The extension of the shelf-life of 'pesto' sauce by a combination of modified atmosphere packaging and refrigeration

Summary This study was intended to extend, by optimizing modified atmosphere packaging (MAP), the shelf-life of the Italian vegetable sauce used for spaghetti and known as 'pesto'. A mathematical model was developed in order to predict gas composition inside the polymeric package (CO₂ concentration). Predictions of equilibration time and equilibrium gas composition showed moderately good agreement with experimental data. A useful extension of pesto shelf-life, up to 120 days, was achieved by adopting a target atmosphere containing, at steady-state, 10% CO₂ and 90% N₂ at 5 °C. Microbial growth was inhibited by the CO₂ levels, but was not accompanied by significant changes in odour and colour.     

Microbiological, physicochemical and organoleptic changes of shredded carrots stored under modified storage

The effect of initial head spaces of air, 4.9% CO₂/2.1% O₂/93% N₂ and 5% CO₂/95% N₂ on the microbial flora of shredded carrots was studied at 4 and 10°C. The microbial flora of shredded carrots comprised lactic acid bacteria, pseudomonads and yeasts. Lactic acid bacteria were the predominant organisms in all samples. The pH dropped during the storage of carrots and this was more pronounced at 10°C. The concentration of different organic acids such as lactic, acetic, tartaric, citric and succinic increased in all samples stored under modified atmosphere packaging conditions at both temperatures. The spoilage of carrots stored under 5% CO₂/95% N₂ was delayed, as indicated by the changes in their texture, colour and odour, compared with those samples stored under air or 4.9% CO₂/2.1% O₂/93% N₂.     

Quality changes in fresh-cut Fuji apple as affected by ripeness stage, antibrowning agents, and storage atmosphere

ABSTRACT:  The effect of ripening state, modified atmosphere, and the use of antibrowning agents was investigated in an attempt to determine optimum ripeness and processing conditions for extending the shelf-life of fresh-cut Fuji apple. Apples were classified in 3 groups: mature-green, partially ripe, and ripe; after peeling and slicing, fruits were treated with 1% (w/v) N -acetylcysteine, or 1% (w/v) ascorbic acid (control), and then packed into polypropylene trays with air or a gas mixture (2.5% O₂+ 7% CO₂+ 90.5% N₂) and sealed. Trays containing the apple slices were stored in darkness at 4 °C ± 1 °C and analyzed periodically during 43 d. Changes in atmosphere composition, color, and firmness were examined. Partially ripe apples, based on their lower ethanol production and maintenance of their original color and firmness, were the most suitable to prepare the fresh-cut commodities. A postcutting dip in 1% (w/v) N -acetylcysteine was the most effective treatment to prevent cut surface browning and preserve the initial appearance of Fuji apple slices during more than 1 mo at 4 °C. Low O₂ and elevated CO₂ (2.5% O₂+ 7% CO₂) atmosphere extended the shelf life of apple slices because of a significant inhibition of ethylene production.     

INFLUENCE OF MODIFIED ATMOSPHERE PACKAGING ON SHELF-LIFE OF CHICKEN CARCASSES UNDER REFRIGERATED STORAGE CONDITIONS

The effect of modified atmosphere packaging (MAP) (70% CO₂/30% N₂; 30% CO₂/70% N₂) on the shelf-life of fresh chicken carcasses stored at 2, 4, 7 and 9C was investigated. The shelf-lives of MAP carcasses (70% CO₂/30%N₂) stored at 2, 4, 7 and 9C were 25, 21, 12 and 8 days, respectively compared with 7 days for air-packaged ones stored at 4C; the shelf-life of MAP carcasses (30% CO₂/70%N₂) stored at the same temperatures were 20, 15, 8 and 8 days, respectively. The inhibitory effect of MAP on the growth of Enterobacteriaceae and on the production of spoilage metabolites, such as free fatty acids and extract release volume, was negligible at higher temperatures (7 and 9C) and more pronounced at lower temperatures (2 and 4C), especially at higher concentrations of CO₂ (70% CO₂/30% N₂). The occurrence and growth of organisms such as Escherichia coli, coliforms , Staphylococcus aureus, Salmonella and Campylobacter in carcasses stored at different temperatures were also documented .     

