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     

Foaming capacity of fish minces during frozen storage

This work covers a year's study of the foaming capacity (FC) of minced muscle of three fish species—blue whiting (Micromesistius poutassou R). horse mackerel (Trachurus trachurus L), and mackerel (Scomber scombrus L)—caught in two different seasons (January and July) and stored at – 18°C. Periodic assays were performed to determine protein solubility, FC and dimethylamine formation. The results show that FC is initially inhibited by the presence of the species own lipids; however, during frozen storage this effect is attenuated and thus FC increases. The results corroborate the view that protein solubility is not an indispensible requisite for FC, and that mere dispersion of proteins is sufficient. However, FC is not diminished by changes in protein during frozen storage when this deficiency is offset by sufficient protein concentration. On the other hand, FC is clearly affected by the formaldehyde generated during frozen storage, so that beyond a certain level the aggregates formed as a result of formaldehyde formation are too large to disperse, and hence FC decreases drastically.     

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     

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.     

Deterioration of European hake (Merluccius merluccius) during frozen storage

European hake (Merluccius merluccius (L)) was frozen as whole fish and as fillets and stored at ?18°C, ?24°C and ?30°C for up to 39 weeks. Sensory properties, peroxide value and thiobarbituric acid value, lipid fatty acid composition, adenosine nucleotide degradation products, dimethylamine and formaldehyde were measured at intervals during storage. Changes at ?30°C were negligible, otherwise fillets deteriorated faster than whole fish. Hedonic rating gave a storage life of around 9 months for whole fish stored at ?18°C.     

Prediction of frozen storage time of Cape hake (Merluccius capensis and Merluccius paradoxus) by instrumental methods

An instrumental method to predict frozen storage time of Cape hake was developed by evaluation of a combination of methods previously known to classify hake into different quality categories, such as apparent viscosity, Kramer and puncture tests. The results showed that with multiple linear regression analysis it was possible to obtain linear models for the prediction of storage time at ? 20°C. Only apparent viscosity (η_app) and Kramer shear resistance (Kramer) were included in the regression model (months = 15.003 ? 0.001η_app + 0.144 Kramer; ). The model had a typical error of estimation of 2.0 months. The simplicity of the model, which requires only two parameters, and the easiness of their measurement make the method a good candidate for use in quality control laboratories of hake processing industries. Copyright © 2006 Society of Chemical Industry     

Changes in chemical composition and nutritional quality of fried sardine (Clupea pilchardus) produced by frozen storage and microwave reheating

Modifications in proximate composition, fatty acids, amino acids and –SH groups content, as well as changes in solubility and nutritional quality of protein, were studied in fillets of sardine (Clupea pilchardus) that had been successively pan-fried, frozen stored and reheated by two different means, namely conventional oven and microwave oven. Upon pan-frying in olive oil the sardine absorbed C18: 1(n-9) and C18: 2(n-6) and lost saturated (SFA) and polyunsaturated fatty acids (PUFA); this loss continued upon reheating, and as a consequence the percentage of MUFA increased compared to the just-fried sardine. A loss of water was observed during all processes. Upon frying there was a decrease of cyst(e)ine. Upon reheating by both microwave and conventional oven, methionine decreased; however, cyst(e)ine only decreased with the use of a conventional oven. A loss of –SH groups was recorded during frying and this phenomenon continued upon reheating. Biological value (BV) together with net protein utilisation (NPU) decreased upon both frying and reheating. © 1997 SCI.     

