Preservation of salted,vacuum-packaged,refrigerated sea bream (Sparus aurata) fillets by irradiation: microbiological,chemical and sensory attributes

The effect of gamma irradiation (1 and 3 kGy) on the shelf-life of salted, vacuum-packaged sea bream (Sparus aurata) fillets stored under refrigeration was studied by monitoring the microbiological, chemical and organoleptic changes occurring in fish samples. Non-irradiated, salted, vacuum-packaged fish served as control samples. Irradiation affected populations of bacteria, namely, Pseudomonas spp., H₂S-producing bacteria, Brochothrix thermosphacta, Enterobacteriaceae and lactic acid bacteria. The effect was more pronounced at the higher dose (3 kGy) applied. Of the chemical indicators of spoilage, trimethylamine (TMA) values of non-irradiated, salted sea bream increased slowly to 8.87 mg N (100 g)⁻¹ flesh (whereas for irradiated, salted samples significantly lower values were obtained, reaching a final TMA value of 6.17 and 4.52 mg N (100 g)⁻¹ flesh at 1 and 3 kGy, respectively (day 42). Total volatile base nitrogen values increased slowly attaining a value of 60.52 mg N (100 g)⁻¹ for non-irradiated, salted sea bream during refrigerated storage whereas for irradiated fish, lower values of 48.13 and 37.21 mg N (100 g)⁻¹ muscle were recorded at 1 and 3 kGy, respectively (day 42). Thiobarbituric acid values for irradiated, salted sea bream samples were higher than respective non-irradiated (salted) fish, and increased slowly until day 28 of storage reaching final values of 1.01 (non-irradiated, salted), 2.15 (1 kGy) and 3.26 mg malonaldehyde kg⁻¹ flesh (3 kGy), respectively (day 42). Sensory evaluation (taste) showed a reasonably good correlation with bacterial populations. On the basis of sensorial evaluation, a shelf-life of 27–28 days was obtained for vacuum-packaged, salted sea bream irradiated at 1 or 3 kGy, compared to a shelf-life of 14–15 days for the non-irradiated, salted sample.     

Effect of ungutting on microbiological, chemical and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice

The effect of ungutting on microbiological, chemical and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice were studied. The total viable mesophilic and psychrophilic bacterial counts increased throughout the storage period of ungutted sea bream and sea bass. Mesophilic counts of ungutted sea bream and sea bass reached 7.39 log cfu/g and 7.26 log cfu/g after 9 days. At the end of the storage period of 14 days; TVB-N, TBA, TMA-N values of ungutted sea bream were determined as 37.5±0.51 mg/100 g, 3.82±0.03 mg MA/kg, 7.73±0.25 mg/100 g, respectively. TVB-N, TBA, TMA-N values of ungutted sea bass were reached 35.4±0.9 mg/100 g, 3.75±0.81 mg MA/kg, 6.94±0.08 mg/100 g on day 14th, respectively. Result of this study indicates that the shelf life of whole ungutted sea bream stored in ice as determined by the overall acceptability sensory scores, chemical quality and microbiological data is 12, 9 and 9 days, respectively. Each chemical, sensory and microbiological results for sea bream showed us that there was a correlation and similarity, and day 9 was the beginning of spoilage. Whole ungutted sea bass stored in ice as chemical results for sea bass showed us that day 7 was the beginning of spoilage and for sea bream day 9 was the beginning of spoilage.     

Comparison of gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle proteins during iced and frozen storage

Gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle behave differently during storage, whether in ice or deep frozen. Rapid changes have been observed in the texture of hake muscle during frozen storage, while gilthead sea bream has proved to be more stable. In order to ascertain the role of muscle proteins in the changes observed during storage, parameters related to protein functionality and the properties of extracted natural actomyosin (NAM) were studied initially and during storage in ice or at ?20 °C. Initially, the parameters related to functionality had higher values in hake muscle and extracted NAM than in gilthead sea bream. At the end of iced storage (22 days), less myosin heavy chain (MHC) and actin were extracted from hake, but there was practically no change in gilthead sea bream. This decrease was not accompanied by lower Ca²⁺‐ATPase activity. Freezing produced no drastic changes, with lower values for gilthead sea bream. However, this species was more stable after 1 year, except for the Ca²⁺‐ATPase activity of NAM. This suggests that the changes that hake proteins underwent during storage particularly affected properties related to aggregation, whereas in gilthead sea bream the changes hardly affected the formation of soluble or insoluble aggregates but did affect the active sites of myosin. © 2002 Society of Chemical Industry     

