2013 ASHS Annual Conference

There is considerable interest in the use of modified atmosphere packaging (MAP) for maintaining pear (Pyrus communis L.) quality similar to controlled atmosphere storage without the extensive investment in infrastructure and instrumentation. The objectives of this research were to study respiration physiology of the major pear varieties (‘Starkrimson’, ‘Bartlett’, ‘Bosc’, ‘Comice’, ‘Forelle’, and ‘Anjou’) grown in U.S. Pacific Northwest  and their responses to MAP during storage at –1.1 °C. Results indicate that varieties vary significantly in respiration rate, ethylene production rate, and internal CO₂ concentration at –1.1 or 20 °C after satisfying the chill requirement of each variety, which in turn affects MAP response. The storage life with marketable quality of fruit packed in standard perforated polyethylene liners were 3 months for ‘Bartlett’, 4–5 months for ‘Comice’, ‘Bosc’, and ‘Forelle’, and 5–6 months for ‘Anjou’. The commercial MAP equilibrated with atmospheres of 10% to 16% O₂ + 3-6% CO₂, depending on variety, inhibited ethylene production, and respiration rates and extended storage life up to 4–5 months for ‘Bartlett’ and 6 months for ‘Comice’, ‘Bosc’, ‘Forelle’, and 6–7 months for ‘Anjou’ with maintenance of fruit flesh firmness and skin color without physiological disorders. After extended cold storage, MAP packaged fruit could be ripened to their characteristic texture and flavor. However, ‘Starkrimson’ developed internal browning (IB) after 2 months of storage in MAP with atmospheres of either  9.5% O₂ + 6.0% CO₂ or 18.0% O₂ + 2.5% CO₂. ‘Starkrimson’ was highly susceptible to CO₂ injury, possibly related to its high respiration rate and internal CO₂ concentration. In conclusion, the storage life of ‘Bartlett’, ‘Bosc’, ‘Comice’, ‘Forrelle’, and ‘Anjou’ with high quality could be increased by up to 2 months when packed in MAP compared with fruit packed in standard perforated polyethylene liners.