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M. LIN1, A. G. Cavinato, D. M. Mayes, S. Smilley, Y. Huang, M. Al-Holy, and B. A. Rasco. (1) Dept. of Food Science & Human Nutrition, Washington State Univ., PO Box 646376, Pullman, WA 99164-6376 Bruising is a particular problem with aquatic food products. Deep bruising is a condition that cannot be readily detected by examining the surface features of the fish. Deep bruising is generally caused by crushing or injuring a fish while it is still alive. Bruising is a major product defect in whole wild caught salmon. It dramatically reduces the value of fish fillets. Visible and SW-NIR (600 - 1100 nm) spectroscopy radiation travels over long path lengths and penetrates fish skin and scales into the muscle tissue, thus permitting analysis of intact whole fish. Visible and SW-NIR can detect the presence of muscle bruises in salmon since oxyhemoglobin and deoxyhemoglobin in fish muscle absorb in this spectral region. The objective of this study was to evaluate the ability of visible and SW-NIR spectroscopy to detect bruises in intact Pacific pink salmon (Oncorhynchus gorbuscha) by partial least squares (PLS) modeling. The measurements were performed non-invasively through fish skin and scales in the diffuse reflectance mode. Digital images of bruised and non-bruised regions of fish were captured after the fish samples were filleted. Image analysis was conducted using Adobe Photoshop 7.0 with relative gray values used as reference values in a partial least squares (PLS) model. A PLS cross-validation model yielded a standard error of prediction (SEP=0.05%, R=0.83). Approximately 84% of all non-bruised spectra were correctly classified, while approximately 81% of all bruised spectra were correctly classified. These results suggest that visible and SW-NIR could be used to control bruise defects of fish products during processing, thereby improving product consistency and quality. This technique could be of a possible commercially relevant application in aquatic industries, and may be transferable to other food system as well.
Session 63, Aquatic Food Products: Quality, processing, antioxidants and surimi
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