Nucleotide breakdown products of seer fish (Scomberomorus commerson) steaks stored in O2 scavenger packs during chilled storage

Freshness of seer fish (Scomberomorus commerson) steaks packed with and without O₂ scavenger was assessed by sensory and chemical methods. O₂ scavenger used in the present study reduced the O₂ level in the pack to less than 0.01% within 24 h. Samples in air packs were sensorily acceptable only up to 12 days compared to 20 days in O₂ scavenger packs. TVB-N levels were 37 and 34 mg N₂/100 g and TMA-N levels were 16.4 and 15.2 mg N₂/100 g on the day of sensory rejection for air and O₂ scavenger packs, respectively. IMP decrease and Hx increase was significantly (P < 0.05) faster in air packed samples compared to O₂ scavenger packs. On sensory rejection day, the average K, Ki, P and H values were 63–65%, Fr value was 34% and G value was 178% for O₂ scavenger packed samples compared to 81%, 18% and 443% for air packed samples, respectively.Industrial relevanceThe O₂ scavenger is an innovative active packaging technique, which is highly effective in reducing the O₂ present inside the pack. This can be used in place of traditional vacuum packaging for extending the shelf life of fish products, which reduces the use of vacuum packaging equipments thereby making the process cost effective.     

Prevention of Transient Discoloration of Beef

Oxygen absorbent technology in conjunction with controlled atmosphere packaging(CAP) was used to prevent transient discoloration in master‐packaged beef steaks. Two types of commercial O₂ scavengers were used in the study. The master packs were stored at 1± 0.5 °C. The steaks from master packs were presented in a display‐case for visual evaluation. Reflectance spectra from each steak‐surface were obtained to estimate metmyoglobin content. Steaks packaged without O₂ scavengers showed more discoloration, and had significantly higher proportions of metmyoglobin when compared to steaks with O₂ scavengers, after most storage intervals (p < 0.05). Prevention of metmyoglobin formation was influenced by the number but not the type of O₂ scavenger employed (p > 0.05). Keywords: oxygen scavengers, centralized meat operations, transient discoloration     

Biogenic amines formation in seer fish (Scomberomorus commerson) steaks packed with O2 scavenger during chilled storage

A comparative study of the effect of O₂ scavenger on the formation of biogenic amines during chilled storage of seer fish (Scomberomorus commerson) was carried out. O₂ scavenger was effective in reducing the O₂ content of the pack up to 99.95% within 24 h and it extended shelf-life up to 20 days compared to only 12 days for air packs. The biogenic amine content increased significantly (P < 0.05) in air packs compared to O₂ scavenger packs. Histamine, putrescine and cadaverine reached maximum levels of 6.8, 14.6 and 14.7 μg/g, respectively, in air packed samples at the end of 15th day. Spermidine and spermine levels increased slightly and did not change much throughout the storage period. Agmatine was absent in the O₂ scavenger packs throughout the storage period, whereas tyramine was observed only towards the end of storage study.     

Use of smart packaging technologies for monitoring and extending the shelf-life quality of modified atmosphere packaged (MAP) bread: application of intelligent oxygen sensors and active ethanol emitters

Following commercial assessment of the packaging materials and systems used for modified atmosphere packaged (MAP) speciality breads, a study was carried out to assess the bread quality and shelf life following the implementation of an improved MAP (10 % CO₂, 90 % N₂) process and compared to controls (held in air). O₂ sensors permitted the continuous and non-destructive monitoring of in-pack O₂ levels over time. Ethanol emitters (EE) or product surface sprays (ES) were used for MAP and control treatments to establish their effects on product shelf life. MAP samples had a continuous O₂ level of <0.1 % throughout storage. Samples packed in air showed contrasting O₂ profiles, where control samples showed that O₂ levels were depleted by day 6, whereas controls utilising EE and ES demonstrated a reduced O₂ decline over time. ES in control packs slowed O₂ decline over time, with complete O₂ depletion occurring by day 14, whereas the use of EE in control packs showed an even slower decline with complete O₂ depletion occurring by day 35 of storage. The use of ES, but particularly EE, reduced mycological counts in bread samples, reflecting the reduced O₂ utilisation in control packs. This was mirrored, but not to the same extent, for bread held under MAP conditions. Sensory evaluation of breads demonstrated that the use of ethanol in packs produced no negative organoleptic issues. In conclusion, O₂ sensors clearly demonstrate their ability to assess pack containment and O₂ utilisation within packs over time by yeasts/moulds while the use of EE controlled mycological growth, thereby extending product shelf life.     

