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Home , Food packaging, Modified atmosphere

Packaging; A Progressive Technology for Shelf-Life Extension of Fruits and Vegetables

Mahmoud Soltani Hossein Mobli University of Tehran University of Tehran [email protected] [email protected]

Reza Alimardani Seyed Saeid Mohtasebi University of Tehran University of Tehran [email protected] [email protected]

ABSTRACT

Packaging and storage are the final phases in the industry. preservation, improving safety and reduction of postharvest losses waste are some objectives of the . One of techniques that widely used in packaging of fruits and vegetables are modified atmosphere packaging (MAP). In MAP for fresh fruits and vegetable the air of packaging headspace replaces with a predetermined atmospheric gases different in proportion from that of air. , and are the main gases used in MAP for injection to the headspace of pack. The choice and ratio of gases are very dependent upon the material that being packed. respiration rate of crop, O2 and

CO2 permeability of package material, volume of headspace present inside the package and storage are some factors that affect the quality of MA packaging. Polymeric films are widely used in MAP engineering. The most application of polymeric films for MAP are in flexible package structures. In many cases the plastic packaging films are combined with one another or with other materials such as or aluminum through , , coextrusion and metallization processes. The equipment used in MAP is divided into two main categories: pillow wrap and chamber. Flexible pillow wrapping machines are composed of Horizontal Form-Fill-Seal (HFFS) machines and Vertical Form-Fill-Seal (VFFS) systems. This paper reviews some recent developments in MAP technology applied for fruits and vegetables.

Key Words:

Modified atmosphere packaging, Fruits, Vegetables, Shelf-life, Headspace, Polymeric films, MAP equipment.

Modified Atmosphere Packaging 33 INTRODUCTION was introduced, nylon was integrated into packaging films, steel cans were modified with , cans Packaging is an inevitable component of the were developed with aluminum alloys, and improve- , for assuring the safe handling and ments were made to the formation of cans used in delivery of fresh and processed agricultural prod- food processing. In the 1960s and 1970s, most of ucts from producer to the consumer (Opara and the major packaging accomplishments involved the Mditshwa, 2013). Quality preservation, improv- development of plastic , , tubs, and films ing safety and reduction of postharvest losses waste from polyolefins, polyvinyl, , vinyli- are some objectives of the packaging engineering. dene, vinylchloride, surlyn, and nylon. Based on Agricultural products packaging is rooted in man’s sealability, tensile strength, rigidity, temperature, advancement in the production and processing of barrier, vapor, and moisture properties, the crops (Sacharow & Griffin, 1970). Along with these use of plastic products for is limitless. developments, humans invented methods to protect In addition to plastic, researchers have demonstrated food products from dirt and damage. Utilization of that edible films can be processed from soy , natural made from tree trunks or rocks, chitin, corn zein, , cellulose, and milk proteins gourds, shells, leaves, papyrus, woven twigs, animal (Opara and Mditshwa, 2013). hides, animal parts such as bladders or horns, and Many (specially fruits and vegetables) spoil pieces of bark are some techniques that were invented rapidly in air due to moisture loss or uptake, reaction for foods storage (Sacharow & Griffin, 1970; Kelsey, with oxygen and the growth of aerobic microorgan- 1989, Opara and Mditshwa, 2013). The limitations isms. Microbial growth results in changes in texture, of these containers led to the development of textile, color, and nutritional value of these prod- wood, , and ceramic containers. Tinplate was ucts. Storage of crops in a modified gaseous atmo- invented in approximately 1200 A.D., leading to sphere can protect quality and extend product shelf the fabrication of soldered metal for storage. life, by slowing chemical and biochemical deteriora- The next 7 centuries saw improvements in the man- tive reactions and by slowing the growth of spoilage ufacture of wood, paper, metal, ceramic, and glass organisms (Coles et al., 2003). packaging materials that ultimately led to advance- ments in . Eventually, packag- MODIFIED ATMOSPHERE PACKAGING ing progressed to inventions such as the metal can by Durand in 1810 leading to the beginnings of the Modified atmosphere packaging known as MAP industry. In the 1840s, Pasteur found that technology and controlled atmosphere storage (CAS) were the main reason of food spoil- are novel techniques that are widely applied for pres- age and that heat and sterilization by steam could ervation of agricultural products especially for fruits inactivate these organisms. During the early twen- and vegetables. These techniques are used to sup- tieth century, substantial improvements were made plement low temperature management to delay rip- to both rigid and flexible packaging materials. The ening, reduce physiological disorders, and suppress first commercial aluminum foil was rolled after 1910 decay in many fresh fruit and vegetable (Smith et and film was given heat sealability and al., 1987; Kader et al., 1989). MAP is defined as ‘the resistance to moisture during the 1920s. During the packaging of a perishable product in an atmosphere 1950s, rubber and components were made which has been modified so that its composition is available, heat-shrinkable (PVC) other than that of air’ (Hintlian & Hotchkiss, 1986;

34 Journal of Applied Packaging Research Coles et al., 2003), whereas controlled atmosphere state, the total amounts of carbon dioxide produced storage (CAS) involves maintaining a fixed concen- and oxygen consumed by respiration are the same tration of gases surrounding the product by careful as that permeated through the membrane exchange. monitoring and addition of gases, the gaseous com- Active modification involves the air evacuation position of fresh MAP foods is constantly chang- within the pack and then replacing the atmosphere ing due to chemical reactions and microbial activity. with the desired gas mixture to accelerate gas com- Gas exchange between the pack headspace and the position modification and to avoid product exposure external environment may also occur as a result of to high concentrations of unsuitable gases (Zhang et across the package material (Coles et al., al., 2014). Figure 1 shows a schematic diagram of a 2003). The first use of MAP was in transportation modified atmospheric packaging. of lamb meat from Australia to England in the early The basic idea of the MAP technique of fresh 12th century. Then, the first application of MAP was fruits and vegetable is the replacement of the air of reported in extending the of apples in an packaging headspace with a predetermined atmo- atmosphere with reduced O2 and increased CO2 con- spheric gases different in proportion from that of centrations in 1927 (Phillips, 1996). MAP is divided air (Parry, 1993). Oxygen, carbon dioxide and nitro- into passive and active condition. In passive MAP, gen are the main gases used in MAP for injection respiration rate of crop and permeability of the pack- to the headspace of pack. The choice and ratio of aging film are the most parameters. Because of the gases are very dependent upon the material that respiration of food material, the consumption of being packed. These gases are used to balance safe oxygen is proportional to carbon dioxide production shelf-life extension with optimal organoleptic prop- in the atmosphere packaging. After a certain time, erties of the product. Temperature control should gas composition in the package of fresh product be considered extremely in MAP design, as this reaches a definite balance between respiration rate will influence the gas permeability properties of the and permeability of packaging film. In equilibrium film. Also respiration rate of the product is highly

Produce respiration nO2 + (CH2O)n nCO2 + nH2O

Figure 1. Biochemical and physical processes occurring in a modified atmosphere pack (Paine and Paine, 1992).

