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     

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     

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.     

The Effects of Essential Oils Addition on the Quality of Wild and Farmed Sea Bream (<Emphasis Type="BoldItalic">Sparus aurata</Emphasis>) Stored in Ice

The preservative effect of laurel (Laurus nobilis) and cumin (Cuminum cyminum) essential oils (EOs) on fresh vacuum-packed (VP) wild and farmed sea bream (Sparus aurata) fillets was evaluated during ice storage by microbiological, physicochemical and electrophoretic analyses. In the present study, wild (W) and farmed (F) fillet treatment included the following lots: control vacuum-packaged samples (WV and FV), VP with added EOs (0.5% v/w) of cumin (WVC and FVC), and of laurel (WVL and FVL). Wild and cultured fish were found to differ significantly in their muscle proximate compositions irrespective of fillet treatments with particularly higher fat and carbohydrate contents in farmed sea bream (4.82 and 0.32 g/100 g, respectively, vs. 1.53 and 0.22 g/100 g in wild fish). The treatment of wild and farmed sea bream fillets with laurel or with cumin EOs induced a decrease in bacterial growth by ca. 0.5 to 1 log cfu/g and in lipid oxidation by ca. 40% of TBA value, extending the shelf life of fish fillets by approximately 5 days of ice storage. However, the addition of EOs to VP fillets resulted in a reduced liquid holding capacity (LHC) throughout ice storage suggesting an early proteolysis initiation confirmed by the myofibrillar and sarcoplasmic electrophoretic profiles. Laurel and cumin EOs as natural and efficient antibacterial and antioxidant compounds can be used in conjunction with VP to enhance ice-stored sea bream quality.     

Seasonal changes in the fatty acids of gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>) and white sea bream (<Emphasis Type="Italic">Diplodus sargus</Emphasis>) captured in Iskenderun Bay,eastern Mediterranean coast of Turkey

Seasonal variations in the fatty acid compositions of gilthead sea bream (Sparus aurata) and white sea bream (Diplodus sargus), captured in Iskenderun Bay, Eastern Mediterranean of Turkey, were investigated. Results from studying the composition over all seasons showed that the basic saturated, monounsaturated and polyunsaturated fatty acids for gilthead sea bream and white sea bream were palmitic acid (16:0), oleic acid (18:1) and docosahexaenoic acid (DHA, 22:63). The other main fatty acids for both species were myristic acid (14:0), stearic acid (18:0), palmitoleic acid (16:1), linoleic acid (18:26) (especially in autumn and winter for gilthead sea bream), and eicosapentaenoic acid (EPA, 20:53). Gilthead sea bream and white sea bream exhibited seasonal fluctuations in their fatty acid contents. EPA ratios in gilthead sea bream in the autumn, winter, spring and summer were 5.42%, 4.69%, 5.20% and 4.27%, whereas the ratios in white sea bream in autumn, spring and summer were found to be 5.03%, 4.53% and 6.97%, respectively. DHA ratios in gilthead sea bream in autumn, winter, spring and summer were 15.37%, 14.16%, 9.51% and 7.07%, whereas the ratios in white sea bream in autumn, spring and summer were found to be 11.49%, 20.17% and 7.74%, respectively. The present study suggests that the daily consumption of either 100 g of gilthead sea bream captured in any season or 100 g white sea bream captured in spring or summer could meet peoples needs for EPA+DHA fatty acids.     

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.     

Effect of Postmortem Storage on Cold-Shortened Bovine Muscle: Analysis by SDS-Polyacrylamide Gel Electrophoresis

Myofibrils were isolated from the longissimus (L) muscle of control (CON) and cold-shortened (CS) muscles after 0, 1, 3, 7, and 10 days of postmortem storage at 2°C. Isolated myofibrils were then examined by SDS-polyacrylamide gel electrophoresis to monitor the changes in the myofibrillar proteins during postmortem storage. The main changes in CS muscles were the gradual appearance of 110,000-, 95,000-, and 30,000d-dalton components and the disappearance of desmin and troponin-T components of myofibrils. In addition, there was a gradual increase in the intensity of a protein around 55,000-daltons. CON samples showed similar changes to those of CS samples. It appears that myofibrillar proteins of cold-shortened muscles are affected by postmortem aging in a manner similar to that of the normally chilled muscles.     

