Mackerel Muscle Research Articles

Preservative Effect of a Gelatin-Based Film Including a Gelidium sp. Flour Extract on Refrigerated Atlantic Mackerel

This research evaluated the preservative properties of flour from the alga Gelidium sp., which is a waste substrate resulting from commercial phycocolloid extraction. Gelatin-based biofilms, which included two different concentrations of red alga flour, were developed and used as packaging systems during refrigerated storage (up to 9 days at 4 °C) of Atlantic mackerel (Scomber scombrus) muscle. In all batches tested, a progressive decrease in quality could be observed in the muscle of the fish as the storage time increased. Compared with the control fish, the Gelidium alga flour extract had an inhibitory effect (p < 0.05) on microbial activity (total aerobes, psychrotrophs, and proteolytic bacteria), lipid oxidation (peroxide, thiobarbituric acid, fluorescence and polyene indices), lipid hydrolysis (formation of free fatty acids) and pH increase in refrigerated mackerel muscle. In contrast, no significant effect (p > 0.05) was observed on trimethylamine formation, Enterobacteriaceae, or lipolytic bacteria counts. A preservative effect resulting from the incorporation of Gelidium alga flour into the gelatin-based biofilm was observed, indicating both quality and safety enhancement. In accordance with current global interest in the search for natural and waste sources, a novel and beneficial use of Gelidium flour for enhancing the quality of refrigerated fish has been proposed.

High levels of the health-relevant antioxidant selenoneine identified in the edible mushroom Boletus edulis

BackgroundSelenoneine, the selenium analogue of the sulfur antioxidant ergothioneine, has been ascribed a multitude of beneficial health effects. Natural nutritional sources for this selenium species are, hence, of high interest. So far marine fish is the only significant selenoneine source consumed by larger parts of the population worldwide. MethodsAs selenoneine and ergothioneine share their biosynthetic pathways and transport mechanisms and the popular edible porcini mushroom Boletus edulis is rich in ergothioneine and selenium, we conducted a preliminary study investigating a composite sample of two specimens of B. edulis for their selenoneine content by HPLC coupled to elemental and molecular mass spectrometry after aqueous extraction. ResultsSelenium speciation analysis by HPLC-ICPMS revealed that ca. 860 µg Se kg−1 wet mass (81 % of the total Se) co-eluted with a selenoneine standard and a minor selenium species with Se-methylselenoneine. The presence of selenoneine was rigorously proven by HPLC-ESI-Orbitrap MS. The selenoneine content of the investigated specimens of B. edulis was higher than that of commonly consumed muscle of marine fish species, like tuna or mackerel. ConclusionThis is the first report of a terrestrial food source containing significant selenoneine levels. Our results suggest that B. edulis might represent a complementary natural supply with this health-relevant selenium species for humans.

Development of Serum-Reduced Medium for Mackerel Muscle Cell Line Cultivation

Development of Serum-Reduced Medium for Mackerel Muscle Cell Line Cultivation

Microplastics in Different Tissues of a Commonly Consumed Fish, Scomberomorus guttatus, from a Large Subtropical Estuary: Accumulation, Characterization, and Contamination Assessment.

Microplastics (MPs) ingestion by fish signifies a worldwide threat to human health but limited research has examined their existence within the consumable portions (muscle) of fish. Thus, this study was undertaken to unveil the prevalence, characterization, and contamination extent of MPs across various body tissues, including the muscle of the king mackerel (S. guttatus) from the lower Meghna estuary in Bangladesh-a pioneering investigation in this region. In our analysis, we identified a total of 487 MPs, with an average abundance of 48.7 ± 20.3 MPs/individual. These MPs were distributed across different tissues, with respective concentrations of 0.84 ± 0.45 items/g in the digestive tract, 2.56 ± 0.73 items/g in the gills, and 0.3 ± 1.72 items/g in the muscle tissue. The observed variations among these tissue types were statistically significant (p < 0.05). Moreover, a significant positive correlation indicated that fish with higher weight had higher MPs in their gills and DT (digestive tract). The majority were <0.5 mm in size (97.74%) and exhibited a fiber-like shape (97.74%), with a notable prevalence of transparent (25.87%) and a pink coloration (27.92%). Remarkably, the majority of MPs were discovered within the size range of <0.5-1 mm (100%), particularly in the muscle tissue, signifying a substantial transfer of MPs into the human diet. Besides, we discovered only three polymer types of microplastics which could be attributed to the extensive use of food packaging, plastic containers, wrapping plastics, residential garbage, and plastic pipes that end up in the aquatic environment via river discharges. The contamination factor (CF) values of fish muscle (5.75) and the digestive tract (5.50) indicated that these fish organs were considerably contaminated (3 < CF < 6) with MPs. The pollution index of MPs (PLI > 1) indicated a high contamination level for MPs pollution of S. guttatus in the lower Meghna River estuary.