Modified Atmosphere Packaging 3 5 affected by temperature. Biological reactions gener- CO2 dissolves readily in water (1.57 g/kg at 100 ally increase two to three-fold for every 10 °C rise kPa, 20 °C) to produce carbonic acid (H2CO3) that in temperature. Therefore temperature control is increases the acidity of the solution (Coles et al., vitally important in order for a MAP system to work 2003). Carbon dioxide has a powerful inhibitory effectively. Film permeability also increases as tem- effect on bacterial growth. It is particularly effetive perature increases (Ščetar et al., 2010). against gram-negative, aerobic spoilage bacteria. Each packaging design has to be optimized for However, carbon dioxide does not retard the growth a specific crop, since the behavior of agricultural of all types of microorganisms. The inhibitory effect products are different and also MA packages are of carbon dioxide is increased at lower dynamic systems during which respiration and per- because of its increased solubility (179.7 ml per 100 meation occur simultaneously. Factors affecting both ml water at 0°C). Carbon dioxide permeates packag- respiration and permeation must be considered for ing film up to thirty times faster than any other gas package designing (Cameron et al., 1989; Mannap- used for the packaging of products (Parry, 1993). peruma et al., 1989; Yam and Lee, 1995; Jacxsens et al., 2000). Food mass inside the package, storage Oxygen temperature, oxygen, carbon dioxide and Oxygen is probably the most important gas in partial pressures and stage of maturity are factors food deterioration being used metabolically by both influencing respiration in a package (Kader et al., aerobic spoilage microorganisms and plant tissues 1989; Ben-Yehoshua et al., 1994; Das, 2005). Type, and taking part in some enzymic reactions in agricu- thickness, and surface area of the packaging film that tural products. Therefore, in MAP, oxygen is either is exposed to atmosphere and across which perme- excluded or the levels set as low as possible. The exceptions occur where oxygen is needed for fruit ation of O2 and CO2 takes place, volume of headspace present inside the package, temperature, relative and vegetable respiration (Parry, 1993). humidity, and gradient of oxygen and carbon dioxide Nitrogen partial pressures across the film affect permeation (Ashley, 1985; Renault et al., 1994; Kader, 1997; Das, Nitrogen is a relatively un-reactive gas with no 2005). In MAP designing it is required to determine odor and color and with a low solubility in both water intrinsic properties of the produce such as respiration and . It is commonly used in MAP to displace oxygen. It can also indirectly influence the microor- rate, optimum O2 and CO2 concentrations, and film permeability characteristics (Cameron et al., 1989; ganisms in perishable foods by retarding the growth Talasila and Cameron, 1993). Table 1 shows optimum of aerobic spoilage organisms. The third role of nitro- gaseous environment and recommends storage tem- gen is to act as a and prevent package collapse in perature for quality retention and shelf-life extension foods that absorb carbon dioxide (Parry, 1993). It has of some fruits and vegetables. a lower density than air, non-flammable and has a low solubility in water (0.018 g/kg at 100 kPa, 20°C) and other food constituents (Coles et al., 2003). GASES USED IN MAP Other Gases Carbon Dioxide The potential of various other gases such as eth- ylene oxide, nitrogen dioxide, ozone and sulphur Carbon dioxide is a colorless gas, an asphyxiant dioxide for MAP have been investigated experimen- and slightly corrosive in the presence of moisture. tally but their commercial use for packaging foods

36 Journal of Applied Packaging Research Table 1. Recommended modified-atmosphere conditions for some fruits and vegetables. (Adapted from Kader et al., 1998; Gorris and Peppelenbos, 1999; Rahman and Amad, 2012)

Modified Atmosphere Packaging 3 7 needs approval from the regulatory authorities. For Prasad, 1995; Kong, 1997; Hernandez et al., 2000; instance, is a gas that is highly Lange, 2000; Abdel-Bary, 2003; Ahvenainen, 2003; reactive and very flammable. It has a low solubility Massey, 2003; Del Nobile et al., 2007; Marsh and in water but is relatively soluble in some organic sol- Bugusu, 2007; Mangaraj et al.,2009). Although an vents and its commercial application has been limited increasing choice of packaging materials is available because of its and the formation of potentially to the MAP industry, most packs are still constructed explosive mixtures with air (Parry, 1993). Also the from four basic : polyvinyl chloride (PVC), noble gases are a family of elements characterized by polyethylene terephthalate (PET), polyproylene (PP) their lack of reactivity. These gases have been applied and polyethylene (PE), for packaging of fruits and in some foods. While from a scientific perspective, vegetables (Kader et al., 1989; Calderon and Barkai- it is difficult to see how the use of noble gases would Golan, 1990; Exama et al., 1993; Prasad, 1995; Kader offer any preservation advantages compared with N2 and Watkins, 2001; Van Willige, et al., 2002; Ahve- they are being used (Coles et al., 2003). nainen, 2003; Marsh and Bugusu B, 2007; Mangaraj et al.,2009). These materials provide a range of per- APPLICATIONS OF POLYMERIC meability to gases and together with the FILMS FOR MAP OF FRUITS AND necessary package integrity needed for MAP (Table 2 VEGETABLES and Table 3). Sometimes, the packaging films, do not singly offer all the properties required for a MAP and MA packaging of commodity refers to the tech- to achieve the best properties of polymeric films, a nique of sealing actively respiring produce in poly- combination of materials is used. Therefore, in these cases the plastic packaging films are combined with meric film packages to modify the 2O and CO2 levels within the package headspace (Mangaraj et al.,2009). one another or with other materials such as paper or Polymeric films have been used to package fresh aluminum through coating, lamination, coextrusion products for over 35 years (Ščetar et al., 2010). The and metallization processes (Mangaraj et al., 2009). most application of polymeric films for MAP are in flexible package structures (Mangaraj et al., 2009). Tg : Glass transition temperature (°C) The most commonly used polymeric films for MAP T : Melting temperature (°C) are Polyolefin, Low-Density Polyethylene (LDPE), m

