|Abstract or Summary
- In surimi manufacturing, less than 25% of the total weight of the fish is utilized. This research focused on meat recovery from fish frames, the residual portion of the fish after filleting headed and gutted fish. A new technology, the water jet deboning (WJD) system, was tested. The WJD system uses oscillating high pressure water jet nozzles to recover edible flesh from the frames without breaking the kidney located under the backbone. To evaluate the function of added salt on dewatering and process recovery, the WJD was operated without NaCl (WJD1) and with 0.2% NaCl added to the discharge slurry (WJD2). In conventional mechanical deboning process (MD), which was the other deboning system applied in the study, no salt was used. The recovered frame meat was further processed to surimi and then stored at -18°C. Meat recovery and surimi processing yields were compared between the three meat recovery processes.
Functional properties of gels (texture and color) were evaluated after 1 and 6 mo frozen
storage and compared to commercially manufactured surimi, which served as a control.
As a result of manual trimming, the maximally recoverable meat from the frames was 42.8% of frame weight. MD showed the highest mince yield (mince prior to cryoprotectant addition), 24% of frame weight, while the two WJD methods resulted in only 5% yield. Color and shear strain for gels from WJD1, MD surimi and mixtures of those and control (10-20% frame mince surimi/80-90% control), were comparable to control. Gels from WJD2 showed significantly lower lightness (L*) but did not differ otherwise. Shear stress values of all frame meat surimi gels and the gels from mixtures of those and the control were significantly lower than the control. This low shear stress is probably due to a difference in processing equipment and processing conditions between the lab scale and the commercial scale.
Due to the promising processing yield for the MD system an additional study was performed where effects of kidney and kidney blood contamination in the frame mince were investigated. Pacific whiting frames were mechanically deboned with/without kidney and the frame mince further processed into surimi. Functional properties of gels (texture and color) were evaluated after 1 and 6 mo frozen storage and compared to commercially manufactured surimi, which served as a control. At 1, 2, 4, and 6 mo, salt extractable proteins (SEP) concentration, dimethylamine (DMA) formation and pH were measured to monitor protein denaturation. Removing the kidney and washing the frames prior to MD resulted in higher gel strength after 1 and 6 mo frozen storage.