February 15-18, 2009 Washington State Convention Center Seattle ...

ROE AND CAVIAR BACTERIOLOGY: In vivo, In situ, In sushi
Brian Himelbloom* and Chuck Crapo
University of Alaska Fairbanks
School of Fisheries and Ocean Sciences
Fishery Industrial Technology Center
118 Trident Way
Kodiak, AK 99615-7401 USA
ffbhh@uaf.edu
Fish roe and caviar are delicacies consumed worldwide. These raw eggs are marketed as salt-cured whole skeins (sujiko) and
singles (ikura). Bacteria may be present in either product since no processing treatment is used for inactivation or prior to
consumption. Concerns have been raised regarding the potential for pathogenic bacterial species being present in these products.
Also, the shelf life of the product depends on the conditions at wholesale and retail and handling by the end user at the
restaurant, supermarket or home. This review covers the aspects of roe and caviar bacteriology regarding live fish in vivo, egg
deposition in nature in situ and as products for consumers in sushi.
The literature is scant for the first two instances in which fish eggs are contained in the female fish or released during spawning
and obtained for aquaculture fertilization. Unless the fish is diseased, the ovaries are considered bacteriologically sterile.
Exposure to the environment in streams or hatchery tanks does allow bacteria to become associated with the eggs upon release
from the female. In either situation, damage to egg integrity can provide entrance by fish pathogens to the live eggs. Otherwise,
nature has provided the eggs a protective barrier to bacteria invasion but not necessarily against bacterial adhesion.
Handling and processing into whole skeins or caviar are operations that the fish processing facilities isolate from other activities.
These highly valuable commodities command high prices due to species preference, limited availability and intrinsic
factors such as egg size, color and shape. Caviar grades, as decided by corporate inspectors and buyer specifications, are
based on the raw characteristics for batches of sujiko and ikura. Bacteriological content and species identification are analyzed
separately to evaluate the safety and quality of these products. If declared unsafe by regulatory agencies, sujiko and ikura are
recalled from the market.
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