Research

Ethanol-Producing Bacteria as Spoilage Indicators in Pink Salmon.

Problem: As fish spoil, the ethanol concentration increases. The literature on this subject shows a consensus of researchers have concluded that ethanol is produced in spoilage. However, the identification of specific ethanol-producing microorganisms during fish spoilage is scarce. Moreover, little information is available regarding location of ethanol-producing bacteria in fish and the identity of possible chemical precursors in fish that may be used by bacteria to produce ethanol. Therefore, the main objectives of this project are to compare the levels of bacterial activity in different fish tissues during fish spoilage, to identify the ethanol-producing bacteria and, potentially, the identity of active chemical precursors.

Approach: This project is ongoing. We have conducted spoilage trials using pink salmon, and harvested bacteria from a variety of tissues. Bacteria counts were carried out and microbial isolation and subsequent identification are underway. Ethanol levels in these tissues will be determined and correlated to the types of spoilage bacteria identified. The seafood industry in Alaska will benefit from the findings of this research because understanding the causes of ethanol formation in pink salmon can help determine appropriate fish handling techniques to delay quality deterioration of salmon prior to canning.

Results: Ethanol concentration was highest in the belly cavity area. Both anaerobes and endogenous fish enzymes may contribute to the occurrence of ethanol in fish. Our results indicate chilling, prompt evisceration and de-skinning will improve canned salmon quality by excluding these sources of ethanol. New studies will focus on identifying microorganism(s) responsible for ethanol production during pink salmon spoilage that are present in pink salmon intestinal tract.

Publications:
Chantarachoti, J., Oliveira, ACM., Himelbloom, BH., Crapo, CA. & McLachlan, DG. 2007. Alaska pink salmon (Oncorhynchus gorbuscha) spoilage and ethanol incidence in the canned product. J. Agric. Food Chem. 55(7): 2517-2525.

Presentations:
Chantarachoti, J., Oliveira, ACM., Himelbloom, BH., Crapo, CA. & McLachlan, DG. 2006. Assessment of pink salmon spoilage and ethanol levels in the canned product. AAAS Annual Meeting St Louis.

Contact person: Dr. Alexandra Oliveira email: acoliveira@alaska.edu