A review of modified atmosphere packaging of fish and fishery products – significance of microbial growth, activities and safety

Modified atmosphere packaging (MAP) extends shelf-life of most fishery products by inhibiting bacterial growth and oxidative reactions. The achievable extension of shelf-life depends on species, fat content, initial microbial population, gas mixture, the ratio of gas volume to product volume, and most importantly, storage temperature. The shelf-life of fishery products is usually limited by microbial activity, although for some fatty fishes or at superchilled storage, it can be limited by nonmicrobial activity. Packaging of fishery products under modified atmospheres (MA) increases shelf-life compared with those packaged under air, but confers little or no additional shelf-life increase compared with vacuum packaging. The specific spoilage organism (SSO) of MA packaged cod at 0 °C has been found to be Photobacterium phosphoreum . Whether or not this bacterium is the general SSO for all marine temperate fishes at different storage temperatures and under various CO₂/N₂/O₂ mixtures needs to be resolved. Without proper control of storage temperature, the benefits of MAP may be lost. Higher temperatures inevitably lead to less dissolved CO₂ in the product and consequently loss of inhibitory effect, which may result in higher microbial and enzymatic activity, and uncertainties concerning the microbial safety, as food-borne pathogens might be present in the product.     

Influence of oxygen concentration and temperature on respiratory characteristics of fresh-cut green onion

The characteristics of the respiration rates in precut green onion, as influenced by oxygen levels and temperature, were examined to provide design factors for modified atmosphere packaging (MAP). Fresh-cut green onions ( Allium fistulosum L.) were prepared and sealed, with and without a CO₂ absorbent, in gas-tight glass containers that had initially been purged with air or a gas mixture (O₂ 9%/N₂ balance). The containers were stored at different temperatures (0, 10, 20 °C). At 10 °C, the maximum O₂ uptake rate (V_m) and the O₂ concentration at half-maximum (K_m) uptake rate were 30.95 mL kg⁻¹ h⁻¹ and 1.63%, respectively. Regardless of temperature, the lower O₂ limit was estimated to be about 1.0% O₂ on the basis of respiratory quotient (RQ) increase. Respiration of cut green onion was dependent on O₂ concentration as well as temperature, as shown by applying the Michaelis–Menten type model and the Arrhenius equation. However, the presence of CO₂ had little effect on O₂ uptake of cut green onion at relatively high O₂ concentrations (≤20%).     

Effect of irradiation and modified atmosphere packaging on the microbiological and sensory quality of pork stored at refrigeration temperatures

The effect of combining low-dose irradiation (1.75 kGy) with modified atmosphere packaging (MAP) on the microbiological and sensory quality of pork chops stored at refrigeration temperatures was studied. The microflora of irradiated MAP pork was almost exclusively composed of lactic acid bacteria, predominantly Lactobacillus spp. Modified atmospheres containing either 25 or 50% CO₂, balance N₂, resulted in the best microbial control in irradiated pork held at 4°C, compared to an unirradiated MAP control, and these atmospheres were subsequently used in sensory studies. The atmosphere containing 25% CO₂ 75% N₂ maintained the uncooked colour and odour of irradiated pork chops more effectively than 50% CO₂ 50% N₂. Therefore packaging in a modified atmosphere containing 25% CO₂, balance N₂, followed by irradiation to a dose of 1.75 kGy is recommended to improve the microbiological and sensory quality of pork chops.     

EFFECT OF OXYGEN-ENRICHED ATMOSPHERES ON STORAGE QUALITY OF PACKAGED FRESH MEAT

SUMMARY —The extension of fresh meat shelf-life is important from both practical and theoretical points of view. Color is usually used as a measure of fresh meat quality during storage. Beef top-round slices were prepared using sanitary precautions. Meat slices were enclosed in a thermally sealed semi-rigid polyvinyl chloride tray system of special design. Face-to-face meat samples were used to compare the effects of high oxygen with normal air atmospheres. One package from each pair was evacuated and the atmosphere readjusted to approximately 90% oxygen through a septum. Packages were kept at 4 ± 0.5°C and gas chromatographic readings for CO₂, O₂ and N₂ were conducted daily. Spectrophotometric and bacteriological evaluations were made on selected pack ages during storage to determine pigment oxidation and microbial growth. Three experiments each containing six to eight pairs of samples were conducted. The generation of CO₂ was observed in two periods–the first immediately after packaging and lasting for 1–2 days, after which the CO₂ level remained approximately stable up to 8—9 days, when it again started to increase in correspondence with increased bacterial growth. There was more CO₂ produced than O₂ utilized in the stored samples. In the first stage, samples stored in oxygen-enriched atmospheres had higher O₂ uptake than samples stored in air. Microbial growth was similar in both atmospheres. Under conditions of this study, head space enrichment to about 90% oxygen prolonged acceptable meat color when compared with samples stored in an air atmosphere.     

