Comparison of gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle proteins during iced and frozen storage

Gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle behave differently during storage, whether in ice or deep frozen. Rapid changes have been observed in the texture of hake muscle during frozen storage, while gilthead sea bream has proved to be more stable. In order to ascertain the role of muscle proteins in the changes observed during storage, parameters related to protein functionality and the properties of extracted natural actomyosin (NAM) were studied initially and during storage in ice or at ?20 °C. Initially, the parameters related to functionality had higher values in hake muscle and extracted NAM than in gilthead sea bream. At the end of iced storage (22 days), less myosin heavy chain (MHC) and actin were extracted from hake, but there was practically no change in gilthead sea bream. This decrease was not accompanied by lower Ca²⁺‐ATPase activity. Freezing produced no drastic changes, with lower values for gilthead sea bream. However, this species was more stable after 1 year, except for the Ca²⁺‐ATPase activity of NAM. This suggests that the changes that hake proteins underwent during storage particularly affected properties related to aggregation, whereas in gilthead sea bream the changes hardly affected the formation of soluble or insoluble aggregates but did affect the active sites of myosin. © 2002 Society of Chemical Industry     

Biochemical and physicochemical properties of actomyosin from pre- and post-spawned flounder (Paralichtys patagonicus) stored on ice

The biochemical and physicochemical properties of actomyosin from pre- and post-spawned flounder stored on ice were studied. Irrespective of the gonadal condition of the fish, a gradual decrease in reduced viscosity, Mg²⁺ATPase and Mg²⁺Ca²⁺ATPase activities of actomyosin was observed. A similar decrease in the Mg²⁺ EGTA ATPase activity of actomyosin from post-spawned flounder was also observed. The decrease in enzymatic activities was accompanied by an increase in surface hydrophobicity of the protein. No signs of proteolysis of the major components of the actomyosin complex were detected. The relative percentage of myosin decreased and that of actin increased in actomyosin from pre- and post-spawned flounder stored on ice. These changes occur earlier in actomyosin from prespawned flounder. The results of this paper indicate that actomyosin from flounder denatured during fish storage on ice and suggest that this denaturation is due to structural and conformational changes in myosin which led to aggregation of this protein.     

CHARACTERISTICS OF MUSCLE FROM TWO SPECIES OF BIGEYE SNAPPER, PRIACANTHUS TAYENUS AND PRIACANTHUS MACRACANTHUS

Composition and some properties of muscle from two species of bigeye snapper, P. tayenus and P. macracanthus, were investigated. Both species had a similar composition with the same myofibrillar protein content. However, muscle proteins from P. tayenus had higher thermal stability than those from P. macracanthus, as indicated by the higher enthalpy for transitions as well as the lower inactivation rate constant (K_D). Upon 15 days of iced storage, natural actomyosin Ca^2*‐ATP ase and Mg²⁺‐Ca²⁺‐ATPase activities decreased, whereas Mg²⁺‐EGTA‐ATPase activity increased, suggesting the denaturation of myosin, actomyosin and troponin/tropomyosin complexes, respectively. Increased surface hydrophobicity and decreased sulfhydryl groups indicated the denaturation possibly occurred via hydrophobic interaction and disulfide formation. Heading and eviscerating offish retarded the denaturation and physicochemical changes of proteins during iced storage. The results indicated that a rapid and proper post harvest handling was of importance to maintain the muscle quality of bigeye snapper.     

Protein Denaturation of Frozen Pacific Whiting (Merluccius productus) Fillets

Protein denaturation in Pacific whiting fillets stored at ?8, ?20, ?34, and ?50°C was investigated over a 10-mo period by several methods, including salt-soluble protein extractability, Ca⁺⁺-ATPase activity, and the torsion test. Changes in quality of fillets stored at ?8°C were significantly greater than those stored at lower temperatures. Fillets stored at ?34 and ?50°C showed no significant advantage over those stored at ?20°C as measured by salt-soluble protein extractability and Ca⁺⁺-ATPase activity. However, fillets stored at the lower temperatures had slightly higher torsion shear strain.     

