Traditional and alternative strategies to protect apple fruits against scald

V.A. Gudkovskii, L.V. Kozhina
The described research was conducted from 2015 to 2018 at the I.V. Michurin Federal Research Centre (Tambov region, Russia) with apple cultivars that differ in susceptibility to scald: ‘Granny Smith’, ‘Antonovka obyknovennaya’, ‘Martovskoye’, ‘Bogatyr’, etc. Currently, the following strategies to protect fruits against scald are used – postharvest treatment with an ethylene biosynthesis inhibitor (1-MCP), storage in ultra-low oxygen atmosphere (ULO), dynamic atmosphere (DCA), and a combination of different storage methods along with a 1-MCP treatment. However, the scald problem is not completely resolved in some cultivars. The aim of the study was to determine the fruit protection mechanisms against scald by using various postharvest treatments and to develop a strategy for a new fruit protection method against this physiological disorder. Fruits were treated with 1-MCP, wrapped in oiled napkins and stored in an air (RA), modified (MA), or controlled atmosphere (CA, CO2 1.2-1.5%, O2 1.2-1.5%). Results indicated that that the level of ethylene, α-farnesene and its oxidation product (CT281) in fruits placed in controlled atmosphere, oiled napkins, and indicator tapes (IT), impacted losses from scald and also fruit firmness. Reduction of fruit susceptibility to scald by oil treatment or wrapping in oiled napkins was due to a decrease in the content of α-farnesene (oxidation substrate) and its oxidation products in fruit peel due to the mineral oil absorbing this compound, by the 1-MCP treatment – due to inhibiting the synthesis of ethylene, α-farnesene, and KT281, in ULO and DCA conditions – due to the inhibition of ethylene synthesis under low oxygen, in DCA conditions – due to the high content of ethanol which inhibits they synthesis of ethylene and α-farnesene. In the napkins impregnated with vaseline oil (in which the fruits were packed), and in indicator tapes located in the chamber without direct contact with fruits, a highly active compound – α-farnesene was found. This demonstrates that this compound can move from the cuticle peel to the surrounding atmosphere and possibly affect scald development. The amount of α-farnesene in IT was dependent on the cultivar, method of storage, 1-MCP treatment, etc. Absorption or oxidation of α-farnesene in storage atmosphere provides the opportunity to develop a new non-chemical method for protecting fruits against scald.
Gudkovskii, V.A. and Kozhina, L.V. (2021). Traditional and alternative strategies to protect apple fruits against scald. Acta Hortic. 1325, 167-176
DOI: 10.17660/ActaHortic.2021.1325.25
apple fruits, scald, 1-MCP, RA, MA, ULO, ethylene, α-farnesene, CT281

Acta Horticulturae