Effects of Commercial Natural Compounds on Postharvest Decay of Strawberry Fruit

Gray mold and Rhizopus rot, which is caused by Botrytis cinerea and Rhizopus stolonifer, respectively, are the most destructive forms of postharvest decay of the strawberry fruit. In this work, we tested the effectiveness of the control on the postharvest decay of the strawberry fruit (Fragaria × ananassa Duch cv. ‘Monterey’) following postharvest applications of six commercial natural compounds: chitosan-based coating compound (1% of ‘ChitP’, ‘ChitS’, ‘ChitK’, ‘ChitO’), commercial essential oil (EOs) products based on grapefruit seed extract (0.5% of ‘GraFr’), sweet orange (0.5% of ‘SwOr’), a product that included eugenol, geraniol, and thymol EO, (0.4% of ‘EuGeTh’), an organic compound as humic acid (0.5% w/v of ‘HuAc’), and, lastly, methyl jasmonate plant growth regulator (1% v/v ‘MeJA’). Strawberries were dipped in solution for 30 s and incubated at room temperature (20 ± 0.5 °C) or at cold storage conditions (4 ± 0.5 °C) following 4 days of shelf life at 20 °C. The treatments with ‘ChitP’, ‘ChitS’, and ‘ChitO’ provided ~30%–40% reduction of gray mold in cold storage conditions, while the ‘MeJA’, ‘SwOr’, and ‘GraFr’ with high activities of volatile substances were more effective at controlling gray mold at room temperature. ‘HuAc’, ‘ChitK’, and ‘ChitO’ were more effective at controlling Rhizopus rot in both cold storage (~50%) and room temperature conditions.