Abstract: Newhall navel oranges were used to evaluate the effect of Huanglongbing (HLB) on fruit quality such as appearance, physicochemical properties, bioactive ingredients and essential oil components. Results showed that infection with HLB could decrease single fruit mass, prevent the peel from turning yellow, remarkably reduce soluble sugars and soluble solids contents, representing fruit maturity, and ultimately result in significant quality deterioration. Moreover, the contents of hesperidin in the peel and pulp increased significantly, and the number of volatile components in the essential oil also increased by 90.90% after the infection. In conclusion, the eating quality of HLB-infected navel oranges is severely reduced and cannot meet the requirements of consumers. But the increased contents of functional ingredients such as fiber and hesperidin highlight the necessity of byproduct extraction for rational utilization of orange resources. This study provides a theoretical basis for the comprehensive utilization of HLB-infected navel oranges.

Key words: navel orange, Huanglongbing, quality, essential oil, hesperidin, color