Does eating fish cause cancer? A case study metal(loid)s accumulation in mackerel and sardine tissues from İskenderun Bay, Türkiye.

Due to the increasing harmful effects of metal(loid)s over time, it has become important in environmental studies carried out to increase environmental awareness. It is important to investigate the cumulative presence of metal(loid)s in nature, their interactions with each other and risks posed by fish consumption for human health. Total concentrations of As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn were determined in muscle and gill tissues of horse mackerel (Trachurus trachurus) and sardine (Sardina pilchardus). Metal analyses were carried out using Inductively Coupled Plasma-Mass Spectroscopic (ICP-MS) methods. In both tissues, Fe and Zn concentrations were the highest and Cd, Cu and Pb concentrations were the lowest. The target hazard coefficient, estimated daily intake, target cancer risk, total target hazard coefficient, and hazard indices were calculated to assess the risks to an individual's health from consuming fish. Hazard index and total target hazard coefficient values calculated for each fish exceeded 1 but were very close to 1. Target cancer risk values of As and Ni were found to be 10-6 and 10-4 for Pb. These limit values indicate the need for regular monitoring of the region. In addition, the interactions between the metal(loid)s accumulated in the tissues were analyzed and a high correlation was found between As-Ni, which poses a risk to public health.

Application of a porous graphitic carbon column to carbon and nitrogen isotope analysis of underivatized individual amino acids using high-performance liquid chromatography coupled with elemental analyzer/isotope ratio mass spectrometry.

Isolation of underivatized amino acids (AAs) using high-performance liquid chromatography (HPLC) is becoming a popular method for carbon (δ13 C) and nitrogen isotope (δ15 N) analyses of AAs because of the high analytical precision and for performing dual-isotope analysis. However, some AAs in natural samples, especially small, hydrophilic AAs, are not suitably separated using reversed-phase columns (e.g., C18) and ion-exchange columns (e.g., Primesep A). We developed a new method for HPLC using a porous graphitic carbon column for the separation of nine hydrophilic AAs. After purification, δ13 C and δ15 N values of AAs were determined using elemental analyzer/isotope ratio mass spectrometry (EA/IRMS). We demonstrated the application of this method by determining δ13 C and δ15 N values of individual hydrophilic AAs in a biological sample, the muscle of blue mackerel (Scomber australasicus). Chromatographically, the baseline separation of hydrophilic AAs was achieved in both the standard mixture and the biological sample. We confirmed that δ13 C and δ15 N values of AA standards remained unchanged during the whole experimental procedure. The δ13 C values of AAs in mackerel muscle are also in good agreement with the values obtained using another verified method for δ13 C analysis. The good separation performance of hydrophilic AAs and the reliability of δ13 C and δ15 N analyses of individual AAs using the porous graphite column offer a significant advantage over conventional settings. We suggest that, in the future, the HPLC × EA/IRMS method can be used for reliable δ13 C and δ15 N analyses of AAs in natural samples.

Optimization of Enzymatic Hydrolysis of Mackerel (Rastrelliger sp.) Muscle Protein Hydrolysate Using Response Surface Methodology

