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.     

Biochemical and Functional Properties of Myofibrils from Preand Post-Spawned Hake (Merluccius hubbsi Marini) Stored on Ice

Enzymatic activities assayed at beginning of storage in myofibrils from post-spawned hake were 3 X those in myofibrils from pre-spawned hake. Ca²⁺ sensitivity of myofibrils from pre-spawned hake was 40% less than that of myofibrils from post-spawned hake. The profiles of SDS-PAGE gels of pre-spawned myofibrils at beginning of storage showed a partially denatured myosin heavy chain, and polypeptide bands under myosin heavy chain. They probably represent proteolytic fragments produced by degradation of MHC in vivo. No proteolysis was detected in myofibrils during storage. These results help predict functional properties of fish proteins and changes during storage.     

Extractability and thermal stability of frozen hake (Merluccius merluccius) fillets stored at −10 and −30 °C

The relationship between thermal stability changes and functionality loss was monitored in hake muscle fillets stored for 40 weeks at ?10 and ?30 °C. The evolution of changes in apparent viscosity, dimethylamine formation and extractability of muscle proteins in NaCl, sodium dodecyl sulphate (SDS) or SDS plus mercaptoethanol showed drastic differences as a function of temperature. At the higher storage temperature, both myosin heavy chain and collagen were the most severely unextracted in salt and SDS solutions, with actin becoming unextractable at the end of storage. Differential scanning calorimetry showed differences with storage time and temperature in both onset temperature and thermal denaturation enthalpy, mostly affecting the myosin transitions. Some protein denaturation occurred with little or no functionality loss. A considerably high fraction of hake muscle proteins remained in the native‐like condition even at the higher frozen storage temperature. In these conditions both apparent viscosity and myosin and actin extractability in NaCl were very low. © 2002 Society of Chemical Industry     

Effect of freezing on theβ-hydroxyacyl-CoA-dehydrogenase (HADH) activity of fish meat

Changes in the β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of squid (Loligo vulgaris), mackerel (Scomber scombrus), tuna (Thunnus alalunga), sea bream (Pagellus centrodontus), sole (Solea solea), hake and small hake (Merluccius merluccius) meat due to freezing treatment at ?10° C, ?18° C, ?35° C, ?80° C or ?196° C were investigated. With the exception of the small hake, the HADH activity of aqueous extracts from meat was significantly higher (p<0.0001) in all frozen/thawed fish species studied than in unfrozen animals because during freezing there was a release of HADH. HADH activity values of frozen/thawed squid, unfrozen mackerel, frozen/thawed and unfrozen sea bream and unfrozen hake were affected by the storage time in crushed ice.     

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.     

Effect of oregano and rosemary essential oils on lipid oxidation of stored frozen minced gilthead sea bream muscle

The study aimed to determine the effect of oregano and rosemary essential oils addition to minced gilthead sea bream muscle on lipid oxidation during frozen storage. Each essential oil was added to minced fish muscle at 500 mg/kg concentration which then was stored at ?22 °C for 12 months. Oregano essential oils inhibited the formation of conjugated diene and triene hydroperoxides and thiobarbituric reactive substances when compared with untreated samples after the first month and rosemary essential oils after the first and third month of frozen storage. Oregano and rosemary essential oils could be used as ingredients to prevent oxidation in stored frozen minced gilthead sea bream muscle, when long term preservation is not needed. The rate of lipid oxidation depends on antioxidant source. The rosemary essential oil proved to be more efficient in preventing lipid oxidation of minced gilthead sea bream muscle than oregano essential oil.     

Gilthead seabream (Sparus aurata): suitability for freezing and commercial alternatives

The quality of portion‐size farmed gilthead seabream (Sparus aurata) during frozen storage and the influence of post‐mortem treatments were studied in order to find new ways of marketing this species. Portion‐sized gilthead seabream, fasted for 48 h prior to slaughter, were frozen and stored at ?20 °C for up to one year. Whole fish were frozen immediately after rigor mortis; gutted fish were frozen immediately after rigor and after 5 days of storage in ice. All lots were stored at ?20 °C for up to one year. The myofibrillar protein of this species was very stable and a slight decrease of solubility in salt solutions was found only after one year of frozen storage. A slight decrease in water‐holding capacity and a slight increase in shear strength were observed, but these were lower than in other species. These changes were reflected as increased toughness and reduced juiciness in sensory analysis of the cooked fillets after one year. The main changes in the cooked fillets were observed in odour and flavour. No significant detrimental effect due to the guts was detected during frozen storage. Storage in ice prior to freezing was reflected in sensory assessment of the raw fish, mainly in terms of initial higher demerit points for fishy odour, gills and eyes; however, no effect was observed in the cooked fillets. Copyright © 2004 Society of Chemical Industry     

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.     

