Cell Wall Changes of Papaya Fruit Treated with 1-Methylcyclopropene: Postharvest Analysis through SEM and FT-IR Spectroscopy

Abstract

1-Methylcyclopropene (1-MCP), is a widely researched and commercially used molecule to delay fruit ripening and improve the shelf life, both climacteric and non-climacteric fruits. Increasing the shelf life and keeping quality, especially of important climacteric fruits like papaya using 1-MCP, which undergoes a rapid softening during the ripening process required a detailed investigation of the structural changes of fruit cell wall. These changes include modifications in the cell wall polysaccharide structure due to increased activity of hydrolyzing enzymes, pectin, hemicellulose and cellulose degradation that results in fruit softening. Pectin degradation in papaya determines the extent of softening during ripening. Hence, the present investigation describes the role of 1-MCP in retaining the firmness, postharvest. The ultrastructural changes of papaya peel and pulp were studied using Scanning Electron Microscope (SEM). The pectin degradation in untreated and 1-MCP treated fruits was analyzed through a rapid and reliable technique, FTIR spectroscopy (Fourier transform-infrared (FT-IR)). The study revealed that postharvest application of 1-MCP at 900 ppb to papaya fruits, stored under cold storage (14°C) was effective in retaining higher fruit firmness by suppressing the rapid cell wall modifications and activity of pectin degradation, which are triggered by ethylene.