Controlled atmosphere storage to decrease physiological disorders in nectarines

'Fantasia', 'Flavortop', and 'Flamekist' nectarines were examined for their response to controlled atmosphere (CA) storage. All three cultivars stored well for up to 6 weeks at 0°C in an atmosphere of 10% O₂+ 10% CO₂, while some but not all the cultivars also stored well in 2% O₂+ 5% CO₂ or 10% O₂+ 5% CO₂. The physiological storage disorders of internal breakdown and reddening were almost completely absent in nectarines kept in 10% O₂+ 10% CO₂. When 'Flamekist' nectarines from two harvests were stored in 10% O₂+ 10% CO₂ atmosphere for 6 or 8 weeks at 0°C, the fruit from the first harvest was of better quality after post-storage ripening. Although this controlled atmosphere prevented internal breakdown and reddening, after extended storage fruit did not develop the increased soluble solids content or extractable juice during post-storage ripening that occurred in non-stored fruit. Therefore, while preventing storage disorders, CA does not reduce the loss of ripening ability occurring during nectarine storage.     

Effect of pyrophosphate and 4-hexylresorcinol pretreatment on quality of refrigerated white shrimp (Litopenaeus vannamei) kept under modified atmosphere packaging

ABSTRACT:  The effect of pretreatment with pyrophosphate and 4-hexylresorcinol in combination with modified atmosphere packaging (MAP) (80% CO₂, 10% O₂, 10% N₂, or 80% CO₂, 20% N₂) on the quality of white shrimp during storage at 4 °C was investigated. Shrimp pretreated with 2% pyrophosphate and 0.25% 4-hexylresorcinol and stored under MAP showed the lower microbiological and chemical deteriorations as evidenced by delayed microbial growth as well as lower trimethylamine (TMA) and total volatile base nitrogen (TVB) production ( P < 0.05). Additionally, the growth of coliforms was inhibited effectively. White shrimp pretreated with 4-hexylresorcinol had the lower melanosis throughout the storage compared with those without treatment ( P < 0.05). This was associated with the lowered polyphenol oxidase (PPO) activity in shrimp treated with 4-hexylresorcinol. Therefore, the effective retardation of microbiological and chemical deterioration of white shrimp stored under MAP with the decrease in melanosis could be achieved by pretreatment of the shrimp with pyrophosphate and 4-hexylresorcinol. Furthermore, decapitation could be another means to lower the microbial load and melanosis in white shrimp, particularly those stored under MAP.     

INFLUENCE OF MODIFIED ATMOSPHERE PACKAGING ON GROWTH OF CLOSTRIDIUM PERFRINGENS IN COOKED TURKEY

Clostridium perfringens containing samples of sterile ground turkey were studied to assess growth under modified atmosphere conditions. Samples were packaged under various atmospheres (CO₂/O₂/N₂: 75/5/20, 75/10/15, 75/20/5, 25/20/55, 50/20/30), stored at 4, 15 and 28C, and sampled periodically for growth. Diluted samples were plated on Shahidi Ferguson perfringens agar (Difco Laboratories, Detroit, MI) to determine vegetative cell counts. Temperature abuse (cyclic and static) of the turkey product was also investigated. The results showed that the growth of C. perfringens was slowest under 25–50% CO₂/20% O₂/balance N₂ at 15 and 28C. There was no growth at 4C for up to 28 days. Temperature abuse (28C storage) of refrigerated products for 8 h did not permit C. perfringens growth. Use of 25–50% CO₂/20% O₂/balance N₂ may extend the shelf-life of turkey, but in the absence of proper refrigeration, it cannot be relied upon to eliminate the risk of C. perfringens food poisoning .     

PHYSICAL AND MICROBIAL CHARACTERISTICS OF PORK LOINS IN MODIFIED ATMOSPHERE PACKAGES

Bone-in pork loins (n = 45) were selected from a commercial facility, subjected to one of three gas flush packaging treatments: NC: 75% N₂, 25% CO₂; ONC₁: 45% 0₂, 35% N₂, 20% CO₂; ONC₂: 66% O₂, 9% N₂, 25% CO₂, and stored for 7, 14 or 21 days at 0±2C. After storage, treatment and storage effects on visual evaluations, storage characteristics, microbial analysis and retail display characteristics were determined. The ONC¹ and ONC²treated loins had less discoloration after 21 days than NC treated loins, and NC treated chops had the least desirable retail display characteristics (P < 0.05). Fewer (P < 0.05) lactic acid producing bacteria (day 21) were found on NC treated loins, resulting in chops with a shorter retail shelf-life. These results indicate that higher oxygen levels (45 and 66%) are necessary for the modified atmosphere storage of fresh pork loins for 21 days.     