Mackerel (Rastrelliger sp.) is a widely distributed epipelagic species in South East Asia. Mackerel has a high amount nutrient such as protein (20.83 %) and fat (1.03 %). The high amount of protein and low amount of fat will allow it to be used as a material to produce a good protein hydrolysate. The aim of this study is to determine the optimal enzymatic hydrolysis conditions (time, temperature, and pH) using Response Surface Methodology (RSM). Mackerel Protein Hydrolysate (MPH) was prepared using commercial Flavourzyme. Optimization of MPH was performed by employing Box Behnken Design method of RSM. SN-TCA method was used to calculate the degree of hydrolysis (DH) which is the key parameter in hydrolysis reaction. Optimum hydrolysis conditions were obtained at pH 7, temperature 55°C and 60 min of process. Under these conditions the DH obtained was 17.7293 % with 4% enzyme to substrate ratio. The suggested model for the hydrolysis process is quadratic with the desirability factor of 1. The MPH was further assessed for its amino acid composition using High Performance Liquid Chromatography (HPLC). The hydrolysis process increases the amino acid amounts namely L-Glutamic Acid (19.77%), L-Valin (14.20%), L-Aspartic Acid (11.42%), Glycine (11.04%), L-Alanin (14.20%), L-Prolin (16.80%), and L-Histidin (27.06%). The study suggested that mackerel muscle can be considered to be utilized as fish protein hydrolysis materials.

Ultrastructural and biochemical changes of sarcoplasmic reticulum in spotted mackerel (Scomber australasicus Cuvier, 1832) muscle during cold storage at 5 °C

SummarySpotted mackerel were stored at 5 °C for 0–5 days. To reveal changes in freshness and provide the fundamental knowledge of sarcoplasmic reticulum (SR), structural and biochemical changes were investigated by optical microscope, transmission electron microscopy and biochemical detection, including pH, myosin Ca2+‐ATPase activity, adenosine 5′‐triphosphate (ATP) content, SR recovery field and SR Ca2+‐ATPase (SERCA) activity. The result exhibited that SR swelled on day 1 and ruptured after 2 days. Muscle structure showed significant changes from day 0 to day 5. SERCA activity and SR recovery field were 0.46 μm Pi/min/mg and 1.05 mg/g at day 0 and 0.106 μm Pi/min/mg and 0.109 mg/g at day 2, respectively, highly corresponding to the decline of pH, myosin Ca2+‐ATPase activity and ATP content with a significant difference from day 0 to days 1 and 2. The biochemical properties of SERCA exhibited the maximum activity at pH 6.8–7.0 (0.408 μmol Pi/min/mg). Treated at pH 5.5 for 80 min or incubated at 35 °C for 40 min inactivated SERCA of 80%. Therefore, keeping at a freezing temperature of 5 °C and maintaining SR functionality was essential to delay freshness decrease.

Türk Süpermarketlerindeki İthal Balıklarda Zoonotik Anisakis Larvalarının Varlığına İlişkin Devam Eden Veriler: Dondurulmuş Atlantik Uskumru (Scomber Scombrus) ve Füme Atlantik Somonu (Salmo Salar)

Anisakis pegreffii and A. simplex sensu stricto (s.s.) are the main etiological agents causing human anisakiasis. Here, we aimed to investigate based on the pepsin digestion method of the occurrence of Anisakis larvae in imported deep-frozen whole Atlantic mackerel (Scomber scombrus) from FAO 27 to Turkey and smoked Norwegian farmed Atlantic salmon fillets (Salmo salar) between 2018 and 2019. A total of 100 whole Atlantic mackerel and 180 Atlantic salmon fillets were randomly sampled from local Turkish supermarkets. No Anisakis larvae were detected in smoked Atlantic salmon fillets. In total, 827 Anisakis larvae were found in mackerel, and the prevalence was 68% (68/100). The mI and mA of Anisakis larvae in mackerel were 13.1 and 8.2, respectively. Whereas the 95.28% (788/827) of the Anisakis larvae were found in abdominal cavity/viscera, the 4.72 % (39/827) of the larvae in the muscle. The prevalence and mI of Anisakis larvae in the abdominal cavity/viscera and muscle of mackerel was 63.0% (63/100) and 42.0% (42/100), and 12.5 and 0.9, respectively. The subsample of 100 larvae was molecularly identified by ITS RFLP patterns. The 99 (99.0%) larvae were identified as A. simplex (s.s.), and 1 (1.0%) larva was A. pegreffii. Consequently, there is low or no risk of anisakiasis in smoked farmed Atlantic salmon for Turkish consumers. The 42.0% prevalence of zoonotic Anisakis species larvae in imported Atlantic mackerel fillets could have public health risk in Turkish consumers for anisakiasis or allergy.