Linear Low-Density Polyethylene (LLDPE), High- Th : Heat distortion temperature, at 455 kPa (°C) Density Polyethylene (HDPE), (PP), FT : Tensile strength (Mpa) Polyvinyl Chloride (PVC), , Polyethyl- WVTR : Water vapor transmission rate at 37.8°C and ene Terephthalate (PET), Polyvinylidene Chloride 90% RH (g μm/m2 day) (PVDC), Ethylene-Vinyl Alcohol (EVOH), Polyam- ide (Nylon), Polychlorotrifluoroethylene (PCTFE), PO2 and PCO2 : permeability at 25°C for O2 and CO2 respectively (cm3 μm/m2 -h-atm) Polyvinyl Alcohol (PVOH), Ethylene-Vinyl Acetate (EVA), Ionomers, Polycarbonate Films, Polysty- E P and E P : permeability activation energy of films O2 CO2 rene, Cellulose-Based Plastics., Biodegradable Poly- for O2 and CO2, respectively (kJ/mole) mers (Couzens and Yearsely, 1956; Karel et l., 1975; PO PCO Q 2 and Q 2 : permeability quotients for 10°C rise in Sacharow and Griffin, 1980; Crosby, 1981; Salame, 10 10 temperature of films for O and CO respectively 1986; Burton et al., 1987; Kader et al., 1989; Berins, 2 2 1991; Exama et al., 1993; Parry, 1993; Maier, 1995;

38 Journal of Applied Packaging Research POLYETHYLENE FILMS POLYPROPYLENE POLYVINYL POLYETHYLENE POLYVINYLIDENE ETHYLENE-VINYL POLYAMIDE CHLORIDE TEREPHTHALATE (PET) CHLORIDE ALCOHOL (EVOH)

PVC

Table 2. Major packaging films and their typical properties (Mangaraj et al., 2009).

Modified Atmosphere Packaging 3 9 TYPE OF FILMS PRODUCT CHARACTERISTICS /FOOD COMPATIBILITY CONSUMER & ISSUES ENVIRONMENTAL ISSUES COST

Advantages Disadvantages Advantages Disadvantages Advantages Disadvantages

Soft, flexible and strong material Light weight Sight haze or Recyclable Easily recycled Low cost LDPE Good moisture barrier translucency in semi-rigid form but Resistance to chemicals identification Heat sealable and easy to seal and separation Relatively transparent and more difficult predominantly used in film for films application

High ratio of CO2 to O2 permeability Can be laminated and coextruded

Soft, flexible and strong material Not suitable for Light weight Sight haze or Recyclable Easily recycled Low cost LLDPE Better impact strength, tear applications translucency in semi-rigid resistance and higher tensile involving form but strength and elongation, better significant identification resistance to environmental stress exposure to heat. and separation cracking, and better puncture more difficult resistance for films Good moisture barrier Good grease resistance and inert. Good low-temperature performance

Flexible, strong and tough Poor clarity Light weight Sight haze or Recyclable Easily recycled Low cost HDPE Higher softening point than LDPE translucency in semi-rigid and superior barrier properties form but identification Resistance to chemicals and and separation moisture more difficult Permeable to gases for films Easy to process and easy to form

Polypropylene Stronger, denser and more Light weight Recyclable Easily recycled Low cost transparent than polyethylene High clarity, in semi-rigid Moderate gas barrier and good strength and form but (BOPP) water vapour barrier (high gas durability as identification barrier and moisture vapour barrier compared to and separation than polyethylene) LDPE more difficult for films Excellent grease resistance Favorable response to heat sealing

Polyesters Excellent transparency and Light weight Recyclable Easily recycled Inexpensive mechanical properties High clarity/ in semi-rigid but higher (PET/PEN) Good/adequate barrier to gases glass-like form but cost among and moisture and specially odors’ transparency identification plastics and and separation Shatter more difficult Good resistance to chemical resistance for films degradation, heat, oil, solvents and acids.

Polyvinyl Strong and transparent High clarity Recyclable Contains Inexpensive chloride Good gas barrier and moderated chlorine barrier to moisture vapour Requires (PVC) Excellent resistance to chemicals, separating oils/ and grease etc. from other waste Largely used as packaging films

Polyvinylidene High barrier to gases and water High gas barrier Maintains Recyclable Contains Expensive chloride vapor product quality chlorine but higher Heat sealable Requires cost among plastics (PVdC) Also used in hot filling, retorting, separating low-temperature storage, etc. from other waste

40 Journal of Applied Packaging Research TYPE OF FILMS PRODUCT CHARACTERISTICS /FOOD COMPATIBILITY CONSUMER & MARKETING ISSUES ENVIRONMENTAL ISSUES COST

Advantages Disadvantages Advantages Disadvantages Advantages Disadvantages

High tensile strength and excellent Poor barrier to Good clarity Recyclable Requires Inexpensive Polystyrene transparency moisture vapor separating Used for produce where a and gases from other waste ‘breathable’ film is required

Polyamide Strong Poor barrier to Recyclable Requires Relatively Reasonably good oxygen barrier moisture vapor separating costly but from other inexpensive (nylon-6) Excellent odor and flavor barrier waste when used as Good chemical resistance thin films Mechanical and thermal properties similar to PET Excellent high-temp. performance

Ethylene-vinyl Excellent barrier to gases, Low moisture Maintains Recyclable Requires Inexpensive especially to oxygen, odor and barrier/moisture product quality separating when used as alcohol flavor sensitive for oxygen- from other thin films Often used as O barrier material sensitive waste (EVOH) 2 products

Ethylene-vinyl Excellent transparency Poor gas barrier Excellent clarity Recyclable Requires Inexpensive Very good heat seal Poor moisture Mainly used as separating acetate from other Very good adhesive properties barrier component of the sealant layer waste (EVA) and adhesive in multilayer films

Polylactide Biodegradable Suitable for Recyclable Requires Relatively Hydrolysable MAP of fresh separating expensive produce from other (PLA) waste

Laminates/ Properties can be tailored for Flexible in Often allows Layer Relatively product needs design and for source separation is expensive but Coextrusions characteristics reduction required cost-effective for purpose.

