INHIBITORY EFFECTS OF FLAVOR COMPOUNDS ON STAPHYLOCOCCUS-AUREUS WRRC B124

Acetanisole (4'-methoxyacetophenone) (AC), benzaldehyde (BE), cinnamal dehyde (CI), diacetyl (DI), phenylpropionaldehyde (PH), and pyruvaldeh yde (PY) were tested against growth of S. aureus WRRC B124 in brain he art infusion broth. Activity was assessed in the presence and absence of oxygen at 12, 19 and 37C, and in combination with mild (20 min at 5 0 or 60C) heat treatments. The carbonyl compounds limited S. aureus gr owth. at minimal inhibitory concentrations (MIG) of less than or equal to 0.5-8.0 mM. After 4 h at 37C, a 2 to 3-log(10) CFU/ml population r eduction was observed with cultures containing 8.0 mM PH, PY, DI or Cl . Activity was O-2-tension independent, with CI (0.5 mM), DI(2.0 mM) a nd PY(2.0 mM) being most active. The MIC for CI was temperature indepe ndent, while PY was most effective at 19C, and PH and DI at 12C. Mild heat treatment of carbonyl-supplemented samples reduced previously obs erved MICs. At 60C, for example, the MICs for AC and BE, 4.0 and 8.0 m M respectively, were both reduced to less than or equal to 0.5 mM. The decimal reduction times for S. aureus exposed to both UV-light and 8 mM flavor compounds were 3.3 and 4.3 s for CI and DI, respectively. Ho wever, the other compounds were not as effective in the presence of UV since the decimal reduction rimes ranged from 77 to 9.0 s. The carbon yl compounds tested were effective antistaphylococcal agents and their use in combination with thermal processing may serve as a new approac h to control S. aureus growth and other gram-positive foodborne pathog ens.