Nondestructive and Continuous Monitoring of Oxygen Levels in Modified Atmosphere Packaged Ready‐to‐Eat Mixed Salad Products Using Optical Oxygen Sensors,and Its Effects on Sensory and Microbiological Counts during Storage

The objective of this study was to determine the percentage oxygen consumption of fresh, respiring ready‐to‐eat (RTE) mixed leaf salad products (Iceberg salad leaf, Caesar salad leaf, and Italian salad leaf). These were held under different modified atmosphere packaging (MAP) conditions (5% O₂, 5% CO₂, 90% N₂ (MAPC—commercial control), 21% O₂, 5% CO₂, 74% N₂ (MAP 1), 45% O₂, 5% CO₂, 50% N₂ (MAP 2), and 60% O₂, 5% CO₂, 35% N₂ (MAP 3)) and 4 °C for up to 10 d. The quality and shelf‐life stability of all packaged salad products were evaluated using sensory, physiochemical, and microbial assessment. Oxygen levels in all MAP packs were measured on each day of analysis using optical oxygen sensors allowing for nondestructive assessment of packs. Analysis showed that with the exception of control packs, oxygen levels for all MAP treatments decreased by approximately 10% after 7 d of storage. Oxygen levels in control packs were depleted after 7 d of storage. This appears to have had no detrimental effect on either the sensory quality or shelf‐life stability of any of the salad products investigated. Additionally, the presence of higher levels of oxygen in modified atmosphere packs did not significantly improve product quality or shelf‐life stability; however, these additional levels of oxygen were freely available to fresh respiring produce if required. This study shows that the application of optical sensors in MAP packs was successful in nondestructively monitoring oxygen level, or changes in oxygen level, during refrigerated storage of RTE salad products.     

Effect of reduced oxygen atmosphere and sodium acetate treatment on the microbial quality changes of seer fish (Scomberomorus commerson) steaks stored in ice

The effect of reduced oxygen atmosphere and sodium acetate treatment on the microbial quality of seer fish (Scomberomorus commerson) steaks was determined during chilled storage (1–2 °C). The O₂ absorber reduced the oxygen content in the pack to less than 0.01% corresponding to 99.96% reduction within 24 h. The use of O₂ absorber with sodium acetate dip treatment (2% w/v) extended the sensory shelf life up to 25 days compared to only 12 days for control air packs and 20 days for untreated samples with O₂ absorber. A prominent lag phase was observed for many bacterium studied, particularly for the sodium acetate treated samples with O₂ absorber. On the day of sensory rejection, both the total mesophilic and psychrotrophic counts reached 7.7–8.1 and 7.1–7.9 log cfu/g, respectively. The sodium acetate treatment and reduced O₂ atmosphere affected the type of major spoilers. In air packed samples, H₂S-producers predominated followed by Brochothrix thermosphacta, Pseudomonas spp., where as in the untreated samples with O₂ absorber, H₂S-producers predominated the microbial flora followed by Lactobacillus spp. For treated samples with O₂ absorber, B. thermosphacta formed the major micro-flora followed by Lactobacillus spp. The use of O₂ absorber inhibited the growth of Pseudomonas spp., and total Enterobacteriaceae.     

