Articles
DIFFERENTIAL EFFECTS OF CO2 AT LOW AND HIGH O2 ON THE STORAGE QUALITY OF TWO APPLE CULTIVARS
Article number
326_17
Pages
165 – 174
Language
Abstract
The horticultural effects of elevated CO2 at low and high O2 tensions were examined on ‘Jonathan’ (JO) and ‘Golden Delicious’ (GD) apples.
The gas combinations examined were 0, 5, 10, 15 and 20% CO2 at 3 and 15% O2, using a flow-through system, where the fruit was stored at 0°C in 30 1 plastic barrels.
The fruit was examined 3 times at intervals of 2 months, upon removal from storage and after 1 week at 20°C. JO was more sensitive than GD to CO2 injury, which appeared both externally and internally in the former and only externally on the latter.
The threshold for peel injury to JO was 10% CO2 and it occurred more severely and earlier at 15% O2 than at 3% O2. GD peel injuries occurred at 15% CO2 + 3% O2, with little difference between the two O2 levels at 20% CO2. The responses of the two cvs. to CO2 were both similar and dissimilar.
The development of superficial scald (which did not occur at 3% O2 on either cv.), diminished at 15% O2 with increasing CO2 and was completely inhibited by 20%. Fruit softening was inhibited with increasing CO2 levels in a similar manner at both O2 tensions, even though the higher O2 level enhanced softening.
At 20% CO2 the O2 level was irrelevant even after one week in air at 20°C, as no softening occurred at this level both during storage and subsequent ripening.
Both responses could be related to the total inhibition of ethylene evolution, which occurred at 20% CO2 at both O2 tensions.
Different responses of the two cvs to CO2 were observed with regard to its effects on chlorophyll degradation and titratable acid content.
Chlorophyll degradation was predominantly inhibited by increasing the level of CO2 for JO and by reducing the O2 level for GD. Titratable acid, which is higher in JO than in GD, was affected in the formeronly by reducing O2 tension.
In GD, acidity was higher when CO2 was increased to 10% at 15% O2 and to 5% at 3% O2. The differences became more significant as storage progressed and during ripening at 20°C. These differences in organic acid metabolism in response to CO2 might be related to the different susceptibilities of the cvs. to CO2 injury.
The gas combinations examined were 0, 5, 10, 15 and 20% CO2 at 3 and 15% O2, using a flow-through system, where the fruit was stored at 0°C in 30 1 plastic barrels.
The fruit was examined 3 times at intervals of 2 months, upon removal from storage and after 1 week at 20°C. JO was more sensitive than GD to CO2 injury, which appeared both externally and internally in the former and only externally on the latter.
The threshold for peel injury to JO was 10% CO2 and it occurred more severely and earlier at 15% O2 than at 3% O2. GD peel injuries occurred at 15% CO2 + 3% O2, with little difference between the two O2 levels at 20% CO2. The responses of the two cvs. to CO2 were both similar and dissimilar.
The development of superficial scald (which did not occur at 3% O2 on either cv.), diminished at 15% O2 with increasing CO2 and was completely inhibited by 20%. Fruit softening was inhibited with increasing CO2 levels in a similar manner at both O2 tensions, even though the higher O2 level enhanced softening.
At 20% CO2 the O2 level was irrelevant even after one week in air at 20°C, as no softening occurred at this level both during storage and subsequent ripening.
Both responses could be related to the total inhibition of ethylene evolution, which occurred at 20% CO2 at both O2 tensions.
Different responses of the two cvs to CO2 were observed with regard to its effects on chlorophyll degradation and titratable acid content.
Chlorophyll degradation was predominantly inhibited by increasing the level of CO2 for JO and by reducing the O2 level for GD. Titratable acid, which is higher in JO than in GD, was affected in the formeronly by reducing O2 tension.
In GD, acidity was higher when CO2 was increased to 10% at 15% O2 and to 5% at 3% O2. The differences became more significant as storage progressed and during ripening at 20°C. These differences in organic acid metabolism in response to CO2 might be related to the different susceptibilities of the cvs. to CO2 injury.
Authors
R. Ben-Arie, A. Levine, L. Sonego, Y. Zutkhi
Keywords
Controlled atmosphere, superficial scald, ethylene, ripening, titratable acidity, Malus sylvestris
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