Effect of controlled atmospheres with varying O2/CO2 levels on the postharvest senescence and quality of broccoli (Brassica oleracea L. var. italica) florets

Abstract

Controlled atmosphere (CA) has been widely used to help extend the shelf life and maintain the quality of horticultural products. In the present study, broccoli (Brassica oleracea L. cv. Youxiu) florets were stored under CA with high levels of O2/CO2 at 15 °C, including 100 % O2, 80 % O2 + 20 % CO2, 60 % O2 + 40 % CO2, 40 % O2 + 60 % CO2, and air (control), to determine the effects of CA on storage period and on some physiological properties during storage. The results showed that compared with the control, the treatments combining O2 and CO2 effectively extended the storage period and inhibited respiration rate, ethylene production, and reductions in weight loss, chlorophyll, and ascorbic acid levels. Moreover, the CA treatments inhibited the increases in both superoxide radicals (O2−·) production rate and hydrogen peroxide (H2O2) level and reduced malondialdehyde accumulation, which could be beneficial in delay of senescence by alleviation of oxidative damage. In addition, broccoli florets exposed to CA conditions maintained lower activities of superoxide dismutase and peroxidase that are responsible for scavenging of O2−· and H2O2 and alleviating lipid peroxidation. Among the treatments, the maximum efficacy was observed with a CA of 40 % O2 + 60 % CO2, which prolonged the storage period of broccoli heads to 17 days (d) compared with 4 d under air treatment. Conversely, 100 % O2 treatment accelerated senescence and deterioration in the quality of broccoli, resulting in a shorter storage period. These results suggest that the establishment of an appropriate CA condition with high levels of O2/CO2 may be an ideal strategy for maintaining the quality of broccoli florets during storage.