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     

Effect of controlled and modified atmospheres on the production of biogenic amines and free amino acids during storage of hake

Free amino acids (FAAs) and biogenic amines were determined in whole hake (Merluccius merluccius L) stored in bulk under controlled or modified atmosphere (60% CO₂:15% O₂:25% N₂) for 12 days at 2 °C and followed by storage in trays either under the same special atmosphere or under air for 31 days at 2 °C, which was the control. At the end of the storage, significant differences were observed (PА.05) in the amino acids isoleucine, leucine, methionine, phenylalanine, valine, glutamic acid and glycine between the control lot and the treated lots, and it was the control lot which exhibited the highest concentrations. However, the lots kept in special atmospheres exhibited higher levels of alanine, #-alanine, threonine, and tryptophan than the control lot. There was no relationship between the decreases in histidine, tyrosine, lysine, arginine and ornithine initial concentrations and the increases in their corresponding biogenic amine concentrations (histamine, tyramine, cadaverine, agmatine and putrescine, respectively) which appeared as a result of decomposition of fish by decarboxylation of the FAA. Significant differences (PА.05) were observed in the biogenic amine concentrations among the lots kept under special atmospheres. The bulk-stored lot in controlled atmosphere for the first 12 days and then packed in trays with modified atmospheres exhibited the lowest levels of biogenic amines, except for agmatine, throughout storage.     

Residual effect of CO2 on hake (Merluccius merluccius L.) stored in modified and controlled atmospheres

 The residual effect of CO₂ on whole gutted hake kept with three different CO₂/O₂/N₂ gas mixtures: 60/15/25, 80/20/0 and 40/40/20, and two different kinds of atmospheres (controlled and modified) during 12 days followed by conventional storage in ice for up to 30 days was examined by physical, chemical and sensory analyses. Shelf life was longer in lots kept in atmospheres than in control lots and was further prolonged by controlled than by modified atmospheres. The lots kept in the atmosphere with the highest concentrations (80%) of CO₂ exhibited the lowest trimethylamine nitrogen and total volatile basic nitrogen values. However, these were also the lots that scored worst in sensory analysis. The lots that scored best in sensory analysis were those which were kept in the gas mixtures with 60% and 40% of CO₂. Oxidative rancidity was not a problem in the samples stored in the atmosphere with 40% O₂; Thiobarbituric acid levels were lower than 2 mg/100 g in all lots throughout storage, and the assessors detected no rancidity. The residual effect of CO₂ on whole gutted hake was more effective in controlled atmosphere lots. Received: 15 June 2000 / Revised version: 17 August 2000     

Chilled bulk storage of gutted hake (Merluccius merluccius L.) in CO2 and O2 enriched controlled atmospheres

This work compares hake gutted whole and placed in boxes in ice under controlled atmospheres (CA) with four different gas mixtures: M1 CO₂/O₂/N₂(%) (60/15/25), M3 (40/40/20), M4 (60/40/0) and M5 (40/60/0) and hake in air for 33 days of storage. The storage chamber temperature was 0±1°C. Biochemical analyses [pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA index) and sensory analyses (inspection and tasting)] were carried out to study the quality of the hake. The hake, kept under controlled atmospheres, did not exceed the limits for acceptability of 35 mg/100 g and 12 mg/100 g of TVB-N and TMA-N, respectively, throughout the storage period, and the TBA values remained lower than the recommended limits of 14 mg of malonaldehyde/100 g. Chemical results accorded with the tasters who did not detect any off-odour in the samples, and the M4C lots stored under 60/40/0 (CO₂/O₂/N₂%) was rated the best. However, this result did not accord with the inspection or pH by which all the lots were rejected at day 25 of storage. Despite this, the atmosphere system for preservation of chilled hake could be used safely and effectively on fishing boats to extend the shelf life of this species, and was better than conventional storage in ice.     

Formation of biogenic amines in bulk-stored chilled hake (Merluccius merluccius L.) packed under atmospheres.

