Validation of antimicrobial treatments to reduce E.coli O157 and Salmonella spp. in beef trim and ground beef



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Texas Tech University


Research determining the antimicrobial effects of interventions on beef trim has been limited. The objectives of this study were to validate the effectiveness of acidified sodium chlorite (1200 ppm), acetic and lactic acids (2% and 4%) in reducing pathogen levels in beef trim prior to grinding in a simulated processing environment. The reduction of pathogen loads, Salmonella spp. And Escherichia co//0157:H7, were determined prior to treatment (control) and at the following processing points: 1) trim just after treatment; 2) ground beef just after grinding, 3) ground beef 24 h after refrigerated storage; 4) ground beef 5 d after refrigerated storage; and 5) ground beef 30 d after frozen storage.

Preparation of product for sensory testing was similar to the previous experimental design protocol except none of the trim was inoculated with pathogens. The organoleptic properties were evaluated during short-term (6 and 24 h; 5 d) refrigerated storage and during long-term (30 and 90 d) frozen storage. Ground products were vacuum packaged and stored at 4°C for 5 d or were stored frozen. Triangle tests for comparison of controls and treated samples were conducted on 6 and 24 h; 5, 30 and 90 d after treatment. Panelists (n=24) were given three coded samples, each set of three samples included two of the same samples and one odd sample. Panelists were asked to determine the odd sample. Equal numbers of the six possible combinations (ABB, BAA, AAB, BBA, BAB, ABA) for each treatment were randomly served to panelists.

Raw patties were packaged on a supermarket Styrofoam tray, and displayed in a retail display case. Visual panelists were trained for color, color uniformity, percentage of discolorations and browning evaluations of the raw products for appearance and composition. Additionally, muscle luminance, redness and yellowness of the raw product were objectively measured using the Minolta Spectrophotometer. Biochemical composition of the product's percentage of moisture, fat, and protein were analyzed.

Results conclude all antimicrobial interventions reduced the lower inoculation level of pathogens to a non-detectable level with significant reductions of the higher inoculation levels of pathogens on trim and in ground beef. There were not any visual differences assessed by a trained visual panel for patties undergoing short-term refrigerated storage, thus more indicative of consumer perceptions in the retail case. Four percent lactic acid was the only treatment to produce significantly different CIE L*, a*, b*, C, and H values for long-term frozen storage (90 day).

A non-trained sensory panel utilizing a triangle test only detected differences between the controls and 4% lactic acid treatment for the 30-day long-term storage sampling period. The panel was not able to detect any adverse sensory differences between the controls or treatments for the short-term refrigerated storage periods, or 90-day frozen storage period. Thus, antimicrobial treatments did not have adverse sensory or visual characteristics during short-term storage.