Effect of Modified Atmosphere Packaging on Shelf-Life of Iced Fresh Hake Slices

Shelf-life of hake slices (Merluccius merluccius) stored in the ice state (2±1°C) under modified atmosphere packaging (MAP) conditions was determined by measurements of pH, total volatile bases (TVB) and trimethylamine (TMA) content, mesophilic and psychrophilic bacterial counts, malonaldehyde content, exudation, protein functionality and sensorial analyses (colour and odour). The effect of different gas mixtures were evaluated: (1) 40% CO₂, 50% N₂, 10% O₂; (2) 60% CO₂, 30% N₂, 10% O₂; (3) 40% CO₂, 30% N₂, 30% O₂; (4) 60% CO₂, 10% N₂, 30% O₂ and (5) air (control). Important differences were found between MAP-stored and air-stored hake slices. Shelf-life of hake stored under MAP conditions was two-fold extended. Bacterial growth wasinhibited, increases of pH, TMA and TVB were reduced, and alterations inprotein functionality were delayed, and off-odours were not noted in MAP-stored hake slices after 21 days storage. Significant correlations were found between TMA content and total viable count (TVC), as well as between apparent viscosity and exudation. Hake slices could be stored in the ice state under MAP conditions for about three weeks without an important loss of quality. Fish freshness, handling practices and initial bacterial load have an important influence of shelf-life of hake.     

Biogenic and volatile amines in Chinese mitten crab (Eriocheir sinensis) stored at different temperatures

Biogenic amines, total volatile base nitrogen (TVB‐N) and trimethylamine nitrogen (TMA‐N) concentrations in the muscle of postmortem Chinese mitten crab stored at 4 and 20 °C were studied. Among five biogenic amines, histamine, tyramine, tryptamine, putrescine and cadaverine, histamine was the main biogenic amine formed during the storage time and reached highest levels of 91.22 mg kg^?1 after 72 h at 4 °C and 181.23 mg kg^?1 after 24 h at 20 °C. Histamine could be used a safety index for crab. The levels of other biogenic amines were less than 10 mg kg^?1 and fluctuated with storage time. TVB‐N and TMA‐N levels did not change greatly throughout 72 h storage at refrigerated temperature. TVB‐N and TMA‐N were not considered to be reliable indicators of the freshness of crab.     

POSTMORTEM BIOCHEMICAL AND TEXTURAL CHANGES IN THE ADDUCTOR MUSCLE OF CATARINA SCALLOP STORED AT 0C

Postmortem characteristics of the adductor muscle of the Catarina scallop were evaluated for biochemical, chemical and textural changes during a 15‐day storage period in ice (0C). K‐value, pH, nitrogen of trimethylamine (TMA‐N), nitrogen of total volatile bases (TVB‐N), water‐holding capacity (WHC), color and texture changes were monitored. K value increased linearly from an initial value of 20.5 to 68.5% at day 15. Spoilage indicators TVB‐N and TMA‐N (mg/100 g) increased from 13.5 and 2.6 to 21.4 and 3.4, respectively. However, they remained below critical limits, suggesting low microbial activity. In contrast, texture, pH, WHC, and color were not affected. Overall results indicated that the quality of iced Catarina scallop adductor muscle packed in ice was maintained over a period of 15 days.     

Quality Changes of Shrimp (Pandalus borealis) Stored under Different Cooling Conditions

The influence of different cooling techniques and storage temperatures (‐1.5 °C or 1.5 °C) to prolong the shelf life of shrimp was evaluated by sensory analysis, physical methods, chemical analysis, and microbial analysis. Storage in liquid ice was more effective than flake ice or brine mixed with flake ice in delaying spoilage of the shrimp by slowing down microbial growth and formation of total volatile basic nitrogen (TVB‐N) and trimethylamine (TMA). Total viable counts (TVC) showed that bacteria grew most quickly in shrimp stored in flake ice and in brine mixed with flake ice, followed by those in liquid ice at 1.5 °C and ‐1.5 °C, respectively. Lowest counts were observed in shrimp stored in liquid ice at ‐1.5 °C where the lag phase of growth was apparently extended at the beginning of storage. Principal component analysis (PCA) showed a good correlation between quality indicators related to microbial growth, TVC, pH, TVB‐N, TMA, responses of an electronic nose and sensory evaluation.     

