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

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.