EFFECT OF ATMOSPHERE ON BROCCOLI SENSORY ATTRIBUTES IN COMMERCIAL MAP AND MICROPERFORATED PACKAGES1

Broccoli was packaged using 2 microperforated (cross-micro, SM60®) and 3 modified atmosphere packages (MAP) (polyethylene MAP, broccoli MAP, lettuce MAP). Packaged broccoli was stored 9 days at 2C and an additional 1, 3, 4 and 6 days at 13C, for a total storage 10, 12, 13 and 15 days, respectively. Concentrations of CO₂ and O₂ were determined after 12 days. Sensory analyses were conducted after 10, 12, 13, and 15 days. Broccoli quality was evaluated for ten sensory attributes by eight trained judges. Analysis of variance and principal component analysis were used to determine the effect of packaging and storage time. Broccoli packaged in lettuce MAP was most anaerobic (3.9% CO₂, 1.2% O₂) and developed sauerkraut-like odors/flavors after 10 days of storage. The microperforated wraps did not alter the gas composition of the packages (16.3% O₂, 0.2% CO₂) and broccoli became yellow and limp after 15 days. In contrast, broccoli packaged in the polyethylene and broccoli MAP packages modified the CO₂ and O₂ concentrations and maintained the broccoli quality for the duration of the experiment (15 days).     

The effects of packaging film and storage temperature on the quality of a dry coleslaw mix packaged in a modified atmosphere

Summary The effects of six packaging treatments on the quality of dry coleslaw packaged in modified atmospheres and stored at 4 and 8 °C for 9 days were determined. The coleslaw was packaged within either oriented polypropylene (OPP) or one of four microperforated OPP films, PA‐120, PA‐160, PA‐190, and PA‐210. It was also stored within punctured OPP (i.e. in air). Packaging within OPP resulted in an atmosphere with very low O₂ (<1%) and extremely high CO₂ (25–35%) levels. These storage conditions had detrimental effects on the quality of coleslaw: loss of firmness, falling pH, high cell permeability and exudate, high surface moisture and poor acceptability of aroma. By contrast, the microperforated films generated less atmosphere modification; in some cases this was insufficiently modified to be technically useful. The relatively high O₂ levels in these microperforated packs resulted in lower appearance and colour scores, increased surface dryness and higher firmness values. Increasing storage temperature from 4 to 8 °C resulted in a reduction in shelf‐life for all film types. While still not optimal, packaging within microperforated films allowed better preservation of quality and reduced cell membrane damage.     

Application of Modified Atmosphere Packaging and Active/Smart Technologies to Red Meat and Poultry: A Review

This paper reviews the current advances in modified atmosphere packaging (MAP) of red meat and poultry products. This type of packaging results in shelf-life prolongation by inhibiting microbial growth and promoting oxidative stability, compared to those packaged aerobically. High O₂ modified atmosphere packaging results in the desirable red colour, but it also enhances both lipid and pigment oxidation and promotes the growth of aerobic spoilage microorganisms. The presence of high levels of CO₂ in modified atmosphere packages inhibits microbial growth but can also cause meat discoloration through oxidation. Low O₂ MAP atmospheres limit microbial growth but change the colour of meat to purple. The use of CO gives promising results due to its positive effects on colour and microorganism growth inhibitions which result in shelf-life prolongation during wider distribution of case-ready products. The use of MAP can lead to an effective growth reduction of pathogenic microorganisms like Listeria sp. and Salmonella sp. The combination of MAP and vacuum with other treatments can be an effective tool in delivering safe minimally processed foodstuffs. In response to the changes in consumer demand and market trends, the area of active and intelligent/smart packaging is becoming more and more important. These relatively new technologies are capable of providing better results regarding product safety and shelf-life prolongation as well as communicating information on several quality characteristics of packaged food during transportation and storage.     

