EFFECT OF WATER TEMPERATURE, PRESSURE AND CHEMICAL SOLUTION ON REMOVAL OF FECAL MATERIAL AND BACTERIA FROM LAMB ADIPOSE-TISSUE BY SPRAY-WASHING

The objectives of this study were to determine the efficacy of various water temperatures, pressures and chemical solutions of spray-washing on the removal of fecal and bacterial contamination from lamb carcass samples taken from the breast area (<15 min post mortem) and inoculat ed (6.50 cm(2) area) with an ovine fecal paste containing Escherichia coli (A TCC 11370). Inoculated samples were held for 15 min and then k nife-trimmed and/or spray-washed with varying water temperatures (16, 35 or 74 degrees C), pressures (2.76, 13.79, 20.68 or 27.58 bar) and c hemical solutions (12% trisodium phosphate, 2% acetic acid, 5% hydroge n peroxide or 0.003% available chlorine) for 18 s. After the respectiv e treatments, samples were evaluated visually for presence of fecal ma terial and microbiologically for aerobic plate counts (APC). Knife-tri mming reduced (p < 0.05) APC of inoculated samples, while subsequent s pray-washing of knife-trimmed samples reduced APC (p < 0.05), even com pared to uninoculated control samples. Spray-washing with any temperat ure and pressure combination reduced (p < 0.05) visible fecal contamin ation on the samples. Bacterial reductions ranged from 1.48 to 3.83 lo g colony forming units (CFU/cm(2)) at the inoculation site. Use of 74 degrees C water was more effective (p < 0.05) in decreasing APC than e ither 16 or 35 degrees C water, while water pressure effects were simi lar. Use of 2% acetic acid reduced the APC more than the use of any ot her chemical solution tested. APC for the areas surrounding the inocul ation site were similar to APC at the inoculation site, thus indicatin g that either there was no major spread of bacterial contamination to areas above or below the inoculation site or that contamination was di luted to levels lower than initial contamination. Overall, acetic acid and water temperature were the most important factors in reducing APC and fecal contamination on lamb adipose tissue. (C) 1997 Elsevier Sci ence Ltd.