The bactericidal activity of beta-caryophyllene photooxidized in acetonitrile was examined for 5 Gram-positive and 4 Gram-negative foodborne bacteria. The beta-caryophyllene (5 x 10(-3) M) was photooxidized in acetonitrile containing Rose Bengal (6.25 x 10(-4) M) for 24 h under fluorescent light. The antimicrobial activities of samples were determined by the agar-disc diffusion method. Active compounds from the photooxidized beta-caryophyllene were isolated by silica gel open-column chromatography in conjunction with recyclic high-performance liquid chromatography (HPLC), and were identified by infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. The antimicrobial activity of the photooxidized beta-caryophyllene was strongly enhanced against Streptococcus aureus and Vibrio parahaemolyticus, relative to that of beta-caryophyllene, but was weakly enhanced against other tested bacteria. The photooxidized beta-caryophyllene contained 3 active compounds specific for these 2 bacteria, and the compounds were identified as 5-alpha-hydroxycaryophylla-4(12),8(13)-diene, 5-alpha-hydroxycaryophylla-3(4),8(13)-diene, and 5-beta-hydroxycaryophylla-3(4),8(13)-diene. The efficacies of these compounds were similar, but the efficacy of 5-beta-hydroxycaryophylla-3(4),8(13)-diene was slightly higher than that of the other 2 compounds. The results suggest that the antibacterial activities of beta-caryophyllene for S. aureus and V. parahaemolyticus could be enhanced by dye-sensitized photooxidation, and the photooxidized beta-caryophyllene and the isolated individual compounds could be useful antimicrobial agents to control the growth of S. aureus and V. parahaemolyticus in certain food systems.

Summary and ImplicationsAdding 2% SL increased the hardness, springiness, cohesiveness, chewiness, and resilience of breast rolls. The color a* and b*values of turkey rolls with 2% SL added were significantly lower than those of the control, and this difference was maintained after irradiation and during storage. Breast rolls containing antimicrobials had more lipid oxidation than control. Irradiation promoted the formation of dimethyl disulfide and dimethyl trisulfide. Adding PB in breast rolls greatly increased the formation of benzene during irradiation. It also implies that certain spices or foods containing high amounts of phenolic compounds may not be suitable for irradiation. The combination of SL and SDA has a strong potential as an antimicrobial treatment for RTE meats, but low-dose irradiation (<2.0 kGy) is preferred due to side effects of irradiation.