Volatile substances of Callicarpa japonica Thunb. were examined for their antibacterial activities against six foodborne microorganisms using the optical densitometer Bioscreen C. METHODS AND RESULTS: Extracts of C. japonica were obtained by simultaneous steam distillation and solvent extraction (SDE), and those extracted for 1.5 and 2.0 h at pH 6.0 strongly inhibited the growth of Bacillus cereus and Salmonella typhimurium; the content of the volatile substances of leaves at these pH levels were 543.1 and 706.7 mg/kg, respectively. All foodborne microorganisms tested were strongly inhibited by the addition of >8% (v/v) of the SDE extracts to broth medium. The major volatile components of the SDE extracts obtained at 1.5 h and pH 6.0 were gamma-caryophyllene, 1-octen-3-ol, 2-hexenal, germacrene B, and aromadendrene II, with corresponding peak areas of 44.14, 15.6, 9.86, 5.24, and 4.01%, respectively, and major antibacterial components were 1-octen-3-ol and 2-hexenal. CONCLUSIONS: Among the 32 materials identified as volatile flavor components, 2-hexenal, 2,4-hexadienal, 1-octen-3-ol, 2,4-heptadienal, and Epiglobulol strongly inhibited microorganism growth. In particular, 2-hexenal (107.52 mg/L) and 1-octen-3-ol (678.64 mg/L) inhibited the growth of most microorganisms tested by >90%. |