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.     

Superchilled,chilled and frozen storage of Atlantic mackerel (Scomber scombrus) fillets – changes in texture,drip loss,protein solubility and oxidation

Changes in quality characteristics in relation to protease activity and protein oxidation in chilled, superchilled and frozen mackerel fillets during storage were studied. The solubility of sarcoplasmic proteins was quite stable in mackerel samples for all storage experiments, whereas the solubility of myofibrillar proteins decreased in both superchilled and frozen samples. A significant correlation (r = 0.983, P < 0.05) between the increased activity of cathepsin B+L in chilled fillets and softening of the fish flesh during storage was revealed. Contrary with chilled samples, the texture of superchilled mackerel fillets became tougher along the storage period, which can be explained by a higher rate of myofibrillar oxidation (r = 0.940, P < 0.05). The hardness and drip loss decreased slightly at the end of frozen storage. Superchilling preserved the quality of mackerel fillets with the least side effects in relation to protein solubility, drip loss and softening of the fish tissue as compared to chilled and frozen storage.     

Alteration of the electrophoretic pattern of myofibrillar proteins in fish mince during frozen storage

A study was made of the variations in the electrophoretic profile of myofibrillar proteins in the muscles of blue whiting (Micromesistius poutassou R.), horse mackerel (Trachurus trachurus L.) and mackerel (Scomber scombrus L.). It was shown that all species presented different deterioration patterns during frozen storage. The fish were caught at two separate times of the year (winter and summer) and were stored frozen at -18°C for 1 year. The results indicate that during frozen storage, electrophoretic patterns varied according to species. Comparison of myosin heavy chain/actin (MHC/A) ratios indicates that blue whiting is the species that undergoes most alteration, and that this is more intense in fish caught in the summer than in the winter. Alteration of the MHC/A ratio was similar in horse mackerel and mackerel caught in the winter, whereas in the summer horse mackerel proved to be the most stable species. In all cases, the reduction of the MHC/A ratio was due essentially to alteration of the MHC, an effect which was particularly marked in blue whiting. Tropomyosin remained stable throughout the storage period in all three species.     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

Effect of previous gutting on rancidity development in horse mackerel (Trachurus trachurus) during frozen storage at −20 °C

Gutting was applied to fresh horse mackerel (Trachurus trachurus) to study its effect on rancidity development during a prolonged frozen storage (up to 12 months at −20°C). To do so, chemical (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescence ratio, FR) and sensory (odour and taste) analyses were carried out. The results showed that the gutting of horse mackerel led to a higher degree of oxidation in the frozen product, according to the chemical (PV, TBA-i and FR) and sensory (odour and taste) analyses. However, a lower extent of lipid hydrolysis (FFA formation) was detected at the end of the storage (twelfth month) as a result of gutting. It is concluded that the gutting of a medium-fat fish species such as horse mackerel is not recommended as previous treatment to frozen storage.     

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     

The effect of frozen storage of mackerel (Scomber scombrus) on its quality when hot-smoked

Whole mackerel (Scomber scombrus) were frozen using a horizontal plate freezer, wrapped in plastic bags and frozen stored at - 20°C. At suitable intervals (11, 22 and 33 weeks) the fish were removed from the cold store and subsequently hot smoked (in gutted from) using an AFOS-Torry Mini Kiln. All smoked mackerel samples, despite their different previous histories, were assessed by the panellists as moderately acceptable products in- terms of their texture and flavour, even after 33 weeks frozen storage prior to smoking. Protein denaturation, as related to salt-soluble protein, was influenced by the frozen storage history (24% drop after 33 weeks frozen storage) and seemed to be affected by the free amino acids formed during frozen storage. After smoking the denaturation was extensive (above 80%) in all mackerel samples. Lipid oxidation was quite extensive (PV 108 meq kg^?1) in the 22 and 33 weeks frozen stored mackerel samples. However, no rancid flavour in the latter smoked mackerel samples was detected by taste panellists. A 58% increase in free amino acids during frozen storage was observed. Extensive losses of 74% in available lysine were observed in the 22 and 33 weeks frozen stored mackerel samples after smoking which could be due to aminocarbonyl reactions with the products of lipid oxidation. A 40% loss of thiamine was observed in the 33 weeks frozen stored samples after smoking. The histamine contents did not exceed 94 mg kg^?1 and would not be expected to cause symptoms of scombrotoxin poisoning.     

