Results

1. Introduction Alaska’s commercial weathervane scallop fishery is primarily prosecuted by catcher-processor vessels that shuck, wash, grade, and freeze scallop muscles onboard. The 2006-2008 average for weathervane scallop harvest was about 204,545 Kg with an ex-vessel value of $3.36 million dollars. From 1994-2002 the eastern Gulf of Alaska region (GOA; Yakutat) accounted for 31% of statewide scallop landings. Fishermen have reported that scallops caught in some GOA areas are of lower value due to poor quality; characterized by weak muscle strength, stringy and spongier texture, and off-white to grayish muscle color. The objective of this research was to quantify variability in meat quality of commercially harvested weathervane scallop using physical and biochemical analyses. Materials and methods In summer of 2009, two groups of 40 whole scallops, Weak (WS) and Not Weak (NWS), were sampled from Yakutat. Kodiak scallop meats (KS1, KS2), known for their high quality and market value were procured locally in April and August 2009. Physical characteristics studied included shell and muscle dimensions and weights (WS and NWS), texture analysis of edible muscle, and determination of animal age. Proximate composition was determined using standard AOAC methods. Lipid classes, fatty acids, amino acid, minerals and pH were determined as previously described by Bechtel and Oliveira (2006). Figure 3: pH of scallop adductor muscle Discussion Proximate composition of NWS, Kodiak 1 and Kodiak 2 are consistent with published data (Krzynowek and Murphy, 1987), while WS are higher in moisture and lower in protein and carbohydrate than expected. Conversions of fatty acids into fatty acid methyl ester for analysis was very low due to the high PL content of the scallop muscle; however, the FA profile is consistent with specimens having high PL levels (Richoux et al, 2005). FA analysis indicated lower levels of key FA in WS than in NWS, Kodiak 1 and Kodiak 2. In general, analysis quantified that there are significant physical and biochemical differences between WS and NWS, and not surprisingly, that there are also differences between eastern GOA (Yakutat) and western GOA (Kodiak). Further research would perhaps shed light on the reasons behind these physical and biochemical differences. Figure 1: Proximate composition of scallop adductor muscle Different superscript letters indicate statistical difference between groups at P<0.05 Different superscript letters within a variable indicate statistical difference at P<0.05 Figure 2: Mean annuli (growth rings) of scallop shell Figure 4: Lipid class analysis of scallop adductor muscle Different superscript letters indicate statistical difference between groups at P<0.05 S Meat Wt. S Body Wt. X 100 (%) CI= References AOAC. Helrich K, editor. 1990. Official methods of analysis of the Association of Official Analytical Chemists. 5th ed. Arlington, VA: Official Analytical Chemists, Inc Bechtel PJ and Oliveira ACM. 2006. Chemical characterization of liver lipid and protein from cold water fish species. J. Food Sci. 71(6):S480-485. Krzynowek J, Murphy J. 1987. Proximate composition, energy, fatty acid, sodium, and cholesterol content of finfish, shellfish, and their products. NOAA Technical Report NMFS 55. U.S. Department of Commerce. NOAA. NMFS. Gloucester, MA. Pp1-52. Richoux NB, Deibel D, Thompson RJ, Parrish CC. 2005. Seasonal and developmental variation in the fatty acid composition of Mysis mixta (Mysidaxea) and Acanthostepheia malmgreni (Amphipoda) from the hyperbenthos of a cold-ocean environment (Conception Bay, Newfoundland). J. Plankton Research. Volume 27, number 8, pp719-733. Quality assessment of commercially harvested weathervane scallops (Patinopecten caurinus) from Alaska Kathryn Brenner*1, Alexandra Oliveira1, Gregg Rosenkranz2, Ryan Burt2, Marsha Spafard2, Peter J. Bechtel3, Charles Crapo 1,4, and Raymond RaLonde4 1Fishery Industrial Technology Center, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Kodiak, AK 99615-7401, USA. 2Alaska Department of Fish and Game, Division of Commercial Fisheries, Kodiak, AK 99615-7401, USA 3USDA-ARS, Subarctic Research Unit, Fishery Industrial Technology Center, Kodiak AK, 99615-7401, USA. 4Marine Advisory Program, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Anchorage, AK 99501.USA KAMSS 2011 Kodiak , Alaska Results Figure 1 shows that WS had significantly higher moisture (81.6%) than NWS (78.1%), KS1 (76.4%) and KS2 (76.8%), while protein content was significantly lower in WS (15.4) than in NWS (17.5), KS1 (19.3%) and KS2 (19.2%). WS were significantly older (14.8 annuli) than NWS (5.4 annuli) as shown in Figure 2. A condition index (CI) of edible meat to body ratios was calculated using Formula 1 and was significantly lower in WS (23.6) when compared to NWS (33.7) (Table 1). Figure 3 shows that pH in all three samples was significantly different, and that WS had the highest pH (6.8), however, all pH values were below 7. Lipid class analysis (Figure 4) showed high levels of phospholipids (PL) and low levels of triglycerides (TG) overall, with WS having significantly lower PL than NWS, KS1 and KS2. WS had lower FA levels overall compared to NWS, KS1 and KS2 (Table 2), and ω3 FA levels were significantly lower in WS (112.2mg/g) than in NWS (179.9 mg/g), KS1 (138.9 mg/g) and KS2 (171.5 mg/g). Table 2: Fatty acid (FA) profiles of scallop adductor muscle showing most abundant FAs (>10mg/g oil) a a,b b b a b c a a a,b b a a a a c a,b a a a a b,c a a,b a,b b Different superscript letters within rows indicate statistical difference at P<0.05 a a a,b a,b b a a,b a,b b b Different superscript letters within a variable indicate statistical difference at P<0.05 TG Triacylglycerols; FFA Free Fatty Acids; ST Sterol; PL Phospholipid Formula 1. Condition Index (CI) of edible meat to body Table 1: Mean weights and CI of scallop body and adductor muscle Different superscript letters within rows indicate statistical difference at P<0.05