Addition of sardine to hake minces and subsequent effect on dimethylamine and formaldehyde formation

Formaldehyde formation and reaction with muscle proteins in lean fish species during frozen storage is considered to be a major factor affecting texture and functionality deterioration. Formaldehyde formation and reaction with muscle compounds was reduced in lean fish minces and model systems when lipids with different degrees of oxidation were added. In order to increase the lipid content and slow down functional and textural changes, hake (Merluccius merluccius) and sardine (Sardina pilchardus) minces mixed in the ratios 3:1; 1:1 and 1:3 (w/w) were stored at ?20 °C and studied for 1 year. Dimethylamine formation and, by deduction, formaldehyde formation increased. However, less free formaldehyde was detected, probably owing to reaction with muscle compounds in the mixed minces. Nevertheless, addition of sardine minces improved the texture, protein solubility and viscosity of the mixed minces compared with the hake minces. In the mixed lots, formation of large protein aggregates was delayed or prevented. This suggests that in the mixed minces formaldehyde reacted with proteins in a different way from that in lean fish or reacted with other muscle components not directly involved in textural changes. © 2002 Society of Chemical Industry     

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     

EFFECTS OF CRYOPROTECTANTS IN MINIMIZING PHYSICOCHEMICAL CHANGES OF BOVINE NATURAL ACTOMYOSIN DURING FROZEN STORAGE1

Physicochemical changes in bovine natural actomyosin extracted from prerigor semimembranosus muscle were investigated during frozen storage at ?28°C as affected by the addition of cryoprotectants (5.6% Polydextrose® or 5.6% mixture (1:1) of sucrose and sorbitol). Proteins were destabilized during freezing and frozen storage as reflected by decreases in protein solubility, the visual appearance of aggregates in protein sols, decrease in intensity of flow birefringence, intrinsic viscosity and ATPase activity, and changes in size, shape, or charge of the protein (especially myosin) as evidenced by nondenaturing electrophoresis. These effects were reduced to some extent by the two cryoprotectant treatments.     

A Simple Method for Evaluating Textural Changes of Frozen Fish Minces

A simple and objective method for the evaluation of fracture force of frozen fish minces is presented. Fracture force determinations during frozen storage of red hake (Urophycis chuss) minces indicated a relative coefficient of variation of 4.7% and a significant correlation between fracture force data of frozen samples and force of compression data of thawed samples. No significant changes of fracture force of frozen samples have been observed between 2 and 45 days of storage, but fracture force increased five times between 45 and 90 days of frozen storage.     

EFFECT OF SEASONAL VARIATIONS ON PROTEIN FUNCTIONAL PROPERTIES OF FISH DURING FROZEN STORAGE

Influence of seasonal variation (February, July and October), time elapsed before freezing, and type of processing of the muscle on several functional properties (protein solubility, emulsifying capacity, and viscosity) in two species of fish with differing seasonal behavior (hake and sardine) were studied. Correlations between the changes in these functional properties during frozen storage were established. Although proximate analyses of the hake muscle were similar throughout the year, significant differences were observed in viscosity and protein solubility during storage between lots of fish caught in different seasons. Changes in the functional properties were less evident in sardine, which undergoes wide seasonal variations. The larger differences in the functional proprities of hake muscle, depending on season, were related to differences in the dimethylamine content after the fifth month of frozen storage. High correlations were established between functional properties in fish caught in the same or different seasons. Any of the three functional properties studied can be used as a suitable index of the quality of frozen fish, irrespective of the different conditions studied.     

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.     

Effect of Calcium Salts on the Properties of Proteins from Oil Sardine (Sardinella longiceps) During Frozen Storage

ABSTRACT:  The effect of calcium sulfate and calcium chloride on the enzymatic and structural properties of actomyosin isolated from sardine was investigated. Mince was prepared from sardine and different concentrations of calcium chloride and calcium sulfate were added to the mince and kept in frozen condition at −20 °C. The physico-chemical and functional properties of proteins from mince were analyzed as a function of time. The solubility of proteins decreased during storage. The reduction in solubility was less for samples treated with calcium chloride. However, sardine mince showed better functionality during storage in the presence of calcium compounds. The ATPase enzyme activity of actomyosin increased with increase in concentration of calcium and decreased after reaching the maximum value. ATPase activity of proteins from mince decreased during storage at low temperature. The reduction in ATPase activity did not correlate with the loss of functionality of proteins. SDS-PAGE did not reveal any major changes in the protein profile during storage as well as in the presence of different concentration of calcium compounds. The secondary structural content of actomyosin was not altered in the presence of both calcium chloride and calcium sulfate as evident from circular dichroic measurements.     

