ASHS 2024 Conference

Ethylene affects the postharvest quality and storage life by affecting the physiological changes related to ripening in apple fruits. 1-Methylcyclopropene (1-MCP), a cyclopropane-derived compound, is an effective ethylene inhibitor that blocks ethylene receptors at the cellular level, preventing ethylene effects and delaying its production. Several commercial products are available that provide controlled release of 1-MCP. In this study, a new 1-MCP technology was used, which uses a polymer sheeting material coated with cyclodextrin-encapsulated 1-MCP that is released when exposed to high humidity. Red Delicious apples were commercially harvested in Elbridge, Michigan, and 1-MCP sheets were applied targeting different 1-MCP concentrations (50, 100, 1000, 4000 ppb) and were placed on top of the fruit held in vented cardboard apple boxes in an open room. Another commercial 1-MCP product, Easyfresh®, powder (EF), (Fine Americas, Walnut Creek, CA) was applied at multiple dosages (0, 5, 50, 100, 1000 ppb) to fruit in cardboard apple boxes within sealed chambers as controls. Treated and untreated apples were stored in a cold room at 0 °C temperature and >90% relative humidity. We examined changes in ethylene production, respiration rate, firmness, soluble solids, titratable acidity, weight loss, and superficial scald during 7 months cold storage. The EF treatment was more effective than the 1-MCP sheet treatment for a given target concentration. The effect of 4000 ppb 1-MCP sheet was similar to the 50 ppb EF for the first 3 months of cold storage. The lack of effectiveness of the 1-MCP from sheet was likely due to escape of the 1-MCP from the apple box and off-target sorption by the cardboard.  EF 100 and 1000 ppb concentrations resulted in the lowest ethylene production, respiration rate, weight loss, and superficial scald values in the overall study for 6 months. These concentrations were also influential in preserving firmness, brix, and titratable acidity values. 1-MCP sheet efficacy could be improved by raising the dosage target or changing the architecture and the materials of the boxes in which treatment occurred.