Effects of Oxygen Levels on Pigment Concentrations in Cold-Stored Green Beans (Phaseolus vulgaris L. Cv. Perona)

Abstract

Controlled-atmosphere (CA) effects on chlorophyll and carotenoid concentrations in green beans were studied. Green bean pods (cv. Perona) were stored at 8°C and 98% relative humidity, with and without controlled atmospheres (samples: air, 5% O2-3% CO2; 3% O2-3% CO2; 1% O2-3% CO2), and then transferred to 20°C to simulate ambient temperature. Green beans stored in air at 8°C had good appearance for 18 days, whereas an atmosphere of 1% O2-3% CO2 extended the storage period to 22 days. Samples stored in other assayed atmospheres (5% O2-3% CO2 or 3% O2-3% CO2) had the same shelf life as the air-stored sample (18 days). Maximum chlorophyll accumulation in air-stored green beans took place at 6 days of storage, whereas the 1% O2-3% CO2 stored sample showed the maximum chlorophyll concentration at 13 days of storage, and no significant increase of this pigment was observed in the first 6 days. Degradation of chlorophylls a and b did not yield the corresponding pheophytin compounds, because the pheophytin content also showed a significant decrease during storage. Green bean carotenoids showed similar changes in chlorophyll concentrations during storage in air, 3% O2-3% CO2, and 5% O2-3% CO2.