UBC Theses and Dissertations
The influence of ration level and swimming speed on sensory attributes, gas chromatographic properties, instron texture profile analysis and PH of cooked muscle from farmed chinook salmon (Oncorhynchus tshawytscha) cultured in seawater Siemens, Beverly Ruth
Representative samples of post-juvenile Chinook salmon were obtained from the Department of Fisheries and Oceans Canada - West Vancouver Laboratory. The fish were part of a study directed to assessing the influence of two ration levels (75% and 100% of maximum ration) and three swimming speeds (0.5, 1.0, and 1.5 body lengths/second) on growth, body composition and thyroid function of chinook salmon in seawater. All analyses in the present study were conducted using cooked muscle. Sensory analysis, conducted in 19 sessions (10 days), was performed by 6 trained panellists. The treated and reference samples, composed of randomly mixed slices of muscle from farmed chinook salmon obtained at a local fishmonger, were graded for 28 sensory attributes; 9 aroma, 10 flavour, 8 texture as well as "overall acceptability". After completing preliminary analyses of the sensory data, data from panellist 6 and the first panel session were eliminated due to excessive inconsistencies in the results. ANOVA revealed that 8 attributes were significantly affected by ration level. After standardising the significantly affected attributes' data, using a z-transformation to remove the panellist effect, one aroma term was no longer significant. Principal Component (PC) Similarity graphs using the standardised data clearly illustrated the effect of ration level on these sensory attributes. The effect of using a replacement panellist for panellist 5 on two occasions became apparent from a PC 1 vs. PC 2 graph of that panellist's data. Purge and trap extracts were used for gas liquid chromatographic analysis of volatile compounds from cooked salmon. An ANOVA of consistently appearing peaks revealed that 27 of these were significantly affected by either SS or RL. Principal Component Similarity graphs of data from these peaks showed a clear separation on the basis of RL but not SS. The Instron Texture Profile Analysis statistics differed sharply from the other results since they indicated that SS and not RL significantly affected the texture of the cooked salmon. The pH values for cooked fish were significantly affected by RL. The results of this study, with the exception of those from Instron TPA , agreed with those of Kiessling et al. (1994a,b) who generally found that RL and not SS significantly affected the growth and whole-body and muscle proximate composition of chinook salmon in seawater.
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