Effects of Postmortem Storage on Muscle Protein Degradation: Analysis by SDS-Polyacrylamide Gel Electrophoresis

Changes in myofibrillar proteins of bovine longissimus and semitendinosus muscles were examined during 14 days of postmortem storage at 2°C by SDS-Polyacrylamide gel electrophoresis. Major changes in both muscles were: (1) appearance of a 95,000-dalton component; (2) gradual disappearance of troponin-T and gradual appearance of a 30,000-dalton component; (3) gradual increase in intensity of a protein around 55,000-daltons; and (4) gradual appearance of a 110,000-dalton component. With the exception of the 95,000-dalton component, the other changes have been reported previously by other authors. At the present time we have no knowledge of the origin of the 95,000-dalton component, but it is known that calcium-activated factor (CAF) is responsible for degradation of troponin-T. Appearance of the 95,000-dalton component during postmortem storage suggests involvement of CAF for increasing tenderness during postmortem storage.     

Effects of differences in diet and seasonal changes on the fatty acid composition in fillets from farmed and wild sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.)

The effects of dietary fatty acids and seasonal variation on the fatty acid profiles of farmed and wild sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were determined by analysis of their fillets. Farmed sea bream and sea bass were fed on the same commercial feeds all year. Fatty acid profiles in the fillets reflected the fatty acid profiles of the commercial feeds. The predominant fatty acids in the trial feeds, fillets of farmed and wild sea bream and sea bass were 16:0, 18:1n‐9, 18:2n‐6, 20:5n‐3 and 22:6n‐3. The fatty acid profiles in the fillets of farmed sea bream and sea bass did not differ (P > 0.05) except in the winter season compared with those of their wild counterparts. However, the content of eicosapentaenoic acid (20:5n‐3), docosahexaenoic acid (22:6n‐3) in the fillets of the farmed and wild sea bass were significantly (P < 0.05) higher than the farmed and wild sea bream. The wild sea bream had significantly (P < 0.05) higher total saturated fatty acid and monounsaturated fatty acid (MUFA) levels, and lower total n‐6 and n‐3 polyunsaturated fatty acid (PUFA) levels in winter than in the summer and spring seasons. Similarly, in the fillets of wild sea bass, total n‐3 PUFA levels were significantly (P < 0.05) lower, and the MUFA levels were higher in winter than in the other seasons. These results indicate that the farmed fish fillets were good sources of n‐3 PUFA in each of the three seasons. However, wild fish were good sources of n‐3 PUFA in the spring and summer.     

Effects of cooking and reheating methods on the fatty acid profile of sea bream treated with rosemary extract

BACKGROUND: The effects of rosemary extract on the fatty acid profile of sea bream fillets cooked by different methods (oven baking, grilling and pan frying) as well as the effects of different reheating methods (microwave and conventional oven) on the fatty acid composition of fish after frozen storage for 4 months were investigated. RESULTS: The proportion of saturated fatty acids increased only slightly in fried samples but significantly in oven‐baked and grilled samples, while the proportion of polyunsaturated fatty acids (PUFAs) increased significantly in fried samples but only slightly in oven‐baked and grilled samples. The proportion of monounsaturated fatty acids remained relatively constant after cooking. Of the fatty acids analysed, the most significant increases (P < 0.05) were observed in C18:1n‐9 and C18:2n‐6 and the most significant decreases (P < 0.05) in C14:0, C16:1, C20:5n‐3 and C22:6n‐3. Although sea bream fillets fried in sunflower oil showed an increase in PUFAs, the lowest eicosapentaenoic and docosahexaenoic acid contents were found in fried samples. CONCLUSION: Sea bream fillets treated with rosemary extract showed slower oxidation than untreated fish. Neither conventional nor microwave reheating after frozen storage for 4 months had a detrimental effect on the fatty acid profile and its stability. Copyright © 2009 Society of Chemical Industry     

Gel Electrophoretic Analysis of the Protein Changes in Ground Beef Stored at 2°C

Purified myofibrils and sarcoplasmic proteins were prepared from ground (GR) and intact (CON) beef semitendinosus muscle samples after 0, 1, 3, 6, and 10 days of storage at 2°C. SDS-polyacrylamide gel electrophoresis analysis revealed the following major postmortem changes in GR samples: the gradual disappearance of nebulin and desmin, appearance of 110,000-, 95,000- and 30,000-dalton polypeptides, and an increased content of myosin light chain-3 and 55,000-dalton component in myofibrils. Also noted was emergence of 100,000- and ?500,000-dalton polypeptides and diminution of 300,000-dalton protein in the sarcoplasmic fraction. Since GR samples showed proteolytic changes similar to those of CON samples, it was concluded that grinding had little effect on postmortem muscle protein degradation.     

