Assessment of eucalyptus oil integrated with carboxymethyl cellulose (CMC) for controlling postharvest soft rot in Citrus sinensis fruits induced by Colletotrichum gloeosporioides and Aspergillus niger

Abstract Background The demand for oranges remains unsatisfied due to low market yields, often attributed to postharvest diseases. Addressing this issue necessitates the exploration of natural antimicrobials as alternatives to synthetic preservatives to ensure safety and extend shelf life. Methodology This study investigated the efficacy of carboxymethyl cellulose integrated with eucalyptus oil in mitigating postharvest soft rot in Citrus sinensis fruits induced by Colletotrichum gloeosporioides and Aspergillus niger . Gas chromatography/mass spectrometry (GC/MS) was employed to identify eucalyptus oil phytoconstituents. In-vitro and in-vivo assays were conducted to assess the coating’s antifungal properties and quality parameters (weight loss, antioxidant activities, pH, total soluble solids, water activity, firmness, and electrical conductivity) over 20 days. The impacts of the coating on the catalase and peroxidase activities in orange fruits were also evaluated. Results GC/MS analysis revealed eucalyptol (76.60%) as the predominant constituent in eucalyptus oil. The study confirmed C. gloeosporioides and A. niger as causative agents of soft rot in orange fruits. Integration of carboxymethyl cellulose with eucalyptus oil positively influenced orange fruit quality parameters, including weight loss, antioxidant activities, pH, total soluble solids, water activity, firmness, and electrical conductivity, while enhancing antioxidant enzymatic activities. Conclusions This study demonstrates the efficacy of the carboxymethyl cellulose-eucalyptus oil coating as a potentially cost-effective approach to improving the safety, control of postharvest diseases, and quality of orange fruits.