Gelling Properties of Actomyosin from Pre- and Post-Spawning Hake (Merluccius hubbsi)

The biochemical properties and the characteristics of heat-induced gelation of natural actomyosin (NAM) from pre- and post-spawning hake were studied. Mg²⁺ ATPase activity, reduced viscosity and myosin/actin mole ratio of NAM from post-spawning fish were higher than those of pre-spawning ones. Gelation of both actomyosin at 10 mg mL^?1 of protein concentration was optimal at 60°C and pH 6.0. The highest rigidity was reached at 0.40M and 0.44M KCl with NAM from pre and post-spawning hake, respectively. Irrespective of heating temperature, ionic strength conditions and at pH range 5.5–7.5, rigidity of post-spawning hake NAM gels was higher than those of pre-spawning fish. Scanning electron micrographs of pre- and post-spawning hake NAM showed “actin-type” and “myosin-type” ultrastructures, respectively.     

Biochemical and Physicochemical Properties of Actomyosin from Pre- and Post-spawned Hake (Merluccius hubbsi) Stored on Ice

Biochemical and physicochemical properties of natural actomyosin (NAM) from pre- and post-spawned hake stored on ice were studied. At the beginning of storage both reduced viscosity and ATPases activities of NAM from post-spawned hake were about 3 times higher than those of the pre-spawned ones, except for the Mg²⁺-(Ca²⁺)-ATPase. Higher loss of functional components during pre-spawned hake NAM purification was found compared to NAM from post-spawned fish. Reduced viscosity and Mg²⁺-(EGTA)-ATPase activity of NAM from both pre- and post-spawned hake decreased following ice storage. SDS-PAGE patterns of NAM from pre-spawned hake showed an absence of the myosin heavy chain and the presence of a 160 kDa component at zero time of storage. No proteolysis occurred in ice-stored fish caught in both gonadal stages.     

ADENOSINE TRIPHOSPHATASE OF SACCHAROMYCES CARLSBERGENSIS

The ATPase activity of whole cells of anaerobically grown Saccharomyces carlsbergensis was low, but EDTA or glucose revealed ATPase activity. The ATPase was activated by Mg⁺⁺ and Ca⁺⁺; excess Ca⁺⁺ was inhibitory. The optimum pH was 8·0 and optimum temperature about 40° C. The enzyme liberated less than two moles of phosphate from one mole of ATP and other nucleoside triphosphates and released phosphate slowly from ADP; nucleoside monophosphates were not hydrolysed. The enzyme was inhibited by atebrin, sodium azide and ADP, but was unaffected by ouabain, sodium fluoride or 2,4-dinitrophenol.     

Application of Antifreeze Protein for Food Preservation: Effect of Type III Antifreeze Protein for Preservation of Gel-forming of Frozen and Chilled Actomyosin

Type III antifreeze protein (AFP) remarkably preserved Ca²⁺ ATPase activity of actomyosin during frozen and chilled storage. Under frozen conditions, AFP helped to retain the Ca²⁺ ATPase activity of actomyosin much higher than that of conventional cryoprotectants (sucrose‐sorbitol mixture). The Ca²⁺ ATPase activity increased with increasing AFP concentration and reached a maximum at 50g/L AFP. After 3‐d chilled storage, the Ca²⁺ ATPase activity of control and sucrose‐sorbitol samples had lost 80% and 50%, respectively, while the AFP samples remained unchanged. A Type III AFP mechanism based on freezing temperature depression (more unfrozen water) and inhibition of ice recrystallization that protects against the freezing of muscle proteins in chilled or frozen conditions is proposed.     

