- Sep 28, 2017 -
A number of factors influence apple and pear fruit responses to 1-MCP. These include 1-MCP concentration during treatment, duration of exposure, fruit maturity, temperature at the time of treatment, and the interval between harvest and when the treatment is applied. In large storage rooms, longer treatment durations (i.e., 24 hours) may be needed to ensure adequate distribution of 1-MCP throughout the room and sufficient contact time with fruit. For example, 'Granny Smith' apples, treatment within 2 weeks of harvest induced maximal responses including complete control of superficial scald. However, fruit treated 4 or more weeks after harvest developed superficial scald and had lower firmness and titratable acidity compared to fruit treated at or within 2 weeks of harvest. Riper fruit may require treatment using concentrations at the high end of the range (~1 ppm) to achieve maximum duration of 1-MCP induced responses.
Both Controlled Atomsphere storage and 1-MCP treatment reduce fruit ethylene production. Comparisons of untreated apples stored in Controlled Atomsphere with 1-MCP treated fruit treated indicate no differences in fruit quality for the first several months after treatment. For 'Gala' apples, values for firmness and titratable acidity were similar through 3 months after harvest. As storage duration increased beyond 3 months, fruit stored in Controlled Atomsphere had slightly higher firmness and titratable acidity compared to 1-MCP treated fruit; however, 1-MCP treated fruit remained firmer with more titratable acidity than fruit stored in air. We have observed the combination of 1-MCP treatment at harvest then storage in Controlled Atomsphere can provide an additional benefit in titratable acidity retention after long-term storage (7 months) of 'Gala' apples.
Ethylene regulates production of volatile compounds that contribute to apple and pear aroma and flavor. Long-term Controlled Atomsphere storage tends to reduce the capacity of fruit to produce these compounds, and 1-MCP treatment induces the same response. The duration of this 1-MCP response is determined by treatment conditions, particularly treatment concentration.