A metabolomics approach to study the effects of pre- and postharvest factors on Braeburn browning disorder

Braeburn (Malus domestica Borkh.) is a popular apple cultivar worldwide. During storage, Braeburn is susceptible to the development of an internal browning disorder (Braeburn Browning Disorder; BBD). The incidence and intensity of BBD vary with batch and growing season. The objective of this study is twofold: 1) to study the effects of various pre- and postharvest conditions on the metabolic profile of Braeburn apple; and 2) to identify a biomarker that can predict the occurrence of BBD. Braeburn was grown in an orchard of the experimental tree fruit research station (RSF-pcfruit) in Sint-Truiden (Belgium) under 8 different treatment combinations of different levels of calcium and potassium fertilisation with different levels of triazole fungicides. Fruit were harvested at two dates (early and late), with cortex samples being collected at harvest and after 2 weeks, 4 weeks, 2 months, 4 months and 6 months of controlled atmosphere storage at 1°C and under 8 different combinations of 2 levels of O2 (optimal versus low), CO2 (optimal versus high) and 1-MCP (treatment versus no treatment). Metabolomics analyses were performed using a GC-MS based protocol optimized for apple. In this study, about 30 metabolites were identified and quantified from the polar extracts of the Braeburn apple cortical tissue. By comparing the at-harvest metabolic profile of the samples, the effects of the different preharvest treatments is determined. Further, by analysing the metabolic profile of the samples from the different storage conditions, a differentiation is made between the fruit ripening related changes and the BBD specific changes.status: publishe