Activity of trans-2-hexenal against Penicillium expansum in 'Conference' pears

Aims: To investigate the effects of trans-2-hexenal on blue mould disease, patulin content and fruit quality in 'Conference' pears. Methods and Results: Fruits, wounded and inoculated with Penicillium expansum or non-inoculated, were exposed to trans-2-hexenal vapour treatment (12.5 mu l l(-1)) at 20 degrees C. A greater reduction of decay was obtained by treatment application 24 or 48 h after inoculation, in contrast trans-2-hexenal application 2 h after inoculation was ineffective. Fruit storage temperature (-1 degrees C) after treatment did not affect the antifungal activity. Although 2-h exposure to trans-2-hexenal was effective in reducing blue mould, an exposure of at least 8 h was required to reduce fruit patulin content. Treatments did not affect fruit physical-chemical characteristics. After 6 days at 20 degrees C following exposure, trans-2-hexenal residue in treated fruits was less than the natural content of the compound in unripe fruits. Conclusions: trans-2-Hexenal treatment is effective in the reduction of blue mould infections and patulin content in Conference pears when applied 24-48 h after pathogen inoculation. Significance and Impact of the Study: trans-2-Hexenal could be a natural alternative to fungicides in the control of P. expansum infections. Further work is needed to study the methods and conditions avoiding the persistence of off-odours and off-flavours in pears after their exposure to trans-2-hexenal vapours.