Selective-Targeted Effect of High-Pressure Processing on Proteins Related to Quality: a Proteomics Evidence in Atlantic Mackerel (Scomber scombrus)

The effect of high hydrostatic pressure (HHP) treatment (150, 300, and 450 MPa for 0, 2.5, and 5 min) on total sodium dodecyl sulfate (SDS)-soluble and sarcoplasmic proteins in frozen (?10 °C for 3 months) Atlantic mackerel (Scomber scombrus) was evaluated. Proteomics tools based on image analysis of SDS-polyacrylamide gel electrophoresis (SDS-PAGE) protein gels and protein identification by tandem mass spectrometry (MS/MS) were applied. Total SDS-soluble proteins, composed in high proportion of myofibrillar proteins, were stable under pressurization treatment in terms of solubility and electrophoretic gel profiles. However, pressurization reduced sarcoplasmic proteins’ solubility, modified their one-dimensional (1-D)/two-dimensional (2-D) SDS-PAGE patterns in a direct-dependent manner, and exerted a selective effect on particular sarcoplasmic proteins depending on processing conditions. Thus, protein bands assigned to creatine kinase, fructose-bisphosphate aldolase A, glycogen phosphorylase, and β-enolase were degraded at 300–450 MPa. Additionally, the stability of triosephosphate isomerase B, phosphoglucomutase, and phosphoglycerate kinase-1 was found to be HHP-reduced when submitted at 450 MPa. HHP processing (300–450 MPa) also induced a cross-linking product formation of pyruvate kinase and two compounds derived from tropomyosin at 450 MPa. Frozen storage time of pressurized samples induced an additional lessening in protein solubility, but electrophoretic patterns were not modified. The present investigation emphasizes the higher lability of sarcoplasmic proteins under HHP treatment and the important role of these proteins in the sensory quality enhancement provided by milder HHP conditions on frozen mackerel. HHP technology is expected to boost the development of novel tailored processing approaches to tackle food quality challenges.     

Effect of Smoking on the Proximate Composition of Atlantic Mackerel (Scomber scombrus)

Fall (fat) and spring (lean) Atlantic mackerel (Scomber scombrus L.) were both used in a study of the effects of “hot” smoking on proximate composition. The AFOS-Torry Mini Kiln and the method described in Advisory Note No. 82, Torry Research Station, Aberdeen, Scotland were employed. For particular comparisons both nonsmoked and smoked fish were taken from the same identical catch. The overall process resulted in an approximately 10% loss of protein. This was offset by the moisture loss, twice as much in the lean fish as in the fatter fish. The much higher fat content in and under the skin of fall fish acted as a protective barrier during smoking and helped diminish the moisture loss. The overall process, which included brining, led to an elevation of salt content.     

Effect of High Hydrostatic Pressure Treatment (HHPT) on Quality and Shelf Life of Atlantic Mackerel (Scomber scombrus)

The ability of high hydrostatic pressure treatment (HHPT) to extend the shelf life of Atlantic mackerel (Scomber scombrus) was assessed in this study. For that purpose, fillets were subjected to pressure treatments at 200, 300, 400 MPa at 5, 10, 15 °C for 5 and 15 min. The influence of pressure treatments on the levels of trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) as well as color changes was investigated. The suitable combinations were determined as 200 MPa, 15 °C for 5 min. and 400 MPa, 5 °C for 5 min. In the second stage, the shelf life of samples, which were treated at these conditions, stored at 4?±?0.5 °C were studied by monitoring pH, color, sensorial features (appearance and odor), TMA-N, TBA, total volatile basic nitrogen, histamine, and total mesophilic aerobic count. The unpressurized mackerel samples were acceptable up to only 7 days compared to 17 and 19 days after 200 and 400 MPa treatments; respectively. The results obtained in this study showed that HHPT in combination with chilled storage can improve the shelf life and quality of fish.     

Quality of Atlantic Mackerel (Scomber scombrus L.) Fillets during Modified Atmosphere Storage

Sensory, physical, biochemical and microbial quality were investigated in mackerel fillets stored under CO₂ modified atmosphere packaging (MAP) at -2°C for 21 days. Packaging gas composition remained constant during storage. An experienced sensory panel found seaweedy and cucumber-like odors (raw) decreased whereas sourness corresponded with lactic acid bacteria increase. Both sensory (raw) fillet ‘yellowness’ and Hunter ‘b’ values increased. Visual (cooked) moistness and expressible fluid decreased but no difference was found in cooking losses. Small increases in total volatile base-nitrogen and trimethylamine-nitrogen paralleled aerobic plate counts; ethanol increased linearly. Coliforms, yeasts and molds were detected at < 10 CFU/g. CO₂ MAP storage at – 2°C can maintain Grade 1 shelf-life extension for ≥ 21 days     

