FISHERY BULLETIN: VOL. 85, NO. 4 



thickness, cooked in an oven at 375°F for 20 to 50 

 minutes. The texture of the fish was then deter- 

 mined organoleptically. 



Mechanical texture was determined on 180 

 randomly selected fish, in which duplicate shear 

 press readings were taken on 15 g of muscle 

 tissue removed from the dorsal portions of the fish 

 samples to correlate with the portions taken for 

 sensory evaluations. The successful use of me- 

 chanical texture analysis to correlate with the 

 sensory texture of Pacific whiting was previously 

 reported by Nelson et al. (1985). The tissues were 

 teased into flakes which were leveled to a height 

 of 8 mm in a Kramer shear-compression cell 

 which was reduced in size to 29 mm wide, 71 mm 

 long, and 64 mm deep to accommodate the sam- 

 ple. The assembly, consisting of four blades, was 

 similar to the one described by Bilinski et al. 

 (1977) and used by Tsuyuki et al. (1982) to evalu- 

 ate objectively the texture of Pacific whiting. The 

 cell operated in conjunction with the Food Tech- 

 nology Corporation FTA 3000 transducer^, TP-4 

 Texturepress, and the TR-5 Texturecorder. A plot 

 was made of the force required to drive the blades 

 through the sample at a ram speed of 1 cm per 

 minute and at a set recorder range. The peak 

 force in pounds per 15 g tissue was calculated 

 from the plot (Bourne 1982). 



Culling was performed on partially thawed 

 halves offish. Pseudocysts are visible as white or 

 black threads of varying intensities imbedded 

 longitudinally along the muscle fibers. The 

 culling categories were modeled after the scheme 

 of Patashnik et al. (1982) for both white and black 

 pseudocysts as none, light (<20%), moderate 

 (20 to 30%), and heavy (>30%) as determined 

 visually, based on the percent area of fillet 

 affected. 



Only fish over 27 cm were used for all analyses, 

 since in commercial operations fish smaller than 

 27 cm would not likely be taken because domestic 

 and foreign fishermen use 50 mm (2 in) to 100 mm 

 (4 in) cod end mesh size as regulated by the 

 Pacific Coast Groundfish Fishery Management 

 Plan.5 



Data representing sensory textures and Kudoa 

 pseudocyst counts (made on a total of 562 fish 

 exclusive of fish under 27 cm) were analyzed on 



■^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



y. Wall, REFM Division, Northwest and Alaska Fisheries 

 Center, National Marine Fisheries Service, NOAA, 7600 Sand 

 Point Way N.E., BIN C15700, Seattle, WA 98115, pars, com- 

 mun. March 1985. 



the NWAFC Burroughs 7800 computer system 

 using the SPSS software package described by 

 Nie et al. (1970) and SPSS Update 7-9 (Hull and 

 Nie 1981). 



Fitted regression curves between cooked tex- 

 ture values and white and black pseudocyst 

 counts were drawn using robust locally weighted 

 regression analyses described by Cleveland 

 (1979). The method was used to smooth scatter- 

 plots by calculating a polynomial fit to data using 

 weighted least squares. 



RESULTS AND DISCUSSION 



Relationship Between 



Sensory Texture Ratings and 



Shear Press Values 



Since any nonsensory evaluations of a fishery 

 product must ultimately relate to the products' 

 intrinsic organoleptic properties, emphasis in 

 this study was placed upon taste tests despite the 

 inherent fatigue factor associated with testing 

 large numbers of samples. No consumer-type 

 panel was carried out to test the accuracy of the 

 texture evaluation, because fish with abnormal 



o 



Q. 



7 - 



> 

 o 



• • t* 



• • •••9 • ••• 



• •••••• Al* 



t • • •• • 



•••»* I I 



• *•«•« t 



•• •• m\ • • 

 t« ••• •• I • 



• I • 



I t . 



• • • 



••• I 



r = 0.90 



20 40 60 80 100 



Shear press in pounds / 15 grams tissue 



120 



Figure 4. — Scatterplot and Spearman correlation coefficient (r) 

 between sensory texture rating and shear press force of cooked 

 flesh of Pacific whiting fillets. 



748 



