Fumigating 'Crimson Seedless' table grapes with (E)-2-hexenal reduces mold during long-term postharvest storage

Seedless table grapes (Vitis vinifera L.) cv. Crimson Seedless were exposed to (E)-2-hexenal vapor during cold storage to determine its potential as a fumigant for long-term control of postharvest mold. Fruit were fumigated with 0.86 or 1.71 mmol (100 or 200 mu L neat compound, respectively) (E)-2-hexenal per 1.1-L container for 2 weeks during 2 degrees C storage. Containers were moved to 20 degrees C storage after 4,8, and 12 weeks for determination of mold incidence and berry quality over 12 days. The headspace concentration of (E)-2-hexenal, measured by gas chromatography, reached a maximum of 2.5 and 4.2 mu mol.L-1 for 0.86 and 1.71 mmol per container, respectively, after 1 day and declined to <1 mu mol.L-1 for both treatments by 14 days. Upon removal from cold storage at 4, 8, and 12 weeks, the incidence of mold was significantly lower for (E)-2-hexenal-treated fruit. Control of mold by (E)-2-hexenal fumigation persisted through 12 days of 20 degrees C storage, even though mold generally increased in all treatments. The two levels of(E)-2-hexenal were similar in their suppression of mold. Fumigation did not affect O-2 or CO2 concentrations within the containers, nor were fruit firmness or soluble solids content affected. Postharvest fumigation of seedless table grapes with the natural volatile compound (E)-2-hexenal shows promise for control of mold.