Figure 4. Evaluation of bananas ripening with and without crystalline silk coating.

Fruits were stored at 22 °C and 38% RH as received (no coating) and after coating with silk fibroin materials. Bananas were hanged from their respective stem throughout the whole experiment. (a) Time lapse photography of banana ripening indicating that silk fibroin coating decreased the ripening rate. (b) Investigation of silk fibroin-coated banana turgidity (i) when compared to uncoated controls. Turgidity was studied qualitatively by applying a dead load (200 g) on the surface of the fruit. (ii). The test was accomplished ad day 9 after coating. Silk fibroin-coated banana showed an increased firmness, when compared to uncoated control. (c) Images of the internal flesh of non-coated (i) and silk fibroin-coated (ii) bananas at day 9 post coating-treatment. Flesh of non-coated banana presented a brown colour, while silk fibroin-coated fruits preserved a tallow flesh, indication of a decreased ripening rate for the silk fibroin-coated samples.