Detection of alpha-Farnesene and 6-Methyl-5-hepten-2-one Involved in the Development of Apple Superficial Scald by PTR-ToF-MS

To date, the accepted hypothesis about the development of superficial scald in apple fruit is related to the accumulation of harmful alpha-farnesene auto oxidation products, such as conjugated trienols or 6-methyl-5-hepten-2-one (MHO). The aim of this research was the implementation of an alternative, rapid, reliable, analytical technique based on PTR-ToF-MS (proton transfer reaction - time of flight - mass spectrometry) to measure the volatile organic compounds released during the progression of this disorder in an apple. This assessment was performed with three specific tissues (skin, under skin, and pulp) taken into consideration, as well as the comparison between control and treated samples with 1-MCP applied before storage. The results described here suggest the use of MHO as a novel biochemical marker to monitor the oxidative stress of apple fruit, since its concentration is significantly correlated with the early development of visible superficial scald symptoms.