100-6 |
Effects of cryoprotectants on physicochemical attributes of intact rainbow trout, Oncorhynchus mykiss, fillets |
S. JITTINANDANA1, P. B. Kenney, S. D. Slider, and R. Kiser. (1) Dept. of Animal & Veterinary Sciences, West Virginia Univ., Agricultural Sciences Bldg., PO Box 6108, Morgantown, WV 26506-6108 Losses in protein functionality of frozen fish are explained by changes in protein physicochemical attributes. Cryoprotectants would minimize deleterious effect of frozen storage on physiochemical properties of myofibrillar proteins. This study was conducted to evaluate sucrose/sorbitol or sodium lactate as cryoprotectants and determine if phosphates or magnesium chloride had an additive effect on stabilizing physicochemical attributes of intact frozen fillets. Stabilization of fish myofibrillar proteins during frozen storage by 8.0% (w/v) sucrose/sorbitol (1:1 w/w) or 1.0% (w/v) sodium lactate was investigated, alone or in combination with 0.5% (w/v) sodium tripolyphosphate/tetrasodium pyrophosphate (1:1 w/w) and 0.05% (w/v) magnesium chloride. A 3x2x2 factorial, randomized incomplete design was conducted with three replications. Water was used as control treatment. After soaking in cryoprotectant, fillets were vacuum packed and stored at –20°C for 90 days. Frozen storage decreased actin solubility, myosin solubility, and total protein solubility, and increased actin and myosin susceptiblility to thermal denaturation, surface hydrophobicity, and free sulfhydryl, disulfide sulfhydryl, and total sulfhydryl content. Frozen storage effects on actin solubility and surface hydrophobicity (P<0.05), and actin susceptibility to thermal denaturation (P<0.10) were minimized in sucrose/sorbitol and sodium lactate compared to water; disulfide sulfhydryl content of fillets increased less for cryoprotectants than for water (P<0.10). Differences caused by frozen storage for myosin solubility, myosin susceptibility to thermal denaturation, free sulfhydryl and total sulfhydryl content (P<0.05), and total protein solubility (P<0.10) were less for sucrose/sorbitol than for sodium lactate. Phosphates minimized frozen storage effects on actin solubility, myosin susceptibility to thermal denaturation (P<0.05), and surface hydrophobicity (P<0.10). Magnesium chloride increased the negative effects of storage on myosin solubility and total sulfhydryl and disulfide sulfhydryl content; whereas, actin solubility was preserved (P<0.10). Freeze-induced denaturation of fish muscle proteins was minimized by cryoprotectants; and sucrose/sorbitol was more effective than sodium lactate.
Session 100, Seafood Technology: Texture, Chemistry
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