51A-7

A. HUNT¹, J. W. Park¹, and K. Linck². (1) OSU Seafood Lab and Dept of Food Science & Technology, Oregon State University, 2001 Marine Dr. #253, Astoria, OR 97103, (2) Solutia

JUSTIFICATION: Phosphate is added as a possible synergist and/or chelating agent to the cryoprotective effect of carbohydrates. Phosphate is currently used at ~0.25 % as a mixture (50:50) of sodium tripolyphosphate and tetrasodium pyrophosphate (STP/TSPP), but an optimum level for Pacific whiting has not been scientifically determined. In addition, the trend in the surimi industry to use mechanically recovered meat might cause relatively fast denaturation of fish proteins during frozen storage. Therefore, we hypothesized that hexametaphosphate (HMP) could function better as a cryoprotectant and an antioxidant when meat is not thoroughly washed during manufacturing.

OBJECTIVES: To determine the effects of different concentrations (0, .2, .3, .4%) of STP/TSPP and HMP on the functional and biochemical properties of fish proteins in Pacific whiting surimi obtained from two different local manufacturers.

METHODS: Fresh surimi was obtained directly from the processing line of the respective plants before cryoprotectants were added. The surimi samples from each plant were then divided into 7 batches and mixed with 4% sucrose, 5% sorbitol, and the respective phosphate. The samples were frozen using a plate freezer and stored at -18°C. Surimi was tested at 0 - 9 months to evaluate changes in salt extractable protein (SEP), dimethylamine (DMA), color, and gelation properties. For gel evaluation the samples were prepared with 2% salt, 1.5% BPP, and adjusted to 78% moisture using ice/water. The gels were then cooked at 90°C for 15 minutes.

RESULTS: The pH was affected by STP addition, while no pH changes with HMP was observed. As frozen storage continued, DMA increased. However, HMP appeared to be more effective in controlling DMA. For textural values, the higher the phosphate the higher the stress and strain.

SIGNIFICANCE: The higher level (0.4%) also showed the better shelf life. The effectiveness of HMP was more pronounced for surimi manufactured from plant II where meat was not thoroughly washed.