Mango tolerance to reduced oxygen levels in controlled atmosphere storage

'Haden' and 'Tommy Atkins' mangoes (Mangifera indica L.) were stored in air , 2, 3, 4 or 5 kPa O-2 plus N-2, or 25 kPa CO2 plus air for 14 days at 15 d egreesC or 21 days at 12 degreesC, respectively, then in air for 5 days at 20 degreesC to determine their tolerance to reduced O-2 levels for storage times encountered in typical marine shipments. All low 9 treatments reduced mature green mango respiration (CO2 production), however, elevated ethanol production occurred in 2 and 3 kPa O-2 storage, with the levels two to thr ee times higher in 'Tommy Atkins' than 'Haden'. In contrast, 'Haden' fruit at the onset of the climacteric also accumulated ethanol in 4 kPa O-2 and p roduced 10 to 20-fold more ethanol in 2 and 3 kPa O-2 than preclimacteric f ruit. While there were no visible injury symptoms, off flavor developed in mature green fruit at 2 kPa O-2 and in ripening initiated fruit at 2 and 3 kPa O-2, Ethanol production was not affected by storage in 25 kPa CO2. Ethy lene production was reduced slightly by low O-2, however, 'Haden' fruit als o showed a residual inhibitory effect on ethylene production after 2 or 3 k Pa O-2 storage, while 'Tommy Atkins' fruit stored in 2 kPa O-2 produced a b urst of ethylene upon transfer to air at 20 degreesC. Fruit firmness, total sugars, and starch levels did not differ among the treatments, but 2, 3 or 4 kPa O-2 and 25 kPa CO2 maintained significantly higher acidity than 5 kP a O-2 or air. The epidermal ground color responded differently to low O-2 a nd high CO2 in the two mango cultivars. Only 2 kPa O-2 maintained 'Haden' c olor better than air, while all low O-2 levels maintained LTommy Atkins' co lor equally well and better than air. High CO2 was more effective than low O-2 in maintaining 'Haden' color, hut had about the same effect as low O-2 On 'Tommy Atkins'. Results indicate that preclimacteric 'Haden' and 'Tommy Atkins' mango fruit are able to tolerate 3 kPa O-2 for 2 or 3 weeks at 12 t o 15 degreesC and that tolerance to low O-2 decreases as mangoes ripen. Res ults also show that Low O-2 and high CO2 affect mango ripening differential ly.