Comparing the Recovery of Indicator Microorganisms from Beef Trimmings Using Swabbing, Rinsing, and Grinding Methodologies

Different bacterial sampling methods that are destructive or nondestructive in nature have been developed to evaluate the microbial quality of meat and determine if it fulfills criteria for distribution to the public. The purpose of this study was to evaluate the effectiveness of swabbing, rinsing, and grinding as sampling methodologies for recovery of indicator microorganisms on beef trimmings. A total of fifteen samples (n = 15) of beef trimmings were collected using the N60 trim sampling technique adopted by the USDA Food Safety and Inspection Service. Each of the 15 samples were divided into 3 parts, with each part assigned to a methodology (swabbing, rinsing, or grinding), and subjected to multiple sequential sampling for a total of three times. A comparison was made between the first sampling and the total bacteria recovered by each methodology. For total aerobic counts (TAC) obtained by the rinse and the grinding methodology, the first sampling as well as the total resulted in aerobic bacteria counts that were not significantly different (P > 0.05); however, swabbing yielded counts that were significantly lower (P 0.05). Linear models showed strong relationships, with a coefficient of determination (r2) of 0.81 (swabbing vs. grinding), 0.67 (swabbing vs. rinsing), and 0.70 (rinsing vs. grinding). Although the sampling methodologies investigated are reliable to determine true bacterial counts of tested samples, consistency and uniformity of sampling is required for the proper interpretation of the acquired results.