Control of fruit postharvest decay with tran-2-hexenal: prospectives and problems

The α,β-unsaturated aldehyde trans-2-hexenal, one of the most widespread volatile compounds naturally occurring in fruits and vegetables, is known for its antimicrobial activity and interaction in plant defence signalling. Trials were carry out to test it as potential postharvest biofumigants against Monilinia laxa in stone fruits, Penicillium expansum in pome fruits and Botrytis cinerea in strawberries. All tested pathogens were controlled by treatment, with efficacy ranging from 33% to 98% depending on species and cultivars. Particularly interesting was the control of P. expansum in ‘Golden Delicious’ apples, where treatment (12.5 μLL-1) applied 24 hours after inoculation highly reduced blue mould infection (98% of efficacy) and patulin content in fruit (under limit of quantification). No significant difference in quality traits and trans-2-hexenal residue were found in treated ‘Golden Delicious’ apples with respect to control after shelf-life. In contrast, some detrimental effects were induced by treatment with concentrations of trans-2-hexenal effective in decay control in other cvs. Phytotoxic symptoms were observed in apricots, nectarines, peaches, strawberries and ‘Abate Fetel’ pears, while off-odours and or off-flavours were perceived in plums, ‘Conference’ and ‘Bartlett’ pears, and ‘Royal Gala’ apples.