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United States Department of Agriculture

Agricultural Research Service

Research Project: CONVERTING ALASKA FISH BY-PRODUCTS INTO VALUE ADDED INGREDIENTS AND PRODUCTS Title: Sustainable Harvests Through Increased Utilization of Salmon By-Products

Author
item Bower, Cynthia

Submitted to: Book of Abstracts World Aquaculture Society
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2007
Publication Date: N/A

Interpretive Summary: The growing demand for fish meals and oils has produced a steady rise in the market price garnered by these commodities. However, the practice of discarding fish-processing wastes is still widespread. Alaska’s fishing industry generates over one million metric tons of fish by-products each year, much of which is discarded during processing when fish meal facilities are not located nearby. To take advantage of the increasing world market for fish oils and protein, remote and seasonal processors may have to adopt a by-products strategy of “Preserve them now, deal with them later”. In Alaska, fish meal production is the most common method for preserving fish by-products. Other techniques, (ensilage, fermentation, and hydrolysate production), are less prevalent, but can also successfully stabilize perishable fish. In this study, Pink Salmon (Oncorhynchus gorbuscha) heads, viscera, and head-viscera mixtures were preserved using either direct acidification with formic acid or through pH reduction using lactic acid bacteria (LAB). Significant differences among the initial pH values of viscera, heads, and mixtures were apparent for the entire 18 weeks of storage, suggesting that individual by-product varieties may require separate handling for best preservation. Increased utilization of fish processing wastes promises environmental and economic benefits while conserving valuable fish resources. By-products preserved without protein loss can be used in agriculture and aquaculture feeds. Silages with shorter peptides resulting from longer storage times, may be more suitable for use as fertilizers, compost, and as feedstocks for energy production.

Technical Abstract: The growing demand for fish meals and oils has produced a steady rise in the market price garnered by these commodities. However, the practice of discarding fish-processing wastes is still widespread. Alaska’s fishing industry generates over one million metric tons of fish by-products each year, much of which is discarded during processing when fish meal facilities are not located nearby. To take advantage of the increasing world market for fish oils and protein, remote and seasonal processors may have to adopt a by-products strategy of “Preserve them now, deal with them later”. In Alaska, fish meal production is the most common method for preserving fish by-products. Other techniques, (ensilage, fermentation, and hydrolysate production), are less prevalent, but can also successfully stabilize perishable fish. The objective of this study was to compare the efficacy of different methods of acidification for stabilizing salmon heads, viscera, and mixtures of both. Increased knowledge in this area will provide fish processors with more choices for preserving the underutilized fish components for later sale. In this study, Pink Salmon (Oncorhynchus gorbuscha) heads, viscera, and head-viscera mixtures were preserved using either direct acidification with formic acid or through pH reduction using lactic acid bacteria (LAB). Control samples were not acidified, relying entirely on endogenous proteolytic enzymes to break down tissues. 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. The distribution of nitrogen was also followed (Table 1), since proteins degrade into shorter peptides and free amino acids during storage. Results from this study demonstrated that control samples were unable to prevent spoilage of salmon by-products. Only silages and fermentates stabilizing at pH 4.5 or lower successfully preserved samples for 120 days. Significant differences were apparent among initial pH values of salmon viscera, heads, and mixtures, and differences remained for the entire 18 weeks of storage, suggesting that individual by-product varieties may require separate handling for best preservation. Increased utilization of fish processing wastes promises environmental and economic benefits while conserving valuable fish resources. By-products preserved without protein loss can be used in agriculture and aquaculture feeds. However, silages with shorter peptides resulting from longer storage times may be more suitable for use as fertilizers, compost, and as feedstocks for energy production.

Last Modified: 9/1/2014
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