Some effects of modified-atmosphere packaging and vacuum packaging in combination with antioxidants on quality and storage life of chilled potato strips

A modified-atmosphere packaging system for chilled fresh potato strips, which rapidly produced oxygen levels < 3%, was identified. This system enclosed the strips within 25 μ low density polyethylene film heat sealed to a fibre tray lined with Surlyn-PVdC-Surlyn, and the package flushed with an initial atmosphere of 5% O₂, 10% CO₂. An equilibrium-modified atmosphere of 3–4% CO₂, 1–2% O₂ was established after 3 days' storage at 5°C. This modified-atmosphere package, used in combination with dipping of potato strips in a 10% ascorbic acid solution, inhibited enzymatic discoloration for 1 week at 5°C. Vacuum packaging within a Surlyn/PVdC-coated polyester film, with or without dipping in ascorbic acid solution, inhibited discoloration of chilled potato strips stored at 5°C for at least 2 weeks.     

Physicochemical, Microbiological, and Sensory Evaluation of Minimally Processed Tarocco Clone Oranges Packaged with 3 Different Permeability Films

ABSTRACT: Fruits of 3 Tarocco clones ('Gallo', 'Arcimusa', and 'Scirè') were sliced, packaged with different permeability films, and stored at 4°C for 14 to 15 d to find the best clone for processing and the most suitable packaging conditions to extend the shelf life of these products. Physicochemical parameters of Tarocco oranges slices, packaged with 3 films of different permeability, did not show marked decay phenomena during the storage days. Only a reduction in the ascorbic acid content was observed in almost all the examined clones, especially in products packaged with the most O₂ permeable films. Concerning microbiological contamination, all clones, packaged with the 3 films, showed, until the 12th storage day, a lower number of colony forming units (CFU)/g (≤ 3.6 × 10⁷ CFU/g) for mesophilic viable counts than the 2 microbiological criteria generally used for fresh-cut fruit and vegetables (10⁸ CFU/g for mesophilic viable counts). In fact, for these products it is possible to expect a shelf life longer than 12 to 13 d. Regarding sensory results, it was observed that the minimally processed Tarocco clone slices packaged with the most permeable to O₂ film were the most appreciated.     

Quality characteristics of minimally processed leek packaged using different films and stored in lighting conditions

Since minimal processing of vegetables does not impede their capacity to react to external stimuli, this work sought to study the effect of lighting on minimally processed leek during storage. White and green cuts were processed separately and packaged using films with different permeability: a totally permeable PVC film and two P-Plus films: P-Plus 120 and P-Plus 90, with O₂ permeability of 8000 and 5000 cm³ m⁻² 24 h⁻¹ atm⁻¹ at 25 °C, respectively. All the packaged leek was stored at 4 °C for more than 26 days in two different conditions: in complete darkness and in light. Lighting caused an increase in stomatal aperture and respiratory rate. Thus, the white cut achieved atmospheres with higher CO₂ (10%) and lower O₂ (12%) content than samples packed in the same film kept in the dark. The green cut saw respiratory activity compensated by photosynthesis, and the atmosphere composition remained similar to atmospheric conditions until day 18. Lighting also affected the colour, accelerating the changes in appearance. Exposure to light had a negative effect on the quality parameters.     

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.     

EFFECT of MODIFIED ATMOSPHERE PACKAGING ON GLUTATHIONE and ASCORBIC ACID CONTENT of ASPARAGUS SPEARS

Asparagus (Asparagus Officinalis L.) spears were packaged in ordinary and microperforated oriented polypropylene (OPP) films and were stored at 15C and 75% RH for up to 10 days. CO₂ concentrations ranged from 15.5 to 23% at 10 days of storage. Weight loss was less than 1.2% in microperforated film packages compared with 15% in air storage under similar conditions. Ascorbic acid content was found to be adversely affected at all the O₂ levels (1–6%) prevailing in microperforated film packages, but it was retained to the extent of 45–55% of its original concentration in ordinary OPP film packaged asparagus. the O₂ concentrations in microperforated film packages were also associated with higher glutathione concentrations in packed asparagus spears. Results of the study indicated that to preserve ascorbic acid and glutathione simultaneously in stored asparagus through MAP under high CO₂ and low O₂ conditions, O₂ concentration levels must be selected between 1 and 6% in such a way so as to get acceptable retention levels of ascorbic acid and glutathione.     

