Effect of Kelulut Honey Nanoparticles Coating on the Changes of Respiration Rate, Ascorbic Acid, and Total Phenolic Content of Papaya (Carica papaya L.) during Cold Storage

This study evaluated the respiration rate of coated and uncoated (control) papayas (Carica papaya L.) with 15% of Kelulut honey (KH) nanoparticles (Nps) coating solution during cold storage at 12 ± 1 °C for 21 days. The respiration rate of the papayas significantly changed during storage, with an increase in CO(2) and a decrease in O(2) and C(2)H(4), while the ascorbic acid and total phenolic content was maintained. The changes in respiration rate were rather slower for coated papayas when compared to control ones. A kinetic model was established from the experimental data to describe the changes of O(2), CO(2), and C(2)H(4) production in papayas throughout the storage period. All O(2), CO(2), and C(2)H(4) were experimentally retrieved from a closed system method and then represented by the Peleg model. The outcomes indicated the Peleg constant K(1) and K(2), which were gained from linear regression analysis and coefficients of determination (R(2)), seemed to fit well with the experimental data, whereby the R(2) values exceeded 0.85 for both coated and control papayas. The model confirmed both the capability and predictability aspects of the respiration rate displayed by papayas coated with KH Nps throughout the cold storage period. This is supported by the differences in the stomatal aperture of coated and control papaya shown by microstructural images.