Antioxidative and antimicrobial activities of shrimp chitosan on gilthead sea bream (Sparus aurata) during refrigerated storage

This study aims to determine the effects of chitosan obtained from Metapenaeus stebbingi shells on the shelf life of refrigerated gilthead sea bream. It was determined that 1% chitosan‐coated samples had the lowest thiobarbituric acid (TBA) (3.05 mg malondialdehyde (MDA) kg^?1) and free fatty acids (FFA) value (2.79% oleic acid), while the control group had the highest TBA (5.08 mg MDA kg^?1) and FFA value (6.13% oleic acid) on the 27th day of storage. In the last day of storage, TVB‐N was found higher in control group (25.62 mg 100 g^?1) than chitosan‐coated samples (14.57 mg 100 g^?1). Total viable count value of the control group exceeded maximum permissible limit on the 27th day of storage. However, it was lower than 7.0 log CFU/g in chitosan‐coated samples during the refrigerated storage. As a result of this study, it was determined that shelf life of refrigerated gilthead sea bream can be increased up to 27 days with chitosan.     

Shelf‐life extension of vacuum‐packaged sea bream (Sparus aurata) fillets by combined γ‐irradiation and refrigeration: microbiological,chemical and sensory changes

The combined effect of γ‐irradiation and refrigeration on the shelf‐life of vacuum‐packaged sea bream (Sparus aurata) fillets was studied by monitoring the microbiological, chemical and sensory changes of non‐irradiated and irradiated fish samples using low‐dose irradiation doses of 1 and 3 kGy. Fish species such as sea bream and sea bass are very popular in the Mediterranean countries due to their high quality characteristics, and their preservation is a constant challenge given their extreme perishability. Irradiation (3 kGy) dramatically reduced populations of bacteria, namely, total viable counts (3 vs 7 log cfu g^?1) for the non‐irradiated samples, Pseudomonas spp (<2 vs 7.6 log cfu g^?1), H₂S‐producing bacteria typical of Shewanella putrefaciens (<2 vs 5.9 log cfu g^?1), Enterobacteriaceae (<2 vs 6.0 log cfu g^?1) and lactic acid bacteria (<2 vs 3.5 log cfu g^?1) after 10 days of storage. The effect was more pronounced at the higher dose (3 kGy). Lactic acid bacteria, Enterobacteriaceae and H₂S‐producing bacteria typical of Shewanella putrefaciens showed higher sensitivity to γ‐radiation than did the rest of the microbial species. Of the chemical indicators of spoilage, Trimethylamine (TMA) values of non‐irradiated sea bream increased very slowly, whereas for irradiated samples significantly lower values were obtained reaching a final value of 7.9 and 6.3 mg N per 100 g muscle at 1 and 3 kGy respectively (day 42). Total volatile basic nitrogen (TVB‐N) values increased slowly attaining a value of 67.3 mg N per 100 g for non‐irradiated sea bream during refrigerated storage, whereas for irradiated fish, lower values of 52.8 and 43.1 mg N per 100 g muscle were recorded (day 42). Thiobarbituric acid (TBA) values for irradiated sea bream samples were higher than respective non‐irradiated fish and increased slowly until day 21 of storage, reaching final values of 1.1 (non‐irradiated), 2.0 (1 kGy) and 2.2 mg malonaldehyde kg^?1 muscle (3 kGy), respectively (day 42). Sensory evaluation showed a good correlation with bacterial populations. On the basis of overall acceptability scores (sensory evaluation) a shelf‐life of 28 days (3 kGy) was obtained for vacuum‐packaged sea bream, compared with a shelf‐life of 9–10 days for the non‐irradiated sample. Copyright © 2004 Society of Chemical Industry     

Effects of gutting and ungutting on microbiological, chemical, and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice

The effect of gutting and ungutting on microbiological, chemical, and sensory properties of aqua-cultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice were studied. The total viable mesophilic and psychrophilic bacterial counts increased throughout the storage period of gutted and ungutted sea bream and sea bass. The mesophilic counts reached 8.19 log cfu/g for ungutted sea bream and 7.93 log cfu/g for ungutted sea bass after 14 days of storage. The mesophilic counts reached 8.89 log cfu/g for gutted sea bream and 8.16 log cfu/g for gutted sea bass after 14 days of storage. On day 14 of storage the psychrophilic counts of ungutted sea bream and sea bass were 8.24 log cfu/g and 8.03 log cfu/g, respectively, and for gutted sea bream and sea bass were 8.93 and 8.22, respectively. At the end of the storage period of 14 days, TVB-N, TBA, and TMA-N values of ungutted sea bass were determined as 50.13 +/- 0.25 mg/100 g, 2.66 +/- 0.06 mg malonaldehit/kg, 9.86 +/- 0.01 mg/100 g respectively. TVB-N, TBA, and TMA-N values of ungutted sea bream reached 55.90 +/- 0.36 mg/100g, 2.51 +/- 0.21 mg malonaldehit/kg, 9.79 +/- 0.01 mg/100 g on day 14 respectively. And also at the end of the storage period of 14 days, TVB-N, TBA, and TMA-N values of gutted sea bass were determined as 48.00 +/- 0.26 mg/100 g, 2.48 +/- 0.03 mg malonaldehit/kg, 8.71 +/- 0.06 mg/100 g respectively. TVB-N, TBA, and TMA-N values of gutted sea bream reached 49.66 +/- 0.77 mg/100g, 2.64 +/- 0.07 mg malonaldehit/kg, 8.97 +/- 0.01 mg/100 g on day 14 respectively. The result of this study indicates that the shelf-life of whole ungutted sea bass and sea bream stored in ice as determined by the overal acceptibility sensory scores, chemical quality, and microbiological results show us that the fish were spoilt on day 14. Each chemical, sensory, and microbiological result for sea bream showed us that there was a correlation and similarity and on day 14 it was spoilt.     

Freshness assessment of cultured sea bream (Sparus aurata) by chemical,physical and sensory methods

The quality changes of cultured sea bream (Sparus aurata) stored in ice for a period of up to 23 days were determined by K and related values, sensory assessment and texture by texturometer. Sensory schemes, based on the Tasmanian Food Research Unit (TFRU) scheme for raw fish and on the Torry scheme for cooked fish were modified to be appropriate for whole cultured sea bream, according to the trained panellists’ perceptions, during the storage period in ice. The TFRU sensory score of fish showed good agreement with K value and texture results throughout the storage period. The limit for acceptability of cultured sea bream stored in ice was about 17–18 days. Generally, K, K_i and G values had good correlation with the degree of freshness and can be used as freshness indicators.     

Biochemical, sensory and microbiological attributes of bream (Megalobrama amblycephala) during partial freezing and chilled storage

BACKGROUND: Bream is one of the main farmed freshwater fish species in China. This study aimed to examine the nucleotide degradation of bream during partial freezing and chilled storage and to assess the possible usefulness of nucleotide ratios (K, Ki, H, P, Fr and G values) as freshness indices in comparison with sensory assessment and total viable counts. RESULTS: Total viable counts were 5.74 and 4.66 log(colony‐forming units g^?1) on the day of sensory rejection under chilled storage and partial freezing storage respectively. The inosine 5‐monophosphate decrease and inosine increase were faster in chilled storage than in partial freezing storage. Hypoxanthine levels increased continuously with time under both storage regimes. Among the nucleotide ratios, the K, Ki, P, G and Fr values were superior to the H value and provided useful freshness indicators for both storage conditions. CONCLUSION: Bream in chilled storage were sensorially acceptable only up to 10 days, compared with 33 days for bream in partial freezing storage. Partial freezing delayed the nucleotide degradation of bream. Copyright © 2011 Society of Chemical Industry     

The effect of high hydrostatic pressure on the microbiological, chemical and sensory quality of fresh gilthead sea bream (Sparus aurata)