Effect of previous chilled storage on rancidity development in frozen horse mackerel (Trachurus trachurus)

Rancidity development during frozen storage (?20 °C) of an underutilised medium‐fat‐content fish species, horse mackerel (Trachurus trachurus), was studied. Special attention was given to the effect of previous chilled storage (0, 1, 3 and 5 days) on the quality of the frozen fish. For this, chemical (free fatty acid and conjugated diene contents; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compound formation) and sensory (rancid odour and taste) analyses were carried out. Hydrolytic rancidity showed an increase with frozen storage time; however, no effect of previous chilling time was observed on the frozen product. Oxidative rancidity measured by chemical (PV, TBA‐i and fluorescence) and sensory (odour and taste) indices increased with frozen storage time and also with previous chilling time. Satisfactory quality was maintained up to 7 months of frozen storage of horse mackerel provided that a short chilling time (not longer than 3 days) was employed. © 2002 Society of Chemical Industry     

Effects of Vacuum Packaging, Glazing, and Erythorbic Acid on the Shelf-Life of Frozen White Hake and Mackerel

The quality changes during frozen storage of two underutilized species of fish: mackerel (Scomber scombrus), a fatty species, and white hake (Urophycis tenuis) a nonfatty, gadoid species, with or without a bag, vacuum, and/or erythorbic acid, were measured using the dimethy-lamine (DMA) test for hake and the thiobarbituric acid (TBA) test for mackerel, and by Instron deformation, expressible moisture, thaw drip, cook loss, and sensory evaluation for both species. Texture deterioration and lipid oxidation limited the shelf-life of hake and mackerel, respectively. Air (oxygen) prolonged the shelf-life of hake but lessened that of mackerel. Erythorbic acid accelerated the rate of texture deterioration in hake but inhibited the rate of lipid oxidation in mackerel.     

Sensory and Chemical Characteristics of Selected Gulf of Mexico Coastal Herring Species

Gulf of Mexico coastal herrings may become an important alternative fisheries resource for U.S. commercial fisherman. Effects of on board handling on sensory characteristics of chub mackerel (Scomber japonicus) and rough scad (Trachurus lathami) were investigated. Proximate and fatty acid composition of chub mackerel, rough scad, round scad (Decapturus punctatus), round herring (Etrumeus teres), and silver rag (Ariomma bondi) were determined to provide nutritional and product formulation data. Chub mackerel and rough scad had similar sensory characteristics found in other commercial species, which, with proper on board handling, could be maintained during frozen storage. Proximate and fatty acid compositions of the fish varied by species, season, and year.     

Effectiveness of a natural Rosemary (Rosmarinus officinalis) extract on the stability of filleted and minced fish during frozen storage

 The objective of this study was to evaluate the effect of adding a natural Rosemary (Rosmarinus officinalis L.) extract to filleted and minced frozen fish and to compare the fat stability of the samples with that of the controls. Horse mackerel (Trachurus trachurus), a relatively fatty fish, and Mediterranean hake (Merluccius mediterraneus), a low-fat fish, were used. Fat stability evaluation was done by comparing the changes of the malondialdehyde (MDA) content and the percentage of polyunsaturated fatty acid (PUFAs) degradation that occurred during frozen storage at –18°C for 120 days. Total volatile bases-N (TVB-N) were also measured to assess for quality. The results showed that the natural antioxidant extract retarded the oxidation process throughout storage. The control samples of both filleted and minced frozen fish of both species showed a significant reduction (^* P <0.05) of PUFAs until day 50 of storage, while the oxidation was gradual but slower in the treated samples. Fillets and minced samples of both species treated with antioxidant contained significantly (^* P <0.05) less MDA compared with the controls during storage. Received: 2 December 1996     

Effectiveness of a natural Rosemary (Rosmarinus officinalis) extract on the stability of filleted and minced fish during frozen storage

 The objective of this study was to evaluate the effect of adding a natural Rosemary (Rosmarinus officinalis L.) extract to filleted and minced frozen fish and to compare the fat stability of the samples with that of the controls. Horse mackerel (Trachurus trachurus), a relatively fatty fish, and Mediterranean hake (Merluccius mediterraneus), a low-fat fish, were used. Fat stability evaluation was done by comparing the changes of the malondialdehyde (MDA) content and the percentage of polyunsaturated fatty acid (PUFAs) degradation that occurred during frozen storage at –18°C for 120 days. Total volatile bases-N (TVB-N) were also measured to assess for quality. The results showed that the natural antioxidant extract retarded the oxidation process throughout storage. The control samples of both filleted and minced frozen fish of both species showed a significant reduction (^* P <0.05) of PUFAs until day 50 of storage, while the oxidation was gradual but slower in the treated samples. Fillets and minced samples of both species treated with antioxidant contained significantly (^* P <0.05) less MDA compared with the controls during storage. Received: 2 December 1996     

