Respiration and Quality Responses of 'Bing' Sweet Cherry to Different Atmospheres during Cold Storage and Shipping

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.