Changes in Volatile Flavor Substances during Postharvest Infection of Fresh Ginger with Fusarium graminearum

In this study, Fusarium graminearum was identified as the pathogen causing the decay of ginger from Jiangshan, Zhejiang Province during postharvest storage by tissue separation, morphological characterization, ribosomal DNA internal transcribed spacer (rDNA-ITS) sequence analysis and phylogenetic tree construction. By using solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS), the changes of volatile flavor in fresh ginger during infection with F. graminearum postharvest were studied through the determination of volatile flavor compounds in healthy tissues, the junction between healthy and diseased tissues, and diseased tissues of fresh ginger. Principal component analysis (PCA) was used to evaluate the flavor quality of fresh ginger during postharvest disease development. The results showed that a total of 58 volatile flavor substances were detected in ginger, of which 40 substances were detected in healthy tissues, 35 substances in the junction of diseased and healthy tissues, and 39 substances in diseased tissues. These volatile flavor substances mainly included olefins, alcohols, esters, aldehydes, and ketones. Olefin compounds were the major components contributing to fresh ginger flavor, accounting for more than 80% of all flavor compounds. During disease development, the content of olefin flavor compounds increased significantly (P < 0.05), and the sesquiterpene components zingiberene and β-sesquiterpene were detected in different parts of fresh ginger and their contents continued to increase, which could be used as the indexes for determining whether or not fresh ginger is infected with F. graminearum after harvest. This may be due to the activation of the resistance mechanism of pathogen infected fresh ginger and consequent release of sesquiterpene components in large quantities.