Starch/Agar Blend Film With Polyphenolic Extract From <i>Sargassum Polycystum</i> : Film Properties and Effect of Coatings on Quality of Bananas

After harvest, bananas experience biochemical changes that impact the ripening, storage quality, shelf life, and marketability of the fruit. This work investigates the effects of a polyphenolic extract from the brown alga Sargassum polycystum on the properties of a starch/agar blend film developed as a coating to maintain the quality of bananas during storage. The results showed that the addition of the polyphenolic extract improved the thermal stability of the starch/agar blend film. Moreover, the tensile strength of the neat starch/agar blend film was increased from 32.28 MPa to 34.65 MPa by adding 5 wt% of the polyphenolic extract. The tensile strength improvement was due to the homogeneous structures of the well-distributed polyphenolic extract embedded in the matrix. Fourier transform infrared spectroscopy revealed the formation of hydrogen bonds between agar, starch, and the polyphenolic extract. However, the visual appearance of the film changed when 10 wt% of the polyphenolic extract was added. The incorporation of the polyphenolic extract produced a coating that slowed down respiration, reducing weight loss, and delaying the conversion of starch to sugar in the banana pulp. Therefore, the proposed starch/agar blend with polyphenolic extract from S. polycystum has the potential to be developed for use as a safe, environment-friendly active coating to extend the shelf-life of fruits.