The effect of different temperature/time/pressure high hydrostatic pressure (HHP) treatment on quality and shelf life of sea bream were studied. Different high-pressure treatments (at 3, 7, 15 and 25 °C, 5–10 min and 220, 250 and 330 MPa) were tested to establish the best processing conditions for quality of sea bream. The effect of the process on the quality of the sample was examined by colour, trimethylamine nitrogen and thiobarbituric acid number analysis. Based on the results of the parameter, the best combinations of HHP treatments were determined as 3 °C/5 min/250 MPa–15 °C/5 min/250 MPa for sea bream. The effects of this combination treatment on sensory, chemical and microbiological properties of sea bream stored at 4 °C were studied. The results obtained from this study showed that the shelf life of untreated and HHP treated stored in refrigerator, as determined by overall acceptability of sensory and microbiological data, is 15 days for untreated sea bream and 18 days for treated sea bream at 3 °C/5 min/250 MPa and at 15 °C/5 min/250 MPa treated sea bream.     

Effect of smoking on quality parameters of farmed gilthead sea bream (Sparus aurata L.) and sensory attributes of the smoked product

The effect of smoking on the proximate composition, chemical parameters and microbial loads of farmed gilthead sea bream (Sparus aurata L.), as well as the sensory attributes of the smoked product were investigated. The process reduced the moisture content and the total aerobic count and increased the protein, lipids and total volatile basic nitrogen content and the thiobarbituric acid number . The values of the last two parameters were much lower than acceptable limits reported in the literature references for smoked fish products. No effect was noted on the fatty acid composition of total lipids. The new product was highly acceptable to laboratory and consumer panels.Kyriakos Vareltzis deceased     

Nucleotide degradation products of gamma‐irradiated sea bream (Sparus aurata) stored in ice

Nucleotide degradation products of irradiated sea bream stored up to 19 days in ice were investigated. Irradiation had significant effect on the nucleotide concentrations in sea bream muscle (P < 0.05). The results showed that the highest value of inosine monophosphate (IMP) was observed in irradiated sea bream at 5 kGy, followed by at 2.5 kGy. Initial inosine (INO) concentration in irradiated sea bream at 5 kGy was 4.26 μmoles g^?1, which reached maximum value of 8.83 μmoles g^?1 when fish completely spoiled (19 days). When the fish reached the limit of acceptability, the mean values of K, Ki, H and G were 86.8%, 90.3%, 59.8% and 213.9% for unirradiated sea bream, 85.2%, 87.8%, 56.8% and 197.8% for irradiated sea bream at 2.5 kGy and 88.4%, 90.9%, 57.8%, 211.5% for irradiated sea bream at 5 kGy, respectively. The results of this study indicated that nucleotide degradation was more rapid in unirradiated sea bream than those irradiated. K, Ki, H and G value in irradiated fish can be used as a freshness index because there is a good linear relationship between values and storage time of fish.     

Effects of different cooking methods on the mineral contents of wild and farmed sea bream (Sparus aurata)

The effects of different cooking methods (steaming, boiling, oven cooking, grilling, frying in olive oil, frying in soybean oil, frying in corn oil and frying in sunflower oil) on mineral contents (Ca, Mg, K, Na, Fe, Zn, Cu and Mn) of wild and farmed sea bream (Sparus aurata) were determined. The moisture rate decreased significantly (P < 0.05) after boiling, grilling, oven cooking and frying but remains stable after steaming. The fat content increased with different frying treatments. The Ca, Mg, Na, K and Zn contents of wild and farmed sea bream cooked by almost all methods significantly decreased (P < 0.05). The Cu content in grilled wild and farmed sea bream increased significantly (P < 0.05). Losses of mineral content in fried sea bream were higher than those of fish cooked by other methods. On comparing the raw and cooked fish, the results indicated that cooking had considerable effect on the mineral contents.     