For selecting the packaging materials, consid- • The type of package (i.e. flexible pouch or rigid or ering the following parameters would be helpful semi-rigid lidded tray) (Mangaraj et al., 2009): • The barrier properties needed (i.e. permeability of individual gases and gas ratios when more than one gas is used) • The physical properties of machinability, strength, clarity and durability • Integrity of (heat sealing), fogging of the film as a result of product respiration. • Sealing reliability • Water vapor transmission rate • Resistance to chemical degradation • Nontoxic and chemically inert • Printability • Commercial suitability with economic feasibility

Modified Atmosphere Packaging 4 1 Three types of polymeric films have been devel- The mediated MAP does not require oped for MAP (Mangaraj et al., 2009): very high technical knowhow and holds enough • Microperforated or non- polymeric films promise for storage of perishable commodities. It has • Macroperforated polymeric films. been successfully tried by researchers for enhancing the shelf life of commodities like button mushroom, • Perforation-mediated packaging systems. oyster mushroom, shiitake mushroom (Dhalsamant et al., 2015). In the perforation-mediated packaging system the regulation of the gas exchange is achieved The microperforated films allow the rapid by single or multiple tubes that perforate an otherwise development of proper CO and O concentrations 2 2 impermeable packaging material. From an engineer- in the package headspace to extend produce shelf- ing point of view, the transport of gases through per- life (Kartal et al., 2012). The gas permeability of a forations is a complex phenomenon that involves dif- microperforated film is controlled by the number fusion gradients together with co-current transport of and dimensions of the perforations. By altering multiple species, with oxygen entering the package the size and density of the micro hole, packaging and carbon dioxide leaving it. It is also a good solu- films with specific flow rates can be adjusted for a tion for packing high-respiring products, due to the specific product. The size of the perforations nor- high gas exchange rates and low permeability coef- mally used in MAP is between 50 and 200 μm in ficients achieved (Montanez et al., 2010). diameter (Kartal et al., 2012). These materials are suitable for less CO2 tolerant commodities such as mango, banana, grapes and apples. The gas permea- MAP MACHINERY bility in microperforated polymeric films is temper- ature dependent and this dependence is commonly In the late 1950s and early 1960s, the first efforts described by Arrhenius-type equations (Exama , et were made to develop the commercial use of MAP al., 1993; Mahajan et al., 2007). that resulted in the development of equipment for Perforated films have higher permeability rate industrial use. Afterwards, another useful technique than those of microperforated materials. Such films called vacuum packaging was presented. In this are used for commodities tolerating simultaneously phase, the production of efficient, safe, and low-cost machinery was very important. Next researches and low O2 and high CO2 levels such as fresh-cut prod- ucts and commodities having high respiration rate innovations in this field led to manufacture of differ- (Fonseca et al., 2000; Montero et al., 2008; Rediers ent machines and equipment for MAP (Arvanitoy- et al., 2009) The package headspace dynamics vary annis, 2012; Brody et al., 2011; Parry, 1993). Recent with the number of macroperforations. This tech- advances in micro-electronics provides an accurate nique is simple and involves only the punching control of all machine functions in packaging indus- of desired macroperforations in the ordinary film try including temperature settings and movement of package to affect higher gaseous diffusion across the web through the machine so that the optimum the film packages. However, the attainment of ideal results can be achieved. The control of these func- tions has enabled some very complex material struc- steady-state headspace partial pressures of O2 and tures to be handled (Parry, 1993). CO2 under any type of MAP is still a difficult task in the design of MAP and often requires repetitive MAP equipment is divided into two main cat- experimentation; which increases the cost of exper- egories: pillow wrap and chamber. Flexible pillow iment (Rai and Singh, 2012). wrapping machines are composed of Horizontal

42 Journal of Applied Packaging Research Form-Fill-Seal (HFFS) machines and Vertical Form- other. The preformed trays used for packaging are fed Fill-Seal (VFFS) systems. to machine and the product is loaded. The tray and Chamber machines can use two different tech- the material of the top are then transferred to the niques. The first is the technique. In atmosphere modification chamber.. It should be added the second technique, ready containers can be used for that the top lid is heat-sealed (Arvanitoyannis, 2012). the packaging of products named preformed This type of machines are divided in to three groups; machines (Blakistone , 1999; Arvanitoyannis, 2012). Automatic machines, Semi-automatic machines and Gas flushing without evacuation (Blakistone, 1999). Thermoforming Machines The thermoforming technique involves the use of HFFS a rigid or semi-rigid base material which is fed from HFFS machines have been invented for many a reel into grippers or clamps held on chains running years and are used in many applications to pack a wide either side of the web and the length of the machine. variety of products in pillow-pack style (Figure 3). In the heating section, the material is heated to the These machines have been developed for the specific point that can be treated. Then, the treated material requirements of MAP whilst retaining the consider- is transferred to a forming station. The next step in able flexibility associated with non-MAP machines this procedure is the cooling of the material and its (Blakistone, 1999). Typically, to perform MA pack- transfer to the product loading area. modification of ages, a roll of polymeric film is used. The roll passes headspace in the packages can be carried out by air through a forming collar, named the folding , extraction and gas flushing into the trays (Arvanitoy- then it is transformed into a and the two edges annis, 2012). Figure 2 shows a packing process in a of which are sealed together by heated rollers under thermoforming machine. a definite pressure. The food material is then passed through the tube in different ways depending on its Preformed Container Machines nature. Gas flushing is used for atmosphere modi- Performed container machines or tray sealers and fication by a lance that is entered in the tube when thermoforming machines seem to be similar to each the HFFS machine is operated (Arvanitoyannis,

Figure 2. Thermoforming packaging machine fed from two film coils. One inner thermoformable film (1) is formed into a tray (2). The food product is placed in this tray covered by an upper film (3). A vacuum is created in the tray (4), and broken by the gas mixture just before the upper film is sealed (Paine and Paine, 1992).

Modified Atmosphere Packaging 43 Figure 3. a schematic diagram of horizontal form-fill-seal machine with box-motion sealing head (Blakistone, 1999)

2012; Blakistone, 1999). The box motion cross sealing unit is designed to extend the dwelling time by which the cross sealing jaws that are in contact with the polymeric film, so it can be able to transfer more heat and long-time press into the film as opposed to increasing temperature which can potentially melt the film. To make a box motion unit separate actuators (servo or pneumatic) must be used for the horizon- tal and vertical motions allowing a variable amount of jaw separation and dwell distance to be achieved. A knife, integral with the sealing jaws, cuts through adjacent packs to produce the separation.

