42-7 |
Inactivation kinetics of Staphylococcus aureus in surimi seafood under electron beam |
J. JACZYNSKI1, J. W. Park1, and C. Zinn2. (1) Seafood Laboratory, Oregon State University, 2001 Marine Dr., Astoria, OR 97103, (2) IBA Sterigenics, 7695 Formula Pl., San Diego, CA 92121-2418 Surimi seafood industry currently relies on thermal pasteurization by either hot water or steam. However, manufacturers use various pasteurization settings, which have not been scientifically validated. There is a great need to provide industry with precise pasteurization guidelines that would assure microbiological safety as well as impart minimal changes in sensory attributes. E-beam technology, which differs from cobalt irradiation, has proven to be successful for the microbiological control in red meats. When electrons, which are generated from ordinary electricity, are accelerated to nearly the speed of light, they kill bacteria. Our objective was to determine inactivation kinetics of S. aureus in surimi seafood under various processing conditions and develop an inactivation model. Thermally pasteurized surimi seafood sticks were ground up homogeneously before inoculating six strains of S. aureus. Samples were incubated for 72 hrs at 37°C, resulting in 109 CFU/g. Then the samples were e-beam treated. Four factors were tested: Irradiation level (0,1,2 and 4 kGy); Package size (15 and 30 mm); Oxygen availability (vacuum and non-vacuum); Sample temperatures at the time of irradiation (-18, 5, 23 °C). Spread plate technique on Staphylococcus 110 medium (Difco) with serial 10-fold dilutions was used to determine survivors at various treatments. Data showed that e-beam successfully inactivated S. aureus in surimi seafood. At the lowest irradiation level (1 kGy) a 3-log reduction was obtained. Greater reduction (6-log) was observed at 2 kGy and complete sterilization at 4 kGy. However, inactivation effects on frozen samples were significantly low suggesting e-beam penetration is limited when the product is frozen. No difference was found for two package sizes and oxygen availability. Survival curves were plotted. D- and Z-values were calculated. The research demonstrated successful application of e-beam in surimi seafood, suggesting that e-beam could be used as an alternative to conventional steam or hot water pasteurization.
Session 42, Seafood Technology: Safety, Processing
|