Volatile and Nonvolatile Amines in Mediterranean Hake as Function of their Storage Temperature

ABSTRACT: The main amines in frozen and fresh hake (Merluccius merluccius) are the natural polyamines, spermidine. The levels of volatile and nonvolatile amines during storage of hake were strogly dependent on temperature. In samples stored at -20° only changes in dimethylamine and agmatine were found, whereas major changes were observed in samples stored at higher temperatures. Cadaverine was the major amine formed followed by histamine, putrescine and tyramine. The maximum levels of biogenic amines were lower than those reported for other fish species. Trimethylamine and biogenic amines related to hake spollage showed levels higher in fresh than in frozen samples, whereas levels of natural polyamines were not statistically different.     

Effect of added lipids on the texture of minced hake (Merluccius merluccius L.), megrim (Lepidorhombus whiffiagonis W.) and sardine (Sardina pilchardus W.) during frozen storage.

The effect of added cod liver oil and oxidized cod liver oil on the measurement of texture in minced hake (Merluccius merluccius L.), megrim (Lepidorhombus whiffiagonis W.) and sardine (Sardina pilchardus W.) has been measured during frozen storage (-18 degrees C). The results show that added neutral and oxidized lipids, even at high rancidity levels, do not affect shear resistances measured by the Kramer shear-compression cell in non-formaldehyde forming species such as megrim and sardine, over the frozen storage period. However, in a formaldehyde-forming species such as hake, in the presence of neutral and oxidized lipids at the end of the storage period, the values of shear resistances may be lower than in the absence of these lipids, probably owing to formation of less formaldehyde in these cases. Although it is very difficult to estimate the importance of a single compound or group of compounds on texture, these results seem to indicate that formaldehyde is a much more important factor than oxidized lipids in changes of texture in fish.     

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.     

Conformational Change in Actomyosin from Post-spawned Hake Stored on Ice

The changes that lead to a decrease in the viscosity of actomyosin of post-spawned hake stored on ice were investigated. Surface hydro-phobicity of actomyosin from hake increased significantly in the first 3 days of storage. Compared with that stored 3 days, the viscosity of actomyosin from day 0 was greater and its changes suggested greater hydrophylic surface area. Electron microscopy showed changes in the filamentous structure of actomyosin during ice storage. Actomyosin from hake stored in ice is hypothesized to undergo conformational changes including exposure of hydrophobic groups resulting in drastic changes in hydrodynamic properties and a loss of the characteristic arrowhead structure of fresh acotmysin.     

Aggregation of minced hake during frozen storage

 Aggregation in minced hake muscle (Merluccius merluccius) during storage at –20  °C was studied in conditions where there is progressive deterioration of functionality and texture as measured by apparent viscosity and shear resistance. Natural actomyosin was extracted with 0.6 M NaCl over a period of 49 weeks. Insoluble residue was extracted successively with 2% sodium dodecyl sulphate (SDS) and 2% SDS plus 5% β-mercaptoethanol (ME) solutions. SDS–polyacrylamide gel electrophoresis was performed on the extracted fractions. The results showed a 75% decrease in 0.6 M NaCl extractability by the end of the storage period. Initially the remaining precipitate was all extracted in 2% SDS and although the amount extracted in this solution increased as storage time progressed, its proportion decreased, accounting for as little as 40–50% of the protein aggregate by the end of storage. The proteins most involved in formation of the aggregate not extracted in 0.6 M NaCl were myosin and actin. Neither of these proteins was fully recovered in the fractions extracted with 0.6 M NaCl, 2% SDS, or 2% SDS plus 5% ME, and therefore it was inferred that they were forming part of the aggregates, bound by covalent bonds. Received: 17 November 1998     

INTERACTION BETWEEN TRIOLEIN AND NATURAL HAKE ACTOMYOSIN DURING FROZEN STORAGE AT -18C

The interaction of hake muscle actomyosin with triolein in 0.6 M KCl, pH 7, during frozen storage has been investigated. ATPase activity, protein solubility and relative viscosity measurements were performed. No effect of triolein on these functional properties was observed during the storage period studied. Incorporation of l-14C triolein to the protein was found over the storage period, indicating that despite the lack of effect on functionality, lipid-protein interaction occurs. No differences were found in the electrophoretic patterns between control and neutral lipid added samples.     

