Abstract:
Rigorous control of ethylene inside storage atmosphere is cardinal to maintain
quality of climacteric fruit, including avocado cv. Hass. This can be achieved using the
ethylene action inhibitor, 1-methylcyclopropene (1-MCP). The recent development of a
novel palladium (Pd)-based ethylene scavenger, e+® Ethylene Remover, provides a new
opportunity to delay avocado fruit ripening.
A new method was developed to sequentially extract and quantify both lipids and
sugars from the same avocado mesocarp tissue sample. Extraction by homogenization with
hexane yielded slightly less oil than the standard Soxhlet technique whilst the fatty acid
profiles of the oil extracts were similar. Extraction of the resulting filter residue with
methanol (62.5%, v/v) better recovered sucrose, perseitol and mannoheptulose as compared
to ethanol (80%, v/v). The new method has a shorter extraction time, lower extraction
temperature and requires less solvent.
Presence of e+® Ethylene Remover in storage atmosphere removed all ethylene and
accordingly delayed the ripening of avocado cv. Hass stored at low temperature. 1-MCP
also inhibited ripening, yet, unlike e+® Ethylene Remover it impaired subsequent ripening.
It was possible to slow down the ripening rate after the climacteric has been induced by
removing ethylene below 1 μL L-1 in presence of e+® Ethylene Remover, and the scavenger
was effective in combination with modified atmosphere packaging (MAP).
Blocking ethylene action or removing ethylene did very slightly affect the fatty acid
composition of the mesocarp oil. Depending on the origin and maturity of the fruit, 1-MCP
and e+® Ethylene Remover better maintained seven-carbon sugars concentrations in
mesocarp. Results support the view that mannoheptulose and perseitol could be important
features of the avocado ripening process but more research is necessary to elucidate their
exact function.
Mesocarp abscisic acid (ABA) was quantified using a newly developed LC-ESIMS/
MS method. ABA increased as fruit ripened but appeared to be at least partly regulated
by ethylene. Whether ABA influences the ethylene-associated ripening in avocado cv. Hass
remains to be determined in future.