Biochemical and Physicochemical Properties of Actomyosin from Frozen Pre- and Post-spawned Hake

Protein solubility, reduced and intrinsic viscosity, and enzymatic activities of actomyosin showed that frozen fillets from pre-spawned hake, stored at — 20°C, deteriorated faster than those from post-spawned hake. The post-spawned actomyosin showed an 18% increase in reduced viscosity, a larger hydrophilic surface, and an increase (P<0.001) in Mg²⁺-, Mg²⁺-EGTA- and Ca²⁺-ATPase activities. Protein solubilities of 85.5 52.5 ± and 33 ± 2.0% were obtained at the end of storage for post and pre-spawned fillets, respectively. Enzymatic activities of post-spawned fillets persisted up to 60 days. No changes were detected in characteristic polypeptide bands of actomyosin or in the myosin/actin ratio related to either gonadal condition during storage.     

Comparison of the Thermostability of Red Hake and Alaska Pollock Surimi during Processing

Thermostability of red hake (Vrophycis chuss) mince and its temperature-dependent gel-forming properties were determined while using Alaska pollock (Theragra chalcogrumma) for comparison. Fish mince and surimi were subjected to various washwater, chopping and setting/ cooking temperatures, cooking times at varying salt concentrations and moisture levels. The optimal temperatures for washing and chopping were 15°C and 12°C for red hake and 10°C and 4°C for pollock, respectively. All treatments significantly affected gel properties. For red hake gels, 77% moisture, 2.0% salt, and a 40°C preheat-setting temperature produced the most cohesive gel. Gels of both red hake and pollock gradually became less cohesive with extended cooking time. The results suggest that red hake is more thermally stable than pollock.     

Physicochemical properties and gel-forming ability of surimi from three species of mackerel caught in Southern Thailand

Physicochemical and gelation properties of surimi prepared from three species of mackerel were investigated. The highest whiteness with the lowest redness index corresponding to the lowest myoglobin content especially its oxidised form, metmyoglobin, was found in short-bodied mackerel (Rastrelliger brachysoma) surimi (p < 0.05). Frigate mackerel (Auxis thazard) surimi contained the highest lipid content (p < 0.05). The pH of all surimi was in the range of 6.58–6.80. The highest sulfhydryl group and Ca²⁺-ATPase activity was found in natural actomyosin extracted from short-bodied mackerel surimi (p < 0.05). The highest TCA-soluble peptide content was found in frigate mackerel surimi gels (p < 0.05). Kamaboko gel of short-bodied mackerel surimi exhibited the highest breaking force with the lowest expressible drip (p < 0.05). Heating regime had no effect on deformability of gels from Indian mackerel (Rastrelliger kanagurta) and short-bodied mackerel but not for frigate mackerel. The highest metmyoglobin content with the lowest whiteness was found in frigate mackerel surimi gel (p < 0.05). Therefore, short-bodied mackerel was the best suited for the production of surimi with superior functional attributes including whiteness and gel-forming ability.     

Gel‐forming properties of surimi produced from bigeye snapper,Priacanthus tayenus and P macracanthus,stored in ice

The influence of iced storage of two species of bigeye snapper, Priacanthus tayenus and P macracanthus, on the gel‐forming ability of the resulting surimi was investigated. Upon iced storage, whole fish underwent deterioration faster than beheaded/eviscerated fish. Total volatile base and trimethylamine contents of whole fish were higher than those of beheaded/eviscerated fish, particularly after 9 days of storage (P < 0.05). P macracanthus muscle was more susceptible to proteolytic degradation than P tayenus muscle. Ca²⁺‐ATPase activity decreased as the storage time increased (P < 0.05), indicating the denaturation of myosin. A marked decrease in Ca²⁺‐ATPase activity was found in whole fish kept for more than 6 days in ice (P < 0.05). Breaking force and deformation of surimi gels from both species decreased, with a concomitant decrease in whiteness, as the storage time increased (P < 0.05). Beheading and evisceration of fish retarded the deterioration. However, the gel‐forming ability of surimi produced from both species decreased continuously throughout iced storage (P < 0.05), probably owing to the denaturation and degradation of myofibrillar proteins. © 2002 Society of Chemical Industry     

