Reciprocal Meat Conference Abstracts

Effects of Ultraviolet Light, Organic Acids, and Bacteriophage Interventions on Salmonella Populations in Ground Beef

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Abstract

ObjectivesSalmonella is an emerging beef industry challenge. To reduce pathogen contamination of ground beef, major processing companies apply organic acids to beef trim before grinding. The objectives of this study were (1) to evaluate the efficacy of individual applications of lactic acid (LA), peroxyacetic acid (PAA), ultraviolet light (UVC) and bacteriophages (BA), and (2) to determine which combination provides the optimal control of Salmonella in ground beef.Materials and MethodsA total of 96 (n = 96) samples containing 100 g of 80% lean trim were randomly assigned to 1 of 12 treatments: Control not inoculated (CO), Control Inoculated (COI), LA, PAA, UVC, BA, LA+PAA, LA+UVC, LA+BA, PAA+UVC, PAA+BA, and UVC+BA. Samples were inoculated with a cocktail comprising 4 Salmonella strains to yield approximately 3 log CFU/g (COI = 3.52 log CFU/g). Strains used in this study included: S. enterica (ATCC 51741), S. Heidelberg (ATCC 8326), S. Newport (ATCC 27869), and S. Enteritidis C (Se 13, streptomycin resistant). After inoculation samples were treated with LA at 5%, PAA at 400 ppm, UVC at 254 nm, and BA solution including S16 and FO1a phages at 109 PFU/ml. LA, PAA, and BA solutions (5 mL) were uniformly pipetted onto trim surfaces whereas UVC was applied during tumbling for 2 min. Samples were ground and a 25-g aliquot stomached for 2 min in 225ml of sterile 0.1% BPW. The homogenate was centrifuged and the supernatant was discarded to avoid plating phages. Pellets were resuspended in BPW, vortexed, serially diluted in BPW, and plated onto XLD plates to evaluate Salmonella counts. Data were analyzed as a CRD by using the PROC GLIMMIX procedure of SAS (SAS Inst. Inc., Cary, NC).ResultsNo Salmonella growth was observed in plates from CO samples. Fixed effect of treatment was significant at P < 0.0001. Individual applications of organic acids (LA and PAA) as well the combination of both (LA+PAA) did not significantly decrease Salmonella counts when compared to COI samples (COI = 3.52A, LA = 3.13A, PAA = 3.13A, and LA+PAA = 3.07A log CFU/g). When combined with UVC and BA, LA significantly reduced Salmonella loads in ground samples when compared to COI and organic acids-only treatments (LA+UVC = 2.28B and LA+BA = 2.46B log CFU/g). Similar results were observed for UVC and for the combination of PAA and UVC (UVC = 2.37B and PAA+UVC = 2.20B log CFU/g). Bacteriophage application (BA = 2.29B log CFU/g) and its combination with PAA (PAA+BA 2.07B log CFU/g) led to similar Salmonella decrease when compared to UVC, UVC and organic acids, LA, and LA+BA. Combined application of UVC and BA provided the optimal reduction when compared to all other treatments. (UVC+BA = 1.55C log CFU/g).ConclusionApplication of lactic and peroxyacetic acids on trim prior to grinding did not affect populations of 4 different Salmonella strains in ground beef. When applied to beef trim, exposure of ultraviolet light at 254 nm combined with bacteriophage application led to lowest values of Salmonella loads in ground beef.

Keywords: salmonella, organic acids, ultraviolet light, ground beef, Bacteriophage

How to Cite:

Yeh, Y., de Moura, F., Van Den Broek, K., Fonseca, M. & De Mello, A. S., (2019) “Effects of Ultraviolet Light, Organic Acids, and Bacteriophage Interventions on Salmonella Populations in Ground Beef”, Meat and Muscle Biology 1(3). doi: https://doi.org/10.221751/rmc2017.113