Effect of hexanal vapor on the growth of postharvest pathogens and fruit decay

The effect of the natural volatile hexanal was studied as an antifungal agent on the major postharvest fungal pathogens Botrytis cinerea, Monilinia fructicola, Sclerotinia sclerotiorum, Alternaria alternata, and Colletotrichum gloeosporioides. The antifungal effect of hexanal vapor was dependent on concentration and treatment duration, but sensitivity of the pathogens varied. All spores of B. cinerea and M. fructicola were killed after exposure to 900 μL/L for 12 h at 20 °C, and almost all were killed after a 24-h exposure to 450 μL/L. Only moderate numbers of spores were killed at a concentration of 200 μL/L. Mycelial growth of S. sclerotiorum on agar was completely inhibited after a 12-h exposure to 900 μL/L, but only slight inhibition occurred at 450 μL/L and none at 200 μL/L. Mycelium of A. alternata and C. gloeosporioides appeared more sensitive, with strong inhibition occurring after a 12-h exposure at 450 μL/L. Similar trends in spore viability and mycelial growth were observed at 7 °C. The antifungal effect of hexanal vapor was further tested on raspberry fruit naturally infected with B. cinerea and on peach fruit inoculated with spores of M. fructicola. Decay was markedly reduced in raspberry and almost completely controlled in peach after exposure to 900 μL/L hexanal vapor for 24 h. The potential of hexanal for postharvest decay control is discussed. © 2007 Institute of Food Technologists.