Figure 4. VFFS machine; 1, film from reel made into a tube over forming shoulder; 2, longitudinal seal made; 3, bottom of tube closed by heated crimped jaws which move downwards drawing film from reel; 4, pre- determined quantity of product falls through collar into pouch; 5, jaws open and return on top of stroke; 6, jaws partially close and ‘scrape’ product into pouch out of seal area; 7, jaws close, crimp heat seal top of pre- vious pouch and bottom of new one. Crimp sealed container cut off with knife (Paine and Paine, 1992).

44 Journal of Applied Packaging Research Machinery Selection and Specification products. Pillow wrapping machines and similar To specify a MAP equipment, many factors which employ continuous gas flushing pose a fire should be established to properly facilitate the hazard because of the venting of high levels of process based on the nature of the product and oxygen into the area surrounding the machine. The the market requirements. Some of these parame- packaging machine must be able to give consistent ters are quality, cleanability, throughput, flexibil- and reliable seals minimizing pack leakers, achieve ity, operating cost, processing yield and equipment the desired gas content of the pack and be quickly price. The chamber type of machine gives a better and efficiently adaptable to meet production require- minimum residual oxygen content in the headspace ments. A wide choice is available to the product as compared with the continuous flushing systems. packer intending to enter MAP (Table 4). However, this is unacceptable when handling fragile

Table 4. Some packaging systems for MAP (Parry, 1993)

Modified Atmosphere Packaging 4 5 RECENT ADVANCES AND techniques included chemical treatment, MAP RESEARCHES IN MAP and low temperature storage were developed for improvement of physico-chemical attributes of Mushroom is a highly perishable agricultural oyster mushrooms. Mushrooms were treated with crop and its shelf-life is 1– 3 days at ambient tem- a solution of (0.05%, w/v), citric acid (3%, perature, due to high moisture content and high w/v) and CaCl2 (1%, w/v). They packed chemically transpiration rate (Mahajan et al., 2008). Therefore, treated mushrooms under two different gas com- mushrooms need a special care to keep its quality positions. Physico-chemical, textural and sensory and freshness, especially when they are minimal properties of the samples were assessed as quality processed such as slicing (Iqbal et al., 2009). So factors during storage at 4°C and for 25 days. a MAP technique seems to be helpful for preser- Chemical treatment of mushrooms combined with vation of mushroom. Oliveira et al. (2012) evalu- MAP (5% CO2, 10% O2) resulted better retention of ated the effect of temperature and number of film quality characteristics and higher sensory ratings perforations on quality and developed a shelf-life compared to other samples. They suggested that a kinetic model for a MAP for sliced button mush- combination of chemical treatment and MAP has rooms. They packed the sliced mushrooms in a good promise in maintaining oyster mushroom tray, covered with cellophane film and stored for quality and extending their postharvest life up to 25 7 days at four levels of temperature (0, 5, 10, and days at 4°C. Another important observation made 15°C) and three levels of perforations at each tem- was that the use of chemical treatment alone was perature ranging the number of perforations from more effective than the use of MAP alone with 1 (58 perforations per m2) to 6 (349 perforations either of the two gas compositions used in packag- per m2). They measured headspace gas composi- ing headspace. Also they observed weight loss and tion, weight loss, pH, firmness and colour of mush- senescence in the chemically untreated samples. rooms throughout the storage period. They found Effect of active MAP with different initial gas that increasing the storage temperature required compositions was also investigated by Li et al. (2014) increasing of the number of perforations for having on fresh shiitake mushrooms. They packaged mush- an optimum MAP conditions. Temperature had a rooms at different conditions of high oxygen pack- significant effect on quality of sliced mushrooms, aging (HOP) with 100% oxygen; medium oxygen firmness was identified as a critical quality param- packaging (MOP) with 50% O2 and balanced with eter and a kinetic model was developed to describe N2; low oxygen packaging (LOP) with 3% O2 and 5% the influence of temperature on firmness and for CO2 balanced with N2 initially. They used passive prediction of shelf-life of sliced mushrooms. They MAP with air inside (AIR) as the control treatment resulted fresh sliced mushrooms had a shelf-life of and all packaged samples were stored at 10 °C with 1, 2, 4, and 7.5 days at 15, 10, 5, and 0°C, respec- 90% RH for 7 days. During storage, changes in gas tively, under optimum MAP conditions. Also it was compositions, electrolyte leakage, crude water-solu- concluded that the shelf-life of fresh sliced mush- ble polysaccharides, total phenolic content and free rooms in an optimum package was found to be 7.5 amino acid content were determined. They resulted and 4 days when stored at 0 and 5°C, respectively. that ethanol release was high in LOP and AIR but Jafri et al. (2013) performed a combination of retarded in MOP and HOP. Packaging could not chemical treatments and MAP for quality reten- prevent the polysaccharide content decreasing. Both tion of oyster mushrooms (Pleurotus florida). Three the active and passive MAP maintained the color

46 Journal of Applied Packaging Research and integrity of the mushrooms. The active MAP 4.3 ± 0.2 and 6.5 ± 0.4 kPa. Changes in quality attri- effectively increased total phenolic content and butes of fruit, firmness, titratable acidity, pH, and total amount of free amino acids. Also, LOP had a soluble solids content were not affected by O2 levels. harmful impact on mushrooms with high levels of Overall changes in water activity, levels of ascor- electrolyte leakage. They proposed HOP and MOP bate, and microbial growth were independent of O2 for mushroom packaging because they had a better levels. Oxygen partial pressure inside the packages effect on maintaining the nutritional compounds of affected browning, which was more intense at 16.7 shiitake mushrooms. kPa O2. Browning was more intense at pH 3.0 than Dhalsamant et al. (2015) applied perforation- at pH 7.0 but the kinetics of other quality attributes mediated MAP for extending the shelf life of paddy were not affected by pH. No significant improve- straw mushroom. They kept mushroom specimens ments of quality attributes dependent on the physi- in packages both as untreated and treated with ology of respiration of fresh-cut ‘Rocha’ pear can

CaCl2 to see the effect of CaCl2 on mushroom in be obtained by reducing O2 partial pressure inside the MAP. The area of perforations were kept as 0, the packages. 3.4×10−4, 6.8×10 −4 and 1.02 × 10−3 % (0, 20, 40 and Wang and (2013) investigated effect of 60 perforations) in a package size of 175 mm × 110 M A P t e ch n olog y o n q u a l it y of ‘B a r t le t t ’ p e a r s ( P y r u s mm. They observed that perforation mediated MAP communis L.). The objectives of their research were effectively increased the shelf life of paddy straw to evaluate MAP for preserving ‘Bartlett’ pear mushroom to 6 days at 12°C (±1°C) as compared to quality during storage and transit, determine the

