The detection of fungal diseases in the ‘Golden Smoothee’ apple and ‘Blanquilla’ pear based on the volatile profile

• Volatile changes in fruit inoculated with Penicillium expansum and Rhizopus stolonifer are reported.
• Early non-visual detection of pathogen infection in apples is possible.
• Z-3-hexenyl 2-methylbutanoate could be a biomarker of apple infection.
• Early non-visual detection of R. stolonifer infection in pears is possible.
• 2-Butanone and α-pinene could be biomarkers of R. stolonifer in ‘Blanquilla’ pears.

Blue mould caused by Penicillium expansum is one of the major pathogens causing serious losses during the postharvest and storage periods of apples and pears. Rhizopus stolonifer has also been identified as the causative agent of important rot losses in these fruit in packinghouses after humid spring seasons. An early disease detection system could help to reduce such losses. Biotic interactions affect the emission of volatile compounds during infection, and this changed the volatile profile of ‘Golden Smoothee’ apples and ‘Blanquilla’ pears inoculated with P. expansum and R. stolonifer throughout their shelf-life at 20 ̊C for up to 7 days. Dynamic headspace-gas chromatography was used to determine if infected fruit emitted distinct volatile compounds different from those of non-infected fruit and if volatile emissions could be detected before the infection was visible in the fruit. According to the results obtained in ‘Golden Smoothee’ apples inoculated with both pathogens, Z-3-hexenyl 2-methylbutanoate could be a potential biomarker because it was quantified before these diseases were visible and was not detected in non-inoculated control fruit. Similar results were obtained for 2-butanone and α-pinene in ‘Blanquilla’ pears inoculated with R. stolonifer.