The production of biogenic amines in the lots of whole hake stored bulk under a controlled or modified atmosphere for 12 days with the gas mixture 40% CO2:40% O2:20% N2 and after packing in trays under a modified atmosphere in the same mixture of gases or with air was studied. Results indicated a close relation between the development of trimethylamine nitrogen (TMA-N) and the sensory parameters gill appearance and odor but not with the general appearance of the skin and eyes. These results were related to changes observed in the concentration of gases (CO2 and O2) during storage containers and trays. The lot of bulk-stored whole hake in controlled atmospheres for 12 days with the gas mixture 40% CO2:40% O2:20% N2 and then packed in trays with the same atmosphere exhibited TMA-N levels below the 12.5 mg/100 g limit designated by the legislation in force (Directive 91/143/EU) on day 31 of storage when the sensory parameters general appearance and skin and gill color were not rejected. Histamine and tyramine levels were less than 1 mg/kg, putrescine levels were approximately 7 mg/kg, and cadaverine and agmatine levels were 33.91 and 20.33 mg/100 g, respectively.     

Preservation of bulk-stored Norway lobster at 1 °C in controlled and modified atmospheres

This paper examines the effect on biochemical and sensory parameters of Norway Lobster (Nephrops novergicus (L)) of two gas mixes—60/15/25 and 40/40/20 (CO₂/O₂/N₂(%))—used as modified and controlled atmospheres for bulk storage at 1 °C.The biochemical results indicate that lots stored in the atmospheres kept good for up to 21 days as compared to only 14 days for the control. The biochemical parameters in the control increased significantly throughout storage. The same parameters only began to increase in the atmosphere lots on the 14th day of storage. In no case did the TMA concentration exceed 5 mg/100 g. The only lot rejected upon inspection in the course of storage was the control at 21 days. The parameters that scored worst in all lots were colour and odour, owing to the effect of the melanosis inhibitor. The lots stored in the 60/15/25 mix scored best irrespective of atmosphere type. There were no significant differences between controlled and modified atmosphere samples.     

RELATION BETWEEN THE FREE AMINO ACIDS, ANSERINE AND THE TOTAL VOLATILE BASIC NITROGEN PRODUCED IN MUSCLE OF HAKE (MERLUCCIUS MERLUCCIUS, L.) DURING ICED STORAGE

This work studied the development of free amino acids (FAAs) and dipeptide anserine as quality indices for gutted hake stored in ice for 25 days. The correlation of these compounds was determined with total volatile basic nitrogen (TVBN) which has been used as a quality index, for fish stored in ice. The most abundant free amino acids in hake muscle were found to be threonine, glycine, alanine, glutamic acid, β-alanine methylhistidine. lysine and the dipeptide, anserine. The only hydrophobic free ammo adds which exhibit significant differences (P<0.05) throughout storage was tryptophan. moreover, this amino acid exhibited a very high correlation (r=0.951) with TVBN. A significant decrease in anserine (P<0.05) correlated with the increases in 1-methylhistidine and β-alanine throughout storage. These changes also exhibited a very high correlation with TVBN. Therefore, 1-methylhistidine, β-alanine anserine and tryptophan could be used as quality parameters for hake stored in ice.     

The effect of modified atmosphere packaging on the microbiological,physical, chemical and sensory characteristics of broadtail squid (Illex coindetii)

The aim of this work was to evaluate the effect of various atmosphere compositions (20% CO₂/80% N₂ for modified atmosphere packaging (MAP) 1, 50% CO₂/50% N₂ for MAP 2, 70% CO₂/30% N₂ for MAP 3 and vacuum packaging) on the microbial (mesophiles, psychrophiles, Pseudomonas spp., Brochothrix thermosphacta and Enterobacteriaceae), physical, chemical [trimethylamine (TMA) and total volatile basic nitrogen (TVBN)] and sensorial characteristics of broadtail squid (Illex coindetii) stored for 10 days at 2 ± 1 °C. All microbial populations were severely restrained by MAP 3 with the exception of Enterobacteriaceae, which seemed to take advantage of the lack of competitive microflora and had enhanced microbial counts on MAP samples (P < 0.05). Colour attributes were better maintained on MAP‐stored samples. Drip loss was less on vacuum‐packaged squids. MAP 2 was the best atmosphere for the preservation of tissue consistency. TMA and TVBN formation was limited by high CO₂ atmospheres, even though both elevated in all studied conditions. Shelf life based on sensory characteristics was determined to be 10, 8, 6, 6 and 4 days for MAP 3, MAP 2, MAP 1, vacuum and control samples, respectively.     

