POSTHARVEST DECAY CONTROL OF GRAPE BY ACETALDEHYDE VAPORS

Acetaldehyde (AA) is a natural biological substance which is formed by the anaerobic pathway and is found in all kinds of plant and animal tissues. Treatment of grapes cv. 'Sultanina' with 5000 ppm AA vapors for 24 h reduced decay by 92% as compared with the control fruits. The reduction was achieved in several postharvest fungi, including Rhizopus stolonifer, Botrytis cinerea and Aspergillus niger. 5000 ppm AA vapors also reduced the amount of decay in grapes inoculated with R. stolonifer after 5 days at 20°C by 89%, compared with untreated grapes. Treatment with AA vapors keeps the berries firmer than the control ones. AA treatment leaves almost no residue and causes no off-flavor in the fruits; hence it can serve as an alternative to chemical fungicides in the control of postharvest decays in grapes.