Antioxidant and Antimicrobial Effect of Biodegradable Films Containing Pitaya (Stenocereus thurberi) Extracts during the Refrigerated Storage of Fish.

This study focused on the quality loss inhibition of fish muscle during refrigerated storage. Two parallel experiments were carried out that were focused on the employment of pitaya (Stenocereus thurberi) extracts in biodegradable packing films. On the one hand, a pitaya-gelatin film was employed for hake (Merluccius merluccius) muscle storage. On the other hand, a pitaya-polylactic acid (PLA) film was used for Atlantic mackerel (Scomber scombrus) muscle storage. In both experiments, fish-packing systems were stored at 4 °C for 8 days. Quality loss was determined by lipid damage and microbial activity development. The presence of the pitaya extract led to an inhibitory effect (p < 0.05) on peroxide, fluorescent compound, and free fatty acid (FFA) values in the gelatin-hake system and to a lower (p < 0.05) formation of thiobarbituric acid reactive substances, fluorescent compounds, and FFAs in the PLA-mackerel system. Additionally, the inclusion of pitaya extracts in the packing films slowed down (p < 0.05) the growth of aerobes, anaerobes, psychrotrophs, and proteolytic bacteria in the case of the pitaya-gelatin films and of aerobes, anaerobes, and proteolytic bacteria in the case of pitaya-PLA films. The current preservative effects are explained on the basis of the preservative compound presence (betalains and phenolic compounds) in the pitaya extracts.

Microbiological status of smoked fish placed on the market in Poland

Fish and fishery products are considered to be one of the most nutrient-rich dietary products. The nutritional value of fish depends on its freshness. The greatest role in fish spoilage is played by microbial decomposition. Smoking is one of the methods of fish preservation based on the action of temperature and the penetration into the tissue of preservative substances produced by burning wood. Almost all microorganisms except some pathogenic bacteria are destroyed in the smoking process; nevertheless, fish can be a source of some pathogenic microorganisms, i.e. Listeria monocytogenes, Salmonella spp., Staphylococcus spp., which are present as the result of cross-contamination at the stage after smoking, i.e. marketing and storage (4, 5, 8). Improper and unhygienic handling practices with the ready-to-eat RTE product are also the cause of an increase of the total microbiological contamination, which can be expressed by microbiological contamination indicators, i.e. total viable count (TVC), psychrophilic bacteria count (PBC), coliform count (EBC), total yeast and mould count (TYMC) and total staphylococci count (TSC). In the performed study five smoked fish species (redfish, mackerel, codfish, sprat and herring) were tested at the marketing stage. A total number of 50 (N = 50) samples was tested according to ISO standards. The potential foodborne bacteria in the tested samples were identified using a MALDI-TOF spectrometer combined with MALDI-Biotyper 3.0 software. In the performed study, the highest microbiology contamination TVC on the level 3.63 ± 0.15 log10 cfu/g and PBC on the level 3.04 ± 0.24 log10 cfu/g has been found in redfish muscle compared to herring, codfish, sprat and mackerel muscle. A significantly lower amount of 1.26 ± 0.12 log10 cfu/g yeast and moulds of was found in the muscle tissue of herring, compared to the other tested fish. The highest staphylococcal contamination of muscle tissue of redfish on the level 2.56 ± 0.15 log10 cfu/g and mackerel on the level 2.13 ± 0.15 log10 cfu/g was found. MALDI-TOF identification of isolated bacteria not confirmed the presence of Salmonella spp., Listeria monocytogenes and pathogenic Staphylococci and confirmed the presence of E. coli in tested redfish.

Blood removal and water behavior in horse mackerel Trachurus japonicus muscle using water perfusion