STORAGE QUALITY OF MINIMALLY PROCESSED CABBAGE PACKAGED IN PLASTIC FILMS

The effects of packaging and storage at 3C in a refrigerated case on quality changes of minimally processed cabbage were studied. Shredded cabbage samples were packaged in three forms: bags of monooriented polypropylene film (OPP bags) and polyethylene trays overwrapped with a multilayer polyolefin (RD106-PE tray) or with a plasticized PVC film (PVC-PE tray). All types of package effectively controlled the weight loss. The modified atmosphere in PVC-and RD106- PE trays did not change more than 3% as compared with normal atmosphere levels. However, in OPP bags, O₂ reached 2% and CO₂ increased to approximately 13% after 3 days. The microbiological quality during the storage period for all types of packaging was satisfactory. OPP samples were significantly better (p <0.05) in general appearance, wilting and browning but developed an off-odor. No off-odor was detected in samples packaged in PVC and RD106-PE trays. Shelf life for the three packaging forms was estimated.     

QUALITY OF MINIMALLY PROCESSED LETTUCE AS INFLUENCED BY PACKAGING AND CHEMICAL TREATMENT

Shredded lettuce was packaged in sealed bags of monooriented polypropylene (OPP) film and also in polyethylene (PE) trays overwrapped with a multilayer polyolefin (RD106) or plasticized polyvinyl chloride (PVC) film; and stored at 4C in a refrigerated case during 8 days. Chemical treatment by dipping in a 0.3% ascorbic acid /0.3% citric acid solution did not significantly affect changes in microbial populations or visual sensory attributes. Type of package was not a significant factor for microorganism populations, but was significant (p<0.001) for changes in gas composition and visual sensory attributes. The modified atmosphere within the packages changed from normal air composition to about 1.5% O₂/12% CO₂ for OPP bags and to about 17–18% O₂/1–2% CO₂ for PVC-PE trays and RD106-PE trays after 8 days of storage. The visual sensory quality of the product was retained better in OPP bags than in the other ones.     

Effects of modified atmosphere packaging (MAP) on the microbiological quality and shelf life of ostrich meat

Effects of various concentrations of O₂/CO₂ in modified atmosphere packaging on the microbiological quality and shelf-life of ostrich meat was investigated. Nine–12 months old ostriches were used. The iliofibularis muscle was cut into small cubes that were divided into five groups and then separately packaged under various gas mixes: air and O₂:CO₂:N₂ ratios of 80:20:0, 60:20:20, 60:40:0, and 40:40:20, using 2 different headspace ratios (1:1 and 3:1). The packaged meats were kept at 4 °C for 10 days and were analysed microbiologically, physico-chemically and sensorially. As a result, the meat quality and shelf-life of ostrich meat under various gas compositions were improved; microbial growth was delayed due to high CO₂ usage and shelf-life was increased by 5–7 days. However, an undesired loss of red colour of the ostrich meat may affect consumer acceptance.     

Quality of broccoli as influenced by film wrapping during shipment

'Shogun' broccoli florets were film-wrapped and stored for 7 days at 1 °C to simulate a maximum period of commercial shipment. After cold storage, florets were kept for 2.5 days at 20 °C to simulate a retail sale period. For wrapping, polyvinyl chloride (PVC) 9 µm thickness and low-density polyethylene (LDPE) 11, 15, and 20 µm thickness were used. Soluble solids content, pH, titratable acidity, weight loss, physiological disorders, visual quality, and gas composition within packages were monitored. Gas composition (about 18% O₂ and 1% CO₂ during cold storage and about 16% O₂ and 2-3% CO₂ during shelf life), overall quality, and yellowing and browning of the florets were at similar levels among the films studied. However, weight loss was about sixty times lower for all LDPE films than for PVC film. After shelf life the best results were obtained by using 15 µm LDPE. This polymeric film could be a good alternative to PVC for wrapping broccoli for commercial shipment purposes, particularly to those countries where use of PVC has been forbidden.     

