UV-C radiation and oregano-enriched chitosan improve sour rot control in oranges

Sour rot is one of the most destructive postharvest diseases affecting citrus fruit, causing rapid deterioration and substantial economic losses during storage and distribution. In search of sustainable alternatives to conventional chemical treatments, researchers have evaluated the effectiveness of UV-C radiation and an edible chitosan coating enriched with the main compounds of oregano essential oil to control this disease.

Two complementary technologies

The study was carried out on 'Lima' oranges treated with UV-C radiation, the chitosan emulsion and a combination of both technologies. Researchers assessed the development of sour rot caused by Geotrichum citri-aurantii, together with defense-related enzyme activity, postharvest quality parameters and consumer sensory acceptance.

Results showed that both UV-C radiation and the chitosan coating significantly reduced disease development compared with untreated fruit. The combined application also provided effective pathogen control, highlighting the potential of integrating both technologies to reduce postharvest losses in citrus.

Enhancing the fruit's natural defense mechanisms

Enzymatic analyses revealed that the treatments modulated the activity of several defense-related enzymes during storage. These physiological responses suggest that both UV-C radiation and the chitosan coating help strengthen the fruit's natural resistance against pathogen infection.

Postharvest quality remains unaffected

Beyond disease control, the treatments did not negatively affect the main physicochemical characteristics of the oranges throughout storage. The fruit maintained its commercial quality, demonstrating that these technologies can be implemented without compromising important postharvest attributes.

Sensory evaluations also produced encouraging results. Consumers showed good overall acceptance of all treated fruit, while the combined UV-C and chitosan treatment significantly improved fruit appearance without negatively affecting aroma perception.

A promising sustainable solution for citrus preservation

According to the authors, both the individual and combined application of UV-C radiation and a chitosan emulsion containing oregano essential oil compounds represent an effective strategy for controlling sour rot in 'Lima' oranges. By reducing disease development while preserving commercial quality and consumer acceptance, these treatments offer a promising sustainable alternative for postharvest disease management in citrus.

Source

da Silva, A. M., Terao, D., Silva, I. S. O., Bizeto, M. A., Camilo, F. F., Maia, A. H. N., Marques, A. T. B., Behrens, J. H., Dias Vilela, E. S., & Fracarolli, J. A. (2026). Effects of UV-C radiation and a chitosan emulsion containing oregano essential oil compounds on sour rot control and postharvest quality of orange. Postharvest Biology and Technology. https://www.sciencedirect.com/science/article/pii/S0925521426004540