Blood removal is widely applied in the fisheries and aquaculture industries because it maintains the quality of fish muscle during storage, which improves the market value and effective utilization of marine resources. Water perfusion, such as Tsumoto-shiki, has recently attracted attention as a novel blood removal procedure; however, its detailed effect has not been clarified thus far. Herein, to utilize water perfusion as a novel blood removal technology, the influence of water perfusion according to Tsumoto-shiki with modifications, for 4–60 s on the blood removal and water behavior in horse mackerel Trachurus japonicus muscle was investigated compared with that of a sample conventionally bled by cutting the gill. The results were subjected to multiple comparison tests using the Tukey–Kramer method. The hemoprotein content in the perfused sample was significantly lower than that in the control sample without blood removal and the bled sample (p < 0.05), independent of the perfusion time. The moisture content and expressible drip in the perfused sample increased in a perfusion time-dependent manner. Low-field nuclear magnetic resonance (LF-NMR) measurements showed that 1H T2 relaxation time was prolonged in samples perfused for 30–60 s (p < 0.05). In 1H T2-weighted images obtained using magnetic resonance imaging (MRI), high signal intensities were mainly observed in the dark muscle and segmental arteries and veins of samples perfused for 30–60 s, indicating the presence of free water that leaked from blood vessels. Therefore, water perfusion is an effective procedure for blood removal compared with conventional bleeding. Furthermore, in this study, water perfusion for 4–10 s was appropriate for both removing blood and preventing the quality deterioration induced by increased moisture content and expressible drip in horse mackerel muscle.

Total Mercury and Fatty Acids in Selected Fish Species on the Polish Market: A Risk to Human Health.

The muscles of lake trout (Salvelinus namaycush Walbaum, 1792), crucian carp (Carassius carassius Linnaeus, 1758), flounder (Platichthys flesus Linnaeus, 1758), gilthead seabream (Sparus aurata Linnaeus, 1758), mackerel (Scomber scombrus Linnaeus, 1758) and tench (Tinca tinca Linnaeus, 1758) were examined. The total mercury (THg) was processed using the Milestone DMA-80 and the fatty acids were analyzed using the 7890A Agilent Technologies chromatograph. The THg content in analyzed fish ranged from 0.024 (lake trout) to 0.092 mg/kg wet weight (gilthead seabream). The muscles of fish examined had lower amounts of SFAs, and n-3 and n-6 PUFAs than MUFAs. The ratio of n-3/n-6 was higher in muscles of mackerel than other fish (p < 0.05). Due to the fact that both the THQ and HI are below 1, the tested fish are safe for the consumer from a nutritional point of view. Similarly, fatty acid indices indicate the safe consumption of selected fish species, and the daily consumption of the recommended dose of EPA + DHA (250 mg/day) and the concentration of mercury in fish calculations showed a hazard quotient for the benefit–risk ratio HQEFA below 1, suggesting that the intake of EPA + DHA poses no evident risk to human health. The ratio was calculated for a person weighing 60 kg. Therefore, it is important to monitor the fish, not only bought in the store, but also caught in various aquatic environments.

Effect of Alga Gelidium sp. Flour Extract on Lipid Damage Evolution in Heated Fish Muscle System.

This research aimed to evaluate the antioxidant properties of flour obtained from red alga Gelidium sp., which is underutilised nowadays in food applications. Thus, a model system consisting of minced mackerel (Scomber scombrus) muscle and aqueous flour extract was subjected to heating treatment (50 °C) for 11 days. Resulting levels on conjugated diene (CD) and triene (CT) contents, peroxide value, thiobarbituric acid index, and fluorescent compound and free fatty acid (FFA) formation were monitored at different heating times. As a result, the presence of the aqueous extract of the alga flour led to higher levels (p < 0.05) of primary lipid oxidation compounds (CD and CT assessment) and lipid hydrolysis (FFA content). Contrarily, alga flour addition led to lower (p < 0.05) fluorescent compound formation measured in the aqueous and organic fractions resulting from the lipid extraction of the fish muscle and in the supernatant medium corresponding to the heating reaction system. All effects were found to be more important (p < 0.05) with increased alga flour concentration and heating reacting time. According to the straight relationship between the interaction compound formation and nutritional and sensory values, this study opens the way to the quality enhancement of thermally treated seafood by the addition of flour extract from Gelidium sp.

