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.     

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 Various Processing Methods on Quality of Mackerel (Scomber scombrus)

The effects of combinations of processes (hot smoking, marinating, vacuum packing and seasoning with dill (Anethum graveolens) on the quality parameters of mackerel (Scomber scombrus) stored at 4 °C were investigated in terms of sensory, chemical (total volatile basic nitrogen [TVB-N], thiobarbituric acid [TBA], peroxide value [PV], free fatty acids [FFA]) and microbiological parameters (total viable count [TVC], coliform, Escherichia coli, Staphylococcus aureus) during 9 months of storage. Sensory quality of smoked mackerel marinates with or without dill leaves (Group A, Group B, respectively) decreased throughout storage period. However, at the end of storage period, both the products were still acceptable by the panellist. At the beginning of storage, the initial TVB-N values were 24.14 mg/100 g and showed fluctuations during storage period. TBA values significantly increased (p?<?0.05) for both products during storage period. PV showed fluctuations. FFA increased gradually from 2.46 to 7.33 (expressed as % of oleic acid) for Group A and from 2.57 to 6.90 for Group B at the end of storage period. Coliform, E. coli and S. aureus were not detected during storage period. TVC remained lower than the acceptability limit of 10⁶ log CFU/g at the end of storage period. The results of this study suggest that shelf life of both products was 9 months and also the combination of hot smoking, marinating, vacuum packing and seasoning led to high-quality food item and was found to be effective in controlling the growth of bacteria and biochemical indices.     

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.     

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.     

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.     

Effect of High Hydrostatic Pressure (HHP) Treatment on Physicochemical Properties of Horse Mackerel (Trachurus trachurus)

The basic objective of this study was to determine the effect of high hydrostatic pressure (HHP; 220, 250 and 330 MPa), holding time (5 and 10 min) and temperature (7, 15 and 25 °C) on some quality parameters of horse mackerel such as colour changes, thiobarbituric acid (TBA-i) and trimethylamine nitrogen (TMA-N), free amino acid content. HHP increased L ^* values of horse mackerel. The a ^* and b ^* of treated horse mackerel did not change significantly after HHP applications. After, HHP, TBA-i and TMA values of all HHP-treated horse mackerel samples remained unchanged than those of untreated samples. The results obtained from this study showed that the quality of high pressure treated horse mackerel is best preserved at 250 MPa, 7–15 °C for 5 min, 220 MPa, 15–25 °C for 5 min, 250 MPa, 15 °C for 10 min and 330 MPa, 25 °C for 10 min.     

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.     

气体结合高静压对预制莴笋货架期品质的影响

为了方便莴笋在人们日常生活中的摄入,满足人们对预制产品营养与品质的需求,采用高静压(High Hydrostatic Pressure,HHP,500 MPa,5 min)分别结合二氧化碳、氮气,以及抽真空体系处理新鲜莴笋,研究莴笋贮藏期间叶绿素含量、色泽、质构和微生物的变化。新鲜莴笋切丝烫漂30 s后称量包装热封,气体结合高静压处理后于4℃冷库中贮藏。结果表明:二氧化碳结合高静压处理后的鲜切莴笋货架期长达35 d,且叶绿素含量,色差CIE-L*a*b*值,质构,均优于氮气结合高静压组和真空结合高静压组,菌落总数低于其他两组。二氧化碳结合高静压能提高预制莴笋的贮藏品质并有效延长预制莴笋的货架期。     

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.     

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.     

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     

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.     

超高压处理对鲜杏鲍菇品质的影响

本文以新鲜杏鲍菇为研究对象,研究了超高压不同处理方式下(不同压力100 MPa、150 MPa、200 MPa、250 MPa、300MPa,不同保压时间3 min、6 min、9 min、12 min、15 min、18 min),对杏鲍菇多酚氧化酶(PPO)、失重率、色差、硬度、感官等品质的影响。研究结果表明,超高压处理后杏鲍菇的PPO酶活力和弹性随着压力的升高和保压时间的延长出现先下降后上升的变化,色差的亮度(L*)值和硬度则逐渐降低,黄度(b*)值和失重率则逐渐增加。在储藏期内(0~12 d),贮藏温度为4℃,超高压处理下(压力200 MPa保压时间9 min)的酶活力低于未处理的杏鲍菇样品,而高压处理的失重率增幅大于未处理组样品,而色差和硬度变化则小于未处理组样品。通过实验分析得到杏鲍菇超高压处理的最佳压力和保压时间参数为:200 MPa、9 min。     

