Fabrication, characterization and antifungal evaluation of polyphenolic extract activated keratin starch coating on infected tomato fruits

In recent times, the application of protein-based bio-composite edible films in postharvest preservation of food and agricultural products is attracting increased attention due to their biodegradability, eco-friendliness and sustainability. In this study, an avocado pear peel polyphenolic extract enriched keratin-starch composite film was fabricated, characterized and evaluated for antimicrobial activity against fungal infected tomato fruits after 6 days of storage at room (25 ± 2 °C) temperature. The SEM/EDX and FTIR results revealed the successful film formation with high degree of compatibility and homogeneity. Following a 6-day post-coating loss in weight of the coated tomato fruits decreased significantly (p < 0.05) with increasing extract concentration while titratable acidity showed a significant (p < 0.05) increase with increasing extract load. Ascorbic acid and lycopene contents were significantly (p < 0.05) higher in the avocado pear peel polyphenolic extract-loaded films. No significant effect was observed in catechol oxidase activity of the tomato extract across the different treatment groups. In addition, fungal growth inhibition showed a dose dependent increase consistent with avocado pear peel polyphenolic load in coated tomato fruits compared to control. Results obtained in this study showed that polyphenolic activated keratin-starch coating was able to reduce spoilage-induce weight loss as well as conserve the overall quality (including titratable acid levels, lycopene and ascorbic acid contents) of fungal-infected tomato fruit and reduce microbial growth. Therefore polyphenolic activated keratin-starch coating could serve as a sustainable and ecofriendly postharvest preservation method to prolong the shelf life of tomato fruits.