Shelf‐Life Extension of Chill‐Stored Beef Longissimus Steaks Packaged under Modified Atmospheres with 50% O2 and 40% CO2

This study was conducted to compare the shelf‐life of beef steaks stored in different packaging conditions: overwrapped (OW) packaging and 2 modified atmosphere packaging systems (MAP): 80% O₂ MAP (80% O₂/20% CO₂) and 50% O₂ MAP (50% O₂/40% CO₂/10% N₂). Steaks were stored at 2 °C for 20 d. Headspace gas composition, microbial counts, color stability, pH, purge loss, and lipid oxidation were monitored. Among the packaging types, 50% O₂ MAP was superior to OW packaging and 80% O₂ MAP in delaying bacterial growth and extending shelf‐life to 20 d. 50% O₂ MAP also gave steaks an acceptable color during storage. No significant differences were observed in color stability of steaks packaged in both 50% O₂ MAP and 80% O₂ MAP. This study reveals 50% O₂ MAP is a realistic alternative to preserve beef steaks efficiently.     

Quality changes in sea urchin (Strongylocentrotus nudus) during storage in artificial seawater saturated with oxygen, nitrogen and air

BACKGROUND: Sea urchin gonads are highly valued seafood that degenerates rapidly during the storage period. To study the influence of dissolved oxygen concentration on quality changes of sea urchin (Strongylocentrotus nudus) gonads, they were stored in artificial seawater saturated with oxygen, nitrogen or air at 5 ± 1 °C for 12 days. RESULTS: The sensory acceptability limit was 11–12, 6–7 and 7–8 days for gonads with oxygen, nitrogen or air packaging, respectively. Total volatile basic nitrogen (TVB‐N) values reached 22.60 ± 1.32, 32.37 ± 1.37 and 24.91 ± 1.54 mg 100 g^?1 for gonads with oxygen, nitrogen or air packaging at the points of near to, exceeding and reaching the limit of sensory acceptability, indicating that TVB‐N values of about 25 mg 100 g^?1 should be regarded as the limit of acceptability for sea urchin gonads. Relative ATP content values were 56.55%, 17.36% and 18.75% for gonads with oxygen, nitrogen or air packaging, respectively, on day 2. K‐values were 19.37%, 25.05% and 29.02% for gonads with oxygen, nitrogen or air packaging, respectively, on day 2. Both pH and aerobic plate count values showed no significant difference (P > 0.05) for gonads with the three treatments. CONCLUSION: Gonads with oxygen packaging had lower sensory demerit point (P < 0.05) and TVB‐N values (P < 0.05), and higher relative ATP content (P < 0.01) and K‐values (P < 0.05), than that with nitrogen or air packaging, with an extended shelf life of 4‐5 days during storage in artificial seawater at 5 ± 1 °C. Copyright © 2011 Society of Chemical Industry     

The effects of high oxygen modified atmosphere packaging on protein oxidation of bovine M. longissimus dorsi muscle during chilled storage

Modified atmosphere packaging (MAP) extends the shelf life of beef, especially in the context of visual colour. High O₂ MAP (70-80%) may cause quality deterioration through lipid and protein oxidation, the latter linked to a reduction in meat tenderness. The objective of this study was to investigate the effects of MAP in comparison to vacuum packaging (VP) on protein oxidation and subsequent tenderness of LD (M. longissimus dorsi) beef steaks during chilled storage (4 °C) of periods up to 14 days. Steaks were analysed for carbonyl content, free thiol groups, drip loss, Warner-Bratzler shear force (WBSF) and SDS-PAGE of extracted myofibrillar proteins. Free thiol groups were lower in high O₂ MAP (80% O₂/20% CO₂) steaks, after 14 days of storage, indicating protein oxidation compared to VP steaks. SDS-PAGE (non reducing conditions) showed the presence of high molecular weight cross linked myosin heavy chain aggregates in the high O₂ atmosphere packaged steaks, which were absent in VP steaks.     