Emulsifying capacity of fish mince from several species during frozen storage

Abstract : As a functional property of protein, emulsifying capacity (EC) is of great technological interest. This article examines EC in fish mince from three species differing in fat content and in the pattern of deterioration during frozen storage—blue whiting (Micromesistius poutassou R), horse mackerel (Trachurus trachurus L) and mackerel (Scomber scombrus L)—caught during two seasons of the year in which physiological behaviour is expected to be different (winter and summer). EC and protein solubility were determined periodically. The results indicate the existence of a direct relationship between the fat content of the species used and its EC. Furthermore, in the species studied EC was independent of protein solubility and the amount of protein in the medium, both of which decline as a result of the formation of aggregates during frozen storage. This is not therefore a suitable method for determining protein quality during frozen 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     

Evaluation of various infused cryoprotective ingredients for their freeze-thaw stabilizing and texture improving properties in frozen red hake muscle

ABSTRACT:  Various cryoprotective ingredients were evaluated for their freeze–thaw stabilizing and texture improving properties during 6-mo frozen storage when red hake ( Urophycis chuss ) fillets were injected with sorbitol–sodium tripolyphosphate (STPP) (40% to 60% : 3%), 1.5% alginate, or 0.75% alginate with soy protein isolate (SPI)–sorbitol–STPP (5% to 10% : 40% : 3%). Injection of 10% SPI, 1.5% alginate, or 0.75% alginate–5% SPI effectively improved water binding and retarded the freeze-induced texture changes when drip and cooking loss, centrifugal expressible moisture, protein extractability, SDS-PAGE profile, and Instron and sensory texture were assessed. The sorbitol and STPP combination was not as effective as alginate and SPI. Freeze-susceptible whitefish can be injected with proper cryoprotective ingredients for improved frozen storability.     

Role of formaldehyde in formation of natural actomyosin aggregates in hake during frozen storage

During frozen storage of certain lean species of fish, formaldehyde (FA) is formed, giving rise to changes in texture related to the formation of aggregates of myofibrillar proteins. In order to study these aggregates a model system was prepared with natural actomyosin (NAM) (5 mg/ml) and increasing concentrations of formaldehyde. The system was stored frozen at-20° C for 2 months during which solubility in 0.6 M NaCl, Ca²⁺ATPase activity,cis-parinaric acid (CPA) hydrophobicity, SH groups and sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis (PAGE) were measured. — FA caused an immediate loss of Ca²⁺ATPase activity and a decline in soluble protein and CPA hydrophobicity, an effect that was enhanced when the samples were frozen. The electrophoretic profiles of the proteins that remained soluble showed that in both fresh and frozen samples, when FA reacts with NAM the first protein to be insolubilised is myosin, followed by actin, then the troponins and myosin light chains and lastly tropomyosin, depending on the amount of FA and the reaction time. Aggregates of high molecular mass were found at early stages, probably as a result of covalent binding of myosin molecules. When the amount of FA or the frozen storage time was increased, these aggregates became insoluble, forming high-molecular-mass structures and hence were not found in the soluble fraction.

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Die Bedeutung von Formaldehyd bei der Bildung natürlicher Actomyosin-Aggregate im Seehecht während der Lagerung in gefrorenem Zustand

Zusammenfassung Während der Lagerung gewisser Magerfische in gefrorenem Zustand bildet sich Formaldehyd (FA), was die Bildung von Aggregaten myofibrilärer Proteine verursacht. Diese Aggregate wurden im Modell mit Actomyosin (NAM) (5 mg/mL) und wachsenden Formaldehydkonzentrationen untersucht. Die Muster wurden zwei Monate in gefrorenem Zustand bei -20 °C gelagert. Während dieses Zeitraums wurden die Löslichkeit in 0,6 M NaCl, die Ca²⁺ATPase-Aktivität, die cis-Parinarsäure-(CPA)-Hydrophobie und SH-Gruppen gemessen sowie SDS-Polyacrylamid-Gel Elektrophoresen (PAGE) durchgeführt. — FA verursachte einen sofortigen Verlust von Ca²⁺ATPase-Aktivität sowie einen Rückgang löslicher Proteine und in der CPA-Hydrophobie. Dieser Effekt verstärkte sich bei eingefrorenen Mustern. Die elektrophoretischen Profile derjenigen Proteine, die löslich blieben, zeigten sowohl in frischen als auch in gefrorenen Mustern, daß das erste Protein, das bei einer Reaktion von FA mit NAM gelöst wird, Myosin ist, darauf folgen Actin, die Troponine und leichten Myosinketten und schließlich Tropomyosin, was wiederum von der FA-Menge und Reaktionszeit abhängt. In den Anfangsstadien wurden hochmolekulare Aggregate gefunden, die wahrscheinlich das Ergebnis gleichwertiger Bindung von Myosinmolekülen sind. Bei Erhöhung der FA-Menge oder Verlängerung der Lagerzeit bildeten sich hochmolekulare Strukturen, die im löslichen Teil nicht gefunden werden konnten.