Effects of aluminium foil and cling film on biogenic amines and nucleotide degradation products in gutted sea bream stored at 2±1 °C

Biogenic amines and nucleotide degradation products of sea bream stored in ice, wrapped in aluminium foil (WAF) and in cling film (WCF) at 2±1 °C were investigated by using a rapid HPLC method. Results obtained from this study showed that for household purposes packing fish in different materials has a little effect on the biogenic amines formation and nucleotide degradation products. The highest decrease of IMP content was observed for sea bream in WAF, followed by WCF. INO values showed a fluctuation and remained below the levels of 5.5 μmol/g for all storage conditions. Hx value constantly increased with the storage time during chilled storage. For all of the storage condition, K and Ki value increased linearly with storage time. At the end of the storage period, K, Ki, H and G value reached 60–76%, 65–81%, 30–54% and 89–173%, respectively. Among biogenic amines, (trimetylamine) TMA, putrescine, cadaverine, spermidine, spermine, tryptamine, tyramine, β-phenylalanine and histamine were detected during storage period. TMA and putrescine were observed to increase linearly during storage period. Histamine production was only found at the end of storage period. The highest histamine values for fish wrapped in aluminium foil were 6.4 mg/100 g and fish wrapped in cling film was 4.6 mg/100 g.     

POSTMORTEM CHANGES IN MYOFIBRILLAR PROTEINS OF GOAT SKELETAL MUSCLES

Postmortem changes at 5C in myofibrillar proteins of longissimus dorsi (LD), biceps femoris (BF), semimembranosus (SM) and semitendinosus (ST) muscles and myofibrillar structure of LD muscle of goat were investigated. Muscle samples were immediately collected after killing, and from carcasses stored at 5C for 3, 6, 9, 12 and 20 days. The sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of myofibrils indicated the appearance of a 30 kDa component, depending on the type of the muscles. A new 55 kDa component appeared in BF and SM muscles during postmortem. Titin I and nebulin also disappeared during storage. The disappearance of titin 1 and nebulin and the appearance of a 30 kDa component were confirmed by Western blot analysis. The Transmission Electron Microscopy studies showed that after 3 days postmortem, Z‐disks stayed unaltered. After 6 days postmortem, a little ultrastructural alteration was observed, and at 12 days postmortem a considerable degradation of Z‐disk ultrastructure was shown. The Z‐disk degradation, which results in the fragmentation of myofibrils and the appearance of 30 kDa components, is the major change observed in goat skeletal muscles during postmortem.     

Determination of volatile compounds of precooked prawn (Penaeus vannamei) and cultured gilthead sea bream (Sparus aurata) stored in ice as possible spoilage markers using solid phase microextraction and gas chromatography/mass spectrometry

BACKGROUND: Solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) have been reported as useful techniques for analysing volatile compounds to monitor fish freshness. In this study, SPME/GC/MS was applied to cultured gilthead sea bream and precooked prawn stored in ice for 6 days in order to find possible markers of spoilage. Total volatile basic nitrogen (TVB‐N) was also determined as a common index of spoilage. RESULTS: The TVB‐N value at the end of the storage period for cultured gilthead sea bream (302.40 ± 8.50 mg kg^?1) was within the range of acceptability for edible fish (300–400 mg kg^?1) but could be considered at the beginning of spoilage. For precooked prawn the TVB‐N value at day 6 (863.04 ± 7.84 mg kg^?1) was not acceptable for human consumption. SPME/GC/MS identified 30 compounds in cultured gilthead sea bream and 49 compounds in precooked prawn. In particular, 3‐methyl‐1‐butanol, 2‐methylbutanal, 3‐methylbutanal and 3‐hydroxy‐2‐butanone increased during refrigerated storage both in the two species investigated here and in other species reported elsewhere and could be considered as markers of spoilage. CONCLUSION: This study confirmed that SPME/GC/MS can be considered an efficient method suitable for analysing the volatile compounds of both raw fish and fishery products in order to monitor loss of freshness. Copyright © 2008 Society of Chemical Industry     