Modified atmosphere packaging of shredded lettuce

A retail package system was used to study the atmosphere modification which developed within packages of shredded Iceberg lettuce, sealed in trays with a range of polymer films of different gas permeabilities (oxygen permeability of 3000 to 10,000 ml/m²/day/atm. at 25°C). Modified atmospheres were produced both naturally by respiration, and by application of gas flushing techniques.
The effects of these modified atmosphere conditions on visual and sensory quality of shredded lettuce was observed by monitoring colour change and development of off-odours. An equilibrated modified atmosphere containing 1–3% O₂ and 5–6% CO₂was established with 35 um low density polyethylene film after flushing with 5% O2, 5% CO₂ in N₂. This resulted in a shelf-life of approximately 14 days at 5°C, almost double that of the controls.     

THE EFFECT OF OXYGEN SCAVENGERS ON THE COLOR STABILITY AND SHELF-LIFE OF CO, MASTER PACKAGED PORK

Pork chops were stored with and without O₂ scavengers in a modified atmosphere (50% CO₂/50% N, or 100% CO₂) master pack system at 0C for up to 21 days, At 7-day intervals, the chops were displayed at ca. 4.5C for 96 h. Color (L, a, b, hue and chroma); panelist assessments of color and odor; and drip losses were recorded. Oxygen scavengers reduced O₂ levels, resulting in chops that were generally as red as flesh, but tended to have higher hue angles at 0 h, and towards the end of display (P<0.05). Visually, chops packaged in 50% CO₂/50% N₂ were less acceptable than flesh (P<0.05). There were no odor differences between flesh and packaged chops. Fresh chops had lower drip losses than packaged (P<0.05). An acceptable display life was obtained for pork chops stored for up to 21 days in a modified atmosphere CO₂ master pack containing O₂ scavengers.     

Shelf life of Turkish whey cheese (Lor) under modified atmosphere packaging

In this study, the shelf life of Lor cheese stored under different atmosphere compositions was assessed and compared. Lor cheeses were held in four different atmospheres containing: vacuum packaging (VP), 40% CO₂/60% N₂, 60% CO₂/40% N₂ and 70% CO₂/30% N₂ (modified atmosphere packaging). Control cheeses were stored in air. All cheese samples were kept in the refrigerator at 4°C for 45 days and investigated for physicochemical, microbiological and sensory properties. The acidity index value was significantly higher ( P  < 0.05) in the control and vacuum packaged samples than in those stored for the same period under CO₂. Microbiological results showed that modified atmosphere packaging delayed microbial growth compared with air and VP samples. Of the three modified atmospheres, gas mixtures 60% and 70% CO₂ were the most effective for inhibition of growth of micro-organisms. Sensory evaluation (odour and taste) results showed that Lor cheese packaged under modified atmosphere packaging (60% CO₂/40% N₂ and 70% CO₂/30% N₂ ) retained good characteristics for 45 days of storage, while vacuum and control samples were sensorily unacceptable after 10 days of storage.     

Inhibition of Fungal Growth on Wheat and Rye Bread by Modified Atmosphere Packaging and Active Packaging Using Volatile Mustard Essential Oil

ABSTRACT: Wheat and rye bread artificially inoculated with molds were packed in modified atmospheres of 0%, 50%, 75%, or 100% CO₂ balanced with N₂, and 3 levels of residual O₂, 1%, 0.03%, or <0.01%/O₂-absorber, and stored for 30 to 35 d. Modified atmosphere packaging (MAP) was quantitatively more effective for rye bread because fewer mold species grew at elevated CO₂. However, the major rye bread contaminant, Penicillium roqueforti , was the overall most CO₂-resistant mold and only the use of O₂-absorber could prevent growth of this species. On wheat bread, the most CO₂-tolerant mold was Penicillium commune , growing in 99% CO₂ (with high residual O₂), and Aspergillus flavus was the mold species that grew at lowest O₂ in 75% CO₂ treatment. The spoilage yeast/"chalk mold" Endomyces fibuliger was less affected by the different O₂ levels than the true filamentous molds, and none of the tested MAP treatments could prevent growth, but lag-phase was increased with O₂-absorber on wheat bread and decreased with 1% residual O₂ on rye bread. Experiments with volatile mustard oil showed that A. flavus and Eurotium repens were the most mustard oil-resistant species on wheat and rye bread, respectively. A combination strategy with MAP and mustard oil proved most optimal, and total inhibition was achieved with 2 μL mustard oil/rye bread slice and between 2 and 3 μL/wheat bread. Results indicated that the nature and surface area of the product influences effectiveness of active packaging with mustard oil.     