     

Textural and Microstructural Changes in Frozen Stored Sardine Mince Gels

The freezing of sardine mince gels produced slight alterations in texture, microstructure and degree of chemical aggregation of proteins, irrespective of freezing temperature (– 18°C or – 40°C). The most noticeable changes took place during frozen storage 3 mo, particularly in gels frozen at – 18°C which were strongly affected by storage temperature (– 12°C or – 18°C), unlike those frozen at – 40°C. Better gel integrity was found in those frozen at – 40°C, where cavities were more numerous, but smaller and more evenly distributed than in gels frozen at – 18°C.     

Effect of ice storage on the functional properties of pink perch and oil sardine meat

Ice storage of dressed pink perch (Nemipterus japonicus) and Indian oil sardine (Sardinella longiceps) for 16 and 20 days, respectively, resulted in a decrease in emulsifying capacity (EC), protein solubility (PS), relative viscosity (RV) of salt‐soluble proteins (SSP) and water‐soluble proteins (WSP), water binding capacity (WBC) in terms of absorbed moisture in water (AM_w), absorbed moisture in brine lpar;AM_b), retained moisture in water (RM_w) and retained moisture in brine (RM_b), WSP and SSP, and increase in cook loss (CL). Decrease in protein solubility influenced the EC, RV, CL and WBC in both the species of fish. Significant (P<0.05) correlations existed among various functional properties analysed, in both the fishes during the ice storage. © 1999 Society of Chemical Industry     

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.     

Relation between types of packaging,frozen storage and grilling on cholesterol and fatty acids oxidation in Atlantic hake fillets (Merluccius hubbsi)

Two different commercial samples of frozen and packaged, in low and high-oxygen permeability packaging, Atlantic hake fillets were stored at −18 °C for 4 months and the intensity of lipid oxidation, as well as the formation of cholesterol oxidation products (COP), during storage and subsequent grilling were studied. Raw fillets at the initial time of storage showed low total COP levels, however, after 120 days of storage the concentrations were raised significantly, under both packed conditions. During freezing and subsequent grilling there was a significant decrease (p < 0.02) in the contents of the cholesterol and polyunsaturated fatty acids in all the hake samples. Correlations were found between the cholesterol and fatty acid parameters and cholesterol oxides formation during storage and heat treatment. The commercial frozen storage with a low-oxygen permeability packaging was more effective in preventing lipid oxidation than high-oxygen permeability packaging, with less accented cholesterol degradation as well as cholesterol oxides formation.     

Effect of chitooligosaccharide from squid pen on gel properties of sardine surimi gel and its stability during refrigerated storage

Effect of chitooligosaccharide from squid pen prepared using lipase (COS-L) at various concentrations (0–30 g kg⁻¹) on gel properties of sardine surimi gel was investigated. Breaking force (BF) and deformation (DF) of gel were increased, when COS-L level was increased up to 10 g kg⁻¹ (P < 0.05). Water holding capacity and whiteness of gel were improved with the addition of COS-L than those of control. Gel added with 10 g kg⁻¹ COS-L had denser network with higher likeness score for all sensory attributes, compared to control. When gel incorporated with 10 g kg⁻¹ COS-L was stored at 4 °C, BF, DF and whiteness were maintained during 10 days of storage. Textural properties of surimi gel added with COS-L were higher than those of control throughout storage. Thus, incorporation of 10 g kg⁻¹ COS-L could improve gel properties of sardine surimi gel and retarded the deterioration of gel properties during refrigerated storage.     

