Evaluation of Multiple Temperatures of Lactic Acid and Sodium Metasilicate on Microbial Parameters of Fresh Beef

Introduction: Lactic acid and sodium metasilicate have been used in meat facilities as antimicrobial interventions. Their uses have varied from hot carcasses to ready-to-eat products. Utilizing these antimicrobials in different stages during meat processing may assist in the reduction of the risk of pathogenic microorganisms.

Purpose: The purpose of this study was to determine optimum temperatures of usage of lactic acid and sodium metasilicate for pathogen reduction on beef bottom round muscles.

Methods: Lactic acid 4% (LA, v/v), sodium metasilicate 4% (SM, w/v), the combination of the two solutions (LASM), and a distilled water control were applied at 4, 25, and 60°C. Antimicrobials were mixed in solution with distilled water. Beef bottom round was cut into 100 cm² pieces. Pieces were inoculated with Escherichia coli O157:H7 (5 strains), Non-O157 Shiga toxin-producing Escherichia coli (STEC, 1 strain each of the “Big 6”), Salmonella spp. (5 strains), or Listeria monocytogenes (5 strains). After 30 min of contact time samples were treated with the antimicrobial solution or control and then allowed 30 min of contact time. Samples were serially diluted and plated on MacConkey Agar with Sorbitol (E. coli), XLT4 (Salmonella spp.), or Modified Oxford Medium (L. monocytogenes). Data were analyzed using the PROC MIXED procedure of SAS and Tukey pairwise comparisons.

Results: LA and SM reduced (P < 0.05) the microbial contamination of the meat samples. Temperature of application had no effect (P < 0.05) on bacterial counts in any of the treatments. LA or SM alone were more effective (P < 0.05) in reduction of microbes than when used together (LASM).

Significance: Meat processors can apply LA or SM at refrigeration temperatures and reap the same benefits of applying them at a higher temperature. Both solutions can serve as a hurdle technology in meat processing facilities.