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Research

Recovery of Soluble Proteins from Surimi Washwater.

Problem: As much as 30% of the fish meat (solids) entering the surimi process is washed out in refining. Part of this material can be captured and purified by membrane filtration and employed in various products.

Solution and Approach: To accomplish this task, especially when fatty fish such as arrowtooth flounder (Atherestes stomias) is used for surimi, lipids need to be reduced to achieve required physical properties and shelf life. Initial studies have shown that centrifugation can separate the lipid – protein matrix but methods for reducing binding between the components needs to be refined to achieve a commercial process. Beyond increasing the yield of recoverable protein, the process will solve an effluent disposal problem produced by the discharge of the surimi washwater. This is in particularly true where processors have attempted surimi production from under utilized species like arrowtooth, with high lipid content. Of the total fish solids entering the surimi process 20 to 30+ % of the fish muscle solids are extracted into the washwater. There is a strong interest in the industry to recover and use these solids. However, the solids needs to be refined and the lipid content needs to be reduced before such effort can take place. Membrane filtration can concentrate and purify the solids but the high lipid content remains a barrier for including the protein back into surimi or in other product formulations. Specific project goals include:

  1. Use membrane filtration to selectively concentrating 80% of the higher molecular weight WWS proteins from 20% of the low molecular weight proteins and nitrogen compounds.
  2. Obtain a final concentrated purified protein product with a minimum of 10% solids, an ash content reduced by 50%, and a maximum lipid content of less than 8% on solid basis.
  3. Retain physical and functional properties that that allow for inclusion in surimi or other uses.
  4. Conduct in plant testing to develop and demonstrate process in a continuous operation
  5. Conduct shelf-life studies to evaluate surimi quality of samples containing graded levels of the concentrated protein from WWS.
  6. Chemically and nutritionally analyze the recovered protein fraction for potential use as an aquaculture feed ingredient.

Note: This project is ongoing.

Contact person: Dr. Scott Smiley email: smiley@sfos.uaf.edu