QUALITY CHANGES IN FRESH‐CUT SPINACH (SPINACIA OLERACEA) UNDER MODIFIED ATMOSPHERES WITH PERFORATIONS

ABSTRACT

Fresh‐cut spinach leaves were stored for 4 days at 15C and 75% relative humidity under modified atmosphere packaging to assess the impact of differential in‐pack gas atmospheres generated through different packaging films and variable in‐pack weight on the quality of stored produce. After 4 days of storage, retention of chlorophyll, β‐carotene and ascorbic acid was better in low‐density polyethylene (LDPE) packages than in polypropylene (PP) packages. LDPE film‐packaged samples had higher phenolic content than PP film‐packaged samples. Low in‐pack O₂ (1–2 kPa) along with the buildup of CO₂ (8–10 kPa) seems to have enhanced the retention of antioxidant components, i.e., β‐carotene and ascorbic acid, in LDPE packages. This helped in chlorophyll retention and also prevented formation of oxidation compounds of phenols that otherwise caused browning of cut surfaces. Thus, O₂ and CO₂ permeability of packaging film or in‐pack weight of produce might be such that equilibrated O₂ partial pressures remain near to 1–2 kPa so as to affect a beneficial increase in the phenolic content along with concomitant retention of chlorophyll.

PRACTICAL APPLICATIONS

Fresh‐cut spinach leaves have received an enormous demand due to their utility in various traditional Indian preparations. Shelf life and quality of fresh‐cut produce may be greatly reduced due to high rates of respiration. Traditional packaging and handling techniques reduce the shelf life and sensory quality of fresh‐cut spinach. Temperature control and atmospheric modifications help to maintain produce quality by reducing respiration rate and enhance shelf life by minimizing the adverse effects of cutting. This research focused on evaluation of respiratory behavior of fresh‐cut spinach leaves at a temperature commonly encountered during transportation and retail distribution, i.e., 15C, and the effect of different polymeric films and in‐pack weights on produce quality. The results of the study suggest that packaging of fresh‐cut spinach in polymeric film packages could maintain the sensory quality and reduce degradation of various physicochemical constituents. Utilization of the results for proper design of modified atmosphere packages for this highly perishable produce can prove to be extremely beneficial for safe storage and transportation to urban retail markets.     

Modified Atmosphere Packaging Protects Market Quality in Broccoli Spears Under Ambient Temperature Storage

Broccoli spears were packaged using a semipermeable polymeric film and stored 96 hr at 20°C. CO₂ and O₂ concentrations within the packages equilibrated to about 9 and 3%, respectively. Relative to non-packaged spears, ascorbic acid, chlorophyll and moisture retention were greater; and peroxidase activity was lower in packaged broccoli. No differences were found in total aerobic microbial population growth or Instron shear values between packaged and control spears.     

PROLONGING THE SHELF-LIFE OF FRESH GREEN CHILE PEPPERS THROUGH MODIFIED ATMOSPHERE PACKAGING AND LOW TEMPERATURE STORAGE

The postharvest quality of green chile fruit was compared after storage in 3 types of packages at 2 temperatures (24C and 8C). Package types were corrugated cardboard boxes, pressed cardboard trays overwrapped with VF-71 polyethylene, or low-density polyethylene (LDPE) bags. Fruit packaged in boxes or overwrapped trays had 24.8% and 10.1% weight loss, respectively, after 1 week of storage at 24C. Fruit packaged in polyethylene bags lost 0.3% weight and remained green. After 1 week at 8C, the weight losses were 3.8%, 1.8% and 0% for the boxed, overwrapped and bagged treatments, respectively. Postharvest quality was maintained up to 4 weeks when fruit were packaged in LDPE bags and stored at 8C. In a second study, steady state O₂ and CO₂ levels were determined inside the LDPE packages as fruit weight and temperature were varied. Storage temperatures were 24C, 16C and 8C. At 8C, steady state O₂ levels ranged from 12.0 kPa to 0.9 kPa, and CO₂ levels ranged from 2.0 kPa to 4.6 kPa as fruit weight was increased from 120 to 480 g. At 24C and 16C, fruit packaged in 480 g units had slower ripening rates than fruit packaged in smaller units; however, fruit stored at 8C remained green the longest, regardless of fruit weight.     

