SPONGING AND EXCISING AS SAMPLING PROCEDURES FOR FRESH BEEF CARCASS TISSUE

Summary Sponging and excising were evaluated as sampling procedures for microbiological analysis of beef carcass tissue. Brisket tissue portions (10 x 10 cm) were inoculated with 2 ml of an Escherichia coli ATCC 25922 cell suspension. After 30 min, the portions were sampled by excising (EX) or swabbing (SP) with a sterile sponge (Whirl- PakTM, Nasco, Modesto, CA), and analyzed for aerobic plate counts (APC) on tryptic soy agar (Difco Laboratories, Detroit, MI), and for total coliform counts (TCC) and E. coli counts (ECC) on 3M PetrifilmTM E. coli count plates (3M Healthcare Products, St. Paul, MN). Another set of inoculated samples was analyzed after being spray-washed with water (6 sec, 35 °C, 3.4 bar), acetic acid (2%, 6 sec, 35 °C, 2.1 bar), water (20 sec, 42°C, 20.7 bar) and acetic acid (2%, 6 sec, 35 °C, 2.1 bar). Additional samples were analyzed after chilling at 7 °C for 24 h. Bacterial counts recovered were influenced (P < 0.05) by procedure of sampling (EX vs. SP), time of sampling (0.5 h vs. 24 h), and their interactions. Counts recovered 0.5 h after inoculation, from unwashed or spray washed samples, were similar between the two sampling procedures (EX, SP). However, counts recovered after 24 h of sample storage, were significantly (P < 0.05) lower for the SP compared to the EX sampling procedure. The results indicated that as the carcass tissue was stored, recovery of bacteria by SP was less efficient compared to EX.