1–2 days for control. The firmness of both the cap effect of O2 and CO2 concentrations on MAP-related and stem was better maintained with the pre-treated internal browning (IB) during cold storage, iden- as well as untreated samples in 20 and 40 perfora- tify temperatures and gas atmospheres that result tion packs. They recommended that the paddy straw in MAP-related IB during transit, and determine mushroom should be treated with CaCl2 (0.5%) and the possible relationship of both the development stored in 40 perforation packages in the specific of ripening and IB with ascorbic acid retention and package size at 12(±1) °C for extending the shelf life membrane peroxidation. ‘Bartlett’ pears were up to 6 days. packed in a commercial MAP (MAPc), an exper- Gomes et al. (2012) applied MAP method to imental MAP (MAPe) and commercial perforated control quality changes of ‘Rocha’ pear. “Respi- plastic (control). The storage temperature was ratory behavior of fresh-cut ‘Rocha’ pear sug- fixed on −1.1 °C. After 1 and 3 months of storage, gests that optimization of O2 concentration inside and in order to simulate transit temperatures, MAP is of limited benefit”. To test this hypothesis, samples of commercial and perforated bags were they carried out some experiments, packages were transferred to rooms at temperatures of 2, 4.5, 7.5, designed to achieve three equilibrium O2 partial and 10°C for 3 weeks. They reported MAPc main- pressures. Fresh-cut ‘Rocha’ pear was treated with tained an average internal atmosphere of 12.3% O2

250 mM calcium ascorbate solutions buffered at pH + 5.6% CO2 and extended significantly the storage 3.0 and pH 7.0, packaged under the three MAP con- life of pears with high eating quality and without IB ditions, and stored at 5 °C for 20 days. Actual O2 and other disorders for up to 4 months. The internal levels (mean ± confidence interval at 95%) during gas atmosphere of MAPe equilibrated at 2.2% O2 + the experiment were 16.7 ± 0.2, 1.8 ± 0.2 and 0.25 ± 5.7% CO2 and resulted 25.5% and 62.3% IB of fruit

0.04 kPa with corresponding CO2 levels of 1.3 ± 0.1, after 3 and 4 months of storage, respectively. During

Modified Atmosphere Packaging 4 7 simulated transit conditions of 2, 4.5, 7.5, and 10°C, the browning process, phenolic content, polyphe- the CO2 concentration in MAPc was maintained at nol oxidase (PPO) activity and expression profiles

5.6–7.9% and O2 was reduced to 10.5, 5.0, 2.5, and of phenylalanine ammonia-lyase (PAL) and PPO 1.0%, respectively. The longer the storage dura- genes in the core tissue of ‘Yali’ pears under MAP. tion and the higher transit temperature, the higher The pears were divided into three classes. One was the incidence and severity of IB. The MAPc main- packaged in 10-mm-thick low-density polyethyl- tained firmness, color and higher eating quality of ene film as MAP1, the second class was packaged fruit after ripening, eliminated senescent scald and in 30-mm-thick low-density polyethylene film des- core breakdown, suppressed the loss of ascorbic ignated as MAP2, and the third lot without pack- acid (AsA) and titratable acidity during storage at aging was designated as the control. Table 5 shows −1.1 ◦C for up to 4 months. In contrast, fruit held properties of films that were used for packaging in MAP with low O2 levels (1.0–2.5%) developed of pear fruits They obtained that MAP1 reduced IB that appeared to be associated with a reduction core browning, retarded the peak appearance of in AsA, and exhibited an increase in membrane PPO activity and phenolic content and inhibited leakage. MAP inhibited ripening at high CO2 + high the expression of PbPAL and PbPPO genes in core

O2 but lead to IB when the packaging material or tissue relative to the control, but MAP2 exerted the elevated temperatures resulted in high CO2 + low O2 opposite effects during storage. They concluded O2 conditions. The incidence of IB closely correlated and CO2 concentrations in MAP1 were appropriate with lipid peroxidation and appeared to be related for storing ‘Yali’ pear, and this treatment effectively to fruit AsA concentration. inhibited core browning and when the CO2 concen-

Also the effects of MAP was studied on core tration was very high, as in the MAP2, CO2 injury browning of ‘Yali’ pears during cold storage (Cheng would occur and exacerbate core browning. So they et al., 2015). Core browning and avoidance of this proposed that MAP1 was suitable for cold storage phenomena is a major challenge during postharvest under modified atmosphere storage in ‘Yali’ pears. storage of pear. Control atmosphere (CA) storage Villalobos et al. (2014) studied effect of equi- and MAP are the methods that preserve pear quality librium MAP on the stability of ‘San Antonio’ and and extend its storage life. But, pear fruits are sen- ‘Banane’ breba fruit during cold storage by the sitive to CO2 and high CO2 concentrations that lead use of three different micro perforated films. Gas to core browning in pears. Therefore, it is the main composition in the wraps, weight loss, % disor- problem to understand the mechanism of this process der, and microbial counts were investigated for 21 to optimize atmospheric conditions during posthar- days. The tested micro perforated films extended vest storage of pear. Cheng et al. (2015) investigated time of storage for brebas, minimized weight loss

Table 5. Properties of the films used by Cheng et al. (2015) for packaging ‘Yali’ pear.