Effects of fibre orientation, myoglobin redox form, and postmortem storage on NIR tissue oximeter measurements of beef longissimus muscle

To determine near-infrared tissue oximeter responses to muscle fibre orientation, display time, and surface colour differences of beef longissimus lumborum steaks, beef loins were cut into steaks either perpendicular or parallel to the muscle fibre orientation. Surface colour differences were created by packaging steaks in vacuum (VAC), 80% O₂ and 20% CO₂ modified atmosphere packaging (HiOx MAP), polyvinyl chloride film overwrap (PVC), and HiOx MAP converted to PVC (HiOx-PVC) after 2 days. Changes in surface colour and subsurface pigments during display (0, 2, 4, 10, and 15 days at 2 °C) were characterized by using a reflectance-spectrophotometer and a near-infrared tissue oximeter, respectively. Fibre orientation, storage, and packaging affected (P < 0.05) colour, total pigment, deoxymyoglobin, and oxymyoglobin content. Tissue oximetry measurements appear to have potential for real-time monitoring of myoglobin redox forms and oxygen status of packaged meat, but fibre orientation needs to be controlled.     

Effect of initial oxygen concentration and film oxygen transmission rate on the quality of fresh‐cut romaine lettuce

Modified atmosphere packaging (MAP) is widely used to maintain the quality of fresh‐cut produce by matching the oxygen transmission rate (OTR) of the packaging film to the respiration rate of the packaged product. The effect of the interaction between film OTR and the initial headspace O₂ on quality of fresh‐cut vegetables has not previously been reported. Romaine lettuce leaves were sliced, washed, dried and packaged with film OTRs of 8.0 and 16.6 pmol s^?1 m^?2 Pa^?1, and with initial headspace O₂ of 0, 1, 2.5, 10 and 21 kPa. Packages were hermetically sealed and stored at 5 °C for up to 14 days. For samples packaged in 16.6 OTR film, increasing the initial headspace O₂ concentration delayed O₂ depletion within the packages, hastened the onset and increased the intensity of discoloration, and inhibited the development of CO₂ injury, acetaldehyde and ethanol accumulation, off‐odors and electrolyte leakage. With 8.0 OTR‐packaged lettuce pieces, ≤1 kPa initial headspace O₂ treatments induced an essentially anaerobic environment within the packages and increased acetaldehyde and ethanol accumulation and off‐odor development. Increasing the initial O₂ concentration above 1 kPa in 8.0 OTR packages transiently increased O₂ concentrations and reduced fermentative volatile production, off‐odors, electrolyte leakage and CO₂ injury. Regardless of initial headspace O₂ concentration, all 16.6 OTR‐packaged samples had severe discoloration after 14 days of storage. Quality was better maintained in 8.0 OTR‐packaged lettuce pieces as the initial headspace O₂ concentration was increased. A 21 kPa initial O₂ treatment of 8.0 OTR‐packaged lettuce maintained good quality throughout storage and had the best overall quality score. Copyright © 2005 Society of Chemical Industry     

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.     

Effect of modified atmosphere and vacuum packaging on some quality characteristics and the shelf-life of “morcilla”, a typical cooked blood sausage

The effect of modified atmosphere and vacuum packaging on the shelf-life of “morcilla”, a traditional cooked blood sausage, was investigated. A total of 99 “morcillas” were packaged under vacuum and in modified atmosphere using three different gas mixtures: 15:35:50/O₂:N₂:CO₂ (atmosphere 1), 60:40/N₂:CO₂ (atmosphere 2) and 40:60/N₂:CO₂ (atmosphere 3), and stored during 2, 4, 6 and 8 weeks at 4 °C. Shelf life evaluation was based on pH, water activity (a_w), colour (CIE L*, a*, b*, C* and h*), TBARS formation and microbial counts. The results indicated that, in general, storage time affected (P < 0.05) all parameters whereas no significant differences were observed (P > 0.05) among packaging conditions. Based on the microbial counts, the shelf-life of “morcilla” would be greater than 8 weeks for all packaging conditions. Samples packaged with high CO₂ concentrations (40:60/N₂:CO₂) showed the lowest values of TBARS at the end of storage.     