Improved use of oxygen scavengers to stabilize the colour of retail-ready meat cuts stored in modified atmospheres

A series of three experiments were conducted to develop a retail packaging system suitable for use in centralized meat processing and packaging operations using modified atmosphere master packaging (MAP) of display-ready beef and pork cuts. It was shown that oxygen (O₂) scavengers were needed inside retail trays, lidded or over-wrapped trays could be used with equal success but inclusion of a grid inside the retail tray was not required. It was established that a minimum of eight O₂ scavengers with an O₂ absorption rate high enough to achieve an O₂ half-life of 0.6–0.7 h in the pack atmosphere were needed where the O₂ concentration could otherwise remain ≤500 ppm at any time during storage. Composite results from these experiments clearly showed that the best performance resulted from use of hard plastic retail trays containing eight O₂ scavengers, with high O₂ absorption rate, when placed underneath an absorbent pad and over-wrapped with an O₂ permeable film. Small holes in two corners of the O₂ permeable film to permit free exchange of atmospheres within the retail packages facilitated O₂ reduction during MAP storage.     

CONTROLLED ATMOSPHERE STORAGE AND EDIBLE COATING EFFECTS ON STORAGE LIFE AND QUALITY OF TOMATOES

Tomatoes at pink stage maturities were coated with Semperfresh^TM edible fruit coating which is composed of sucrose esters of fatty acids, sodium carboxymethyl cellulose and mono-diglycerides of fatty acids. One group of coated and uncoated tomatoes were stored at 23 × 2C under air atmosphere, another group was stored at 12C under air atmosphere and third group was stored at 12C, 93–95% RH in a controlled atmosphere (CA) containing 3% CO₂, 3% O₂ and 94% N₂. Samples of tomatoes were analyzed for firmness, weight loss, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene to examine changes in quality during storage. Semperfresh^TM edible fruit coating was found to be significantly effective at both storage temperatures (23 × 2C and 12C) in air to delay changes in firmness, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene. Semperfresh^TM fruit coating reduced fruit weight loss as compared to fruit without coating but the difference between coated and uncoated tomatoes was not significant. Shelf-life of pink tomatoes was increased 3 days at 23 × 2C and 6 days at 12C in air by coating. CA storage delayed compositional changes in tomatoes significantly as compared to air storage of coated and uncoated tomatoes. CA storage also had a significant potential for reducing weight loss and microbial spoilage. Tomatoes were stored 40 days in CA. Coated and uncoated tomatoes exhibited the same results in CA.     

Effectiveness of active and modified atmosphere packaging on shelf life extension of a cheese tart

This study evaluated the shelf life extension of a cheese cake subjected to modified atmosphere (MAP) and active packaging (AP). Cheese cakes were packaged under different N₂/CO₂ ratios (70/30 and 20/80) (MAP batches), by placing a sachet of an iron oxide-based oxygen absorber inside trays (AP batch) and with air (air batch). Changes in microbial growth, in-package gas composition, chemical–physical parameters including texture and sensory attributes were monitored for 48 days at 20 °C. AP allowed a mould-free cheese cake shelf life of 48 days, MAP extended the shelf life of samples packaged under 30% and 80% CO₂ up to 14 and 34 days, respectively, whereas tarts stored with air spoiled after 7 days. MAP resulted in a significant increase in hardness after 14 days of storage, whereas AP tarts recovered the initial texture after 48 days. Panellists judged AP tarts over the acceptability threshold during the whole shelf life of cheese tarts.     

Modified Atmosphere Packaging of Cut Belgian Endives

ABSTRACT: Modified atmosphere packaging of cut Belgian endives was simulated based on experimentally determined package and product parameters. Permeability of commercial packaging films was determined at 3 temperatures. The film permeability ratio for CO₂ and O₂ varied between 1.6 and 6. Respiration rate of cut Belgian endives stored under 10%O₂-10%CO₂-80%N₂ (optimal gas conditions) was measured at different temperatures. Initially, the activation energy for respiration rate was higher compared to the one for film permeability. After 3 d of storage, the E_a-value for respiration rate was similar to the E_a-value for film permeability. Simulations at constant temperature proved that none of the packaging films tested was suitable to maintain optimal gas conditions.     

