Impact of organic acid treatment on the microbial community composition of raw beef during extended refrigerated storage

Limiting bacterial spoilage and thereby protecting the economic value of raw beef destined for export is a top priority of the United States beef industry. Organic acid processing aids are commonly used to decrease pathogenic loads on raw beef, but knowledge of their efficacy against common spoilage bacteria is limited. Beef chuck rolls (IMPS 116A, N = 24) were obtained from two different processing facilities in Nebraska and treated with either 4.5 % lactic acid, 2.5 % Beefxide®, or 380 ppm peroxyacetic acid alongside a no-treatment control. Samples were stored at 2.7 °C for 112 days. Every 28 days, samples were evaluated using aerobic, anaerobic, psychrotrophic, lactic acid bacteria, and Pseudomonas plate counts and using amplicon sequencing of the V4 region of the 16S rRNA gene. Significant differences (P < 0.05) between groups were determined using DeSeq2. Lactococcus became the most abundant genus on day 28 and every subsequent sampling point regardless of treatment group. Pseudomonas and Yersinia were also present at perceptible levels and were identified to be higher in control samples compared to lactic acid treated samples through differential abundance analysis. Concentrations of culturable bacteria increased during storage across all plating methods (P < 0.05), but treatment differences were minimal. Overall, these treatments had impact on the bacterial diversity during storage. When considering the use of processing aids to limit spoilage, the treatment should be chosen based on a targeted specific spoilage organism.