Thermal properties and heat-induced aggregation of natural actomyosin extracted from goatfish (Mulloidichthys martinicus) muscle as influenced by iced storage

Thermal properties and aggregation of natural actomyosin (NAM) extracted from fresh and 9 days ice-stored goatfish were comparatively studied. Myosin of fresh goatfish had the higher thermal stability than that of ice-stored counterpart as indicated by the higher maximum transition temperature (T_max). Additionally, the thermal inactivation rate constant (K_D) of Ca²⁺-ATPase in NAM from fresh goatfish was lower than that of ice-stored counterpart when incubated at the temperature range of 20–40 °C, indicating the lower thermal stability of the latter NAM. NAM from fresh goatfish exhibited the higher turbidity, surface hydrophobicity and disulfide bond formation than did NAM of iced-stored sample when heated at temperature from 35 to 75 °C, suggesting the higher extent of aggregation of the former. However, goatfish NAM showed the lower extent of heat-induced aggregation than did bigeye snapper NAM. As visualized by transmission electron microscopy, network strands of aggregates from bigeye snapper NAM were finer and more uniform than those from goatfish. NAM from goatfish stored in ice showed the lower extent of heat-induced aggregation than did NAM from fresh counterpart. Therefore, heat-induced aggregation of goatfish muscle proteins was governed by freshness.     

冻结和冻藏对冷冻面团流变学以及汤包皮质构特性的影响

研究了冻结温度、冻藏温度、冻藏时间对冷冻面团流变学特性和汤包皮质构特性的影响。实验结果表明,冻结改变了面团的流变性质,降低了面团的弹性;并且-18℃下冻结对汤包皮TPA参数的影响比-30℃的影响大。-30℃的冻藏温度对面团的粘弹性影响较大,而不同冻藏温度对汤包皮的TPA参数影响不大;冻藏时间对面团粘弹性、面团拉伸特性以及汤包皮的TPA参数影响大。     

Effects of Kudoa spores,endogenous protease activity and frozen storage on cooked texture of minced Pacific hake (Merluccius productus)

The effects of Kudoa infection of Pacific hake (Merluccius productus) on endogenous protease activity and on cooked mince texture were investigated. Texture was significantly (p < 0.05) negatively correlated with spore counts as well as protease activity. Soft texture (maximum force <150 g) was observed in fish with 10⁴–10⁶Kudoa thyrsites spores g⁻¹ mince, compared to 10⁵–10⁸K. paniformis spores g⁻¹ mince, suggesting that especially for fish having lower infection levels, K. thyrsites may have a greater impact than K. paniformis on Pacific hake quality. Pre-incubation for 15 min at 52 °C prior to cooking resulted in softer texture in some samples due to endogenous proteolytic action. This pre-incubation effect was not consistently observed in fish held 6 months or longer at −25 °C or after freeze-thaw cycling, which may be explained by an opposing toughening effect attributed to protein denaturation and aggregation during prolonged or abusive frozen storage.     

冻藏时间对扇贝闭壳肌及裙边理化性质的影响

目的研究冻藏时间对华贵栉孔扇贝(Chlamys nobilis)闭壳肌及裙边理化性质的影响。方法通过测定在-18℃冻藏不同时间扇贝的基本成分、氨基酸组成、蛋白质组分、挥发性盐基氮含量及过氧化值,了解其理化性质随时间变化的规律。结果冻藏60 d的闭壳肌和裙边基本成分、水溶性蛋白、盐溶性蛋白含量和氨基酸含量变化不显著,挥发性盐基氮含量略有上升,然而过氧化值变化显著,比原来增长了81%。结论华贵栉孔扇贝在-18℃冻藏60 d,除过氧化值外,其余理化性质变化不明显。