Effects of brining ingredients and antimicrobials on thermal inactivation of Escherichia coli O157:H7 in a meat model system and control of Listeria monocytogenes in frankfurters

One study evaluated the effect of brining ingredients (sodium chloride, sodium tripolyphosphate and sodium pyrophosphate), alone or in combination with antimicrobials (potassium lactate, sodium diacetate, organic acids, nisin, pediocin, sodium metasilicate, cetylpyridinium chloride [CPC], and hops beta acids), on thermal (65°C) inactivation of Escherichia coli O157:H7 in a meat model system. Only CPC reduced (approximately 1 log-unit) counts during storage. Thermal treatment reduced pathogen numbers by 1.5--2.5 log-units. CPC, nisin and pediocin increased thermal inactivation. None of the chemicals protected the cells.Another study examined the effect of lactic acid (LA) dipping solutions on Listeria monocytogenes (4.4 log-units) on frankfurters, and determined parameters (temperature: 4--55°C concentration: 1--3% exposure time: 15--120 s) achieving 1 and 2 log-unit reductions. A developed prediction equation for microbial reduction included significant ( P < 0.05) effects of concentration, exposure time, temperature, and the concentration x temperature interaction.Another study evaluated the effect of LA (5%) and sodium lauryl sulfate (SLS 0.5%), sprayed individually or as a mixture (LA/SLS), against L. monocytogenes (4.8 log-units) on frankfurters. Spraying with LA or SLS after inoculation reduced counts by 1.8 and 2.0 log-units, respectively. The LA/SLS applied before or after inoculation reduced L. monocytogenes populations by 1.8 and 2.8 log-units, respectively. Treatments that contained LA delayed growth and decreased the growth rate of the pathogen during storage (4°C).A final study evaluated the fate of L. monocytogenes (1.8 log-units) on frankfurters stored under variable conditions, to which they can be exposed between manufacturing and consumption. Based on the growth rates obtained in this study it was suggested that fresh frankfurters without microbial growth inhibitors may be stored at 4°C in opened or vacuum-packages for 6 and 13 days, respectively. However, if product without antimicrobials is held under control of the manufacturer/retailer for 20 days or longer, consumers should store it for &le5 days at 4°C, and be advised that if contaminated it may already have high pathogen levels.Results may be useful in developing/improving brining recipes to control E. coli O157:H7 in moisture-enhanced meat products, storage recommendations and interventions to control L. monocytogenes on frankfurters, and in pathogen risk assessments.