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.     

Cryoprotective additives and cryostabilisation effects on muscle fillets of the freshwater teleost fish Rohu carp (Labeo rohita) during prolonged frozen storage

The effects of various cryoprotective additives separately and in combination were studied on the myofibrillar protein integrity, biochemical enzyme activity levels and muscle ultrastructure in the freshwater teleost fish Rohu carp (Labeo rohita). Fish muscle samples were divided into eight groups and immersed in different mixtures of cryoprotective additives (S1–S8), then frozen at ? 20 or ? 30 °C for 24 months. Electrophoretic studies revealed early (within 6 months) alteration of the myofibrillar proteins myosin light chain, α‐actinin and tropomyosin. Reduction of the storage temperature from ? 20 to ? 30 °C slowed down the degradative processes. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that fish muscle treated with cryoprotective mixture S8 (40 g L^?1 sorbitol/3 g L^?1 sodium tripolyphosphate/4 g L^?1 sodium alginate) showed minimal post mortem changes in myofibrillar proteins. Ultrastructural results also revealed post mortem damage to the muscle, seen earliest (within 6 months) in the sample frozen‐stored without additives (S2), as compared with the normal, unfrozen muscle (S1). The influence of cryoprotectants alone and in combination on fish muscle structural proteins, myosin and actin filaments (A and I bands), during prolonged frozen storage was investigated. After 12 months, samples frozen‐stored with various cryoprotective additives (S2‐S7), except S8, showed signs of myofibrillar disintegration. Beyond that time the degradative processes started showing up in all samples, with minimal muscle ultrastructural damage in sample S8. Again, reducing the storage temperature from ? 20 to ? 30 °C slowed down the degradative processes. Ultrastructural results correlated well with levels of biochemical enzymes (Ca²⁺ myofibrillar ATPase and succinic dehydrogenase) during frozen storage. This is the first report of the cryoprotective effects of these additives on this popular edible fish species. Of the various combinations of additives tested, cryoprotective mixture S8 was found to preserve the muscle structure longest under frozen storage conditions. However, even this mixture was only effective for 18 months at ? 30 °C. Beyond that time the myofibrillar degradative processes were apparent with correlative electrophoretic, biochemical and ultrastructural studies. Copyright © 2006 Society of Chemical Industry     

Properties of Kamaboko Made From Red Hake (Urophycis chuss) Fillets, Mince, or Surimi

Fresh red hake (Urophycis chuss) was randomly assigned to three treatments: whole fillets, minced flesh, and surimi. These treatments were stored at −5°C for 10 wk and tested for salt-extractable protein, actomyosin, and Ca⁺⁺– ATPase activity prior to the manufacture of Kamaboko. Kamaboko quality was determined by the fold test and percent expressible fluid. Salt-extractable protein, actomyosin, and Ca⁺⁺– ATPase activity all decreased throughout the storage period and were found to be good measures of the ultimate quality of Kamaboko. The data suggest red hake is suitable for the manufacture of surimi which can be stored frozen and subsequently manufactured into an acceptable Kamaboko.     

Identification by proteome analysis of muscle proteins in sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>)

The present paper reported postmortem changes in muscle proteins on sea bream (Sparus aurata), during ice storage. The postmortem evolution of protein patterns in farmed sea bream was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimension electrophoresis (2DE). Matrix associated laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) was used for identification of proteins. Results of the bio-informatics analysis demonstrate that: (1) the normalized volume of skeletal alpha-actin and tropomyosin is not affected by the time of storage; (2) the normalized volumes of myosin light chain 3 and of major histocompatibility complex (MHC) class II beta1 increase; (3) the normalized volumes of Sec 13-like and parvalbumin significantly decrease.     

Determination of volatile compounds of precooked prawn (Penaeus vannamei) and cultured gilthead sea bream (Sparus aurata) stored in ice as possible spoilage markers using solid phase microextraction and gas chromatography/mass spectrometry

BACKGROUND: Solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) have been reported as useful techniques for analysing volatile compounds to monitor fish freshness. In this study, SPME/GC/MS was applied to cultured gilthead sea bream and precooked prawn stored in ice for 6 days in order to find possible markers of spoilage. Total volatile basic nitrogen (TVB‐N) was also determined as a common index of spoilage. RESULTS: The TVB‐N value at the end of the storage period for cultured gilthead sea bream (302.40 ± 8.50 mg kg^?1) was within the range of acceptability for edible fish (300–400 mg kg^?1) but could be considered at the beginning of spoilage. For precooked prawn the TVB‐N value at day 6 (863.04 ± 7.84 mg kg^?1) was not acceptable for human consumption. SPME/GC/MS identified 30 compounds in cultured gilthead sea bream and 49 compounds in precooked prawn. In particular, 3‐methyl‐1‐butanol, 2‐methylbutanal, 3‐methylbutanal and 3‐hydroxy‐2‐butanone increased during refrigerated storage both in the two species investigated here and in other species reported elsewhere and could be considered as markers of spoilage. CONCLUSION: This study confirmed that SPME/GC/MS can be considered an efficient method suitable for analysing the volatile compounds of both raw fish and fishery products in order to monitor loss of freshness. Copyright © 2008 Society of Chemical Industry     