Microbiological,physical and chemical characteristics of freshwater prawns (Macrobrachium rosenbergii) in modified‐atmosphere packaging

This study evaluated the influence of packaging atmosphere (air versus 50% N₂/50% CO₂) on microbiological (mesophiles, psychrotrophs), physical (gas measurement) and chemical (pH, total volatile basic nitrogen [TVB‐N], NH₃, H₂S and biogenic amines) parameters in freshwater prawns during storage at 0 ± 1 °C for 240 h. To select the most appropriate packaging, 21 batches of each treatment were analysed. Both the packaging permeability and the combination of gases affected the shelf life, but the modified‐atmosphere packaging (MAP) was more efficient than air packaging, increasing the shelf life by 40 h. The parameters of pH and TVB‐N showed no statistical difference between the two atmosphere conditions all along the storage period. The biogenic amine agmatine showed potential for use as a quality indicator due to the increased concentration during storage. In further studies, this amine can be applied as an indicator for public health issue.     

Effect of nano‐TiO2‐LDPE packaging on microbiological and physicochemical quality of Pacific white shrimp during chilled storage

Nano‐TiO₂‐modified low‐density polyethylene (NTLDPE) packaging was prepared by blending LDPE with nano‐TiO₂. The effects of NTLDPE packaging on quality of Pacific white shrimp during storage at 4 °C were investigated. Results showed that NTLDPE lowered the K value by 28.50%, while increased sensory score by 30.77% in comparison with the control. NTLDPE packaging retarded the decrease of whiteness and water holding capacity and the increase of melanosis score based on the signs of freshness and deterioration of shrimp. Furthermore, NTLDPE packaging reduced total viable counts (TVC) by 6.42% and total volatile basic nitrogen (TVB‐N) contents were 14.82% lower than that of control. TVB‐N content and TBARS value, as well as polyphenol oxidase activity and TVC, were maintained and shrimp remained a commercial acceptability for 8 days. The overall results indicated that NTLDPE packaging could preserve the quality and extend the shelf‐life of Pacific white shrimp.     

Modified atmosphere packaging of filleted rainbow trout

Shelf‐lives of filleted rainbow trout (Oncorhynchus mykiss) packaged in over‐wrap, vacuum and gas mixture conditions and stored at 1 ± 1 °C were compared by measurement of pH, total volatile bases (TVB), hypoxanthine content, lipid oxidation (TBARS value), superficial counts of aerobic psychrotrophic flora and sensory analysis (colour, odour and flavour). The gas mixtures evaluated were 10% O₂ + 50% CO₂ + 40% N₂, 10% O₂ + 50% CO₂ + 40% Ar, 20% O₂ + 50% CO₂ + 30% N₂, 20% O₂ + 50% CO₂ + 30% Ar, 30% O₂ + 50% CO₂ + 20% N₂ and 30% O₂ + 50% CO₂ + 20% Ar. Sensory quality deterioration was delayed and bacterial growth as well as increases in pH, TVB and hypoxanthine levels were reduced by modified atmosphere packaging (MAP). Lipid oxidation was higher in gas packages with 20 and 30% O₂ than in those with 10% O₂. Vacuum‐packed fillets presented the lowest TBARS values. In summary, MAP gave rise to a significant extension of shelf‐life when compared with vacuum and over‐wrap packaging. No significant differences were found between the packages containing either N₂ or Ar. The best evaluated atmosphere consisted of 10% O₂ + 50%CO₂ + 40% N₂/Ar. © 2002 Society of Chemical Industry     

Consumer acceptability and physiochemical characteristics of modified atmosphere packed beef steaks

