Understanding the relationship between α-farnesene metabolism and superficial scald induction in ‘Granny Smith’ apples subjected to different storage practices

M. Gerber, T. Karuppanapandian, D.W. Viljoen, A. Botes, I.J. Crouch, E.M. Crouch
Superficial scald is a major postharvest peel browning disorder affecting ‘Granny Smith’ apple during prolonged cold storage. The accumulation of α-farnesene and its auto-oxidation to 6-methyl-5-hepten-2-one (MHO) is indicated to have an associative role in superficial scald development, however, recent studies proposed a more complex model to ‘scald induction’. Postharvest management practices in the fruit industry include at harvest treatments with antioxidant diphenylamine (DPA) and 1-methylcyclopropene (1-MCP) an inhibitor of ethylene action followed by low-oxygen storage such as controlled atmosphere (CA), and dynamic controlled atmosphere-chlorophyll fluorescence (DCA-CF). Despite all these control measures, superficial scald still contributes to significant annual losses, especially in countries where the use of chemical control measures are restricted. This study, therefore, investigated the efficacy of different storage practices used by the industry to prevent scald development and to understand the relationship between α-farnesene metabolism and scald induction. To determine this, ‘Granny Smith’ apples were subjected to 7 different storage practices for 16, 24, and 33 weeks (W) cold storage (1°C) followed by a 6 W regular atmosphere (RA) shipment period (-0.5°C) and 10 days at 20°C shelf-life (10 d SL). The treatments after harvest were DPA and 1-MCP followed by RA, CA (1.5% O2 and 1.0% CO2), and DCA-CF. The results for the 2018-2019 season indicate that the CA, 1-MCP+CA, DCA-CF, and 1-MCP+DCA-CF protocols offered complete control against the development of scald during the 33 W cold storage and the post-storage cold chain. In contrast, the RA had superficial scald incidence only after 16 W of cold storage. The immediate after harvest treatment with DPA was able to delay scald development until 16 W + 6 W RA + 10 d SL. The results showed a significant increase in α-farnesene and MHO before scald symptoms developed and reflect the scald induction period.
Gerber, M., Karuppanapandian, T., Viljoen, D.W., Botes, A., Crouch, I.J. and Crouch, E.M. (2022). Understanding the relationship between α-farnesene metabolism and superficial scald induction in ‘Granny Smith’ apples subjected to different storage practices. Acta Hortic. 1348, 311-318
DOI: 10.17660/ActaHortic.2022.1348.43
https://doi.org/10.17660/ActaHortic.2022.1348.43
α-farnesene, 6-methyl-5-hepten-2-one, 1-methylcyclopropene, controlled atmosphere, dynamic controlled atmosphere-chlorophyll fluorescence
English
1348_43
311-318

Acta Horticulturae