Comparative study on physicochemical changes of muscle proteins from some tropical fish during frozen storage

Physicochemical changes of muscle from croaker, lizardfish, threadfin bream and bigeye snapper during storage at −18 °C were investigated for up to 24 weeks. Ca²⁺–ATPase activity decreased, whereas Mg²⁺–EGTA–ATPase activity increased throughout the storage. However, no marked changes in Mg²⁺–Ca²⁺–ATPase and Mg²⁺–ATPase activities were observed. Among all species tested, lizardfish muscle was most susceptible to those changes. Disulfide bond formation with the concomitant decrease in sulfhydryl group was found in all species. However, croaker and lizardfish contained higher disulfide bonds as storage time increased, compared to other species. Surface hydrophobicity increased in all species with the sharp reduction observed in lizardfish after 12 weeks. For all species, α-glucosidase and β-N-acetyl-glucosaminidase activities increased in association with the increased expressible drip. Therefore, extended frozen storage caused the denaturation of protein as well as the cell disruption in all species, but the degree of changes was dependent upon species.     

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.     

Freezing and frozen storage of actomyosin from different species

A comparative study was made of the influence of freezing (–24°C) and frozen storage (–12°C) on the functional properties (viscosity, solubility) and physico-chemical characteristics (aliphatic and aromatic hydrophobicity, ATPase activity) of actomyosin (AM) from myosystems (chicken and hake) of differing freezing and frozen stability. The difference in functional behaviour between chicken and hake AM as a consequence of freezing and frozen storage suggests that, for hake AM, denaturation and aggregation occur essentially through direct aggregation of AM molecules to produce AM aggregates, whereas in chicken proteins, AM first dissociates into myosin and actin to produce myosin and myosin-actin aggregates.     

LIPID CHANGES IN FROZEN STORED FILLETS FROM PRE- AND POSTSPAWNED HAKE (MERLUCCIUS HUBBSI MARINI)

The lipid composition of frozen stored fillets from pre‐ and postspawned hake was studied. The total lipid (TL) content in the chloroform/methanol extract from unfrozen postspawned hake was four times higher than that of prespawned fish. After freezing, the TL content of postspawning hake muscle remained unchanged whereas the TL extracted from prespawning fish muscle increased about 90%. The TL extractability of muscle from fish in both different gonadal conditions was not affected by frozen storage. Lipolysis in frozen stored fillets from prespawned hake occurs principally by hydrolytic action on phospholipids (PL), and phosphatidylcholine was the main PL hydrolyzed. Triacylglycerols were the main substrates hydrolyzed in frozen stored fillets from postspawned hake. Freezing and frozen storage affected polyenoics and n‐3 fatty acids (FA). The decrease in the contents of n‐3 FA in fillets from postspawned hake was lower than that observed in fillets from prespawned fish.     

Assessment of protein changes in farmed giant catfish (Pangasianodon gigas) muscles during refrigerated storage

Farmed giant catfish (Pangasianodon gigas) muscles (dorsal and ventral sites) were stored in a refrigerator (at 4 °C) for 14 days to determine the effect of refrigerated storage on biochemical and physical changes. The analyses were carried out at 0, 2, 4, 7, 10 and 14 days of storage. At day 14, Ca²⁺ ‐ATPase activity markedly decreased when compared to its value at day 1 (>90%), while a small decrease was observed for surface hydrophobicity and reactive sulfhydryls content. Total volatile basic nitrogen and trichloroacetic‐soluble peptide content gradually increased when the storage period was extended. The myosin heavy chain decreased slightly on SDS‐PAGE for both meat cuts with increased storage time. Expressible drip and cooking loss were highest during the first day of storage and slightly decreased with storage time. Instrumental hardness was significantly higher in the ventral compared to the dorsal muscle, while the toughness was the highest at the second day of storage. The muscle bundles with scanning electron microscopy were less attached, resulting in the observed big gaps over increasing storage time. Results indicated that changes of proteins have detrimental effects on the quality attributes of farmed giant catfish muscles during refrigerated storage, particularly physical and biochemical properties.     

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.