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.     

Changes in free amino acids during chilled storage of hake (Merluccius merluccius L.) in controlled atmospheres and their use as a quality control index

This paper examines the evolution of FAAs in hake stored in ice and kept in controlled atmospheres for 33 days with four different gas mixes (CO₂/O₂/N₂): M1 (60/15/25), M3 (40/40/20), M4 (60/40/0), and M5 (40/60/0). The most abundant FAAs in hake muscle are threonine, glutamic acid, glycine, alanine, #-alanine, tryptophan, 1-methylhistidine, and anserine. Anserine was the compound initially present in the highest concentration (61.65 mg/100 g of fish wet weight). As storage progressed, anserine concentrations fell, the smallest decrease being found in the lot kept in M1. At the end of storage the lot with the lowest level of anserine was M5C, which contained the highest O₂ levels. The levels in the other lots were very similar. This fall in anserine coincided with an increase in 1-methylhistidine and #-alanine, the two amino acids to which it becomes hydrolyzed. As well as the fall in anserine, there was a progressive increase in muscle tryptophan during storage of the hake. This increase became more pronounced from day 12 of storage and was greatest in the control and lots M1C and M3C, which relates to the results of the other biochemical indexes. Both anserine and tryptophan could be used as quality control indexes for chilled hake. In general, no clear relationship was found between the effect of the atmosphere and the behavior of the FAAs.     

Suitability of Volatile Amines as Freshness Indexes for Iced Mediterranean Hake

Batches of gutted Mediterranean hake (Merluccius merluccius var. Mediterraneus) were stored, in different seasons of the year, for up to 20 d in ice. Changes in trimethylamine (TMA‐N), total volatile bases (TVB‐N), P‐ratio and trimethylamine oxide (TMAO) were measured; sensory evaluation of raw and cooked hake samples was also carried out. Similar profiles were observed between the different trials for all the parameters studied. TVB‐N was not correlated with the time of ice storage, and proved to be better as a spoilage index than a freshness one. In contrast, TMA‐N appears to be a good index of hake quality, and the value of 5 mg/100g offish seems an appropriate limit of acceptability. P‐ratio was a poorer index of freshness than was TMA‐N.     

Effect of Delayed Filleting on Quality of Cod Flesh

A study was undertaken to determine the effect of delayed filleting on overall shelf life of cod. One lot of gutted cod was divided into three groups for iced storage and filleted 1,4 or 7 days postmortem. Quality of fillets during subsequent storage at 1–2°C was assessed by physical characteristics, trimethylamine values, and total aerobic plate counts. After day 7, comparison of fillets of the same postmortem age showed that fish which had been most recently filleted was superior to that processed one day after landing, and stored subsequently in plastic trays. Results indicated that maximum overall shelf life could be attained by minimizing time stored as flllets, i.e. delaying filleting.     

The combined effect of superchilling and modified atmosphere packaging using CO2 emitter on quality during chilled storage of pre‐rigor salmon fillets (Salmo salar)

BACKGROUND: Pre‐rigor fillets of Atlantic salmon were either superchilled or chilled prior to packaging in air or in modified atmosphere (MAP, 60% CO₂/40% N₂) with a CO₂ emitter, in 5.3 L high‐density polyethylene trays with three to four layers of fillets (3.0–3.7 kg). All samples were stored at 0.1 °C for 28 days. RESULTS: Fillets stored in MAP had significantly lower bacterial growth compared to fillets stored in air, and MAP superchilled bottom fillets had lower bacterial counts compared to the corresponding chilled fillets. Samples superchilled prior to refrigerated storage in air had similar bacterial growth to ordinary chilled samples. Faster fillet softening during storage and higher liquid loss were observed in superchilled MAP samples. CONCLUSION: Combining short‐term superchilling and MAP with a CO₂ emitter prolonged the shelf‐life of pre‐rigor salmon fillets, which can improve sustainability throughout the value chain. The superchilling method needs to be optimized to avoid negative effects on texture and liquid loss. Copyright © 2009 Society of Chemical Industry     