Thermostable Water Dispersions of Myofibrillar Proteins from Atlantic Mackerel (Scomber scombrus)

A process for preparation of a thermostable, low viscosity water dispersion of myofibrillar proteins from Atlantic mackerel (Scomber scombrus) was developed. The comminuted meat was washed sequentially with cold water, a bicarbonate solution, and cold water. It was then homogenized in ice-cold water. Apparent viscosity of the dispersion depended on protein concentration and temperature. Lowering pH to 3.7 by acetic acid reduced viscosity of the dispersion which remained unchanged irrespective of temperature. The proteins did not precipitate upon heating to 100° followed by centrifugation at 5000 xg for 15 min, even in the presence of 50 mM NaCl solution. However, increasing pH of the acidified solution resulted in precipitation of proteins. Acetic acid also prevented separation of water upon centrifugation of heated dispersion.     

Atlantic Mackerel (Scomber scombrus, L.): Shelf Life in Ice

Spoilage pattern of ice stored Atlantic Mackerel was monitored by determining trimethylamine (TMA), total aerobic plate counts and histamine levels. Hypoxanthine accumulation was used as the freshness index, coupled with sensory evaluation of fresh fish. These tests indicated that mackerel can be stored fresh in ice up to 9 days, after which the accumulation of bacteria, TMA and histamine was rapid. Hypoxanthine levels increased between 0–10 days and appeared to increase at a slightly slower rate until day 16, then it declined.     

Atlantic Mackerel (Scomber scombrus, L): Seasonal Variation in Proximate Composition and Distribution of Chemical Nutrients

The chemical components of Atlantic Mackerel (Scomber scombrus) were investigated. An average of 53.5% of the fish consisted of edible portions, with more than 16% protein. PER values for raw and cooked muscles were 3.7 and 3.1, respectively, with casein being 2.5. The amino acid profile indicated equal or above average values for the essential amino acids when compared to casein. Lipid levels varied seasonally with the moisture content in various edible portions. A 1:3 ratio of saturated to polyunsaturated fatty acids was observed in this species. Sodium levels were 0.07% on a wet basis which suggests inclusion of this species in low sodium diets.     

Ultrasonic characterization of Atlantic mackerel (Scomber scombrus)

The influence of frequency (1–6 MHz), temperature (5–25°C) and composition on the ultrasonic velocity and attenuation coefficient of Atlantic mackerel (Scomber scombrus) was investigated. The ultrasonic velocity was insensitive to frequency, whereas the attenuation coefficient increased with frequency. The fat, water and solids-non-fat content of mackerel tissue was determined by analyzing the temperature dependence of the ultrasonic velocity in the tissue using a semi-empirical equation. There was good agreement between the fat, water and solids-non-fat content determined by ultrasonic velocity and proximate analysis methods. In particular, there was a high correlation between the two methods for the determination of fat content (r²=0.949). There was no correlation between the composition of mackerel tissue determined by ultrasonic attenuation and proximate analysis methods. The increase in ultrasonic attenuation of mackerel with temperature, especially above about 20°C, was attributed to protein denaturation and tissue disruption.     

Supercritical CO2 Extraction of Oil from Atlantic Mackerel (Scomber scombrus) and Protein Functionality

Supercritical carbon dioxide (SC-CO₂) extraction temperature and pressure for oil removal from freeze-dried, fall Atlantic mackerel muscle were optimized. The effect of extraction conditions on pH and water-binding potential (WBP) of the protein residue was evaluated. For the temperature range (35–55°C) and pressure interval (20.7–34.5 MPa), 34.5 MPa/35°C gave highest oil yield and concentration of ω-3 fatty acids. SC-CO₂ extraction at higher pressure levels caused slight decreases in protein residue pH. WBP of residual proteins was maximal at 1.49g H₂O/g protein for 34.5 MPa/45°C. The high lipid removal and retention of protein functionality in the residue after oil extraction may make such processes useful for future food applications.     