Postmortem Degradation of Titin and Nebulin of Beef Steaks Varying in Tenderness

Purified myofibrils were isolated from “tender” and “less-tender” bovine longissimus muscle at death and at 1, 3, 7, and 14 days of postmortem storage (4^oC). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect changes in the myofibrillar/cytoskeletal proteins, titin and nebulin. Titin and nebulin bands were observed to be less intense on gels from “tender” than from “less-tender” steaks. These results suggest that titin and nebulin were more rapidly degraded in “tender” than in “less-tender” steaks, and that the extent of beef loin steak tenderness may be dependent upon the postmortem degradation of titin and nebulin.     

Preservation of iced refrigerated sea bream (Sparus aurata) by irradiation: microbiological, chemical and sensory attributes

Quality and shelf life of non-irradiated and irradiated (2.5 and 5 kGy) sea bream in ice conditions and stored at +4 °C were investigated by measurement of microbiological, chemical and sensory analysis. Microbial counts for non-irradiated sea bream samples were higher than respective irradiated fish. Total volatile base nitrogen (TVB-N) values increased value of 38.64 mg/100 g for non-irradiated, sea bream during iced storage whereas for irradiated fish lower values of 13.48 and 12.06 mg/100 g were recorded at 2.5 and 5 kGy, respectively (day 19). Trimethylamine (TMA-N) values and thiobarbituric acid (TBA) values for irradiated samples were lower than non-irradiated samples. Acceptability scores for odour, taste and texture of cooked decreased with storage time. The sensory scores of sea bream stored in control and 2.5–5 kGy at +4 °C were 13 and 15 days, respectively. The results obtained from this study showed that the shelf life of sea bream stored in ice, as determined by overall acceptability all data, is 13 days for non-irradiated sea bream and 15 days for 2.5 kGy irradiated and 17 days for 5 kGy irradiated sea bream.     

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.     

Study of the volatile compounds useful for the characterisation of fresh and frozen-thawed cultured gilthead sea bream fish by solid-phase microextraction gas chromatography–mass spectrometry

A simple method, based on solid-phase microextraction gas chromatography–mass spectrometry, was developed for the study of the aromatic profile of cultured gilthead sea bream fish during frozen storage. The method was applied to the study of the volatile profile of fresh and frozen-thawed Italian and Spanish cultured gilthead sea bream fish over 266 days of frozen storage. Variations in the chromatographic responses of a number of volatile compounds during storage were detected and the observed differences evaluated on a biochemical basis. Correlations with oxidation parameters, e.g. peroxide value and thiobarbituric acid-reactive substance indices, indicated 1-octen-3-ol, 1-penten-3-ol, and Z-4-heptenal as markers for the differentiation between fresh and frozen-thawed fish.     

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.     

Effect of soluble CO2 stabilisation and vacuum packaging in the shelf life of farmed sea bream and sea bass fillets

The objective of this study was to determine the differences of sensory, microbiological and chemical quality in vacuum-packaged fillets of sea bream and sea bass previously submitted to soluble gas solubilisation (SGS) with 100% CO₂, at 2 bar for 30 and 60 min and stored at chilled temperature for 15 days. Apart from pH value that showed a regular increase during chilled storage, the other chemical index [total volatile bases nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) and thiobarbituric acid reactive substances (TBARs)] had showed to be poor indicators of changes in quality of products. Final TVB-N values ranged from 16.0 to 17.4 mg N per 100 g and from 17.3 to 19.4 mg N per 100 g in sea bream and sea bass, respectively. Sensory evaluation resulted as the most reliable parameter of quality decay. The results show that SGS treatment kept the initial quality of fillets for longer time, which was particularly visible on the sea bream fillets, thus contributing to an extension in 2–3 days of the shelf life. SGS had also a positive effect in the delay of microbial growth.