Quality Properties,Fatty Acids,and Biogenic Amines Profile of Fresh Tilapia Stored in Ice

This work determines quality properties and fatty acids content of Nile tilapia (Oreochromis niloticus) stored in ice for 21 d. The quality properties consist of thiobarbituic acid (TBA), total volatile basic nitrogen (TVB‐N), trimethylamine (TMA), and microbiological analysis (total viable count (TVC), total coliform, Salmonella and Staphylococcus aureus) and determination of biogenic amines content (histamine, cadaverine, putrescine, spermine, spermidine, 2‐phenylethylamine, agmatine, tyramine, and ammonia). Moreover, the fat, moisture, and ash composition as well as fatty acids profile have also been analyzed. The TBA, TVB‐N, and biogenic amines analysis showed rather low levels of spoilage even after 21 d of storage. The microbiological analysis, however, showed that tilapia was unsuitable for consumption after just 10 d. The fat, ash, moisture, and fatty acids profile analysis showed that tilapia is not a good source of n?3 fatty acids. The research indicated that the microbiological analysis was the best method to establish spoilage of tilapia stored in ice, of all analytical methods performed in this study.     

Smoking and polyphenols’ addition to improve freshwater mullet (Mugil cephalus) fillets’ quality attributes during refrigerated storage

The combined effects of hot smoking and added quince polyphenol (0.8% and 1.6% v/w) on the quality attributes of mullet (Mugil cephalus) fillets were evaluated. Biochemical parameters that were monitored in the fillets during 75 days of storage (4 ± 1 °C) included trimethylamine (TMA‐N), volatile basic nitrogen (TVB‐N), fatty acids and amino acids. Data were submitted to principal component analysis (PCA) which revealed that the smoking process combined with polyphenols’ treatment was negatively correlated with TVB‐N, TMA‐N, lipids, indices of lipid quality (index of atherogenicity (IA); index of thrombogenicity (IT)) and storage time. Health concern related to the flesh content of polycyclic aromatic hydrocarbons (PAHs) following hot smoking was also evaluated, and analysis showed that the sum of 4 of the PAHs (chrysene, benzo(b)fluoranthene, benz(a)anthracene and BaP) remained far below the maximum limit set by the European Commission. Sensory analysis revealed that the smoked mullet fillet treated with a low dose of polyphenols was a very acceptable new product.     

QUALITY CHANGES OF BLUE CRAB (CALLINECTES SAPIDUS) MEAT DURING FROZEN STORAGE

The aim of the investigation was to determine the quality changes of blue crab (Callinectes sapidus) meat during frozen storage. Blue crabs were obtained directly from fishing boats in the Gulf of Antalya, Turkey and immediately transferred to the laboratory alive. Whole crabs were placed into polyethylene polyamide (PE/PA) pouches, shrunk and stored at ?18C for 10 months. The main changes that take place in blue crabmeat were investigated by means of sensory assessments (odor, appearance), chemical analyses (total volatile bases (TVB‐N), trimethylamine (TMA‐N)) and physical measurements (pH). TVB‐N, TMA‐N values and pH were significantly (P < 0.01) different following frozen storage. Moreover, it was observed that the differences in odor values were significant (P < 0.05), while appearance values were not. All of the measurements indicated that blue crabmeat kept its good quality at ?18C for 10 months.     

QUALITY OF FROZEN/THAWED SPRAT (SPRATTUS SPRATTUS SPRATTUS) STORED IN CLING FILM AND ALUMINUM FOIL AT 4C1

Frozen sprats (Sprattus sprattus sprattus) were thawed and separated into three lots: two lots were wrapped and kept chilled in a refrigerator at 4C, one wrapped in aluminum foil (AF), the other in cling film (CF) and a third lot left unpackaged and held in melting ice. Biochemical tests, performed at intervals over a 16‐day period, showed better quality and an extension of shelf‐life for sprats stored unpackaged in ice compared with those held at 4C packed in AF or CF. The levels of trimethylamine oxide‐nitrogen (TMAO‐N) decreased throughout storage and significant differences (P<0.05) were observed between the lot in ice and the lots stored in AF or CF (P<0.05). However, significant differences (P<0.05) were not observed between AF and CF lots during the experiment. Increases in total volatile base nitrogen (TVB‐N) and trimethylamine‐nitrogen (TMA‐N) were significantly retarded, as were reductions in sensory quality, in the ice‐stored fish compared with packaged, refrigerated fish.     