Seasonal variation of chub mackerel (Scomber colias) selenium and vitamin B12 content and its potential role in human health

Chub mackerel (Scomber colias), an underutilised fish species, has been identified as an excellent source of selenium and vitamin B12, which may prevent and delay cognitive decline and dementia. Given these nutrients’ contents seasonal variability, a complete monthly sampling, involving a specifically adjusted methodology for the determination of vitamin B12 (LC-MS/MS) and its main vitamers and a sensitive analytical technique (ICP-MS) for Se, was carried out. Regarding total vitamin B12 in the chub mackerel muscle, its content varied from 10.0 ± 1.0 μg/100 g in February to 18.9 ± 1.9 μg/100 g in August. It was also shown that methylcobalamin content ranged from 1.12 ± 0.43 (March) to 6.77 ± 0.80 μg/100 g (August), a sixfold increase. Hydroxocobalamin content varied between 3.49 ± 0.12 (February) and 9.62 ± 0.41 μg/100 g (August). The content of Se also had seasonal variability, ranging from 451 ± 14 μg/kg (December) to 606 ± 11 μg/kg (July). In the worst-case scenario, a weekly 160 g meal of this fish would almost guarantee B12 requirements. Three weekly 160 g meals of S. colias would cover, at least, 56% of the Se requirements. Therefore, as first explored here, it is highly relevant a complete, year-round assessment of the chub mackerel’s nutritional value, in order to elaborate finely tuned dietary recommendations.

Antimicrobial and antioxidant effect of lyophilized Fucus spiralis addition on gelatin film during refrigerated storage of mackerel

Lyophilized alga Fucus spiralis powder was incorporated into a gelatin-based film and employed as a packaging system for mackerel ( Scomber scombrus ) muscle portions throughout a 9-day refrigerated storage period at 4 °C. In global terms, a progressive loss of quality could be observed in fish muscle with increasing storage time. Comparisons between batches allowed us to conclude an inhibitory effect of F. spiralis -containing films on microbial activity (assessment of aerobes, psychrotrophs, and proteolytic bacteria) and on lipid hydrolysis (as determined by free fatty acid formation) in mackerel muscle. The presence of the lyophilized macroalga in the packaging film also led to a higher retention of primary (peroxides) and secondary (thiobarbituric acid reactive substances) lipid oxidation compounds, while the formation of fluorescent compounds (interaction compounds between lipid oxidation compounds and nucleophilic molecules present in the fish muscle) decreased. Both antimicrobial and antioxidant effects were more intense when the concentration of alga in the packaging film was increased. The preservative effect resulting from the presence of F. spiralis in gelatin-based films demonstrates the potential employment of such bioactive films to improve the retention of fish quality and enhance its commercial value. • Lyophilized Fucus spiralis was incorporated into a gelatin packaging film. • F. spiralis in the packaging film inhibited free fatty acid formation in mackerel. • F. spiralis inhibited aerobes, psychrotrophs, and proteolytic bacteria in fish muscle. • F. spiralis in the packaging film inhibited fluorescent compound formation. • Superior retention of primary and secondary lipid oxidation compounds was observed.

Proximate chemical composition and lipid profile of Indian mackerel fish

Fish and fish products of the most available protein sources for human beings. Indian mackerel is the most available and economic fish sold in markets in different countries and is included in many local dishes. Indian mackerel are characterized by dark muscles because of the high contents of myoglobin and lipids. This study aims to investigate the chemical composition, saturated and unsaturated fatty acid contents, and fatty acid fractions in Indian mackerel muscle. Indian mackerel (R. kanagurta) were purchased from the central fish market in Jizan, which is caught from the port of Jizan, Saudi Arabia. The samples were analyzed to estimate the proximate chemical composition, Lipid Fractions, and Fatty acid analyses from Indian mackerel. In this study, revealed that moisture, protein, and fat are the main constituents of Indian mackerel. The Indian mackerel contained high and comparable levels of saturated fatty acids and unsaturated fatty acids, and the different samples exhibited somewhat similar fatty acid contents. Among unsaturated fatty acids, the content of polyunsaturated fatty acids was higher than that of monounsaturated fatty acids, and those with the highest levels in Indian mackerel were palmitoleic, palmitic, myristic, oleic, 15-tetracosenoic, linolenic, and stearic acids in addition to docosanoic, eicosanoic, 5,8,11,14,17-eicosapentanoic, and 11-eicosenoic pentadecanoic acids. We conclude Indian mackerel is a rich source of protein and lipids. Polyunsaturated fatty acids are the main constituents of lipids, which exert positive effects on the body by providing the main nutrients and preventing disease in the consumer.