48 Journal of Applied Packaging Research and delayed disorders due to fungal proliferation. ‘Istanbul’ medlar fruit. The Palliflex system com- Among the tested micro perforated films, biaxially prises a of boxes of stored product and a oriented polypropylene (BOPP) film with one hole plastic cover encompasses the pallet. Several times per 50 mm (a total of three holes, ø = 100 μm) (M50) a day, the system measures the gas concentrations in showed the best performance in terms of delaying the cover and corrects them if necessary with CO2, physicochemical senescence processes of fruit. For O2, N2 or air. In this storage system, it is possible to

‘San Antonio’ and ‘Banane’ cultivars packaged set desired O2 and CO2 compositions in individual with micro perforated M50, the optimal time of cold . O2 and CO2 can be automatically injected or storage was 14 and 21 days, respectively. removed based on operator set points programmed Oliveira et al. (2015) studied effect of modified into the controller. This system is suitable for dif- atmosphere on polyphenols during storage of pas- ferent fruit and vegetables in the same storage teurized strawberry purees. They aimed to evalu- room, because it can provide different atmosphere ate phytochemicals concentration during 90 days- compositions for individual pallets (Selcuk and storage of pasteurised strawberry puree under Erkan, 2015). three atmospheres and at two storage temperatures MAP technology has also been developed to to improve polyphenols preservation of processed control decay of ‘Red Globe’ table grapes during fruit. Strawberry purees flushed with gas mixtures storage. Grapes were packaged in perforated poly- of 10 kPa O2 + 90 kPa N2, 100 kPa N2 and air (78 ethylene (PPE) or MAP bags (ZOEpac or Antimi- kPa N2 + 21 kPa O2 + 0.03 kPa CO2) and were stored crobial) with or without different grades of ethanol for 90 days at 4°C and 23°C. They reported cate- vapor-generating (Antimold®30, Anti- chin, epicatechin and quercetin-3-rutinoside were mold®60 or Antimold®80) or a SO2-generating not affected by the atmospheres for both tempera- pad, and the grapes were kept at 0 °C and 90–95% tures, while ellagic acid concentration was higher relative humidity for 4 months. Packaging of grapes for samples stored in air. 100 kPa N2 at 4°C and with a SO2 pad in PPE or ZOEpac bags provided 23°C, preserved total anthocyanin content of puree better control of fungal decay and stem browning in better form. Totally, MAP allowed higher sta- than PPE or ZOEpac bags alone, PPE or ZOEpac bility on total activity, total phenolic bags with Antimold sachets or bags and total anthocyanin content of strawberry puree, alone. The PPE containing the Antimold®80 while catechins and quercetin-3-rutinoside were the was as effective as the SO2 treatments in most stable. They recommended refrigerated tem- reducing the incidence of fungal decay in natu- perature conditions (4°C) and an anaerobic atmo- rally infected and artificially inoculated grapes for sphere (100% N2) for preservation of nutritional 1 month. Ethanol vapor released by the Antimold properties strawberry puree during storage, since sachets enhanced berry color, but caused stem under these conditions the concentration of straw- browning depending on ethanol vapor concentra- berry colouring polyphenols (anthocyanins) would tions in the headspace of the bags. The ZOEpac-210 be higher and compounds like catechin, epicate- bags alone resulted in significantly lower weight loss chin, quercetin-3- rutinoside and ellagic acid would and incidence of stem browning, compared to other be more stable. treatments; however, they did not reduce fungal Selcuk and Erkan (2015) studied on effects decay or develop an appreciable level of modified of modified and palliflex controlled atmosphere atmosphere (Candir et al., 2012). The storage life of storage on postharvest quality and composition of ‘Red Globe’ grapes was limited to 3 months using

Modified Atmosphere Packaging 4 9 MAP technique developed by them. After 4 months treatments (extrinsic factors) on respiration rate of storage, they observed marked color changes, (RCO2) of fresh-cut pineapple chunks. They devel- more than 90% fungal decay occurred, severity of oped a mathematical model for respiration rate and stem browning increased, taste was unacceptable reported a gradual decrease in rate with time. The and appearance was unacceptable with the absence initial respiration rate (Ri) and equilibrium respira- of SO2 treatment. The SO2 pad in ZOEpac-110 tion rate (Req), were found useful to compare respi- bags was the most effective treatment throughout ration rates for the factors studied. Ri was affected storage for controlling incidence of fungal decay, to a greater extent by physiological age and origin controlling stem browning and maintaining accept- than by season. Cut size had a considerable effect able visual appearance followed by the SO2 pad in on Ri and Req, with larger cut pieces having the PPE bags. ZOEpac-110 bags containing laminated lowest Ri and Req of 5.9 and 2.7 ml/kgh, respec-

SO2 pads may extend storage life of ‘Red Globe’ tively. While, smallest cut pieces had highest Ri of 7 grapes to 4 months without SO2 injury and exces- ml/kgh and Req of 3.2 ml/kgh. Cutting the fruit with sive SO2 residues. a razor sharp blade versus a blunt blade decreased Waghmare and Annapure (2013) carried out the Ri, while only caused a slight reduction in Req. some experiments to explore effect of MAP-chem- The target O2 and CO2 transmission rate required ical treatment on quality of fresh-cut papaya. The for optimal MAP were reported 7300–12,500 and efficacy of chemical dips and MAP, alone and in 13,900–23,500 ml/m2 day atm covering variabil- combinations, on the quality of fresh-cut papaya ity in respiration rate due to intrinsic and extrinsic were studied throughout 25 days at 5°C. Fresh-cut factors studied. papaya were dipped in a solution of calcium chloride Caleb et al. (2013) searched effect of MAP on (1% w/v) and citric acid (2% w/v) and then packed volatile composition and postharvest life of min- with headspace of 5% O2, 10% CO2, 85% N2 and imally-processed pomegranate arils (‘Acco’ and stored at 5°C for 25 days. Physico-chemical exper- ‘Herskawitz’ varieties). Storage temperature (5, 10 iments included package atmosphere, weight loss, and 15°C) and time of storage were also studied as pH, total soluble solids, firmness and color, micro- the effective parameters on the postharvest quality bial quality along with a were mea- attributes of arils. They extracted volatile com- sured during storage period. Significant differences pounds, analyzed by a gas chromatography–mass were reported among the chemically treated and spectrometry and detected 17 and 18 volatiles and non-treated fresh-cut papaya in all the parameters identified in the headspace of pomegranate juices of considered. Chemical treatment followed by MAP, ‘Acco’ and ‘Herskawitz’, respectively. They resulted showed the best results among the treatment in the postharvest life of MA-packaged ‘Acco’ and terms of retaining sensory and quality characteris- ‘Herskawitz’ was limited to 10 days due to fungal tics and extending the shelf-life of 25 days for fresh- growth ≥2 logCFUg−1 at 5°C. Temperature had a cut papaya. Also MAP alone was not effective in significant effect on changes on volatile profile con- preserving quality. Hence, use of chemical dips in centration and composition. Changes in quality combination with MAP has been shown to be effec- parameters and aroma compounds were depen- tive in extending shelf-life of fresh-cut papaya. dent on cultivar differences, storage temperature Finnegan et al. (2013) investigated the effects and duration. Under 5°C storage conditions, MA- of origin, physiological age and seasonality (intrin- packaged pomegranate arils were best kept than sic factors), cut-size, blade-sharpness and dipping at 10 and 15°C. Flavour life was shorter than the

