88D-15 |
Estimation of microbial load of fish surfaces using a new ATP system |
F. M. BIN JASASS and D. Y. C. Fung. Dept. of Animal Sciences & Industry, Kansas State Univ., 202 Call Hall, Manhattan, KS 66506 Adenosine Triphosphate (ATP) technique is a rapid convenient method for hygiene monitoring in the food industry. ATP has also been used to estimate microbial loads in of food with varying degrees of success. In this study a Zylux model FB-14 system was used to determine the ATP level on the fish surfaces. The value, expressed as RHU (Relative Hygiene Unit), was compared with viable cell count (VCC). Five rainbow trout and five salmon fillet were stored at 7oC and monitored at 0, 1, 2, 3, and 4 days. At each sampling time a sterile template (4cm x 4cm) was put on the surface of the fish and a conventional cotton swab sample was taken and suspended in 9 ml of sterile 0.1% peptone water. An aliquot was removed to obtain VCC. For ATP determination, 0.01 ml of liquid sample and 0.01 ml of Zylux ATP extraction reagent were put in a Zylux vial containing lyophilized luciferase / luciferin reagents. After mixing the tube was placed into the luminometer and the RHU of the sample was obtained in 40 sec. Data from rainbow trout and salmon fillet were similar and combined for analysis. The experiment was repeated three times. On day 0, VCC and ATP value of fish surfaces was 3.8±0.2 log CFU/ml and 331±3 RHU, respectively. On day 1 the corresponding values were 4.4±0.3 log CFU/ml and 377±11 RHU; on day 2 the values were 6.0±0.5 log CFU/ml and 438±31 RHU; on day 3 the values were 7.3±0.6 log CFU/ ml and 486±14 RHU; on day 4 the values were 7.9±0.6 log CFU/ml and 494±14 RHU. The correlation coefficient of VCC and RHU ATP value was r=0.95. Thus, the rapid RHU ATP method can be used to estimate VCC of fish surfaces during aerobic cold storage.
Session 88D, Food Microbiology: General
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