Control of Listeria monocytogenes in further processed meat and poultry using organic acid post-cook dips

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Title: Control of Listeria monocytogenes in further processed meat and poultry using organic acid post-cook dips
Author: Johnson, Jennifer Lynn
Abstract: Most major outbreaks attributed to Listeria monocytogenes (LM ) involve post -processing contamination of turkey and ham deli slices , and frankfurters . This study evaluated the antilisterial effects of organic acids applied as post -cook dips to turkey and ham deli slices and beef frankfurters . Two trials were conducted to analyze LM levels . Efficacy was determined by prolongation of the lag phase and overall LM levels at the end of storage . Treatments included sodium lactate (SL ; 3 .6 % ) , potassium lactate (PL ; 3 .6 % ) , sodium citrate (SC ; 0 .75 % ) , a combination of SL and sodium diacetate (SDA ; 0 .25 % ) , and a combination of SL /PL /SDA . Products were formulated with 1 .5 % sodium chloride and 0 .45 % sodium tripolyphosphate . Ham deli loaves and beef frankfurters were also formulated with 156 ppm and 6 .25 % sodium nitrite , respectively . Products were surface inoculated with 104 -105 log CFU /mL of streptomycin resistant (1 ,500 ¥ìg /mL ) LM strain Scott A before immersion treatment . Positive and negative controls were immersed in sterile water . Products were stored in Whirlpak™ bags under refrigerated temperatures ( ~4°C ) for sampling at 0 , 7 , 14 , 21 , 28 , 42 , and 56 d . The SL /SDA combination applied to turkey extended the lag phase until d21 . When applied to ham , the lag phase extended through d14 . For both products , LM concentrations rose less than one log (0 .7 log CFU /g ) throughout the 56 d storage period . The SL /PL /SDA applied to turkey extended the lag phase throughout d 42 with decreasing LM concentrations after d 21 . An overall decrease (0 .1 log CFU /g ) was noted by 56 d . When applied to ham , treatment with a SL and both combination treatments extended the lag phase through d 14 . Lag phase in the inoculated control lasted until d 7 . Single lactic acid treatments and the SL /SDA combination treatment applied to frankfurters extended the lag phase throughout 28 d post -processing . Lag phase was also extended throughout d 28 for control frankfurters . Treatment with SL /PL /SDA extended the lag phase throughout 21 d . The lag phase for the inoculated control persisted until d 28 . Overall growth was limited within the range of 1 .0 log CFU /g for all organic acid treatments . Combination organic acid dipping solutions prolonged the LM lag phase for 2 to 6 weeks on treated turkey deli loaves . Combination dipping solutions and sodium lactate extended the lag phase for an additional week beyond the inoculated control when applied to ham . Single and combination lactic acid treatments prolonged the LM lag phase for 3 to 4 weeks on treated beef frankfurters , but the same results were noted on untreated frankfurters .
URI: http : / /hdl .handle .net /2346 /16752
Date: 2008-05

Citation

Control of Listeria monocytogenes in further processed meat and poultry using organic acid post-cook dips. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /16752 .

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