The Effect of Chitosan-Based Nanocomposite Coating on the Postharvest Life of Papaya (Carica papaya L.) Fruits

Nanochitosan, which was prepared by ionotropic gelation of chitosan and polyphosphate ions, had an average particle size of 112 nm. The nanochitosan was incorporated in formulations for chitosan-based nanocomposite (Ch-NCh) films and coatings. The 80% nanochitosan (v/v) containing film (Ch80NCh + Add) was the most compact and thinnest, followed by the 40% nanochitosan (v/v) containing film (Ch40NCh + Add) and the 1% chitosan-plus-additives film (Ch + Add) which was highly porous and the thickest. The capability of the coating formulations to extend the postharvest life of cv. Sinta papaya fruits, which were stored at 14.6 degrees C and 79% relative humidity, was evaluated. Control (uncoated) and blank (additives only, Add only) coated fruits reached the limit of marketability on the 7th and 10th days of storage, respectively. The Ch + Add coated fruits reached the limit of marketability on the 14th day of storage. The Ch-NCh coated fruits did not reach the limit of marketability at the end of the 26-d storage period. The Ch-NCh coatings retarded peel color change, minimized disease incidence, shriveling and weight loss, and maintained pulp firmness. Titratable acidity of the Ch80NCh + Add coated fruits peaked later (19th day) than that of the other fruit samples which peaked on the 14th day of storage. Total soluble solids (TSS) content generally increased during storage with the Ch-NCh coated fruits generally having lower TSS readings. Results indicate that chitosan-based nanocomposite coatings retard fruit ripening in papaya cv. Sinta.