4 °C - the National Sea Grant Library
4 °C - the National Sea Grant Library 4 °C - the National Sea Grant Library
Conclusion In this study, low dose gamma irradiation was found to be very effective on the reduction of targeted microorganisms except for L.monocytogenes, which required higher dose to achieve radurization. For the irradiation sensitive species like S. aureus and V. parahaemolyticus, 0.5 kGy of gamma irradiation was sufficient to eliminate them from the crabmeat. However, for L. monocytogenes, which can survive the low dose irradiation and multiply rapidly later during ice storage, the irradiation dose had to be higher in order to control this organism for a longer time. The numbers of E. coli and coliform are very low in crabmeat. REFERENCES Bennet, R. W., 1984, Staphylococcus aureus. In “Bacteriological Analysis Manual”.Center for Food Safety and Applied Nutrition. U.S. Food and Drug Administration, 6th Ed., Ch. 14. Cockey, R. R. and Chai, T., 1991, Microbiology of Crustacea Processing Crab. In “Microbiology of Marine Food Products”. Ch. 3, pp. 41-63. Avi Book.
EFFECT OF SPLIT DOSE APPLICATION ON THE RADIOSENSITIVITY OF LISTERIA MONOCYTOGENES L. S. Andrews, R-M. Grodner, and J.A. Liuzzo Department of Food Science Louisiana Agricultural Experiment Station Louisiana State University Baton Rouge, LA 70803 INTRODUCTION The ability of Listeria monocytogenes to survive and proliferate at refrigeration temperatures in a variety of food products, and its potential to survive minimal thermal processing (Doyle, 1988), have caused food safety concerns among food scientists and technologists. Due to the ubiquity of this genus, Listeria spp. have been shown to contaminate a variety of food products including red meats, seafood and dairy products either from harvest or during processing (Donnelly, 1994). The United States Food and Drug Administration (USFDA) currently mandates a zero tolerance level for Listeria in food products (USFDA, 1994) due to the potential severity of infection in immunocompromised individuals due to liver disease, immune disorders, age, and/ or pregnancy. One method suggested as a possible solution to reducing the risk of this bacteria has been irradiation processing. In minimally processed foods such as fresh seafood, dairy, and sous vide products, low dose irradiation might be used to reduce this risk while preserving the fresh quality of these products. Although L. monocytogenes has proven to be among the more radiation resistant vegetative bacteria, if present in small numbers, below 10 4 CFU/g(ml), it has been shown to be sensitive to doses of 2 kGY (Andrews and Grodner, 1992; Huhtanen et al., 1989). In contrast, higher concentrations of the bacterium have been shown to resist 2 kGy of gamma radiation and recover with logarithmic growth (Andrews and Grodner, 1992; Juneau, 1989;Patterson et al., 1993). In general, the radiosensitivity of bacteria varies depending on many different factors including medium in which the irradiation occurs (Urbain, 1986), temperature at time of irradiation (Josephson and Peterson, 1982), initial cell concentration (Kelner, 1955), and many other environmental factors such as oxygen level, pH, and water activity (Urbain, 1986; Josephson and Peterson, 1982). Traditionally, irradiation processing of food products has focused on single dose application to a
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Conclusion<br />
In this study, low dose gamma irradiation was found to be very<br />
effective on <strong>the</strong> reduction of targeted microorganisms except for<br />
L.monocytogenes, which required higher dose to achieve radurization.<br />
For <strong>the</strong> irradiation sensitive species like S. aureus and V.<br />
parahaemolyticus, 0.5 kGy of gamma irradiation was sufficient to<br />
eliminate <strong>the</strong>m from <strong>the</strong> crabmeat. However, for L. monocytogenes,<br />
which can survive <strong>the</strong> low dose irradiation and multiply rapidly later<br />
during ice storage, <strong>the</strong> irradiation dose had to be higher in order to<br />
control this organism for a longer time. The numbers of E. coli and<br />
coliform are very low in crabmeat.<br />
REFERENCES<br />
Bennet, R. W., 1984, Staphylococcus aureus. In “Bacteriological<br />
Analysis Manual”.Center for Food Safety and Applied Nutrition.<br />
U.S. Food and Drug Administration, 6th Ed., Ch. 14.<br />
Cockey, R. R. and Chai, T., 1991, Microbiology of Crustacea<br />
Processing Crab. In “Microbiology of Marine Food Products”. Ch.<br />
3, pp. 41-63. Avi Book.
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