2013 ASHS Annual Conference

Most sweet cherries produced in the U.S. Pacific Northwest that are shipped to distant markets, are often in storage and transit for over 3 weeks. The objectives of this research were to study the effects of O₂ and CO₂ concentrations on respiration physiology and the efficacy of modified atmosphere packaging (MAP) on extending shelf life of sweet cherry. Oxygen depletion and CO₂ formation of ‘Bing’ cherry fruit were measured using a closed system method. While respiration rate was inhibited linearly by reduced O₂ concentration from 21% to ~3% to 4% at 20 °C, at 0 °C it was affected very little from 21% to ~10% but significantly from ~10% to ~1%. Elevated concentration of CO₂ (0% to 16%) did not affect fruit respiration rate in the closed system at 20 or 0 °C. ‘Bing’ cherry fruit were packaged (~8 kg/box) in 5 different commercial MAP bags and a standard perforated polyethylene liner (as control) and stored at 0 °C for 6 weeks. MAP bags that equilibrated with atmospheres of 1.8% to 7.4% O₂ + 8.8% to 10.3% CO₂ reduced fruit respiration rate, maintained higher titratable acidity (TA) and flavor, and reduced stem browning incidence compared to control after 4 and 6 weeks of cold storage. In contrast, MAP bags that equilibrated with atmospheres of 9.9% to 13.0% O₂ + 7.3% to 12.9% CO₂ had little effect on inhibiting TA loss, maintaining flavor, and reducing stem browning during cold storage. Higher CO₂ concentration in MAP retarded anthocyanin accumulation and fruit skin color darkening. All five MAP bags maintained higher fruit firmness (FF) and reduced decay compared to control after 6 weeks of cold storage. In conclusion, the atmospheres of 1.8% to 13.0% O₂ + 7.3% to 12.9% CO₂ generated by the commercial MAP, controlled decay and maintained higher FF, but only the MAP with lower O₂ permeability (e.g., equilibrated with 1.8% to 7.4% O₂) could maintain flavor and stem quality of sweet cherry compared to the standard perforated liners.