DETERMINATION OF DIFFERENT VOLATILE BASE COMPONENTS AS QUALITY CONTROL INDICES IN FISH BY OFFICIAL METHODS AND FLOW INJECTION ANALYSIS

Flesh concentration of Trimethylamine Oxide‐Nitrogen (TMAO‐N), Trimethylamine‐Nitrogen (TMA‐N) and Total Volatile Base Nitrogen (TVB‐N) are the most studied parameters used as indices of spoilage in fish and fishery products. In the present work, the official methods to determine TVB‐N, TMA‐N and TMAO‐N were compared with the Flow Injection Analysis (FIA) technique using three different fish species over their storage in melting ice for a period of 16 days. There was a good correlation between determinations made using official and FIA methods with no apparent significant differences. FIA thus appears to be a suitable method for TMAO‐N, TMA‐N and TVB‐N in fish extract and the use of this system is much faster and simpler than the official methods for determination of these parameters. On the other hand, the individual concentrations of TMAO‐N, TMA‐N and TVB‐N were not found to represent reliable indices of spoilage in fish, which had been frozen and thawed and then presented in chilled format.     

Residual effect of CO2 on hake (Merluccius merluccius L) as a function of the period of time in controlled atmosphere storage

Whole gutted hake kept in a controlled atmosphere (60% CO₂/15% O₂/25% N₂) for 7 and 12 days in containers in the hold of the fishing vessel and then stored conventionally in ice was compared with hake stored in ice and treated in the traditional way. The residual effect of the atmosphere containing CO₂ prolonged the shelf‐life of chilled hake by 2–5 days compared with that of hake stored in ice. This residual effect of CO₂ was dependent on the period of time in the controlled atmosphere; 12 days in this atmosphere was the optimum to obtain the maximum residual effect of CO₂. On day 25 the legal limit of total volatile basic nitrogen (TVBN) was reached in hake previously kept under the controlled atmosphere for 12 days (CA12), and the hake was also rejected in the inspection and pH analyses. However, this lot did not reach the legal limit of trimethylamine nitrogen (TMA‐N) during the 25 days of storage. Similar results were found by a sensory panel, who rated the hake kept in controlled atmosphere storage (CA12) well. Copyright © 2002 Society of Chemical Industry     

Gel Strengthening Effect of Wood Extract on Surimi Produced from Mackerel Stored in Ice

ABSTRACT:  The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel ( Rastrelliger kanagurta ) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously ( P  < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.     

Combination of bulk storage in controlled and modified atmospheres with modified atmosphere packaging system for chilled whole gutted hake

Whole gutted hake placed in boxes of ice were kept in modified and controlled atmospheres for 12 days with the gas mixture 60%CO₂/15%O₂/25%N₂ (v/v/v) at 2 ± 1 °C. Each lot of hake was then subdivided into two other lots and these were packed on trays, some of them in air and some in the same mixture of gases. The trays were kept at 2 °C until spoilage. The shelf‐life of the hake stored in these conditions was assessed by physical (pH), chemical (TVBN (total volatile basic nitrogen) and TMA‐N (trimethylamine nitrogen)) and sensory (inspection and taste panel) analyses. The results of these analyses indicated that the control lot (stored in air throughout) was rejected before the lots kept in adjusted atmospheres. However, the taste panel accepted all the lots, including the control lot, after 24 days of storage. The sample which was kept at 2 °C in a controlled atmosphere for 12 days and then packed in a modified atmosphere of the same gas mixture did not exceed pH 7 after 31 days of storage, nor the limits of TVBN and TMA‐N of 40 and 12 mg per 100 g respectively. As regards oxidative rancidity, TBA (2‐thiobarbituric acid) levels were very low under all storage conditions and did not exceed 2.5 mg malonaldehyde per 100 g muscle. According to the results of this study, bulk storage of whole gutted hake in boxes in ice under a controlled atmosphere could be combined with later packaging in a modified atmosphere on trays stored at 2 °C to extend the shelf‐life of the hake. © 2001 Society of Chemical Industry     

Development of a Quality Index Method to Evaluate Freshness in Mediterranean Hake (Merluccius merluccius)

A Quality Index Method for the sensory assessment of freshness of Mediterranean hake was developed and validated by sensory, chemical, and microbiological parameters. The Quality Index was the ratio between the overall sensory score obtained and the total achievable sensory score of the scheme and ranging 0 (fresh) to 1 (spoiled). This index increased significantly along the time of ice storage, allowing prediction of the remaining shelf life of hake. A value of 0.60 to 0.65 was estimated by statistical treatment as the rejection value, being concordant with sensory score of cooked hake, trimethylamine content, pH, as well as with legal regulations for mesophylic and enterobacteria counts.     