Rheological and microstructural changes in gels made from high and low quality sardine mince with added egg white during frozen storage

 This paper examines the influence of freezing temperature (–40°C or –18°C) and frozen storage temperature (–18°C or –12°C) on gels made from two different sardine minces (M1, high functional quality; M2, low functional quality), with the addition of egg white as a gel enhancing ingredient. To characterize the washed mince, proximate analyses and protein functionality were determined. Freezing at either –40°C or –18°C caused no drastic changes in gel structure. Throughout the course of frozen storage of all samples, a decrease in the water holding capacity (WHC) was detected, along with an increase in the amount of protein soluble in 8 M urea. At 90 days the gels frozen at –40°C exhibited numerous ice micro-crystals; however, they did not affect the external appearance of the gel and had hardly any effect on gel strength, shear strength, hardness, cohesiveness or elasticity. On the other hand, at 90 days the gels frozen at –18°C and stored at either temperature exhibited large, macroscopically visible ice crystals. In these samples, gel strength and shear strength increased while hardness decreased. No definite changes attributable to mince quality were detected during frozen storage. Received: 23 June 1997     

Hake natural actomyosin interaction with free fatty acids during frozen storage

The interaction of hake muscle actomyosin with free fatty acids in 0.6 M KCl pH 7 during frozen storage has been studied up to 280 days. ATPase activity, protein solubility and relative viscosity measurements were performed. Oleic and myristic acid had a detrimental effect on these properties during frozen storage. Oleic acid was bound to the protein from the beginning, mainly to the insoluble fraction. The diminishment of functionality following addition of oleic acid is not due to aggregation caused by covalent-type bonds, since it occurs well before the electrophoretic change is appreciable.     

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.     

Proteolytic Activity of Muscle in Pre- and Post-Spawning Hake (Merluccius hubbsi Marini) After Frozen Storage

The proteolytic activity of fillets from fresh fish and after frozen storage of hake muscle from pre- and post-spawned fish was investigated. The autolytic activity of fresh muscle extracts from pre-spawned muscle extracts was significantly higher than that of post-spawned, except for pH 3.4 and incubation temperature of 60 °C where no significant difference was found. In both gonadal conditions, the freezing of hake fillets affected the proteolytic activity of crude muscle extracts. After 50 d of frozen storage, the proteolytic activity values of crude muscle extracts remained higher than the fresh values, except for pre-spawned extracts incubated at 37 °C. At longer storage period (110 d), the proteolytic activity continued with similar or higher values compared with those observed for fresh muscle extracts. Densitometric analysis of crude muscle extracts indicated degradation of MHC in fresh and frozen storage at both gonadal conditions under incubation conditions of pH 6.2 and temperatures 37 and 60 °C, pH 8.5 and temperatures 37 and 60 °C, pH 3.4 and temperature 4 °C.     

Structural Properties of Aggregates from Frozen Stored Hake Muscle Proteins

ABSTRACT: Raman spectroscopy and electron microscopy were used to examine the structural properties of sodium dodecyl sulfate-mercaptoethanol-unextractable aggregates formed during the frozen storage of hake muscle. Our results showed that: (a) the unextractable residue consisted of thick filaments, which appeared connected and aggregated, forming a network; (b) the protein backbone adopted a conformational structure rich in β-sheets; and (c) Raman spectroscopy revealed for the 1st time the presence of symmetrical stretching v CH₂ bands, whose frequencies are consistent with the presence of lysine-arginine and/or lysine-glutamine/asparagine bridges in the aggregates.     

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.     

Chemical,enzymatical and textural changes during marination and storage period of sardine (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) marinades

In this study frozen fillets of sardine (Sardina pilchardus) were used to make marinades. The marinating process was performed in 7% acetic acid and 14% sodium chloride in barrels. The fish:solution ratio was (1.5:1). After the marination process, sardine fillets were packed in glass jars in two different formulations fish:solution ratio of (1.5:1); the first formulation contained 2% acetic acid and 4% sodium chloride with tomato sauce and spices and the other was 2% citric acid and 4% sodium chloride with lemon and also the same spices. Pasteurization process had been applied on half of the jars at 70 °C for 20 min. Chemical, enzymatical and textural changes during marination and 6 months storage period of sardine marinades were determined. The results obtained in proteolytic activities correlated well with the observed texture measurements according to time of storage. A decrease in the histidine content and an increase in glutamic acid and aspartic acid contents of marinated sardines were determined. Histamine levels were lower than the toxic limit (100 mg/kg) during the marination and storage period of sardine marinades.