The objective of this study was to investigate the physiochemical changes of beef steaks packed under various combinations of gasses and the relationship between consumer perception of flavour and acceptability of modified atmosphere packed beef steaks during retail display. Experimental gas atmospheres included: 40%, 50%, 60%, 70%, and 80% oxygen, with all packs containing 20% CO₂ and the make up gas N₂. Steaks were stored at 4 °C for 12 days and tested for lipid and protein oxidation, heme iron, colour, oxymyoglobin concentration, Warner–Bratzler shear force (WBSF) and consumer acceptability for the resulting cooked meat. The results from 134 consumers indicated a directional preference for the steaks stored in packs containing 40% and 80% oxygen. Samples with high oxygen levels, particularly the O₂60 and O₂70 treatments, were positively and significantly (P < 0.01) correlated to sensory toughness, and significantly (P < 0.05) negatively correlated to juiciness, as determined by consumers. However, the O₂40 samples were most negatively (P < 0.001) correlated to toughness and positively (P < 0.01) correlated to juiciness, which shows that, in general, these higher O₂ levels, >40%, imparted greater meat toughness as determined by the consumers. The greater directional acceptance of the O₂40 samples may be linked to the consumer perceived reduction in sensory toughness and increases in juiciness.     

Influence of Injection, Packaging, and Storage Conditions on the Quality of Beef and Bison Steaks

The combined effects of injection, packaging (modified atmosphere packaging [MAP] with 70% O₂/ 30% CO₂ and vacuum packaging [VP]), storage temperature (‐1 °C and +4 °C), and storage time on the color, microbial and oxidative stability of beef and bison longissimus lumborum (LL) steaks were investigated. Beef LL steaks in MAP retained their bright red color longer than bison steaks. Bison steaks developed higher 2‐Thiobarbituric acid reactive substances (TBARS) during storage, and this might have influenced the resulting rapid loss of redness from the bloomed meat. Storage at ‐1 °C in MAP provided greater color stability and a longer storage life for both meat species studied. Injection of salt/phosphate had a beneficial effect on the color stability of steaks during retail display; however, this positive effect was more pronounced for bison steaks compared with those of beef. Steaks stored overnight under MAP before retail display maintained the highest a* values for up to 5 d compared with those stored under vacuum. MAP‐OV steaks generally maintained the highest OMB content for up to 5 d during retail display compared with those stored under vacuum. Nevertheless, OMB levels were significantly (P < 0.05) lower in bison steaks compared with those of beef irrespective of packaging treatments. Injected steaks and those stored at ‐1 °C had significantly (P < 0.05) higher OMB levels compared with non‐injected counterparts and those stored at +4 °C, respectively. MAP is an excellent option for short‐term storage due to its positive effects on meat color, but for longer storage, VP may be necessary. Storing meat under vacuum and then placing it under MAP just before retail display might be another option to increase shelf life.     

Impact of the O2 Concentrations on Bacterial Communities and Quality of Modified Atmosphere Packaged Pacific White Shrimp (Litopenaeus Vannamei)

The importance of spoilage‐related bacteria in fresh Pacific white shrimp (Litopenaeus vannamei) under different modified atmospheres (MAs) at 4 °C and the effect of O₂ were demonstrated in the current study. The changes of bacterial communities in MA‐packed shrimp during cold storage were studied by a combined method of plate counts with isolation and identification. Three gas mixtures were applied: 80% CO₂/5% O₂/15% N₂, 80% CO₂/10% O₂/10% N₂ and 80% CO₂/20% O₂, and unsealed packages of shrimp were used as the control. In addition, the TVB‐N, pH, whiteness index, and sensory scores were also determined to evaluate the quality changes of shrimp. MA packaging effectively inhibited the increase of total psychrotrophic bacteria counts and H₂S‐producing bacteria counts by about 1.7 and 2.1 log cycles, respectively. The growth of Gram‐negative spoilage bacteria in shrimp, including Shewanella spp., Aeromonas spp., and Pseudomonas spp., was inhibited by MA packaging, but the growth rate of Gram‐positive bacteria such as lactic acid bacteria (LAB) and Brochothrix spp. were less affected by MA as effectively as Gram‐negative bacteria. In comparison with the MA‐packaged samples, the counts of H₂S producers in shrimp under a CO₂‐enriched atmosphere with 20% O₂ were slightly lower than the count in samples under an atmosphere with 5% O₂. However, MA with 20% O₂ led to higher concentrations of TVB‐N, and lower whiteness values and sensory scores. The shelf life of shrimp under 80% CO₂/10% O₂/10% N₂ has been prolonged by > 6 d in comparison with the control according to the sensory scores.     

Detection of cheese packaging containment failures using reversible optical oxygen sensors

This study investigated the capacity of optical oxygen sensors to nondestructively detect containment packaging failures in commercial vacuum packed cheddar cheese. Unacceptable oxygen levels in packs lead to product deterioration and can significantly reduce shelf life. Vacuum packed cheddar cheese was monitored for oxygen levels over time at 4 °C with optical sensors prefitted to packaging laminates polyethyleneterephthalate/polypropylene. Oxygen levels present in packs immediately after packaging were 3% on average. Further ingress of oxygen into all packs occurred over storage time and levels ranged from 3.6% to 8.2% after 6 days. Information obtained using oxygen sensors led to further assessments and identification of the causes of packaging containment failure.     

INFLUENCE OF VACUUM PACKAGING AND ORGANIC ACID TREATMENT ON THE CHILLED SHELF LIFE OF PEARL SPOT (ETROPLUS SURATENSIS, BLOCH 1790)

The present work was carried out to study the effect of vacuum packaging and organic acids drip treatment, namely, sodium acetate and potassium sorbate (2%), on the quality of pearl spot during chilled storage (1–2C). Changes in pH, drip loss, water-holding capacity, total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), total plate counts, instrumental texture properties and sensory characteristics were investigated up to 18 days. Sensory evaluation revealed that the potassium sorbate- and sodium acetate-treated vacuum-packaged samples had good sensory characteristics up to 16 days compared with 7 days in control air packs (CAPs) and control vacuum packs (CVPs). The sensory shelf life followed the following order: CAP  <  CVP  <  sodium acetate-treated vacuum pack  <  potassium sorbate-treated vacuum pack. Chemical analysis demonstrated a significant ( P   <  0.05) reduction in TVB-N, TMA-N and total plate counts, and better textural properties in potassium sorbate- and sodium acetate-treated vacuum-packaged fishes than CAPs and CVPs.

PRACTICAL APPLICATIONS

Limited shelf life is one of the major problems the seafood industry faces today. The study compares the effect of vacuum packaging in combination with preservative chemical treatment on the shelf life of pearl spot. The study indicates that the use of chemical preservative treatments such as sodium acetate and potassium sorbate at 2% level, together with vacuum packaging, helps in extending the shelf life of pearl spot to 16 days compared with 7 days in control air packs and control vacuum packs. Hence, vacuum packaging, together with preservative treatment, is very effective in shelf-life extension compared with vacuum packaging alone.     

Microbial and physicochemical modifications of hake (Merluccius merluccius) steaks stored under carbon dioxide enriched atmospheres

Microbial counts (total viable, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae), biochemical parameters [pH, total volatile nitrogen, nucleotide breakdown products, non‐volatile amines, D (−) and L (+) lactic acid and short‐chain fatty acids] and sensory attributes (colour and odour) of refrigerated (2 °C) hake (Merluccius merluccius) steaks under carbon dioxide enriched air (CO₂ /air, 20/80 v/v and CO₂ /air, 40/60 v/v) and air atmospheres were determined. When compared with air, sensory results showed shelf‐life extension of 4 and 11 days for 20% and 40% CO₂‐enriched atmospheres, respectively. Microbial and biochemical results also revealed that the 40% CO₂‐enriched atmosphere was the most effective packaging type for refrigerated hake. © 2000 Society of Chemical Industry