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.     

Application of multi‐element viscoelastic models to freshness evaluation of beef based on the viscoelasticity principle

The aims of this work were to develop multi‐element viscoelastic models for beef and apply them to detect total volatile basic nitrogen (TVB‐N) content for freshness evaluation. The deformation data were collected by a viscoelasticity detection system that employed the airflow and laser technique. Then, TVB‐N contents were measured to determine the freshness of samples during storage. A universal global optimization (UGO) algorithm was applied to fit the deformation data. Various multi‐element viscoelastic models including the Burgers, six‐element and eight‐element models were built using the obtained fitting parameters, and different viscoelastic parameters representing the degree of beef spoilage were obtained. All the viscoelastic parameters of each multi‐element model and parameter combinations of the selected six‐element model were employed to build mathematical models for predicting TVB‐N content by support vector machine regression (SVR). In comparison, the six‐element model with all the viscoelastic parameters performed the best and was determined to predict TVB‐N content with correlation coefficient in the prediction set (R_P) of 0.891 and root mean squared error in the prediction set (RMSEP) of 1.467 mg/100 g. Based on the results of parameter combinations, combination (E₂, E₃, E₁, η₁, η₂) from the six‐element model performed the best, which was comparatively inferior to all the viscoelastic parameters of the six‐element model. Results demonstrated that it was possible to predict TVB‐N content for freshness evaluation by applying method of developing multi‐element model based on the viscoelasticity with chemometrics.     

暗纹东方不同贮藏温度货架期模型的预测研究

为了研究河豚鱼在冷链流通中的品质变化与货架期,通过不同温度下的贮藏实验研究了河豚鱼的货架期预测模型。将河豚鱼贮藏在273、277和281K条件下,测定了河豚鱼的总菌落数、总挥发性盐基氮(TVB-N)、脂肪氧化(TBA)值和三甲胺值的变化。在Arrhenius动力学方程基础之上,建立了菌落总数、挥发性盐基氮、脂肪氧化(TBA)值和三甲胺值与贮藏时间及贮藏温度之间的动力学模型。实验表明一级化学反应动力学模型和Arrhenius方程对菌落总数、挥发性盐基氮(TVB-N)、脂肪氧化(TBA)值及三甲胺值的变化具有较高的拟合精度。各项指标(菌落总数、挥发性盐基氮、TBA值以及三甲胺)变化预测模型中的活化能(EA)及速率常数(k0)分别为:21.10kJ/mol和1.059×103,76.58kJ/mol和2.888×1013,6.59kJ/mol和4.012,18.35kJ/mol和1.393×103。结果表明:河豚鱼的总菌落数、挥发性盐基氮(TVB-N)、脂肪氧化(TBA)值及三甲胺值随着贮藏时间的延长而增加,且随着贮藏温度的升高而迅速增加。该实验建立的河豚鱼货架期预测模型所获得货架期预测值准确率达到±10%以内,可根据菌落总数和TVB-N值在273～281K范围内,对河豚鱼的剩余货架期进行预测。     

Effects of previous frozen storage on chemical, microbiological and sensory changes during chilled storage of Mediterranean hake (Merluccius merluccius) after thawing

The present work aimed to investigate the influence of freezing (−20 °C for 6 months) on the susceptibility of hake to chemical, microbiological and sensory spoilage once thawed and stored in ice. Thus, volatile and biogenic amines, counts of psychrotrophic and mesophilic bacteria, enterobacteria, pseudomonads and Shewanella together with sensory evaluation (of raw and cooked samples) were monitored during 14 days of iced storage in both fresh and frozen-thawed hake (Merluccius merluccius). At the beginning of ice storage, freshness parameters were equivalent in both batches (fresh and frozen-thawed hake), but different behaviour was observed during the iced storage. Overall, levels of volatile and biogenic amines increased much later and then decreased to lower values in frozen-thawed hake in accordance with the delay of microbial development in comparison with fresh hake. On the contrary, sensory spoilage occurred earlier in frozen-thawed hake. Therefore, the usual accepted or regulated limits of acceptability of chemical and microbiological parameters would not be suitable for freshness assessment of frozen-thawed hake.     