Histamine Production by Morganella morganii in Mackerel, Albacore, Mahi-mahi, and Salmon at Various Storage Temperatures

Morganella morganii was studied for its growth and histamine formation in mackerel, albacore, mahi‐mahi, and salmon stored at various temperatures from ‐30 °C to 37 °C. The optimal temperature for histamine formation was 25 °C. Mackerel, albacore, and mahi‐mahi were shown as good substrates for histidine decarboxylation by M. morganii at elevated temperatures (> 15 °C). M. morganii inoculated in all fish species including salmon formed histamine above the FDA guideline. Their growth was controlled by cold storage of the fish at 4 °C or below, but histamine formation was controlled only by frozen storage. Although histamine was not detected in any frozen samples, it accumulated rapidly in the previously frozen fish stored at 25 °C.     

A DSC study on the effects of various maltodextrins and sucrose on protein changes in frozen‐stored minced blue whiting muscle

A DSC heat denaturation study on the effects of various maltodextrins and sucrose on protein changes in minced blue whiting muscle during frozen storage at −10 and −20 °C was carried out. All maltodextrins slowed down the decreases in the denaturation enthalpies (ΔH_d) ascribed to myosin and actin, making evident a noticeable effectiveness against protein denaturation, especially at −20 °C. Sucrose was as effective as maltodextrins at −20 °C, but was the least effective treatment at −10 °C. Significant correlations between both ΔH_ds and either protein solubility or formaldehyde production were found at each storage temperature. A low protein sensitivity to the small amounts of formaldehyde produced during the first weeks of storage and errors associated with the determination of enthalpies led to poorer correlations at −20 °C. Maximum denaturation temperatures (T_max) correlated with protein solubility only at −20 °C. No clear relationship between either T_max and the effectiveness of cryostabilisation was found, as T_max also depends on the effectiveness of the treatments against the thermal denaturation of proteins. © 2001 Society of Chemical Industry     

Effect of frozen storage on the quality of whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus)

 Whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus) were assessed for quality (physical, chemical and sensory attributes) changes throughout 12 months of frozen storage at −18 °C. The pH, expressible water (EXW), quantities of trimethylamine (TMA), dimethylamine (DMA), formaldehyde (FA), the total volatile base nitrogen (TVB-N) the thiobarbituric acid number (TBA), peroxide value (PV) and amount of free fatty acids (FFA) increased, while sensory attributes (odour, taste, texture) decreased during the frozen storage period. A comparison of quality scores between whole fish and fillets of horse mackerel and mediterranean hake showed that there were no significant differences (P>0.05) in attribute scores. There were, however, significant differences (P<0.05) in pH, EXW, TMA, DMA, FA, TVB-N, TBA, FFA and PV. Received: 19 April 1996/Revised version: 7 September 1996     

Solubility and viscosity of herring (Clupea harengus) proteins as affected by freezing and frozen storage

ABSTRACT:  The aim of this work was to evaluate the effects of freezing and frozen storage at –24 °C on the quality of Icelandic herring fillets, focusing on protein solubility and viscosity at pH 2.7 and 11 used for pH-aided protein isolation. The evaluation of quality was based on chemical analyses, protein degradation measurements, and changes in protein solubility and viscosity at pH 2.7 and 11 after up to 6-mo frozen storage of the herring fillets. Lipid oxidation measured as TBARS values increased significantly during the frozen storage ( P < 0.05). Protein solubility at pH 2.7 decreased during frozen storage for 6 mo, where the solubility was about 10% lower after 6-mo frozen storage compared to the beginning ( P < 0.05). At pH 11, the solubility became approximately 15% lower after 6-mo frozen storage compared to initial solubility ( P < 0.05). Viscosity, measured at pH 2.7, increased after 3 mo of frozen storage ( P < 0.05). At pH 11, the viscosity increased significantly after 1-wk frozen storage, compared to fresh herring fillets, but did not increase significantly with further storage ( P < 0.05). Changes found in solubility and viscosity indicated protein degradation due to freezing and frozen storage. SDS-PAGE analysis did not reveal any protein cross-linking or aggregation formation, either with frozen storage or due to exposure to low pH.     

