Effect of high carbon dioxide storage and gamma irradiation on membrane deterioration in cauliflower florets

Controlled atmospheres and gamma irradiation are technologies which extend storage-life of fruits and vegetables. Separate and combined effects of high CO2 storage and gamma irradiation on cell membranes from cauliflower florets (Brassica oleracea L., Botrytis group) were investigated. Storage of the florets for 8 days at 13°C, either under 15% carbon dioxide or in air after irradiation at 2 kGy, accelerated the deterioration of microsomal membranes during storage. Both treatments caused an early loss in lipid phosphate. Irradiation enhanced the free fatty acid content of the membranes during storage and caused an extensive protein loss. When irradiation and high CO2 storage were combined, electrolyte leakage significantly increased while protein loss was considerably reduced. The results indicate that high CO2 and irradiation accelerate membrane degradation through different mechanisms. The combined effects of the treatments were not additive, but membrane yield was apparently reduced. CO2 protected the membranes from protein loss induced by irradiation. The apparent increase in electrolyte leakage after irradiation may be caused by the release of ions following cell wall deterioration.