Comparing the Effects of High Hydrostatic Pressure and Ultrahigh Temperature on Quality and Shelf Life of Cloudy Ginger Juice

The effects of high hydrostatic pressure (HHP) at 500 MPa for 10 min and ultrahigh temperature (UHT) at 110 °C for 8.6 s on the quality of cloudy ginger juice (CGJ) were investigated during storage for 91 days at 4 and 25 °C. The quality aspects studied were microbial stability and selected properties, including pH, total soluble solids (TSS), titratable acidity (TA), total phenols, gingerols, antioxidant capacity, color, and aroma composition. The results showed that HHP treatment led to a 3.0 log cycle reduction of microbial load but did not influence pH, TSS, TA, antioxidant capacity, and color (day 0). Total phenol content increased by 5.31 % after HHP treatment but decreased significantly by 14.74 % after UHT treatment (day 0). Gingerols increased by 14.43 and 14.18 % after HHP and UHT treatments (day 0), respectively. Monoterpenoids, which are the main volatile aroma compounds, did not change significantly after HHP treatment but decreased significantly by 2.27 % after UHT treatment (day 0). During storage, the decreases in total phenols, gingerols, and antioxidant capacity in the UHT-treated GCJ were more noticeable than those in the HHP-treated GCJ. Kinetic data of changes in total phenols, gingerols, and antioxidant capacity fitted into the combined model well. The changes in antioxidant capacity were positively and significantly correlated to total phenols and gingerols. Color darkened and aroma faded in both HHP-treated and UHT-treated CGJs during storage. The quality changes in samples stored at 25 °C were also more noticeable than those stored at 4 °C.     

超高压和热处理对发酵石榴汁品质的影响

以发酵石榴汁为研究对象,分别用超高压(High hydrostatic pressure,HHP,600 MPa/10 min)和热处理(Thermal processing,TP,65 ℃/20 min)进行杀菌,比较处理前、后及4 ℃贮藏期间发酵石榴汁各理化指标的变化。结果表明,经超高压和热处理后,发酵石榴汁中菌落总数小于10 CFU/mL,且菌落总数在贮藏结束时小于100 CFU/mL,符合行业标准要求;pH、可滴定酸(Titratable acidity,TA)和可溶性固形物含量(Total soluble solids,TSS)在两种处理前、后均无显著变化(p>0.05),在贮藏期内pH、TSS无显著变化(p>0.05),而TA显著下降(p<0.05);超高压处理后的样品具有更高的总酚、花色苷、总黄酮和抗氧化活性;在贮藏过程中,总酚、花色苷、总黄酮含量和抗氧化活性均呈下降趋势,超高压处理能更好地保持样品的总酚、花色苷和抗氧化活性,而热处理组能更好地控制样品中总黄酮的损失;与未处理组相比,超高压和热处理对发酵石榴汁色泽的影响较小,贮藏期间热处理组的色泽变化程度高于超高压处理组。结论:超高压处理的发酵石榴汁在总酚、总黄酮、花色苷和抗氧化性等品质方面优于热处理组。     

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.     

Influence of feeding state and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

Lipid deterioration of mackerel caught in Icelandic waters was studied, as affected by different frozen storage temperatures (?18 °C vs. ?25 °C) and seasonal variation (August vs. September). The lipid stability was investigated by analyses of hydroperoxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acids, as well as changes in fatty acid composition. Results showed significant lipid deterioration with extended storage time, where the lower storage temperature showed significantly more protective effects. Furthermore, a higher lipid oxidation level was recorded for fish caught in September than in August, although lipid hydrolysis occurred to be greater for fish in August than in September. Moreover, results indicated a rather stable level of omega‐3 fatty acid during the whole frozen storage period. The analysis indicated that both lipid oxidation and hydrolysis were affected by the frozen storage temperature and the stability differed with regard to season of catch.