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United States Department of Agriculture

Agricultural Research Service

Title: Preserving Salmon Byproducts through Smoke-Processing Prior to Ensilage

Authors
item Bower, Cynthia
item Hietala, Katie

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 18, 2009
Publication Date: N/A

Technical Abstract: Salmon is an important fishery in Alaska and accounts for about 9% of the annual catch. Processing these fish results in valuable byproducts that contain oils with high concentrations of long-chain n-3 polyunsaturated fatty acids (PUFA). Previous research demonstrated that when discarded salmon heads are smoke-processed prior to oil extraction, natural antioxidants are imparted to the oil. However, unless a fish meal plant is located nearby, the remaining “de-oiled” tissue is difficult to preserve. In this study, heads from pink salmon (Oncorhynchus gorbuscha) were smoke-processed and/or fermented using food-grade lactic acid bacteria (LAB), and the compositional and microbiological characteristics of the resultant tissues were evaluated. When salmon heads were smoke-processed (75 °C, 5h) prior to removal of oil, moisture levels decreased from 71% to 67%. However, smoke alone was not sufficient to prevent spoilage without the additional preservation step of LAB fermentation, which decreased the pH to 4.5 and retained that acidity for over 60 days. The smoked, fermented salmon material acquired pleasant aroma and flavor characteristics and was found to confer antimicrobial activity against Gram-negative bacteria. Control samples did not receive LAB inoculations, relying entirely on endogenous proteolytic enzymes to break down the tissues without acidification. Bacterial cell counts and lactic acid concentrations were recorded as a measure of LAB viability. All samples were analyzed for moisture, ash, and lipid composition. Control samples were unable to prevent spoilage of salmon by-products, whereas fermented salmon tissues stabilized at pH 4.5 for 120 days. This research suggests that smoke-processing can decrease the pH of salmon heads prior to oil extraction, but LAB fermentation is required to produce a completely stable product. Improved preservation methods can lead to increased utilization of fish-processing discards while creating a safe supply of stabilized salmon ingredients for the seafood industry.

Last Modified: 12/19/2014
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