The action of a muscle proteinase on the myofibrillar proteins of bovine muscle

Myofibrillar proteins from bovine muscle have been treated with a Ca²⁺ activated muscle proteinase and the consequent changes in these proteins have been examined by various techniques. Tropomyosin, α-actinin and troponin were substrates for the enzyme, the last losing its property of inhibiting actomyosin ATPase in the absence of Ca²⁺ ions. Actin and actomyosin were apparently not digested but the Mg²⁺-activated ATPase activity of actomyosin was less after treatment whereas the Ca²⁺-activated ATPase was unaffected. It is suggested that the observed destruction of the Z-bands of the myofibrils by this proteinase is due to its digestion of the α-actinin, rather than the actin component.     

Extracellular Protease from Pseudomonas marinoglutinosa: Some Properties and Its Action on Fish Actomyosin

A bacterium isolated from Indian mackerel (Rastrelliger kanagurta) and identified as Pseudomonas marinoglutinosa, was found to produce appreciable amounts of extracellular protease when grown in nutrient medium. This enzyme which degraded several proteins, was found to be most active against mackerel myofibrillar proteins. The optimum temperature and pH range for enzyme activity were 50°C and 7–8 respectively. Treatment of mackerel actomyosin with the protease at 0–2°C for 4 days resulted in degradation of the protein as assessed by release of tyrosine, loss in Mg⁺⁺-dependent ATPase activity and changes in SDS-polyacrylamide gel electrophoretic patterns.     

Inhibition of frozen storage‐induced oxidation and structural changes in myofibril of common carp (Cyprinus carpio) surimi by cryoprotectant and hydrolysed whey protein addition

The objective of the present study was to evaluate the efficacy of combined cryoprotectants (sucrose + sorbitol) and whey protein isolate (WPI) hydrolysates to inhibit protein oxidation and quality loss in common carp (Cyprinus carpio) surimi during frozen storage at ?25 °C. With increasing storage time, the carbonyl content of myofibrillar proteins increased from 4.02 nmolmg^‐1 protein (0 day) to 7.25, 6.31, 5.26 and 4.83 nmol mg^?1 protein (180 days; P < 0.05) for the control and samples with cryoprotectants, with cryoprotectants + WPI hydrolysates and with cryoprotectants + propyl gallate, respectively; protein surface hydrophobicity and turbidity increased in a similar trend, while sulfhydryl content, Ca‐ATPase activity, protein solubility and protein thermal stability decreased (P < 0.05). These results suggest that treatments with combined cryoprotectants and antioxidative WPI hydrolysates offer an effective approach to reducing the extent of protein oxidation in common carp surimi, thereby limiting protein structural changes known to impair texture of surimi products.     

The Cryoprotective Effect of Different Konjac Glucomannan (KGM) Hydrolysates on the Glass Carp (Ctenopharyngodon idella) Myofibrillar During Frozen Storage

The physicochemical properties, Ca²⁺–ATPase activity, and surface hydrophobicity of grass carp myobrillar with different cryoprotectants (0.5 % irradiated degraded KGM, 0.5 % β-glucanase KGM hydrolysate, 8 % sucrose-sorbitol (1:1 w/w)) were investigated. The molecular weight analysis showed that the irradiated degraded KGM and β-glucanase KGM hydrolysate were 1.209?×?10⁴ and 2.093?×?10⁴ Da, respectively. The solubility, Ca²⁺–ATPase activity, and total and reactive sulfhydryl (SH) content of treatments containing KGM hydrolysates were higher than other treatments during frozen storage. Addition of KGM hydrolysates could effectively prevent the increase of surface hydrophobicity. The gel strength and whiteness of surimi showed that the addition of KGM hydrolysates in this experiment resulted in surimi with comparable quality.     

