EFFECT OF 1-METHYLCYCLOPROPENE (1-MCP) AND AN EDIBLE COATING ON ENZYME ACTIVITY AND POSTHARVEST QUALITY OF MANGO ‘ATAULFO’

Abstract

Because of the economic impact of mango (Mangifera indica L.) fruit cv. ‘Ataulfo’ in México, the effect of 1-MCP (1-methylcyclopropene) and of a chitosan-based edible coat (EC) on the quality parameters and shelf life of ‘Ataulfo’ mango, and the effect of 1-MCP on the hydrolytic activity of cell wall enzymes were studied in this work. Physiologically mature fruits were assigned into six treatments: 1) Control; 2) EC; 3) 1-MCP, 400 nL L^-1; 4) 1-MCP, 800 nL L^-1; 5) EC + 1-MCP, 400 nL L^-1; and 6) EC + 1-MCP, 800 nL L^-1. Mangos were first stored for 7 d at 12 °C and then transferred to 20 °C for 15 d. Weight loss, firmness, pH, titratable acidity, total soluble solids (TSS), respiration rate and the activities of polygalacturonase (PG), cellulase (Cx), α- and β-galactosidase and β-glucosidase were evaluated. 1-MCP and EC did not reduce weight loss in mango, but fruits treated with 400 nL L^-1 of 1-MCP maintained the highest values of firmness throughout storage, whereas the control and EC treated fruits had already lost more than 50 % of their initial firmness 3 d after treatment, and the commercial quality was lost by day 9. Fruits did not show any significant change in pH and TSS by the imposed treatments during 12 d at storage condition. Respiration decreased in all treated fruits as compared to controls; 1-MCP + EC treated fruits delayed their climacteric peaks by 3 d. PG and Cx activities increased during fruit ripening, and PG activity was higher in control compared to fruits from other treatments. The highest activity of both glycosidases was observed on day 6. In fruits treated with 1-MCP, a reduction of PG and Cx activities was observed.