Nanocoating spray shows promise in extending fruit shelf life

A plant-derived sprayable nano coating could not only prolong the shelf life of fruits but also provide additional nutrients in a timesaving technique that allows the mass coating of perishable produce. Korean scientists detail the use of a rapid spray coating of iron (III)- tannic acid-metal-organic coordination complex (Fe(III)-TA-MOC) for fruits. The five second of spray coating forms a film around 5 nanometres (nm) in thickness, which can be varied in a controlled, linear fashion by the number of coating cycles. Results of a field test that looked into the post harvest shelf-life of mandarin oranges found that after 28 days of storage at 25°C, 27% of the uncoated mandarin oranges (10 out of 37) were rotten and covered with mould, while the coated mandarin oranges remained edible. Additional tests on strawberries stored at 25°C and humidity (32-45% relative humidity) found after 58 hours of storage, unsprayed strawberries became rotten with white mould, but the sprayed strawberries remained intact. The strawberries were divided into edible and inedible ones: while 56.3% of the sprayed strawberries were edible, only 6.3% of the unsprayed ___ looked edible. The idea of an edible coating for fruits and vegetables is attractive to the food and agricultural industry, where product spoilage and waste are issues the sector are under pressure to address. One such examples of nanotechnology usefulness is the edible coating of strawberries and bananas by dip coating with silk fibroin, that involved multi-cycled dip coatings and long annealing (up to 12 hours). Here, US scientists provide details of using edible silk fibroin as a coating to enhance fruits’ shelf life at room conditions by reducing cell respiration rate and water evaporation. Led by Professor Choi, the team developed a sprayable nanocoating technique using plant-derived polyphenols. These polyphenols are a nontoxic food additive and exhibit antibacterial capabilities. They can also be used with iron ions, which are naturally found in the body, to form an adhesive complex. The research team combined this polyphenol-iron complex with spray techniques. As well as coating select areas more quickly sprays can also prevent cross contamination. The solutions of TA (10 millimols (mM) and Fe(III) (10 mM) were freshly prepared with water, and poured into each container of the spray brushes.