Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef

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Title: Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef
Author: Harris, Deidrea Dee
Abstract: Pathogens are of great concern for processors for food safety issues and for economic reasons . While beef trimmings and ground beef are to be cooked by the consumer , the processor must recall the raw product if testing indicates the presence of Escherichia coli O157 :H7 . Processors have very few interventions for beef trimmings and ground beef . A limited amount of research has been completed to determine antimicrobial effects under commercially simulated conditions on beef trim to reduce pathogens . The objective of this study was to validate the effectiveness of acetic and lactic acids (2 % and 5 % ) , acidified sodium chlorite (1000 ppm ) , and sterile water in reducing pathogen levels in beef trim prior to and after grinding in a simulated processing environment utilizing a belt turning and spray application . The effectiveness of these interventions on Escherichia coli O157 :H7 and Salmonella Typhimurium were determined prior to treatment and at the following processing points : 1 ) just after treatment (20 minutes ) ; 2 ) just after grind (6 hours ) ; and 3 ) 24 hours after anaerobic storage at 4°C . Trim was inoculated with Escherichia coli O157 :H7 and Salmonella Typhimurium , with an inoculation level of 1x105 cfu /g . Sensory preparation was similar to the experimental design above except none of the trim was inoculated with pathogens . The organoleptic properties were evaluated during short term refrigerated storage at 6 and 24 hours after preparation . Raw patties were packaged on a Styrofoam tray and displayed in a retail display case . Visual panelists were trained to determine beef color , color uniformity , percentage of discoloration and browning evaluations of the raw patties based on appearance and composition . Muscle luminance , redness and yellowness of the raw product were objectively measured using the Minolta Spectrophotometer . Triangle test were used for comparison of the control and treated samples at 6 and 24 hours after production . Panelists (n = 24 ) were given three coded samples , including two of the same sample and one odd sample . Panelists were asked to determine the odd or different sample . Results from this study indicate that all antimicrobial interventions , including sterile water , reduced pathogen loads (P < 0 .05 ) for both Escherichia coli O157 :H7 and Salmonella Typhimurium in ground beef by almost 1 log cycle . The antimicrobial treatments of : sterile water , 5 % lactic acid , 2 % acetic acid , 5 % acetic acid , and acidified sodium chlorite (1000 ppm ) significantly reduced Escherichia coli O157 :H7 (P < 0 .05 ) in ground beef . The antimicrobial treatments of : acetic and lactic acids (2 % and 5 % ) , acidified sodium chlorite (1000 ppm ) , and sterile water significantly reduced pathogen loads of Salmonella Typhimurium (P < 0 .0001 ) in ground beef 6 and 24 hours after processing . Utilizing a triangle test there was no significant difference P < 0 .05 in the mean of correct responses between controls , 2 % lactic acid , 5 % lactic acid , 2 % acetic acid , 5 % acetic acid and acidified sodium chlorite (1000 ppm ) within treatment , 6 or 24 hours samples from a non -trained sensory panel .
URI: http : / /hdl .handle .net /2346 /17957
Date: 2006-12

Citation

Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /17957 .

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