Comparison of the Cryoprotective Effects of Trehalose,Alginate, and Its Oligosaccharides on Peeled Shrimp (Litopenaeus Vannamei) During Frozen Storage

The cryoprotective effects of trehalose, alginate, and its oligosaccharides on peeled shrimp (Litopenaeus vannamei) during frozen storage was investigated by monitoring thawing loss, color, texture, myofibrillar protein content, Ca²⁺‐ATPase activity, and performing microscopic structural analysis. Data revealed significant (p < 0.05) inhibitory effects on thawing loss and textural variables (springiness and chewiness) in trehalose‐, alginate oligosaccharides‐, and sodium pyrophosphate‐treated shrimp compared with the control and alginate‐treated batches. L* values revealed that these saccharides had a positive effect on color stability during frozen storage. In addition, the results of chemical analyses showed that trehalose and alginate oligosaccharide treatments effectively maintained an increased myofibrillar protein content and Ca²⁺‐ATPase activity in frozen shrimp. In addition, hematoxylin & eosin staining and SDS‐PAGE confirmed that these cryoprotective saccharides slowed the degradation of muscle proteins and the damage to muscle tissue structures. Overall, the application of trehalose and alginate oligosaccharides to peeled frozen shrimp might maintain better quality and extend the commercialization of these refrigerated products.     

Electrophoretic Identification of Fish Species Used in Surimi Products

Both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and urea gel isoelectric focusing (IEF) were used to identify species-specific protein bands of raw and cooked fish and surimi samples from Alaska pollock (Theragra chalcogramma) and red hake (Urophycis chuss). In raw samples, species-specific bands were found in the water extracts, while in cooked samples 1% SDS and 8M urea extracts were more effective for species identification in both fish and surimi.     

Physicochemical and enzymatic changes of cod muscle proteins subjected to different freeze–thaw cycles

The effects of freeze–thaw cycles on the physicochemical and enzymatic changes of cod muscle proteins were investigated. The activities of α‐glucosidase and β‐N‐acetyl‐glucosaminidase increased as the the number of freeze–thaw cycles increased. A loss of Ca²⁺‐ATPase and Mg²⁺‐Ca²⁺‐ATPase activities was observed, while Mg²⁺‐EGTA‐ATPase activity increased, especially after one cycle of freezing–thawing, with a concomitant decrease in Ca²⁺ sensitivity. The surface sulphhydryl group content decreased with increasing freeze–thaw cycles, while no changes in total sulphhydryl group content were found. The surface hydrophobicity of actomyosin did not change significantly with the number of freeze–thaw cycles. The loss of protein solubility increased with increasing freeze–thaw cycles. However, no cross‐linked proteins induced by formaldehyde were found. The results revealed that freeze–thaw cycles directly affected the physicochemical and enzymatic properties of cod muscle proteins. © 2000 Society of Chemical Industry     

Properties of actomyosin isolated from cod (Gadus morhua) after various periods of storage in ice

Natural actomyosin was isolated from cod (Gadus morhua L) stored in ice for up to 28 days. The gelling properties, apparent viscosity, Ca^2--ATPase activity and component protein composition by sodium dodecyl sulphate (SDS) electrophoresis were determined for each preparation of natural actomyosin. The apparent viscosity, protease activity, trimethylamine (TMA) content and pH of the fish muscle were also determined. The results showed that the apparent viscosity and Ca^2--ATPase activity tended to decrease slightly during ageing of the fish in ice, whereas some of the gelling properties showed a maximum between 3 and 6 days of storage. However, there was no change in the apparent viscosity of the muscle as a whole even after the fish were considered to be stale according to the TMA values. The ratio of myosin heavy chain to actin in the actomyosin changed with the time of storage of the fish, being highest at 3 days when gelling properties were maximal and decreasing progressively thereafter.