Effect of controlled atmospheres on maintaining quality of persimmon fruit cv. "Rojo Brillante"

ABSTRACT:  Astringent "Rojo Brillante" persimmon fruits were stored in air or in 2 different controlled atmospheres: 10% CO₂+ 90% N₂ (CA1) or 97 % N₂+ air (CA2) for up 50 d at 15 °C. After different periods, the fruit were treated with 95% CO₂ for 24 h at 20 °C in order to remove astringency, and then transferred to 20 °C in air free of CO₂ for 5 d to simulate shelf life. Other fruits were directly transferred to shelf life without being submitted to deastringency treatment. Storage under CA2 allowed storability of persimmon "Rojo Brillante" during 30 d at 15 °C, maintaining commercial firmness. Moreover, CA2 had an effect on removing astringency when fruits were stored for 30 d at 15 °C, or after 20 d following to shelf life. As consequence, deastringency treatment could be avoided when the fruits were previously stored under this controlled atmosphere.     

Influence of Storage Atmosphere and Temperature on Quality Evolution of Cut Belgian Endives

ABSTRACT: An optimal combination of O₂, CO₂, and N₂ for storage of cut Belgian Endive was defined, investigating visual quality aspects. In the experimental design, principles of mixture theory were used. The acceptability of cut endives stored under different gas combinations, selected in the range where both CO₂ and O₂ were varied between 2% and 18%, was evaluated by a consumer panel at different time intervals during storage. The response was modeled with a second-degree polynomial, the response surface pointed in the direction of a gas mixture 10% CO₂, 10% O₂, and 80% N₂ for maximum acceptability or best quality during storage. Repeated experiments, including different varieties from 2 different growers, confirmed the optimal gas concentration, (10% CO₂, 10% O₂, and 80% N₂). In a second step, the effect of temperature on quality degradation of cut endives stored under optimal atmosphere conditions, was quantified using the Arrhenius equation. An activation energy of 16.3 kcal/mol was obtained.     

Changes of glucosinolates in mixed fresh-cut broccoli and cauliflower florets in modified atmosphere packaging

ABSTRACT:  Glucosinolates of broccoli and cauliflower florets were assessed to determine the effect of modified-atmosphere packaging on postharvest glucosinolate dynamics in mixed florets of Brassica vegetables. Mixed-packaged broccoli and cauliflower florets stored in food trays sealed with 2 different microperforated biaxial-oriented polypropylene films for up to 7 d at 8 °C were analyzed. Both applied modified atmospheres (1% O₂+ 21% CO₂; 8% O₂+ 14% CO₂) maintained aliphatic glucosinolates in cauliflower florets, whereas in broccoli florets, the aliphatic glucosinolate concentration decreased slightly in each modified atmosphere. In addition, total indole glucosinolate concentration for both broccoli and cauliflower florets was maintained, and even increased in cauliflower florets at 1% O₂+ 21% CO₂ due to rising neoglucobrassicin concentration. Thus, to simultaneously maintain glucosinolates and external appearance as well as to prevent off-odor, a modified atmosphere of 1% O₂+ 21% CO₂ provides a suitable environment for storage of this Brassica floret medley for up to 7 d at 8°C.     

Microbiological and physicochemical properties of red claw crayfish (Cherax quadricarinatus) stored in different package systems at 2 degrees C

ABSTRACT:  This study compared 3 package systems for their influence on the stability of shell-on red claw crayfish tail meat stored at 2 °C for 14 d. Modified atmosphere packaging (MAP, with 80% CO₂/10% O₂/10% N₂) suppressed ( P < 0.05) the growth of aerobic bacteria and coliforms when compared with aerobic packaging using polyvinylchloride (PVCP) and vacuum packaging (VP). MAP and VP tended to retard lipid oxidation, inhibited Ca-ATPase activity change, but produced more intense protein denatuation when compared with PVCP. The MAP packaging enhanced proteolysis and resulted in more ( P < 0.05) cooking losses and a higher ( P < 0.05) shear force than VP and PVCP for samples stored for 6 and 14 d ( P < 0.05). Sensory panel results were in general agreement with the physicochemical changes, suggesting that the specific package systems had a significant impact on the quality of refrigerated red claw crayfish raw meat.