Effects of storage under a modified atmosphere on the microbiological and organoleptic qualities of ground beef prepared from pasteurized manufacturing beef

A 40‐kg lot of manufacturing beef, i.e. meat used for the production of ground beef products, was collected at a beef packing plant. The lot was divided into two batches. One batch was pasteurized by immersion in water at 85 °C for 60 s, the other batch was not pasteurized. Both batches were then ground. The ground meat was packed in overwrapped trays, which were master packaged under a modified atmosphere of 70% O₂ : 30% CO₂. The master packs were stored at 2 °C for up to 12 days. At the time of pack preparation and at 2‐day intervals, a master pack containing pasteurized and another pack containing unpasteurized meat, were opened and retail packs from each master pack were displayed at 4 °C for 3 days. Samples for microbiological analysis were obtained at the times of opening master packs and at the end of display. Displayed meat was assessed daily for colour, discoloration and retail appearance, and for odour intensity and acceptability at the end of display. After either a period of storage or a period of storage and display, the numbers of bacteria recovered from pasteurized meat were less than the numbers recovered from unpasteurized meat. The colour of pasteurized meat was perceived as being paler than that of unpasteurized meat, but discoloration was similar or less, and retail appearance was similar or better for pasteurized than unpasteurized meat at all times. The odours of displayed, pasteurized meat were generally somewhat less intense and more acceptable than those of unpasteurized meat. The findings indicate that pasteurization of manufacturing beef to improve the microbiological safety of ground beef provides a product of acceptable appearance and enhanced stability during storage under a modified atmosphere and subsequent display in air.     

USE OF SEMITRAINED PANEL MEMBERS IN THE SENSORY EVALUATION OF HAKE (MERLUCCIUS MERLUCCIUS, L) ANALYZED STATISTICALLY

Abstract The main objective of this study was to evaluate the responses of semitrained sensory assessors to parameters traditionally used in the sensory analysis of hake and to compare their performance with that of trained inspectors. Appropriate statistical methods were used to validate this objective.
The study was carried out with whole gutted hake stored for 7 and 12 days in a controlled atmosphere consisting of 60%/15%/25% (CO₂/O₂/N₂), followed by conventional storage in ice. The hake stored under the CA conditions were preserved better than the control hake at 7 days and at 12 days the difference was even more in favor of the CA storage. Ten parameters evaluated in the sensory tests could be reduced to five with no loss in essential information. The evaluations of the semitrained assessors largely correlated with those of trained inspectors. A model using five parameters and semitrained assessors could be routinely used to evaluate the quality of cooked hake previously stored in ice.     

Effect of Carbon Dioxide Atmosphere on Microbial Growth and Quality of Salmon Slices

Salmon slices ( Salmo salar ) were packed under CO₂ and stored in a chill room at 2±1°C for 3 weeks. A study was carried out on the effect of CO₂ atmosphere on bacterial growth as well as on chemical deterioration (pH, total volatile bases, (TVB), trimethylamine (TMA), lipid oxidation) and sensory features (exudation, raw fish odour, cooked fish flavour). Results were compared with a control stored in air. Salmon slices stored under CO₂ had a shelf-life of nearly twice as long as those in air, having lower bacterial counts, pH, TMA and TVB, as well as improved sensory features after 18 days at 2±1°C. Exudation was not significantly different between control and CO₂-stored samples after 10 days ice storage. Exudate values extended from 1 to 2% for CO₂-stored samples after 10 and 20 days storage, respectively. Salmon slices can be stored under CO₂ at 2±1°C for about 18 days, with no substantial loss of quality. Shelf-life can vary depending upon the state of fish, handling practices, initial bacterial load and storage temperature.     