Effect of low-dose irradiation and refrigeration on the microflora, sensory characteristics and biogenic amines of Atlantic horse mackerel (trachurus trachurus)

Fresh Atlantic horse mackerel (Trachurus trachurus) were gamma irradiated at 1 and 3 kGy, and stored in ice for 23 days. Quality changes during ice storage at 0±1 °C were followed by sensory analysis and the determination of total viable count, histamine, cadaverine, putrescine, tyramine, agmatine, spermidine, trimethylamine and volatile basic nitrogen contents. The control lot had a sensory shelf life of 8 days, whereas those of the irradiated lots were extended by 4 days. TVCs and levels of amines increased in all lots with storage time, their contents being significantly reduced by irradiation, even when the lower level (1 kGy) was used. Histamine in the irradiated lots was undetectable when the fish was spoiled at the end of 23 days, whereas in the control lot, the concentration did not exceeded the maximum allowed in fresh fish (100 mg/kg). Presumptive identification of microorganisms gave a majority aerobic or facultative Gram-negative anaerobic rods being Gram-positive bacteria circa 10–18% in irradiated samples. Chemical indices were shown to be unsuitable for the determination of the quality changes in irradiated fish.     

Effect of vacuum packaging and low-dose irradiation on the microbial, chemical and sensory characteristics of chub mackerel (Scomber japonicus)

The effects of vacuum packaging followed by gamma irradiation treatment (1.5 kGy) on the shelf-life of fillets of chub mackerel (Scomber japonicus) were examined, during chill storage. The control and the treated packs were analyzed periodically for chemical (TMA, TBARS, biogenic amines) and microbial characteristics. Based on chemical and microbial data, vacuum packaging – by itself – was improper in extending the shelf-life of chub mackerel, estimated to 7 days. On the 7th day, TMA and Histamine contents reached the defect action levels, associated with the presence of mesophiles (3.7 log UFC/g); total coliforms (3.5 log UFC/g); staphylococci (1.9 log UFC/g) and the emergence of Pseudomonas (1.7 log UFC/g), in both the control and the vacuum packaged lots. Combination of vacuum packaging and γ-irradiation was found to delay the spoilage during 14 days of refrigerated storage, based on chemical and microbial analyses. Similarly, consumer hedonic tests were performed to determine the effect of different treatments on the taste of fish fillets. For all treatments, consumers failed to discriminate treated samples from the control, on the 2nd day of storage (p > 0.05). The acceptability test showed that low-dose irradiation (1.5 kGy) optimised the sensory quality, on the 3rd day of storage (p < 0.05). The employment of vacuum packaging combined to a low-dose γ-irradiation (1.5 kGy) on chub mackerel is recommended to enhance microbiological quality (4 log reduction), alleviate chemical changes and extend the shelf-life by 7 days, leading to consumer appreciation of these products.     

Quality and shelf life evaluation of pork nuggets incorporated with fermented bamboo shoot (Bambusa polymorpha) mince

Pork nuggets were processed by incorporating fermented bamboo shoot mince and their physico-chemical, microbiological and sensory characteristics were evaluated during 35 day storage at refrigeration temperature (4 ± 1 °C). Addition of fermented bamboo shoot significantly affects the pH, moisture, protein, fat, fiber, instrumental color values and texture profiles of nuggets, especially at 6% and 8% addition levels. Nuggets with 6% and 8% FBSM had significantly lower TBARS values at the end of the storage period (i.e. 0.39 and 0.33 mg malonaldehyde/kg respectively) compared to the control (0.84 mg malonaldehyde/kg). Bamboo shoot addition significantly improved the microbial and sensory qualities of the pork nuggets. Incorporation of fermented bamboo shoot at 8% level increased the shelf life of pork nuggets by at least two weeks i.e. from 21 days to 35 days at 4 ± 1 °C compared to the control.     

Comparison of effects of slurry ice and flake ice pretreatments on the quality of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored at 4 °C

