Involvement of membrane degradation in response to oleocellosis induced by exogenous orange oil in citrus fruit

Abstract

Navel oranges (Citrus sinensis L. Osbeck) were treated with pure orange oil to simulate the natural cause of oleocellosis and to elucidate the mechanism involving in fruit injury caused by orange oil. Results showed that no injury was found on the rind surface of control fruits during storage. By contrast, application of exogenous orange oil onto the surface of fruits could rapidly induce peel injury. Moreover, the severity of injury increased during storage. At the end of the storage time, the collapse and discolouration scores were 17.3 and 16.7 times higher than those at 4 h after treatment. Oil treatment caused fruit membrane degradation by increasing the activities of phospholipase D and lipoxygenase, reducing the ratio of unsaturated/saturated fatty acids and enhancing the levels of hydrogen peroxide, superoxide anion, malonaldehyde, and electrolyte leakage. In addition, the treatment reduced the activities of superoxide dismutase and catalase, as well as suppressed the ascorbate acid–glutathione cycle, which led to the efficiency loss of the reactive oxygen species scavenging system.