IAFP 2009 Program Book and Abstract Book - AB68

Methods: Validation studies were conducted in 17 very small processing plants from North Carolina, Kentucky, Kansas, and Nebraska. Plants were instructed to apply a hot water intervention of 60°C or greater. Carcass sides were sampled at each plant for Aerobic Plate Count (APC), E. coli, coliforms, Enterobacteriaceae, and E. coli O157:H7 according to standard procedures. The statistical analysis was designed to determine the contribution of plant as a random effect to a model that included state as a fixed effect to determine the contribution of plant to variability. The estimate for plant effect was tested as either greater than or lower than (P < 0.05) the estimates for other plants. Results: Mean intervention hot water temperature was 63°C and application time 2.35 m per side. APC averaged 2.17 CFU/cm2 prior to interventions, 1.74 log CFU/cm2 after intervention, and 1.00 log CFU/cm2 after chilling. Plant effects were significant (P 0.05) for most microbiological measures. Plant effects were also significant (P < 0.05) for estimates of reduction in log CFU/cm2 of APC, coliforms, generic E. coli, and Enterobacteriaceae for the hot water intervention, chilling of the carcass, and the hot water and chilling combined. Two plants had greater (P < 0.05) log reductions and also had greater estimates for bacterial counts. Four plants had lower (P < 0.05) log reduction estimates for at least one of the microbial measures and log reduction measures. No positive samples for E. coli O157:H7 were found at pre evisceration or post chilling. Significance: There was variation among small plants for the number of bacteria on the carcass during harvesting and the log reduction of bacteria on the surface of the carcass from a hot water intervention and chilling. Even though standard operating procedures were established, in-plant validation studies may be important to establish the effectiveness of an antimicrobial intervention. P1-19 Effect of Ozone and Ultraviolet Irradiation Treatments on Listeria monocytogenes Populations in Chill Brines GOVINDARAJ DEV KUMAR, Robert Williams, Susan Sumner and Joseph Eifert Virginia Tech, Food Science and Technology, Blacksburg, VA, USA Introduction: Recirculated chill brines are used in Ready-to-Eat meat manufacture to rapidly cool product after a cooking step. Since recirculated chill brines may be used continuously for many days or weeks, Listeria monocytogenes in these brines may present a significant, ongoing post-processing contamination hazard. Purpose: This study was conducted to evaluate the combined effect of ozone and ultraviolet light on L. monocytogenes populations in freshly prepared brine and spent brine collected at the end of use. Methods: Fresh brine (9% NaCl) was prepared in the laboratory. Spent brine (20.5% NaCl; collected at the end of use) was obtained from a Ready-to-Eat meat manufacturer. Listeria monocytogenes (strains: N1-227, N3-031, and R2-499) were grown in TSBYE at 35°C for 24 h, washed, resuspended in fresh and spent chill brines, and combined in equal proportions. The brines were then subjected to ozonation for 5 and 10 min (fresh brine) or 30, 45, 60 min (spent brine). Following ozonation, the inoculated brines were subjected to ultraviolet light (peak output: 254 nm) in a bench-top photoreactor for 5 and 10 min(fresh brine) or 10 min only (spent brine). After the ozone and UV treatments, 1 ml portions of each brine were serially diluted in 0.1% peptone and surface-plated onto TSAYE, followed by incubation at 35°C for 48h. Results: In fresh brines (transmittance at 254 nm = 91.8%), ozonation for 5 min followed by UV exposure for 5 min resulted in a 5.7 log reduction of L. monocytogenes. Whereas 10 min of ozonation followed 5 min of UV resulted in an 7.8 log reduction. In contrast, reductions of L. monocytogenes in spent brines (transmittance at 254 nm = 0.0%) treated by ozonation for 30 min followed by UV for 10 min were less than 0.5 log CFU/ml. Ozonation of spent brines for 60 min followed by 10 min UV exposure resulted in a 5.4 log reduction in L. monocytogenes. Significance: Reduction of L. monocytogenes in chill brines is significantly affected by the nature of the brine solution (i.e., fresh vs spent) and the method of treatment (i.e., ozone vs UV). P1-20 Addition of Carnobacterium maltaromaticum CB1 to Vacuum-packaged, Sliced Processed Meats Inhibits the Growth of Listeria monocytogenes ALYSSON H. BLAINE, Denise R. Carlson, Michael E. Stiles, Lynn M. McMullen and David C. Smith CanBiocin Inc., Edmonton, AB, Canada Introduction: Listeria monocytogenes is a major concern in the safe production of processed vacuum-packaged meats. Failure to control Listeria on meat products has resulted in major outbreaks of listeriosis. Purpose: The purpose of this investigation was to determine the ability of Carnobacterium maltaromaticum CB1 to control the growth of L. monocytogenes on three types of processed meats: ham, turkey and roast beef. Methods: The sliced meats were inoculated with approximately 103 CFU of a cocktail of four strains of L. monocytogenes per gram of meat and with 104 CFU of live cells of C. maltaromaticum CB1 per gram of meat before vacuum packaging and storage at 4°C. Three replicates of each product were tested over the shelf life (from 35 to 62 days) in duplicate for each treatment and L. monocytogenes were enumerated on PALCAM agar with supplement. Results: In the absence of C. maltaromaticum CB1, L. monocytogenes grew to 108 CFU/g. However, in the presence of CB1, numbers of L. monocytogenes remained at the initial inoculum level (103 CFU/g) on the meats. The growth rate of CB1 on the meat products differed, with a maximum population reached in 27 days on ham, 18 days on turkey and 14 days on roast beef. Listeria alone reached a maximum population after 27 days, 33 days and 21 days, respectively. In contrast, Listeria in the presence of CB1 remained at the inoculum level for 62 days, 56 days and 49 days of storage at 4°C on ham, turkey and roast beef, respectively. Significance: The research indicated that on these three markedly different meat types, in the presence of the lactic acid bacterium C. maltaromaticum CB1, the growth of L. monocytogenes was inhibited throughout the storage life of the products. Bacteriocin-producing lactic acid bacteria, such as C. maltaromaticum CB1, can be used as an effective alternative to chemical interventions to stop the growth of L. monocytogenes on a variety of sliced processed meats. Poster 68 — Abstract Book

IAFP 2009 Program Book and Abstract Book

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