Characterisation of the microbiota of Atlantic mackerel (Scomber scombrus)

In this study the microbiota of Atlantic mackerel (Scomber scombrus) collected by a commercial purse seiner was examined. Fish were collected directly from the purse seine and from the Refrigerated Sea Water (RSW) transport tank after loading. The culturable microbiota and Specific Spoilage Bacteria (SSB) were quantified on Iron Agar Lyngby (IAL) and identified using commercially available Biochemical API® kits on pure cultured isolates. These kits showed to be sub-optimal in characterising the isolates, since only half of the strains were identified. The same isolates were also identified by a nucleic acid based PCR-DGGE approach, and only half of the sequences gave the same results as the API®. Characterisation by PCR-DGGE was also performed on bacterial DNA from IAL plates (bulk cell samples) and on samples where the bacterial DNA was extracted directly from fish material without any cultivation (direct DNA samples). The microbiota of Atlantic mackerel was dominated by members of the Gram-negative genera as Psychrobacter sp., Proteus sp., Photobacterium sp., Vibrio sp., Shewanella sp., Synechococcus sp., Oceanisphaerae sp., Bizonia sp., Pseudoalteromonas sp., and members of Flavobacteriaceae. Gram-positive bacteria in the genera Vagococcus sp., Bacillus sp., Mycobacterium sp., Staphylococcus sp., Mycoplasma sp. and Clostridia sp. were also found. Examination by PCR-DGGE and sequencing of the bulk cell pellet after cultivation on IAL, gave a higher number of taxa as compared to extraction and examination of bacterial DNA from fish materials without prior cultivation. This shows the benefit of combining both culture dependent and culture independent methods, when studying the microbiota of marine fish. Several Vibrio spp. were found only in gut samples collected from the purse seine, but in all samples including the skin and the gills collected from the RSW tank, indicating microbial contamination by faecal bacteria from the fish under these transport conditions.     

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     

The Effects of Natural Extracts on the Quality Changes of Frozen Chub Mackerel (Scomber japonicus) Burgers

The effects of the use of natural antioxidants on the quality of frozen chub mackerel (Scomber japonicus) burgers stored at ?18 °C were investigated in terms of sensory, biochemical (thiobarbituric acid reactive substances-TBARS, total volatile basic nitrogen, peroxide value and free fatty acids) and microbiological analyses (total viable count—TVC, total psychrotrophic count—TPC). Oregano, green tea, sage and laurel extracts were obtained by using steam distillation method. After that, thawed fish were headed, gutted and filleted. Fillets were then minced and divided into nine groups. These were the control without plant extract, O1 with 0.3% oregano extract, O2 with 0.6% oregano extract, G1 with 0.3% green tea extract, G2 with 0.6% green tea extract, S1 with 0.3% sage extract, S2 with 0.6% sage extract, L1 with 0.3% laurel extract and L2 with 0.6% laurel extract. Plant extracts together with burger ingredients were added to each group. All groups were stored at ?18 °C for 9 months. According to the results of sensory analyses, the control at 7 months of storage, oregano and green tea at 9 months of storage, sage and laurel groups at 8 months of storage were rejected by panellists and considered as unaccepptable. Natural extracts were effective in controlling biochemical indices. TVC content of fish burgers did not exceed the limit during storage period for all groups (<6 log CFU/g). TPC slightly decreased with storage time. Additions of oregano, green tea and laurel extracts except sage extract reduced (P?<?0.05) lipid oxidation in fish burger and have the potential to be incorporated into fish burgers.     

Inhibition of mackerel (Scomber scombrus) muscle lipoxygenase by green tea polyphenols

The high polyunsaturated fatty acid content of oily fish such as mackerel (Scomber scombrus) makes it particularly susceptible to oxidative degradation. We have shown previously the presence of lipoxygenase (LOX), a lipid oxygenase, in mackerel muscle. In the current study, commercially available green tea polyphenols were shown to effectively inhibit the LOX activity of mackerel muscle. EGCG (epigallocatechin gallate) was the strongest inhibitor tested with an IC₅₀ (concentration for half maximal inhibition) value of 0.13 nM. All the tea catechins showed a mixed non-competitive type inhibition. In addition, antioxidants such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), esculetin, caffeic acid, ascorbic acid, and ethylene diamine tetraacetic acid (EDTA) were effective to varying degrees (IC₅₀ values between 0.02 and >50 μM) in the inhibition of mackerel muscle LOX. Nordihydroguaiaretic acid (NDGA), a classical LOX inhibitor and potassium cyanide (KCN), a heme protein inhibitor were assayed for their inhibitory activities for comparison.Post harvest spoilage of fish account for loss of as much as 10% of the world’s catches of cultured fish. This data indicates that the green tea polyphenols, nature’s very potent antioxidants, may be used as an effective and natural means of reducing post harvest spoilage in fish.     

Histidine metabolism in fish. Urocanic acid in mackerel (Scomber scombrus)

Urocanic acid, isolated from perchloric extracts of the flesh of mackerel (Scomber scombrus) using an anion exchange resin Dowex-1 acetate, was identified by thin-layer chromatography, u.v. absorption and mass spectra. During storage of sterile and non-sterile tissue the concentration of urocanic acid increased at similar rates, indicating that L-histidine ammonia-lyase is not associated with bacterial spoilage.     