Gas exchange dynamics in modified atmosphere packaging of soft cheese

Modified Atmosphere Packaging (MAP) is a shelf-life extension technique that has been widely applied to horticultural, meat and dairy products. It relies on the interaction between product, packaging material and environment, which determines the gas composition inside the package at steady state. Therefore, MAP design needs to take into consideration O₂ consumption and CO₂ production rates of the product and the mass transfer coefficients for the gas exchange through the packaging material and how they are affected by environmental factors such as storage temperature. In this work, a mathematical model was developed for designing MAP systems for a soft cheese (camembert-type). The model was used to evaluate the effect of perforations on O₂ and CO₂ concentrations of package containing cheese, at constant and varying storage temperatures. The predicted gas composition was compared with those obtained experimentally at 293 and 285 K with packages having different numbers of perforations (1), (2) and (3). Experimental values of gas composition observed at steady state with one perforation were 0.050 and 0.148 (v/v) at 285 K for O₂ and CO₂ respectively, and 0.003 and 0.207 (v/v) at 293 K. Gas composition was found to take values between 0.009–0.058 for O₂ and 0.154–0.200 for CO₂, when the packages with a single perforation were exposed to storage temperature varying between 285 and 293 K during 14 days of storage. The model developed was able to accurately predict the gas exchange dynamics of the package throughout the storage period whether the temperature of storage was constant or not.     

Modified Atmosphere Packaging Affects Ascorbic Acid, Enzyme Activity and Market Quality of Broccoli

Reduced ascorbic acid (RAA) content, total chlorophyll and green color retention, enzyme activities and texture changes were followed in broccoli spears packaged in polymeric film and nonpackaged during 96 hr storage (10°C). Concentrations within packages monitored by gas chromatography were (CO₂,) 8% and (0²) 10%. RAA retention, moisture content, total chlorophyll and color retention were greater in packaged broccoli. No differences were found between packaged and nonpackaged broccoli for ascorbate oxidase and peroxidase activities, or texture.     

Effects of packaging type, gas atmosphere and storage temperature on survival and growth of Listeria spp. in shredded dry coleslaw and its components

The survival and growth of Listeria populations inoculated on to dry coleslaw mix and its components were investigated, focusing on effects of storage temperatures and gas atmospheres within packaging films or storage chambers. There were few significant effects of packaging film at 3 °C, but at 8 °C the elevated CO₂/low O₂ atmospheres generated within orientated polypropylene (OPP) packages and used in controlled atmosphere chambers were inhibitory. Although two strains of Listeria monocytogenes had survival characteristics comparable with Listeria innocua, L. monocytogenes ATCC 19114 survived better at 3 °C and also in the elevated CO₂/low O₂ atmospheres within OPP at 8 °C. The effects of product components on the survival of L. innocua were linked to storage temperature. Shredded carrot reduced initial counts and at 8 °C inhibited survival of L. innocua in comparison with shredded cabbage.     

Influence of different packaging systems on fresh-cut zucchini (Cucurbita pepo)

In this work different packaging strategies aimed to prolong the shelf life of minimally processed zucchini are presented. In particular, two different cultivars (Sofia and Diamante) were tested. The sliced zucchini were packaged in oriented polypropylene-based (OPP) bag and into a bio-polymeric film (COEX) under passive and active MAP. The investigated produce was stored at 5 °C for approximately 9 days. Headspace gas concentrations, pH, mass loss, sensory quality and viable cell load of main spoilage microorganisms were monitored for the entire observation period. In order to determine the respiration activity, O₂ and CO₂ concentrations were monitored not only in OPP and COEX packages but also in the headspace of an aluminum-based package. Results suggested that for Diamante cultivar OPP film under active and passive MAP showed slightly better performances in prolonging the shelf life, compared to COEX film; instead, for Sofia cultivar better results were obtained with OPP film only under active MAP conditions.Industrial relevanceThis paper suggests an effective packaging solution to delay the quality decay kinetic of two cultivars of fresh-cut zucchini. Due to changes in consumer attitudes, the proposed mild strategies to prolong the shelf life of ready-to-cook products could really gain widespread acceptance by industry of the minimally processed food sector. Due to great attention to the environmental pollution a biodegradable packaging system was also studied and compared to the common polypropylene-based film, even though the characteristics of this specific produce could not suggest the substitution with traditionally used plastic materials with eco-friendly polymers.     

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