99E-14

M. Vurma¹, Y.-K. CHUNG¹, T. H. Shellhammer², E. J. Turek³, and A. E. Yousef¹. (1) Dept. of Food Science and Technology, The Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007, (2) Food Science and Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97330, (3) Kraft Foods, Inc., 801 Waukegan Rd., Glenview, IL 60025

Listeria monocytogenes is a foodborne pathogen that poses significant challenges to the food industry. High-Pressure Processing (HPP) is emerging as a valuable alternative to the conventional preservation technologies. Pressure resistance of L. monocytogenes varies considerably with the strain, therefore, targeting the most barotolerant strain is vital in assessing the efficacy of the process. Phenolic ingredients are primarily used as antioxidants and some are known for their antimicrobial potency. A combination of phenolic compounds with HPP is potentially useful in eradicating the most pressure-resistant L. monocytogenes. The objectives of this study were to identify phenolic compounds that enhance the efficacy of HPP against barotolerant L. monocytogenes and to eliminate the tailing pressure-death behavior. Twelve phenolic compounds were screened for their ability to sensitize L. monocytogenes to HPP. Three L. monocytogenes strains (Scott-A, OSY-8578, and OSY-328) were grown to stationary phase and suspended in phosphate buffer (pH 7.0). Listeria monocytogenes was exposed to one of the 12 phenolic compounds (100 ppm each) for ~60 min and pressurized at 400 MPa for 5 min. Inactivation kinetics of L. monocytogenes strains at 300, 500, and 700 MPa, in the presence or absence of tert-butylhydroquinone (TBHQ) were also investigated. Six phenolic compounds increased the efficacy of HPP against L. monocytogenes but TBHQ was the most effective in sensitizing the pathogen to pressure. The lethality of HPP to this pathogen was enhanced by 1.7-log when TBHQ was used. In the inactivation kinetics study, all survivor plots showed non-linear death behavior. The tailing behavior was most prominent when HPP was used alone. Combinations of TBHQ and HPP eliminated the tailing behavior when survivors were monitored by direct plating or enrichment procedures. This study illustrates the feasibility of HPP and phenolic additives as a potent bactericidal combination against one of the most barotolerant pathogens.

Session 99E, Nonthermal Processing: General II
8:30 AM - 12:00 PM, Wednesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana