Innovative uses for under-utilized salmon tissues in Alaska

Authors: Bower, Cynthia; Hietala, Katie

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/28/2008
Publication Date: N/A
Citation: N/A

Interpretive Summary: The increased utilization of high quality fish by-products is receiving more attention as processors look for ways to expand their markets. Fish meals and specialized fractions that can act as palatability enhancers and attractants for aquaculture feeds are an important use, but fish by-products might also attract interest as functional foods affecting vitality and health in humans. Potential exists for innovative products enriched with high-value fish proteins and “omega-3s” obtained from non-fillet components of fish. However, to ensure success, underutilized fish by-products must be safely preserved. In this study, heads from pink salmon (Oncorhynchus gorbuscha) were smoke-processed and/or fermented using food-grade lactic acid bacteria (LAB), and the resultant oils and tissues were characterized. Preservation of ground salmon heads through pH reduction using LAB 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. Oils extracted from smoked salmon heads retained valuable long-chain polyunsaturated fatty acids (PUFAs) in quantities equal to frozen controls despite the high temperatures (95 °C) and extended heating times (5 hours) associated with smoking fish. Additionally, these smoke-processed oils contained fewer products of oxidation than their unprocessed counterparts, suggesting that natural antioxidants are imparted during the smoking process. Salmon heads were also preserved using a combin-ation of smoke-processing and acidification with LAB. Wood smoke contains com-pounds that naturally lower the pH of salmon tissues. A further decrease (to pH 4.6) resulted from LAB addition. Increased utilization of fish processing discards promises environmental and economic benefits while conserving valuable fish resources.

Technical Abstract: The increased utilization of high quality fish by-products is receiving more attention as processors look for ways to expand their markets. Fish meals and specialized fractions that can act as palatability enhancers and attractants for aquaculture feeds are an important use, but fish by-products might also attract interest as functional foods affecting vitality and health in humans. Potential exists for innovative products enriched with high-value fish proteins and “omega-3s” obtained from non-fillet components of fish. However, to ensure success, underutilized fish by-products must be safely preserved. In this study, heads from pink salmon (Oncorhynchus gorbuscha) were smoke-processed and/or fermented using food-grade lactic acid bacteria (LAB), and the resultant oils and tissues were characterized. Preservation of ground salmon heads through pH reduction using LAB 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. Oils extracted from smoked salmon heads retained valuable long-chain polyunsaturated fatty acids (PUFAs) in quantities equal to frozen controls despite the high temperatures (95 °C) and extended heating times (5 hours) associated with smoking fish. Additionally, these smoke-processed oils contained fewer products of oxidation than their unprocessed counterparts, suggesting that natural antioxidants are imparted during the smoking process. Salmon heads were also preserved using a combination of smoke-processing and acidification with LAB. Wood smoke contains compounds that naturally lower the pH of salmon tissues. A further decrease (to pH 4.6) resulted from LAB addition. Increased utilization of fish processing discards promises environmental and economic benefits while conserving valuable fish resources.