Purpose: To determine the effectiveness of lactic acid and peracetic acid treatments combined with acidified sodium chlorite (ASC) to reduce Salmonella embedded in lymph nodes in beef trim during grinding.
Methods: Subiliac lymph nodes were inoculated with 8 log CFU/g of a cocktail containing rifampicin-resistant derivatives of 6 Salmonella strains recognized as the most frequent of clinical significance or isolated from cattle lymph nodes. Beef trim was mixed with the inoculated lymph nodes to reach a final concentration of 4.8 log CFU/g. Organic acids were applied to the trim/node mixture using a six-nozzle sanitizing CHAD spray cabinet. After the first application, the sample was coarsely ground using a meat grinder. The product was then fine ground and an ASC solution was applied through a spray application. Samples were stored at 2-4°C in the dark, and three 1-pound subsamples for each treatment combination were obtained at 1, 24, and 72 h after grinding. Resultant Salmonella population were enumerated on selective medium supplemented with rifampicin with a thin layer of a non-selective medium to allow for recovery of injured cells.
Results: All treatments effectively reduced Salmonella introduced through contaminated lymph nodes on ground beef products (P< 0.05). Peracetic acid + ASC and lactic acid + ASC reduced Salmonella by 0.5 and 0.6 log CFU/g by 72 h, respectively. No significant difference between ASC and peracetic acid + ASC was observed (P=0.23).
Significance: The use of interventions during grinding can reduce Salmonella embedded in lymph nodes in ground beef products.