Proteolytic processing of Atlantic mackerel (Scomber scombrus) and biochemical characterisation of hydrolysates

Research on fish composition has demonstrated that they constitute a promising source of molecules with health benefits. In the present study, Atlantic mackerel ( Scomber scombrus ) was processed using Protamex® and the distribution of nutrients in various fractions obtained following membrane filtration was analysed. The fish starting material was approximately 84% water and the dry matter contained 42.7% proteins, 45.2% lipids and 5.6% minerals. The recovery of fish dry matter in the liquid hydrolysate was 77.8%. Most of the fractions were protein-enriched and characterised by a well-balanced amino acid composition, notably in terms of the most essential amino acids and by molecules of relatively low molecular weight (≤42 kDa). Even before process optimising, the biochemical and nutritional analyses indicate that the Atlantic mackerel may provide high-value products for future applications in the health and food sectors.     

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 a flax seed (Linum usitatissimum) soaking treatment on the frozen storage stability of mackerel (Scomber scombrus) fillets

The effect of a flax seed (Linum usitatissimum) soaking on the development of rancidity in frozen mackerel (Scomber scombrus) was studied. Fresh mackerel fillets were soaked in an aqueous flax seed extract for 20 min and then kept frozen (?20 °C) for up to 7 months. A parallel experiment with non‐soaked fillets was carried out under the same conditions. The development of rancidity was measured by biochemical (free fatty acids, peroxides, conjugated dienes and trienes, secondary oxidation products, fluorescent and browning compounds and lipoxygenase activity) and sensory (general aspect, odour and colour) analyses. An inhibitory effect of the soaking treatment on rancidity development was observed according to the peroxide content and the formation of fluorescence and browning. A lower lipoxygenase activity was detected at 1 month in the soaked fillets; after this, no differences were obtained between either type of sample, whose activities at month 7 were negligible. According to the sensory analyses, non‐soaked fillets had fair quality at 1 month and were rejectable at 3 months, while the soaked ones were still of good quality at 1 month and rejectable at 5 months. According to the present results, soaking in an aqueous flax seed extract could be useful for inhibiting the development of rancidity in fatty fish fillets. Copyright © 2006 Society of Chemical Industry     

Supercritical CO2 Extraction of Oil and Residual Proteins from Atlantic Mackerel (Scomber scombrus) as Affected by Moisture Content

Lipid composition of supercritical CO₂ (SC-CO₂) extracts, residual oil in muscle and changes in sarcoplasmic proteins after extraction of Atlantic mackerel were characterized. Dehydration of the muscle to 10.2% (w/w) resulted in high oil yield with minimum changes in protein content and composition. Sarcoplasmic protein content of fish muscle following SC-CO₂ treatment was lower than that of original muscles at all moisture levels (3.8–64%, w/w). Analysis of sarcoplasmic proteins by capillary electrophoresis indicated aggregation of low molecular weight proteins during SC-CO₂ extraction. SC-CO₂-extracted muscle also had lighter color than original samples. The SC-CO₂ extraction showed potential to provide high quality oil and protein meal.     

不同解冻方式对鲐鱼鲜度及品质的影响

采用4 种解冻方式（空气解冻、静水解冻、微波解冻、鼓气流水解冻）对－18 ℃贮藏的船冻鲐鱼进行解冻,分析其持水力、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、组胺含量、盐溶性蛋白含量、质构值的变化,并进行电子鼻分析和微观结构的观察。结果表明：解冻时间、TVB-N值和组胺之间、持水力与解冻损失率和盐溶性蛋白含量之间分别有极显著的相关性（P＜0.01）。电子鼻的Fisher判别分析能明显区分各种解冻方式,其检测结果与TVB-N值和组胺含量的测定结果一致。4 种解冻方式中,鼓气流水解冻后鲐鱼的持水力、盐溶性蛋白含量最高,质构特性最好,肌束排列紧密,肌内膜较完整,鲜度比微波解冻稍差,与静水和空气解冻相比缩短了解冻时间,与微波解冻相比大大节约了成本。因此,鼓气流水解冻是一种理想的鲐鱼解冻方式。     

Non-dioxin like polychlorinated biphenyls in mackerel (Scomber scombrus) available on the Serbian market

Mackerel is rich in omega-3 fatty acids, but this fish may be contaminated with environmental pollutants. The aim of this study was to evaluate concentrations of non-dioxin like polychlorinated biphenyls (ndl-PCBs) in 160 samples of mackerel available on the Serbian market. Average and maximum ndl-PCB concentrations were 7.9 ng/g and 74 ng/g, respectively. A higher average level of ndl-PCBs was found in mackerel from Spain, but this was still three times lower than the permitted level. We conclude that levels of ndl-PCBs in mackerel available on the Serbian market are acceptable.