Microbiological,chemical and sensory changes of whole and filleted Mediterranean aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of filleting on the microbiological, chemical and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads, H₂S‐producing bacteria (including Shewanella putrefaciens) and Brochothrix thermosphacta were the dominant bacteria at the end of the 16 day storage period in ice for both whole ungutted and filleted sea bass. Enterobacteriaceae were also found in the spoilage microflora of whole ungutted and filleted sea bass, but their counts were always lower than those of pseudomonads, H₂S‐producing bacteria (including S putrefaciens) and B thermosphacta. Total viable counts for whole ungutted sea bass were always lower than those for filleted sea bass samples. Of the chemical indicators of spoilage, TMA (trimethylamine) values of whole ungutted sea bass increased very slowly, whereas significantly higher values were obtained for filleted samples, with respective values of 0.253 and 1.515 mg N per 100 g muscle being reached at the end of their shelf‐life (days 13 and 9 respectively). TVB‐N (total volatile basic nitrogen) values showed a slight increase for whole ungutted sea bass during storage, reaching a value of 26.77 mg N per 100 g muscle (day 13), whereas for filleted fish a corresponding value of 26.88 mg N per 100 g muscle was recorded (day 9). TBA (thiobarbituric acid) values increased slowly for whole ungutted and filleted sea bass samples throughout the entire storage period, reaching final values of 4.48 (day 13) and 13.84 (day 9) mg malonaldehyde kg^?1 respectively. Sensory assessment of raw fish using the EC freshness scale gave a grade E for up to 5 days for whole ungutted sea bass, a grade A for a further 4 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Overall acceptability scores for odour, taste and texture of cooked whole ungutted and filleted sea bass decreased with increasing time of storage. The results of this study indicate that the shelf‐life of sea bass stored in ice, as determined by overall acceptability sensory scores and microbiological data, is 8–9 days for filleted and 12–13 days for whole ungutted fish. Copyright © 2003 Society of Chemical Industry     

Establishment of quality predictive models for bighead carp (Aristichthys nobilis) fillets during storage at different temperatures

Quality predictive models were developed to predict the freshness of bighead carp (Aristichthys nobilis) fillets during storage at different temperatures. Quality indices [sensory score, total volatile base nitrogen (TVB‐N), total aerobic counts (TAC) and K value] at ?3, 0, 3, 9 and 15 °C were estimated and kinetically modelled by the Arrhenius equation. The activation energy (E_A) of sensory score, TVB‐N, TAC and K value was 78.17, 75.93, 106.53 and 76.21 kJ mol^?1, and the corresponding rate constants (k₀) were 1.16 × 10¹⁵, 2.60 × 10¹⁴, 4.05 × 10¹⁹ and 1.36 × 10¹⁵. The high regression coefficients (R² > 0.87) indicated the acceptability of the zero‐order reaction for sensory score, TVB‐N, TAC and K value. Relative errors between predicted and observed freshness indicators values of sensory score, TVB‐N, TAC and K value were all below 10% except the values at 6th day of K value, 3rd day and 9th day of TVB‐N. These results indicated that the models based on sensory score, TVB‐N, TAC and K value could effectively predict the freshness indicators of bighead carp fillets at the range of ?3 to 15 °C.     

CHEMICAL AND MICROBIOLOGICAL QUALITIES OF DRY-SALTED (LAKERDA) BONITO (SARDA SARDA, BLOCH 1793)

In this study, changes in the chemical and microbiological properties of bonito (Sarda sarda, Bloch 1793) salted by dry salting (lakerda) and stored for 6 months at 4 ± 1C were investigated. The fresh gutted and sliced bonitos were used as raw material for salting by using the ratio of fish to salt as 5:1 by weight. Salted fish remained in the liquid pickle formed by salt and the liquid extracted from the fish. This solution was not drained during the storage period. The product is described as “lakerda” in Turkey. In the fresh fish, total volatile basic nitrogen (TVB‐N) and trimethylamine nitrogen (TMA‐N) values were 11.21 mg/100 g and 1.19 mg/100 g, respectively. During the storage period, TVB‐N and TMA values increased slowly to 27.67 mg/100 g and 4.99 mg/100 g, respectively, at the end of the storage period. In the first month after salt processing, the total mesophilic bacteria count was 4.6 × 10² cfu/g. In the later months, mesophilic, psychotropic, coliform bacteria and yeast‐mold did not reproduce. According to the results, bonito salted by dry salting and stored at 4 ± 1C was in good quality in terms of chemical and microbiological properties during the storage period of 6 months.