Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2006
Publication Date: N/A
Alaska’s fishing industry generates over one million metric tons of fish processing wastes each year. In some locations these by-products can be converted into a low value, high ash fish meal, however smaller processors often use the grind-and-dump method of disposal. Production of high protein liquid concentrates can be an inexpensive method to preserve some of the fish by-products currently discarded by processors.
There are many methods for stabilizing fish by-products, however when producing a high protein liquid concentrate, the three most common techniques are ensilage, fermentation, and hydrolysis. Silage is prepared by grinding the fish, acidifying the homogenate below pH 4.0 to prevent microbial spoilage, and then allowing the natural enzymes to break down the fish proteins. Preparation of fermentates is similar to silage, except that an acid-producing bacteria is added to lower the pH, instead of directly adding acid. Hydrolysates are produced through the use of commercial enzymes, which digest the fish by-products to create a liquefied protein solution.
This presentation will describe these three stabilization methods, and discuss some current research projects designed to preserve fish by-products as high protein liquid concentrates in Alaska.
The quality of a high protein liquid concentrate is typically judged by the protein quality, oil content, and percent moisture, as well as the presence of free fatty acids, amino acids, and bitter compounds. Silage and fermentation are relatively simple processes that do not require heat. However, the more complex techniques used in the production of hydrolysates allow more control over the end product. Combinations of these methods may be needed to maximize the efficiency and reduce the cost of stabilizing fish by-products in Alaska.