Combined effect of light salting,modified atmosphere packaging and oregano essential oil on the shelf-life of sea bream (Sparus aurata): Biochemical and sensory attributes

The combined effect of modified atmosphere packaging (MAP: 40% CO₂/30% O₂/30% N₂) and oregano essential oil, on the shelf-life of lightly salted cultured sea bream (Sparus aurata) fillets stored under refrigeration was studied. Quality assessment was based on sensory analysis and biochemical indices determination. Total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values were higher in sea bream fillets stored in air followed by salted fillets stored in air. For salted sea bream fillets stored under MAP the inhibition in the TVBN and TMAN values was evident in the order MAP < MAP/0.4% (v/w) oregano oil < MAP/0.8% (v/w) oregano oil indicating the preservative effect of oregano oil. Salting had a noticeable preservative effect but produced an increase in the 2-thiobarbituric acid (TBA) values while oregano oil had a strong antioxidant activity giving the lowest TBA values. All raw sea bream fillet samples received acceptable sensory scores during the first 15–16 days of storage. The salted samples remained acceptable up to ca. 20–21 days while the MAP salted samples up to ca. 27–28 days of storage. The oregano oil addition in MAP salted samples yielded a distinct but pleasant flavor and contributed to a considerable slower process of fish spoilage given that the fillets treated with 0.8% (v/w) oregano oil were still sensory acceptable after 33 days of storage. The preservative effect was greater as the oregano oil concentration was greater.     

Shelf‐life extension of refrigerated seabass slices under modified atmosphere packaging

The effect of CO₂‐enriched atmosphere in combination with either oxygen or nitrogen on the keeping quality of seabass slices stored at 4 °C was investigated. The inhibitory effect on bacterial growth increased proportionally to the CO₂ concentration in the packaging, maximum inhibition being achieved with 100% CO₂ (P < 0.05). Seabass slices stored in CO₂‐enriched atmosphere had lower total volatile base, trimethylamine, ammonia and formaldehyde contents than those stored in air (P < 0.05). However, increases in lightness and exudate loss were observed for samples packaged in high‐CO₂ atmosphere, suggesting the denaturation of both muscle and pigment proteins by carbonic acid formed. Thiobarbituric acid‐reactive substances (TBARS) increased as the CO₂ concentration increased (P < 0.05). However, odour, flavour and overall acceptability of CO₂‐enriched packaged samples, particularly with 80 and 100% CO₂, were acceptable throughout storage for 21 days. Chemical and microbial changes in all samples were generally in agreement with sensory panel evaluations. The shelf‐life of seabass slices packaged in 80–100% CO₂ atmosphere could be extended to more than 20 days at 4 °C, compared with 9 days for those packaged in air. © 2002 Society of Chemical Industry     

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.     

Influence of modified atmosphere packaging on the chilled shelf life of gutted farmed bass (Dicentrarchus labrax)

The effect of MAP on quality changes of gutted farmed bass when stored at 3 °C were investigated for up to 9 days. Gutted farmed bass was packed with six different atmospheres (0%O₂–70%CO₂; 20%O₂–70%CO₂; 30%O₂–60%CO₂; 40%O₂–60%CO₂; 30%O₂–50%CO₂; 21%O₂–0%CO₂). Headspace gas composition (O₂%; CO₂%), aerobic mesophilic bacteria (AMB) and Enterobacteriaceae, pH, water loss, flesh moisture content, colour, stiffness, odour and eyes appearance were assessed by means of instrumental and sensory analysis after 0, 2, 5, 7 and 9 days of storage. Atmosphere composed of 30% of O₂ and 50% of CO₂ was the best one to preserve the quality of the gutted farmed bass. PCA was an effectively instrument to classify gutted bass samples on the bases of quality changes. The effect of the time was explained by the factor 1, whereas the fish were clearly classified along factor 2 in relation to storage atmosphere.