Hake Fish

November 13, 1997

Not many people have heard of a fish called "hake", even under its proper name of Pacific Whiting. Part of the reason is that hake have not been harvested commercially until recently. This was because the fish has a built-in enzyme that takes action soon after the fish dies. Only recently has an inhibitor been developed to prevent this spoilage.

Recently we ran tests at Bioproducts, Inc. with a rental CP-10. This firm produces meal that is fed to salmon (farm fish) that is made from waste generated in hake filleting operations. Unfortunately the tests proved a total failure.

Seventy percent of the hake is scrap. This waste, cooked, is what we were attempting to press. The problem encountered was that the material was spoiled. It was in the form of a "pudding" at 86% moisture. This waste is trucked from a nearby fish processor, which results in a delivery delay. Worse yet, the processor uses a chopper pump to transport the waste within his plant, and this process opens up the digestive enzymes to the entire mass.

We suggested adding more inhibitors to stop the enzyme action. Unfortunately this could not be done because the final product is a fish hydrolysate. The hydrolysate is digested material produced by enzymes that are added at the end of the process. It was felt that, if we added inhibitors, they would interfere with the final enzyme action. (In addition, inhibitor residuals can have a negative impact on the environment at the fish pen operations.)

Bioproducts had hoped this process would work because of the potential to save energy. Their process involves taking the fish scrap down to 55% moisture content in Dupps cookers. This is followed with open kettle cooking and mixing with previously dried fishmeal. Going from 86% to 55% in the steam cookers involves a significant fuel expense that Bioproducts would like to avoid.

We were told of one hake plant with a decanter (centrifuge) that reportedly takes hake waste down to 60% moisture. This is used in place of steam cookers. Decanters have the disadvantage of being very expensive both to acquire and maintain.

We have continued to pursue hake pressing. Larry Hess, our sales rep, arranged for us to tour the Arctic Five, a Tyson Seafood factory ship. Aboard this vessel cooked hake scrap is in the screw press within hours of swimming. They currently have Atlas-Stord twin screw presses which achieve 70% to 55% press cake moisture. The performance depends on variables such as the species, the length of cook, the amount of oil, the speed of the press.

These presses have corroded severely in the saltwater environment. Consequently Tyson personnel were much impressed with the all stainless construction of Vincent presses. We hope to have our units in their 1998 budget.

Issue 69