Physicochemical Properties and Microbial Stability of Reduced-Fat Chinese-Style Sausage Stored under Modified Atmosphere Systems

ABSTRACT: Physicochemical properties and microbial stability of reduced-fat Chinese-style sausages packaged with various modified atmosphere packaging (MAP) systems were evaluated. With the exception of VAC (vacuum) treatment, the TBARS (thiobarbituric acid-reactive substances) values increased with increasing storage time. Treatments of C100 (100% CO₂), C80 (80% CO₂/20% N₂), and C20 (20% CO₂/80% N₂) were higher in TBARS values than VAC and N2 (100% N₂) after 2 wk of storage. The numbers of total plate counts, psychrotrophs, total anaerobes, or lactic acid bacteria increased slightly, though statistically insignificant, during storage, while N2 was numerically the lowest and VAC was intermediate. Vacuum packaging was more effective than other MAP in maintaining lipid and microbial stability of reduced-fat Chinese-style sausage. Keywords: reduced-fat, Chinese-style sausage, MAP, storage stability, vacuum packaging     

IDENTIFICATION OF HURDLES FOR IMPROVING STORAGE STABILITY OF BRAISED KIDNEY BEANS, A KOREAN SEASONED SIDE DISH

The aim of this study was to identify factors affecting the preservation of braised kidney beans, a traditional Korean side dish, to extend its shelf life. The effects of ingredient formulation, refrigerated storage and modified atmosphere packaging on storage stability and/or sensory quality were examined. Count of yeast/mold was selected as a primary quality index from the storage test at 10C. A formulation was found in cooked kidney beans, sugar, soy sauce and corn syrup to provide the retarded microbial growth and affordable sensory quality. The temperature dependence value (Q₁₀) for the shelf life of the stretch-wrapped product was 2.0 for temperatures of 5 to 20C. Modified atmosphere packaging (60% CO₂/40% N₂ or 100% CO₂) extended the shelf life at 10C by 500% (to 36 days) compared to air packaging (6 days) based on criteria of yeast/mold growth. Equations for estimating microbial spoilage and shelf life were derived as function of temperature.

PRACTICAL APPLICATIONS

Microbial growth retardation by ingredient formulation change, chilled storage and high CO₂ modified atmosphere packaging is useful to design the processing, packaging and distribution of the Korean side dish product. Quality change kinetics of yeast/mold growth established can be used for determining shelf life of the product under different storage temperature conditions. Through the scale-up procedure, the knowledge found in this study will be useful for the industrial processing and storage of the seasoned side dishes.     

Modified atmosphere packaging of common mushroom

Until recently, the films used for packaging fresh fruits and vegetables were not permeable enough to balance the high respiration rate of mushrooms. Consequently, modified atmosphere packaging (MAP) in sealed pouches or punnets was not appropriate for this commodity. Four microporous films in oriented polypropylene (OPP) and one film currently used to overwrap mushroom punnets (stretchable PVC) were tested. Mushroom punnets placed into pouches were stored at 4 and 10°C for 8 days. the influence of the modified atmosphere on the marketing quality of pre-packed mushrooms was assessed by measuring the external and internal colour, development stage, firmness and microbial growth. A mathematical model was used to predict the gas composition within the pouches at steady state as a function of the film properties and the characteristics of the plant tissues. the equation calculated from the simplified model shows a linear relationship between the reciprocal of O₂ concentration at steady state, (1/x) at 10 and 4°C and the reciprocal of the film permeability, (1/PmO₂).     

Microbiological, physicochemical and organoleptic changes in dry-salted olives of Thassos variety stored under different modified atmospheres at 4 and 20 °C

Microbiological, physico-chemical and organoleptic changes were studied in dry-salted olives, cv. Thassos, stored under different atmospheres (100% carbon dioxide and nitrogen, 40% CO₂/30%O₂/30%N₂ and air) at 4 and 20 °C for 180 days. The initial microbial flora comprised of yeasts, no lactic acid bacteria, enterobacteria, pseudomonads or Staphylococcus aureus were detected, as the low water activity/high salt content does not favour their growth. At 4 °C, the population of yeasts declined steadily throughout storage but to a different extent depending on the gaseous atmospheres. At 20 °C, there was an initial decline in yeast counts in all samples followed by a steady increase until the end of the storage period. The CO₂ atmosphere was most effective at keeping the number of yeasts low at both storage temperatures. All gas atmospheres prevented fungal growth at both temperatures apart from the samples stored in air. The pH, a_w and salt content of the olives did not change significantly throughout the storage period. The prevailing yeast species was the salt tolerant Candida famata . The organoleptic characteristics did not differ significantly among differently treated olives. However, increased rancidity and reduced fruit colour was observed in the samples stored at 20 °C.     

