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J. MCGILL1, J. Yongsawatdigul2, J. W. Park1, and A. L. Hunt1. (1) Dept. of Food Science & Technology, Oregon State Univ., OSU Seafood Research Lab., 2001 Marine Dr., Rm. 253, Astoria, OR 97103-3420, (2) Institute of Agricultural Technology, Suranaree Univ. of Technology, School of Food Technology, 111 University Ave., Nakhon Ratchasima, 30000, Thailand For the last twenty-five years, the quantity of fish protein (stabilized myofibrillar proteins) in crabstick formula has changed from over 60% to below 25% in some products. This trend is observed in all markets around the world. Some products contain significantly higher starch and other protein additives as a replacement of fish protein. As a result, there is a large quantity of poor quality crabsticks marketed in the world. Crude protein content can be determined and often declared on the product label. This information though, does not indicate how much fish myofibrillar protein (surimi) is included as an ingredient. Our objective was to develop a new procedure for determining fish myofibrillar protein content in commercial crabsticks, using SDS-PAGE analysis, by measuring myosin heavy chain (MHC). Surimi gels were prepared with various ratios of Alaska pollock surimi, starch, and protein additives. Additives used included, wheat starch, whey protein concentrate, liquid egg white, and beef plasma protein. Surimi, along with other ingredients, was comminuted with 2% salt and ice/water using a Stephan vacuum mixer. The paste was then stuffed into stainless steel tubes and cooked in a water bath set at 90°C. SDS-PAGE analysis was performed on the cooked surimi gels. Various SDS-PAGE patterns were developed for surimi gels with known quantity of fish myofibrillar proteins. The more fish myofibrillar protein used in gel preparation, the more intense the MHC band was on SDS-PAGE. Therefore, based on the accurately measured density of MHC in our known samples, the quantity of MHC in commercial crabsticks was estimated. Then based on the results, the model was developed and verified. Results clearly demonstrated a model for the quantitative assay of fish myofibrillar proteins present in commercial crabsticks. In turn, this model could be used to determine product quality with regard to fish protein content.
Session 63, Aquatic Food Products: Quality, processing, antioxidants and surimi
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