Hamann 08-09 PD Abstract

Title:  Assessment of supercritical CO₂ inactivation of oysters associated bacteria
Project Leader:  Hamann, Mark T.

Many popular seafood products harbor organisms that are particularly dangerous when consumed uncooked or undercooked. Bivalve mollusks (i.e. oysters, clams, scallops, and mussels) have for centuries been a significant constituent in the global diet but have led to a serious increase in shellfish-borne illnesses over the past few years. This maybe due in part to the rise in development along coastal regions leading to increased bacterial and infectious disease contamination of these food products. Regardless of the conditions, any raw oyster product is certain to be at risk for carrying infectious microorganisms. 

 Vibrio spp., Salmonella spp., Shigella spp., Escherichia coli, Clostridium perfringens, Clostridium botulinum, Yersinia enterocolitica, Coxsackie-virus, Hepatitis virus (A and E), among others represent a short list of microorganisms associated with these products. Like other edible bivalve mollusks, oysters filter feed to obtain their nutrients from their aquatic environment by pumping large volumes of water through complex gill systems.  When toxin producing planktons are present in this environment they are filtered from water and have the potential to become highly concentrated. Oysters are of greatest concern among seafood and have been shown to be responsible for the largest number of outbreaks in infectious diseases by a significant margin.

The unique physical properties of SCF CO₂ make it an ideal solvent for extraction of fine chemicals and also a mild method applied to pasteurization of beverages and food products.  Our preliminary studies have exhibited the bactericidal potential of SCF CO₂ on oysters and the utility of SCF CO₂ on the extraction of a wide range of natural products. Our goal is to establish an optimized SCF CO₂ procedure for oyster cold pasteurization and depuration without deteriorating the overall integrity of the product. The social benefits of this project include a reduced incidence of seafood borne infectious disease and a product which is raw or uncooked but has been cold-pasteurized without any type of harmful residue. 

Seafood producers benefit from an extend shelf-life and elimination or reduced concerns for the transmission of diseases associated with their product.