Quality changes of fresh-cut kohlrabi sticks under modified atmosphere packaging

ABSTRACT:  The aim of this study was to determine the effect of different gas compositions on quality attributes and shelf life of kohlrabi sticks stored in modified atmosphere up to 14 d at 0 °C. Two commercial films were tested: oriented polypropylene (OPP) and amide-polyethylene (amide-PE). As a control, a microperforated OPP film was used. In order to study the changes in metabolic activity by minimal processing, the respiration rate and ethylene production at 0 °C were monitored for both intact stems and sticks. Changes in color, chemical parameters, sugars and organic acid contents, and sensorial quality of kohlrabi sticks were evaluated. An initial ethylene production of sticks was 13-fold higher than that of intact stems; meanwhile CO₂ production was 2-fold higher. However after 4 d of storage, a similar respiration rate for stems and sticks was found. Also the ethylene production of sticks and stems was steady around 15 to 20 nL/kg^/h after 10 d. Kohlrabi sticks showed a little change in chemical parameters and very low weight losses during cold storage. Sticks under an equilibrium atmosphere of 7 kPa O₂ and 9 kPa CO₂ at 0 °C reached by amide-PE kept an acceptable sensorial quality for 14 d.     

Maintaining Quality of Fresh-cut Tomato Slices through Modified Atmosphere Packaging and Low Temperature Storage

ABSTRACT: Quality of fresh-cut tomato slices was compared during cold storage under various modified atmosphere packaging conditions. Chilling injury of slices in containers sealed with Film A was higher than with Film B; these films had oxygen transmission rates of 87.4 and 60.0 ml · h^-1· m^-2· atm^-1 at 5 °C and 99% RH, respectively. While slices in containers with an initial atmospheric composition of air, 4% CO₂+ 1 or 20% O₂, 8% CO₂+ 1 or 20% O₂, or 12% CO₂+ 20% O₂ showed fungal growth, slices in containers with 12% CO₂+ 1% O₂ did not. Low ethylene in containers enhanced chilling injury. Modified atmosphere packaging provided good quality tomato slices with a shelf life of 2 w or more at 5 °C.     

Effect of ripeness at processing on fresh-cut 'Flor de Invierno' pears packaged under modified atmosphere conditions

The effects of ripeness at processing and packaging conditions on respiration, microbiological stability as well as colour and firmness of fresh-cut 'Flor de Invierno' pears were evaluated throughout storage. Although a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere led to an inhibition of ethylene synthesis and carbon dioxide production compared with non-modified atmosphere packaging, the more advanced the ripeness stage at processing, the higher the physiological activity and thus, the higher production of carbon dioxide, ethylene and ethanol. A 2.5-kPa O₂ + 7-kPa CO₂ atmosphere inhibited bacterial growth, yeast and mould proliferation in mature-green pears but fast microbial growth was observed especially on ripe pears, under both packaging conditions. In conclusion, the shelf-life of ripe pears was reduced by increased respiration response to processing and accelerated microbial spoilage. Instead, pears processed in a partially ripe stage were suitable for conservation while gathering desired sensory attributes. Therefore, for commercial purposes, a shelf-life of 10 days was suggested for partially ripe fresh-cut pears packaged under a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere.     

Influence of exposure to light on the sensorial quality of minimally processed cauliflower

ABSTRACT:  The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 °C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O₂ and high levels of CO₂ in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h * and L * were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O₂ contents and high CO₂ contents. These atmospheres produced a loss of texture and the development of off-odors.     

Mesophilic Aerobic Population of Fresh-cut Spinach as Affected by Chemical Treatment and Type of Packaging Film

ABSTRACT: Fresh-cut spinach was treated with citric acid and ascorbic acid solutions and packaged in mono-oriented polypropylene bags or low-density polyethylene bags. Response surface methodology was used to study the simultaneous effect of chemical treatment and refrigerated storage time on headspace gas composition, mesophilic aerobic population (AP), and pH of fresh-cut spinach. Type of film affected %CO₂, %O₂, and pH but did not influence AP. Chemical treatment reduced initial pH values and initial microbial counts. AP and pH increased during refrigerated storage. The model developed for AP enabled finding acid concentrations that lowered AP below any proposed microbiological criterion at production and consumption stages of fresh-cut spinach stored at 4 °C.     

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 quality of shredded Cheddar cheese packaged in modified atmospheres

The microbiological quality of shredded Cheddar cheese packaged in different modified atmospheres with and without oxygen scavengers included in the packaging film was studied with the aim of determining how modified air packaging would affect the mould species present on shredded Cheddar cheese. The film with oxygen scavengers was more effective than the control film against mould growth, whereas the 73% CO₂/27% N₂ atmosphere resulted in the cheese with the best microbiological qualities. The three modified atmospheres and the packaging film influenced the mycoflora of shredded Cheddar cheese as the mould species isolated initially differed, from those isolated at 16 weeks in the six treatments. This study demonstrated that O₂ scavengers were effective in controlling the growth of moulds on shredded Cheddar cheese.