4 °C - the National Sea Grant Library

EFFECTIVENESS OF IRRADIATION AS A METHOD TO ENSURE
HYGIENIC QUALITY OF FRESH AND FROZEN SEAFOOD
Irradiation is an effective method to ensure hygienic quality of fresh and frozen
food of animal origin including seafood. Its use, however, should not be a substitute
for good manufacturing practices (GMPs) required for such products.
A. Irradiation of Fresh Seafood
The primary objective of irradiation of fresh seafood is for shelf-life extension
under refrigeration or melting ice and to inactivate any non-spore forming pathogenic
bacteria which may be present. The optimum radiation dose levels for various
seafoods is generally in the range of 1.0 to 2.5 kGy according to Table 1.
Irradiation of fresh seafood at these optimum dose levels does not significantly
affect quality but reduces significantly the microbial content of the product, thereby
increasing-the shelf-tie. The quality and shelf-life of radiation pasteurized seafood is
a function of many variables such as:
initial quality (post-mortem age or microbial counts)
qualitative/quantitative composition of the microbial flora
packaging atmosphere
absorbed dose
presence or absence of microbial inhibitors such as sorbate, etc.
biochemical composition of the seafood product
post-irradiation storage temperature.
Fresh fish and shellfish can be contaminated with certain non-spore forming
bacteria such as enteropathogenic E. coli Salmonella, Shigella, Vibrio
parahaemolyticus, V. vulnificus, V. cholerae, faecal streptococci, Staphylococcus
aureus and viruses if caught from polluted waters or through post-harvest handling.
Viruses are generally resistant to radiation at the dose levels required for
pasteurization or shelf-life extension. Other means of disinfection of viruses such as
depuration would have to be considered in addition to irradiation. Non-spore forming
pathogenic bacteria are, however, relatively radiation sensitive. Vibrio spp., in
particular, is sensitive to radiation with D-value in various seafood ranged from 0.03
to 0.16 kGy depending on salt concentration and serotype Loaharanu, 1972; Grodner
and Andrews, 1991; Kilgen, 1993). Quinn et.al (1967) estimated radiation resistance
of various pathogens or non-pathogenic members of genera containing pathogenic
- species in different seafood as follows: