The effects of soluble gas stabilisation on the quality of packed sardine fillets (Sardina pilchardus) stored in air,VP and MAP

Sardine (Sardina pilchardus) is a species that for its abundance assumes great importance in the Portuguese fishing sector. In order to contribute for a better utilisation of this species, the aim of this study was to investigate the effect of the pre‐treatment with soluble gas stabilisation (SGS) (100% CO₂ at 2 bar, during 15 and 30 min) on the quality and shelf‐life of sardine fillets, packed in air (AP), vacuum (VP) and modified atmosphere (MAP: 5% O₂/35% CO₂/60% N₂). During the chilled storage, the quality changes were evaluated by sensory evaluation, chemical and microbiological analysis. The total volatile basic nitrogen content remained almost constant, between 16 and 19 mg N/100 g muscle, during the storage period, for all samples. The TBARs values increased with storage time, for all batches and storage conditions. The application of SGS treatment to sardine fillets, resulted in a bacteriostatic effect, contributing to the improvement of the microbiological quality of fillets. Considering a sensory criteria, the shelf‐life of SGS pre‐treated sardine fillets was found to be 5 days in AP and MAP while in VP‐treated fillets a shelf‐life of 8 days was reported. At sensory rejection, sardine fillets presented a K‐value of 30% in AP and MAP batches and 40% in VP batch.     

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.     

Combined effect of active coating and modified atmosphere packaging on prolonging the shelf life of low-moisture Mozzarella cheese

In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO₂ and 25% N₂ (MAP1), 25% CO₂ and 75% N₂ (MAP2), or 50% CO₂ and 50% N₂ (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions.     

Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese

Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ～4 log₁₀ cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm high-barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N₂ and CO₂ [100% N₂ (MAP1), 30% CO₂:70% N₂ (MAP2), 50% CO₂:50% N₂ (MAP3), or 70% CO₂:30% N₂ (MAP4), 100% CO₂ (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO₂ had lower pH levels during storage compared with those stored in conditions with lower levels or no CO₂ at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO₂ content, whereas conditions consisting of 100% N₂, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ～2 log₁₀ cfu/g on cheeses packaged in air, vacuum, and 100% N₂ (MAP1) conditions at d 7 and an additional ～1.5 log₁₀ cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO₂ (MAP4) and 100% CO₂ (MAP5) limited increases in mean L. monocytogenes counts to <1 log₁₀ cfu/g through 14 d and ～1.5 log₁₀ cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 and MAP3 on d 21, on d 28 for MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO₂ may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.     

Original article: Effect of modified atmosphere packaging using different CO2 and N2 combinations on physical,chemical, microbiological and sensory changes of fresh sea bass (Dicentrarchus labrax) fillets

The effect of different modified atmosphere packaging (MAPs) on physical, chemical, microbiological and sensory changes of sea bass fillets when stored at 4 °C and standard light conditions was investigated for up to 21 days and compared to a control batch stored in overwrap. Sea bass fillets were packed using different CO₂ and N₂ combinations (40% CO₂–60% N₂; 50% CO₂–50% N₂; 60% CO₂–40% N₂), and quality assessment was based on instrumental, chemical, microbiological and sensory analysis. The results showed that MAP extended shelf‐life of sea bass fillets from 7 days (overwrap packaging) to 14 days. Drip loss, pH values and thiobarbituric acid reactive substances (TBARS) measurements were higher in overwrap samples but no differences (P ≤ 0.05) were found between MAP samples. Bacteria grew most quickly and showed higher counts in overwrap samples followed by 40% CO₂–60% N₂; 50% CO₂–50% N₂ and finally 60% CO₂–40% N₂. Sensory analyses were in good relation with chemical and microbiological results establishing best scores and an extended shelf‐life for MAP samples especially in MAPs with high CO₂ levels.     

Shelf-life of Domiati cheese under modified atmosphere packaging

The present study describes the effects of modified atmosphere packaging (MAP) on shelf-life extension, chemical, microbiological, and sensory properties of Domiati cheese. Five different MAP were studied [10% CO₂/90% N₂ (G1), 15% CO₂/85% N₂ (G2), 25% CO₂/75% N₂ (G3), 100% CO₂ (G4), and 100% N₂ (G5)]. Control samples were packaged in air (CA) and under vacuum. In both groups of cheeses, chemical analysis was significantly affected by MAP during cold storage. Ripening indexes were significantly affected by MAP during cold storage. Microbiological data showed that G4, followed by G5, were the most effective groups inhibiting the growth of total aerobic mesophilic and psychrotrophic bacteria, and yeasts and molds until the end of storage. Sensory evaluation was significantly affected by MAP and storage period, at 45 d CA cheese samples were judged as unacceptable. The best sensory properties were obtained in G5, G4, and G3 treatments, and recorded a relatively higher sensory evaluation scores. The best shelf-life extension was obtained in G5, G4, and G3 treatments.     

Sensory and microbiological quality of shiitake mushrooms in modified‐atmosphere packages

The aim of the present work was to study the influence of modified‐atmosphere packaging on the microbiological and sensory quality of shiitake mushrooms (Lentinula edodes). Mushrooms were packaged under atmospheric air (passive modified atmosphere) and an initial gas mixture of 5% O₂ and 2.5% CO₂ (active modified atmosphere), in bags of two different films: low‐density polyethylene (PE) and polypropylene (PP). As control, mushrooms were packaged in macroperforated PP films. Bags were stored at 5 °C for 20 days. Package atmosphere composition, mushroom respiration rate, weight loss, microbiological counts and sensory quality were determined during storage. Risk assays were also performed. Under the studied conditions, shiitake mushroom deterioration was not due to microorganism growth, and therefore the shelf‐life of this product might be defined by changes in its sensory characteristics. Sensory analysis showed that mushrooms stored under modified atmosphere (active and passive) had a higher deterioration rate than those stored in PP macroperforated films, and lower sensory quality values during the entire storage time. These results suggest that mushroom deterioration was probably due to shiitake mushrooms' sensitivity to high CO₂ concentrations. Copyright © 2007 Society of Chemical Industry     

Combined effect of irradiation and modified atmosphere packaging on shelf-life extension of chicken breast meat: microbiological, chemical and sensory changes

In the present study the combined effect of gamma irradiation (2 and 4 kGy) and modified atmosphere packaging (MAP) (30% CO₂/70% N₂ and 70% CO₂/30% N₂) on shelf life extension of fresh chicken meat stored under refrigeration was investigated. The study was based on microbiological (TVC, Pseudomonas spp., Lactic Acid Bacteria, Yeasts, Brochothrix thermosphacta, Enterobacteriaceae), physicochemical (pH, TBA, color) and sensory (odor, taste) changes occurring in chicken samples. Microbial populations were reduced by 1–5 log cfu/g for a given sampling day depending on the specific treatment. The effect was more pronounced in the case of the combination of MAP (70% CO₂/30% N₂) and the higher irradiation dose of 4 kGy. Of the chemical indicators of spoilage, TBA values for all treatments remained lower than 1 mg malondialdehyde (MDA)/kg meat throughout the 25 day storage period. pH values varied between 6.4 (day 0) and 5.9 (day 25). The values of the color parameters L*, a* and b* were not considerably affected by MAP. Irradiation resulted in a small increase of the parameter a*. Irradiation had a greater effect in extending the shelf life of chicken as compared to MAP. Sensory evaluation showed that the combination of irradiation at 4 kGy and MAP (70% CO₂/30% N₂) resulted in the highest shelf-life extension by 12 days compared to the air packaged samples.     

臭氧水清洗结合气调包装对鲜切杭白菜保鲜效果的研究

以1.8mg/L臭氧水清洗的鲜切杭白菜为试验材料,研究不同气体组分的气调包装(CK为空气;A为5%O_2+5%CO_2+90%N_2;B为5%O_2+10%CO_2+85%N_2;C为10%O_2+5%CO_2+85%N_2;D为10%O_2+10%CO_2+80%N_2)对鲜切杭白菜保鲜效果的影响。结果表明:B组低氧高二氧化碳的包装能有效地抑制鲜切杭白菜上微生物的生长,保持其较好的感官品质,同时延缓VC、叶绿素及可溶性固形物含量的降低,防止杭白菜过快失水,有效地保证鲜切杭白菜的货架期在15d以上。     

Combined effect of MAP and active compounds on fresh blue fish burger

The combined effects of three essential oils [thymol, lemon extract and grapefruit seed extract (GFSE)] and modified atmosphere packaging conditions (MAP) on quality retention of blue fish burgers was studied and discussed. In particular, samples were packaged in air and in three different gas mix compositions: 30:40:30 O₂:CO₂:N₂, 50:50 O₂:CO₂ and 5:95 O₂:CO₂. During a 28-day storage period at 4 °C, the nutritional, microbiological and sensorial quality of the packed products was assessed. The potential development of biogenic amines was also evaluated.The obtained results highlight the possibility to improve the microbial quality of blue fish burgers by using very small amount of thymol (110 ppm), GFSE (100 ppm) and lemon extract (120 ppm) in combination with MAP. Based primarily on microbiological results, the combined use of the tested natural preservatives and a packaging system characterized by a high CO₂-concentration, was able to guarantee the microbial acceptability of fish burgers until the 28th day of storage at 4 °C. On the other hand, results from sensory analyses showed that sensorial quality was the sub-index that limited the burgers shelf life (to about 22–23 days), even if the proposed strategy was also effective in minimizing the sensory quality loss of the product having no effect on its nutritional quality.     

Microbiological,chemical and sensory assessment of mussels (<Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis>) stored under modified atmosphere packaging

Wild mussels (Mytilus galloprovincialis), were packaged aerobically under vaccum packaging(VP) and modified atmosphere packaging (MAP (50%/50% CO₂/N₂: M1, 80%/20% CO₂/N₂: M2, 65%/35% CO₂/N₂: M3), and stored at 2 ± 1 °C. Quality evaluation was carried out using microbiological, chemical and sensory analyses. Microbiological results revealed that M2 and M3 delayed microbial growth compared to M1. Of the chemical indices determined, the TVB-N and TMA-N values of M2 remained lower than the proposed acceptability limits of 35 mg N/100 g and 8 mg N/100 g, respectively, up to 8 days of storage. All of the MAP and VP mussel samples exceeded these limits after 12 days of storage. All samples retained desirable sensory characteristics during the first 8 days of storage. Based on microbiological and chemical analyses along with sensory evaluation, M2 and M3 gave a longer shelf-life compared with VP and M1. M2 gas mixture was the most effective for mussel preservation.     

Shelf Life Assessment of Modified Atmosphere Packaged Turbot (Psetta maxima) Fillets: Evaluation of Microbial, Physical and Chemical Quality Parameters

Quality and safety of turbot fillets under modified atmosphere packaging (MAP) were assessed by microbial (total viable counts), physical (drip loss, pH, colour CIE Lab) and chemical parameters (total volatile basic nitrogen (TVBN), trimethylamine nitrogen (TMAN), biogenic amine contents). Three different atmospheres (MAP 1, 10/40/50 % O₂/CO₂/N₂; MAP 2, 10/60/30 % O₂/CO₂/N₂; MAP 3, 10/80/10 % O₂/CO₂/N₂) were tested. Packaged turbot fillets were stored at 2?±?1 °C and monitored over 30 days, at intervals of 5 days. Fillets from the control group, packaged with air (AIR), were the first to present signs of degradation reaching rejection threshold values for all evaluated parameters. In MAP fillets, total bacterial count was lower than 10⁶ cfu/g for a longer period. After 10 days of storage, MAP and AIR fillets showed significant differences (p?<?0.05) on the values of TVBN, TMAN and biogenic amines. MAP fillets presented a higher drip loss, and fillets in AIR became more yellowish (upper b* values) while those in MAP looked whitish for an increased period (upper L* values). All microbial, chemical and physical traits revealed the protective effect of the different MAP studied, especially those with a higher percentage of CO₂. MAP application added, at least, 5 days to shelf life of turbot fillets.     

Comparison of the shelf lifes of map and vacuum packaged hot smoked rainbow trout (Onchoryncus mykiss)

The objective of this study was to determine the differences of microbiological and chemical quality in MAP and VP packages in refrigerated smoked trout fillets. Such information is important in evaluating the safety of these products. Three groups were constituted: group A – packed in 60%Co₂/40% N₂; group B – packed in 50%CO₂/50% N₂ and group C– vacuum packed. The ratio of fillet to package volume was 1/3 chemical analysis and microbiological analysis were done and also instrumental and sensory analysis were used to determined the shelf life. The observed shelf life of smoked trout was found at least 33 days in vacuum package, 47 days in 60% CO₂/40% N₂ gas mixture and 40 days in 50% CO₂/50% N₂ gas mixture according to results of microbiological analysis. The observed shelf life of smoked trout in MAP group A was determined as 14 days more than VP packs according to results of microbiological and sensory analysis in the study.     

Bulk Storage of Cod Fillets and Gutted Cod (Gadus morhua) Under Carbon Dioxide Atmosphere

The storage-life of bulk-stored cod under CO₂ atmosphere and air were compared. Gutted fish or fillets were distributed in bulk, among coolers containing 100% air or 25% CO₂-75% N₂, which were then stored at 0 ± 1°C for 20 days. Sensory assessments and chemical tests (pH, total volatile nitrogen) were carried out to estimate the raw-state quality and the bacterial spoilage. An important difference was observed between the storage life of cod under carbon dioxide atmosphere and air; microbiological and sensory assessments suggested a storage life exceeding 20 days and total volatile nitrogen results about 6–7 days under gas atmosphere, which was nearly twice as long as in air. Storage in CO₂ atmosphere was effective in inhibiting the growth of some bacteria on the fish, thereby contributing to the significant extension of the shelf life of the product.     

Quality of chilled ready-to-bake pizza stored in air and under modified atmospheres: Microbiological and sensory attributes

Modified atmosphere packaging (MAP) studies on microbiological and sensory analysis were conducted to extend the shelf life of ready-to-bake pizza stored at 7±1°C. The gas combinations used were: atm1: air (control), atm2: CO₂ (100%), atm3: N₂ (100%), atm4: 50% CO₂/50% N₂. Total plate count (TPC), yeasts/molds (Y/M), coliforms, lactic acid bacteria (LAB), psychrotrophs, and anaerobic spore formers were estimated at time intervals of 0, 5, 10, 15, and 20 days. TPC and LAB of pizza samples (atm1) reached 7.10 and 8.14 log CFU/g after 10 days of storage, respectively. Coliforms, psychrotrophs, and Y/M were significantly higher (p<0.05) for pizza samples stored in atm1 than other storage conditions of MAP. Finally, counts of anaerobic spore formers were low (<3 log CFU/g) irrespective of the packaging conditions throughout the entire storage period. It was concluded that among the 4 atmospheres examined, atm2 (100% CO₂) was the best, followed by atm4>atm3>atm1 respectively, in descending order. MAP conditions under this study may extend shelf life of pizza to considerable amount of time.     

Sensory comparison of commercial low and high oxygen modified atmosphere packed sirloin beef steaks

The objectives of this study were to investigate the effects of using commercially low and high modified atmosphere packaging (MAP) on quality characteristics of sirloin beef steaks. Gas mixtures used included 80% O₂:20% CO₂ (O₂80), 70% O₂/30% CO₂ (O₂70) and 50% O₂/30% CO₂:20% N₂ (O₂50) and for commercial packs O₂75 ± 5%, CO₂25 ± 5%, < 5% N₂-(O₂Com). All samples were packed in similar tray and packaging film formats. The experimental parameters monitored included microbiological, physiochemical and sensory measurements (naïve assessors). Microbial counts did not exceed the recommended legal ranges over the storage period. However the numbers of LAB (lactic acid bacteria) were the highest for commercially-packed samples (O₂Com) in comparison to laboratory packaged samples (O₂80, O₂70 and O₂50). Commercially-packaged samples eventually spoiled due to the occurrence of off-flavours and off-odours and subsequently were the least acceptable to sensory naïve assessors.     

The effects of partial replacement of fish meal by vegetable protein sources in the diet of rainbow trout (Onchorynchus mykiss) on post mortem spoilage of fillets

Five test diets were formulated with decreasing levels of fish meal (up to 50%) replaced by alternative protein sources. Rainbow trout were fed the experimental diets for 12 weeks.The effects of feed ingredients on spoilage of Oncorhynchus mykiss in ice and under MAP/ice (40% CO₂, 30% N₂ and 30% O₂) were investigated in terms of sensory, chemical and microbiological analyses. The results showed that the trout in MAP/ice was rejected at 14 days, after sensory analysis, due to excessive drip, whereas trout in ice were found to be acceptable even after 14 days of storage. However, cooked trout fillets, under both storage conditions, were rejected at 17 days. Fish in ice produced higher K values and higher concentrations of biogenic amines during the storage period of 17 days than the fish in MAP/ice. Bacteria grew more quickly in rainbow trout kept in ice than in MAP/ice. MAP/ice storage extended the shelf life of rainbow trout by approximately 2 days compared to ice storage alone in terms of microbiological analyses.     

Different MAP conditions to improve the shelf life of sea bass

Shelf life of cultured sea bass packaged in air, vacuum, and gas mixture packages stored for 40 days at 2.90±0.02°C was compared. The gas mixtures used contained CO₂, O₂, and N₂ at difference percentages (M1: 75% CO₂/25% N₂; M2: 60% CO₂/40% N₂; M3: 30% O₂/30% CO₂/40% N₂). Sensory and physical parameters, chemical changes, and microbiological counts were monitored during storage. Storage with a gas mix including 75 and 60% CO₂ was more effective than vacuum processing and packaging with a gas mix that included oxygen. Vacuum was the most effective method for preventing lipid oxidation. The optimum method for sea bass in view of all analysis results was modified atmosphere packaging (MAP) and the most suitable gas mix ratio was 75% CO₂/25% N₂. The best days for consumption of sea bass packaged with air, MAP (M1, M2, and M3), and vacuum were 4^th, 28^th, 28^th, 16^th, and 20^th days, respectively.     

Effects of novel modified atmosphere packaging on lipid quality and stability of sardine (Sardina pilchardus) fillets

Modified atmosphere packaging (MAP) is an efficient method to increase shelf-life of fishery products by inhibiting bacterial growth and oxidative reactions. Beside the traditional gases used for MAP, novel gases such as argon (Ar) and nitrous oxide (N₂O) were approved for food use in the European Union. The present research investigates the effect of MAP with unconventional gas mixtures, that previously positively affected microbial shelf-life, on colour, lipid oxidation and sensorial characteristics of sardine fillets during storage. Four atmosphere conditions were tested: Air (20.8% O₂/79.2% N₂), N₂ (30% CO₂/70% N₂), N₂O (30% CO₂/70% N₂O) and Ar (30% CO₂/70% Ar). Samples were stored for 12 days at 3 °C. Results showed that the removal of oxygen significantly inhibited the oxidation process; however, most of the investigated parameters related to fat oxidation did not show any improvement, except for a slight decrease in lipid hydrolysis and improvement in sensory properties in the packaging containing Ar.     

The impact of packaging system and temperature abuse on the shelf life characteristics of ground beef

New ground beef packaging systems have warranted investigation of their spoilage and quality characteristics. Furthermore, analysis of ground beef spoilage in modified atmosphere packaging (MAP) and stored at abusive temperature is lacking. This research aimed to determine the effect of packaging systems and temperature abuse on the sensory and shelf-life characteristics of ground beef. Ground beef patties were packaged using polyvinyl chloride overwrap (OW), HI-OX MAP (80% O₂, 20% CO₂), LO-OX MAP (30% CO₂, 70% N₂), CO-MAP (0.4% CO, 30% CO₂, 69.6% N₂), or vacuum (VAC) prior to color, odor, biochemical, and microbial analyses over display. CO-MAP exhibited more desirable color and consumer acceptability throughout display. Lean discoloration and odor scores were lower for anaerobic packaging than aerobic packaging. Microbial results mirrored sensory preferences for anaerobic packaging. These results indicate anaerobic packaging extends shelf-life properties and desirable sensory attributes throughout display and temperature abuse.