Effects of treatment at a subzero temperature on pH, water retention, and metabolites in spotted mackerel (Scomber australasicus) muscle

Studies have shown that storing pre-rigor frozen fish at subzero temperatures before thawing might suppress pH drop after thawing in some migratory fish. Therefore, the mechanisms involved in pH maintenance and the effects on the quality of fish muscle were investigated here. Frozen spotted mackerel (Scomber australasicus) was stored at −10 °C for 1–10 d (hereinafter referred to as “−10 °C treatments”). pH, water retention, and the changes in primary metabolite concentrations were investigated in the frozen and thawed muscles. When the −10 °C treatment lasted for 5 d or longer, the thawed muscle maintained a minimum pH of 6.2, and the water-retention and water-reabsorption capacities of the frozen-thawed spotted mackerel muscle of −10 °C treatment samples increased compared with the control sample. In the −10 °C treatments, nicotinamide adenine dinucleotide (NAD) was consumed and glycolytic intermediate products accumulated in the frozen muscle. This result suggests anaerobic glycolysis was inhibited. The results of this investigation indicate that −10 °C treatments before thawing may increase the meat quality in frozen spotted mackerel.

Concentration and Distribution of Cu, Zn, Pb, and Cd in Mackerel Icefish (Champsocephalus gunnari) in South Georgia, Antarctic, During Winter.

Knowledge of the essential and nonessential elements distribution and behavior in Antarctic fish is important for understanding the essentiality and requirements of minerals in the diet of those species, as well as the bioavailability and storage of trace minerals in the tissues of fishes. In this study, the levels of zinc, copper, cadmium, and lead in muscle, intestine, liver, gill, and skin of mackerel icefish Champsocephalus gunnari (Lönnberg, 1905) in South Georgia were determined during winter. The following element concentration ranking was recorded: Zn > Cu > Cd > Pb in the muscle, Zn > Cu > Cd > Pb in the skin, Zn > Cu > Cd > Pb in the intestine, Zn > Cu > Pb > Cd in liver, and Zn > Cu > Cd > Pb in the gill. The concentration of Zn is higher by about two orders of magnitude than that of the other three elements for the tissues. Generally, apart from Cu levels in the liver and Cd levels in the intestine, the correlation of elements in tissues with both size and weight of C. gunnari is not observed. The levels of elements were compared to those reported for C. gunnari in the Kerguelen waters.

ASSESSMENT OF SELECTED HEAVY METALS AND ESTIMATION OF HUMAN HEALTH RISK IN SOME COMMONLY CONSUMED FISH IN ABEOKUTA, OGUN - STATE, NIGERIA

Fish is a major source of food in many parts of the world because they contribute to solving the global food problem and provide the well-known proteins, minerals, vitamin and trace elements content. Concentrations of iron (Fe), zinc (Zn), copper (Cu), nickel (Ni), lead (Pb) and cadmium (Cd) were determined in various parts of the fish (liver, gill, bone and muscle) of Mackerel (Scomber scombrus), Sardine (Sardinella longiceps), Hake (Merluccius merluccius) and Express (Platax scalaris) which were purchased from two major markets in Abeokuta, Ogun State, Nigeria. Heavy metal levels in the fish samples were analyzed by Atomic Absorption Spectrophotometer (AAS Buck 211). Health risks related to Fe, Zn, Cu, Ni, Pb and Cd were assessed based on target hazard quotient (THQ). Results obtained showed variations in the levels of heavy metals across the various tissues in the fish samples. The concentration of Fe was highest in all the tissues in the fish samples with the gill recording the highest level. There were higher concentrations of heavy metals in the gills than in other tissues of the fish samples. The trend of heavy metal levels in the tissues was found to be Fe &gt; Zn &gt; Cu &gt; Ni &gt; Pb &gt; Cd. Highest levels of Pb and Cd in the muscle were 1.92 ± 0.04 and 0.64 ± 0.04 mg/kg in Merlucciusmerloccius and Scomberscombrus respectively. The concentrations of Pb and Cd were higher in the muscles of all the samples than European Community and Food and Agriculture Organization maximum permissible levels. The health risks from Ni and Pb were found highest among all the heavy metals in the fish samples. THQ values of Cu and Cd in Sardinellalongiceps and Cu in Merlucciusmerloccius were higher than 1. Health risk assessment of Ni and Pb in all the fish studied and Cd in Sardinellalongiceps indicates that their consumption may be unsafe.