Effect of brine freezing on the rancidity development during the frozen storage of small pelagic fish species

Brine freezing was applied to two small pelagic underutilised fish species (mackerel, Scomber scombrus; horse mackerel Trachurus trachurus). Rancidity development was studied during their frozen (–18 °C) storage up to 9 months, and quality change results were compared to common freezing conditions (control treatment). Fish samples treated under brine freezing conditions showed a higher lipid oxidation development (peroxide value and thiobarbituric acid index) and worse marks on some sensory attributes (general aspect, odour and colour) than control fish. However, samples treated under brine freezing conditions provided a lower lipid hydrolysis development (free fatty acid formation) and better scores for consistency. Comparison between both fish species led to a higher secondary lipid oxidation formation (thiobarbituric acid index) for mackerel, while horse mackerel showed to be more prone to interaction compound formation (fluorescence detection); however, both fish species showed the same shelf-life times (3 and 5 months for brine and control freezing conditions, respectively). As a result of the brine freezing conditions, an increase in NaCl content in white muscle of both species was observed. According to the results obtained in the present work, the brine freezing treatment is not recommended for these two small pelagic fish species.     

GEL-FORMING ABILITY OF COMMON CARP FISH (CYPRINUS CARPIO) MEAT: EFFECT OF FREEZING AND FROZEN STORAGE

Effect of freezing and frozen storage on gel‐forming ability of muscle from fresh water fish, common carp (Cyprinus carpio), was investigated. Fresh carp meat had good gel‐forming ability as revealed by large strain test (gel strength of 1027 g·cm) and dynamic viscoelastic behavior. Freezing and frozen storage at ?18C for 180 days significantly (P < 0.01) reduced the gel‐forming ability of common carp meat. Reduction in protein solubility and calcium‐activated adenosinetriphosphatase enzyme activity of common carp meat during frozen storage was also significant (P < 0.05). Structural change of proteins during frozen storage was evident from reduced viscosity and gel filtration profile. Higher drip loss and reduction in gel‐forming ability of carp meat is attributed to denaturation of proteins during frozen storage.     

A comparison of biochemical changes in cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) fillets during frozen storage

Changes in the muscle proteins of frozen cod fillets, which produce significant amounts of formaldehyde, and frozen haddock fillets, which produce negligible formaldehyde, were compared. Protein extractability and hydrophobicity and the amino acid contents of soluble and insoluble proteins, as well as formaldehyde formation, were investigated in matching pairs of cod and haddock fillets stored at ?10 and ?30 °C (control). Formaldehyde production in cod was much higher (845 and 1065 nmol g^?1 at 20 and 30 weeks respectively) than in haddock (93 and 101 nmol g^?1 after 20 and 30 weeks respectively) at ?10 °C. However, a rapid decrease in solubility of proteins, increase in hydrophobicity and decrease in the amino acid content of salt‐soluble proteins at ?10 compared with ?30 °C were observed in both species. The results showed that there were no significant differences in the nature of the protein changes between these two species, thus indicating that factors other than formaldehyde were involved in the denaturation of proteins and the formation of aggregates during frozen storage of cod and haddock fillets, especially at ?10 °C. © 2001 Society of Chemical Industry     

Effect of brine pre-treatment on lipid stability of frozen horse mackerel (<Emphasis Type="Italic">Trachurus trachurus</Emphasis>)

The rancidity development during the frozen storage (-20 °C) of an under-utilised medium-fat fish species (horse mackerel; Trachurus trachurus) was investigated. Special attention was given to a pre-freezing treatment consisting of an immersion in NaCl solution (5%, 10%, and 20%) and its effect on lipid damage during the fish frozen storage. Lipid hydrolysis (free fatty acid content) and oxidation (conjugated dienes formation; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescence formation, FR) were studied up to 270 days of frozen storage. Oxidative rancidity measured by the PV, TBA-i, and FR showed an increase with the frozen storage time and also as a result of an increasing salt content in fish muscle. A high peroxide formation was observed at day 210 of frozen storage, especially in the case of 20% NaCl treated samples. Lipid hydrolysis also increased with the frozen storage time; at the end of the experiment (270 days), a decreasing effect of muscle salt content on lipid hydrolysis was observed. Employment of appropriate antioxidant additions is recommended if salting pre-treatment is to be needed to avoid a large lipid oxidation development and ensure a longer shelf-life time.