectively. Uncoated fruit decomposed and became moldy under the same conditions.
The technology has been patented and is currently being commercialized for widespread use as a means of preserving produce.
“Nanocoating technologies are still in their infancy, but they have untapped potential for exciting applications. As we have shown, nanocoatings can be easily adapted for several different uses, and the creative combination of existing nanomaterials and coating methods can synergize to unlock this potential,” said Choi.
The article can be found at: Park et al. (2017) Antimicrobial Spray Nanocoating of Supramolecular Fe(III)-tannic Acid Metal-organic Coordination Complex: Applications to Shoe Insoles and Fruits.
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Source: Korea Advanced Institute of Science and Technology.
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