• Penicillium expansum;
  • spore viability;
  • hexanal;
  • volatiles;
  • antifungal effect;
  • apple

ABSTRACT: The effects of hexanal vapor on spore viability of Penicillium expansum, lesion development on whole apple fruit, and flavor volatile biosynthesis were investigated. Spore viability was reduced by 94% after exposure to a hexanal concentration of 40 μmol/L for 24 h, compared with 50% at 18 μmol/L and 20% at 9 μmol/L. Decay on whole apple fruit inoculated with 5 × 104 spores/mL of P. expansum was reduced with exposure to hexanal vapor for 48 h. Although almost all of the fruit treated with 8 to 12 jmiol/L developed decay lesions, lesion size was reduced compared with the controls. At concentrations of 15 to 19 μmol/L, and 25 to 29 μmol/L, the incidence of fruit with lesions was 44% and 24%, respectively, compared with 100% and 98% in the inoculated control apples and lesion size was further reduced. Apples treated at 4°C with only 5 to 7 jimol/L hexanal vapor also showed a marked reduction in lesion incidence. Hexanal was rapidly converted to high levels of the aroma volatiles hexanol, hexylacetate, hexylbutanoate, and hexylhexanoate, but these decreased to levels similar to the control after 4 to 7 d of being held in air. There was no detectable hexanal after holding fruit in air for 5 h.