Slurry ice, a biphasic system consisting of small particles of spherical ice immersed in seawater at subzero temperature, was evaluated as a new chilled method for whole sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax). Two types of different chilling methods were used for two species in this study; slurry ice-treated sea bream (Group A), slurry ice-treated sea bass (Group B), flake-ice treated sea bream (Group C) and flake ice-treated sea bass (Group D). The effects of this system on the quality and shelf life of these two species were evaluated. Mesophilic counts for sea bass exceeded 7 log cfu/g, which is considered the maximum level for acceptability for freshwater and marine fish after 13 days for Groups C, D and 15 days for Groups A, B. At day 13, TVB-N values of Groups C, D reached the legal limits (35 mg/100 g set for TVB-N) for consumption. According to the results of sensory analyses, up to day 13, all the Groups were determined as ‘acceptable’ but, on day 15, the Groups A, B, C, D were no longer acceptable. Using slurry ice pretreatment for 2 h before the storage period presumably caused the deleterious effect on appearance as well as salt and water uptake. According to the results of chemical and microbiological analyses, use of slurry ice pretreatment for 2 h extended the shelf life of sea bream and sea bass stored at 4 °C for only two days longer than did use of flake ice.     

Effects of using slurry ice on the microbiological, chemical and sensory assessments of aquacultured sea bass (Dicentrarchus labrax) stored at 4 °C

Slurry ice, a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature, was evaluated as a new chilled storage method for whole sea bass (Dicentrarchus labrax) a sparidae fish species of remarkable commercial interests. Four different group of chilling methods were used in this study; in slurry ice packaged on board (group A), in slurry ice packaged on company after 2 h (group B), slurry + flake ice packaged on board (group C) and only flake ice packaged on board (group D). The effect of this advanced system at the beginning of storage on quality losses and the shelf-life of aquacultured sea bass was evaluated. Mesophilic counts for sea bass exceeded 7 log cfu/g, which is considered the maximum level for acceptability for freshwater and marine fish after 13 days for groups C and D, and 15 days for groups A and B. At day 15; total volatile basic nitrogen (TVB-N) values of groups A–D reached the legal limits (35 mg/100 g set for TVB-N) for consumption. According to the results of sensory analyses, up to day 11, all the groups were determined as ‘acceptable’ but on day 13, the groups A–D were no longer acceptable. The main negative aspect related to quality loss in slurry ice group corresponded to the appearance of eyes and gills. Using slurry ice at the beginning of packaging did not affect the shelf-life of sea bass stored at 4 °C.     

Comparison of selected methods of assessing freshness quality and remaining storage life of iced gilthead sea bream (Sparus aurata)

Quality changes of whole, iced gilthead sea bream were monitored by sensory evaluation, k₁ value, GR Torrymeter, and bacterial counts. The methods were tested for their suitability to determine freshness quality and remaining storage life in ice. Depending on the measured parameter, post-mortem age of the iced fish could be predicted with an accuracy of ±1.5–3.6 days. Although assessment of cooked fish flavour is the underlying basis for establishing the state of the fish, the quality index method can be more effective for routine freshness evaluations. The k₁ value provides a useful means of monitoring early storage change, resulting primarily from autolytic reactions. Counts of sulphide-producing bacteria can be used to determine the time to rejection, while total counts at 20 °C are only poor measures of freshness quality. The GR Torrymeter offers a unique practical tool for assessing freshness quality and remaining storage life of iced gilthead sea bream.     

Effects of frying on the fatty acid composition in farmed and wild gilthead sea bream (Sparus aurata)

The effects of frying in soybean (FWSO) and olive oils (FWOO) on the fatty acid composition of farmed and wild gilthead sea bream Sparus aurata were evaluated. The fat content increased with both frying treatments. However, after FWOO the moisture content of the fish was reduced to a greater extent than that in fish FWSO. The concentration of saturated fatty acids (SFA) decreased significantly during both frying processes ( P  < 0.01). However, the concentration of monounsaturated fatty acids (MUFA) increased significantly in fish fried in olive oil ( P  < 0.01). The fried fish contained a higher level of n-6 polyunsaturated fatty acids (PUFA) and a lower level of n-3 PUFA compared to raw fish. The n-3/n-6 ratio decreased in wild fish FWSO and FWOO from 0.94 ± 0.08 to 0.15 ± 0.01 and 0.15 ± 0.02, respectively. In farmed bream, the ratios decreased from 2.51 ± 0.03 to 0.18 ± 0.03 and 0.36 ± 0.01, respectively. The concentration of trans fatty acids decreased significantly in both fish types after frying ( P  < 0.05). The frying process widely affected the EPA and DHA content, limiting the positive effects of n-3 PUFA.