Characterization of volatile compounds from healthy and citrus black spot-infected Valencia orange juice and essential oil by using gas chromatography-mass spectrometry.

Citrus black spot ( Phyllosticta citricarpa, CBS) is an important fungal disease that causes rind blemishes and affects quality of citrus fruits. The response of citrus to CBS in terms of volatiles was evaluated using molecular sensory science approaches. Fifty and twenty-one volatiles were identified in the orange juice and essential oil samples, respectively, via gas chromatography-mass spectrometry (GC-MS). The total volatile content in the samples increased after CBS infection, especially in the severe-infection group (SEG) juice and moderate-infection group (MOG) essential oil, which reached the highest levels. CBS enhanced floral, fruity, and off-flavor aromas and decreased the green aroma in citrus juice. Citrusy, floral, and green aromas increased in the CBS-infected essential oil. Six/five potential markers were screened in citrus juice/essential oil, respectively using the orthogonal partial least-square discriminant analysis (OPLS-DA) model. The changes in aroma profile and the difference in infection levels in citrus were attributed to these odorants.