50 Journal of Applied Packaging Research postharvest life and was significantly influenced by significant effects were observed on 2C H4 produc- storage temperature. tion. They observed and N2O atmospheres Selcuk and Erkan (2014) studied changes in increased the antioxidant activity of watercress at antioxidant activity and postharvest quality of the end of the storage period, while no significant sweet pomegranate under MAP and during long effects were observed on polyphenol contents and term storage. The pomegranate were packed in two sensorial parameters, there was no clear effect of different types of MAP and were stored at 6 °C and non-conventional gases on the color parameters and 90–95% RH. After 120 days, different quality anal- polyphenol contents of fresh-cut watercress. More- yses were performed on stored fruits. Fruit weight over, there was no clear effect of non-conventional loss, decay index, skin color, total titratable acidity, atmospheres on microbial growth. They suggested total soluble solids content, total phenolic, total that non-conventional atmospheres, combined with anthocyanins and antioxidant activity were deter- other technologies that ensure low microbial counts mined. During cold storage, the CO2 and O2 con- at the beginning of the storage, could be used for centrations were periodically measured inside the watercress leaves. MAP. They reported that MAP reduced weight Elwan et al. (2014) performed an investigation loss significantly after 120 days. During storage, a of storability, shelf-life and of decrease were observed in L*, C* an h° values in sugar snap peas affected by MAP. This investiga- all treatments. A decrease was occurred in titratable tion was aimed to select the most suitable package acidity and total soluble solids after cold storage and to maintain quality of sugar snap peas pods. They shelf-life. Total phenolics, total anthocyanin con- selected five types of polypropylene bags included tents and antioxidant activity showed an increase highly perforated (HPPP), nonperforated (NPPP) during the storage period in control fruit. They con- and micro-perforated with 6, 12 and 24 holes cluded storage of pomegranates in different MAP (MPPP6, MPPP12 and MPPP24) for packaging of treatments significantly reduced weight loss and pods during cold storage at 0 °C and 90–95% RH decay and maintained visual appearance, but had no for 7, 14, 21 days. Also they simulated shelf-life con- significant effect on internal quality of fruit (TTA, ditions at 10 °C and 80–85% RH for 2 or 4 days after

SSC, total phenol content, anthocyanin contents and cold storage. Changes in O2 and CO2 concentrations, antioxidant activity) at the end of both cold storage weight loss, visual quality, off odors, decay, color, and shelf-life periods. Also they proposed ‘Hicran- firmness, crispness, taste, total chlorophyll, nar’ pomegranates can be stored up to 100 days by C, SSC, and total sugar contents were considered. using MAP without decay or serious loss in weight. They reported that O2 decreased and CO2 increased Silveira et al. (2014) applied non-conventional slowly inside MPPP6, MPPP12 and MPPP24 bags,

MAP for quality preservation of watercress. They while, the reduction in O2 and the increments in aimed to investigate the effect of different non-con- CO2 in NPPP bags were very sharp and accompa- ventional MAPs, nitrogen (89.7% N2, 10.3% O2), nied with high levels of off odors. MPPP12 bags pre- (89.9% Ar, 10.1% O2), helium (90.1% He, served quality during storage and simulated shelf-

9.9% O2), nitric dioxide (89.3% N2O, 10.7% O2) and life, in terms of higher scores for visual quality, air (0.03% CO2, 21% O2), on fresh-cut watercress firmness, crispness and taste as well as highest con- leaves preserved for 13 days at 5 °C. They reported tents of chlorophyll, vitamin C and . the respiratory rate was reduced by the non-conven- Ghidelli et al. (2014) explored effect of a soy pro- tional atmosphere up to 3 days of storage, and no tein-based edible coating with antioxidant activity,

Modified Atmosphere Packaging 5 1 and conventional and super atmospheric MAP on fresh-cut eggplants for up to 8–9 days at 5 °C. Also the quality of fresh-cut ‘Telma’ eggplants, during they did not recommend conventional MAP condi- storage. In a first experiment, eggplant pieces were tions (low O2 and high CO2) for storage of fresh- dipped in either a coating composed of soy cut eggplants under the studied conditions, since it isolate (SPI) and 0.5% cysteine (Cys), or water as induces damage of the tissue. Overall, the SPI–Cys an uncoated control. They packed samples in trays coating under air atmospheric conditions provided under atmospheric conditions to reach a passive the best and cheapest approach for extending the MA (MA-P) or two gas mixtures (MA-A: 15 kPa shelf-life of fresh-cut eggplant.

CO2 + 5 kPa O2; MA-B: 80 kPa O2) and stored at Also effect of a soy protein-based coating and 5°C. Atmospheric conditions were used as control. MAP was studied to control browning of fresh-cut They resulted coated samples packed under MA-B artichoke (Ghidelli et al., 2015). SPI-beeswax (BW) and control conditions yielded the highest white- edible coating was optimized based on BW and Cys ness index (WI) values during storage, whereas content to reduce the enzymatic browning of fresh- MA-A did not enhance the shelf-life of minimally cut artichoke. Effect of this optimized coating, com- processed eggplants and had the lowest WI values. bined with different MAs was studied on shelf-life The MA-B and atmospheric control conditions of cut artichokes during storage at 5°C. MAs were maintained firmness, whereas the coating main- made by fluxing two gas mixtures (MA-A: 5 kPa O2 tained the weight loss under MA-A and MA-B. In + 15 kPa CO2; MA-B: 80 kPa O2) or by conventional a second experiment, the commercial shelf-life of passive MA (MA-P). Atmospheric conditions were fresh-cut eggplants was extended to 8 and 9 storage also used as the control. They obtained the use of days by increasing the Cys content in the edible 0.3 g/100 mL Cys combined with a SPI-BW edible coating from 0.5 to 1% under MA-B and control coating helped control enzymatic browning and storage conditions, respectively. They concluded extended the commercial shelf-life of fresh-cut arti- that applying a SPI-based edible coating amended chokes to 4 days without providing off-odors. The with 1% Cys can help control enzymatic brown- combination of the coating with MAs did not affect ing and maintains the visual quality of ‘Telma’ the shelf-life of artichoke slices, but enhanced the

Figure 5. The sketch of packaging tray with silicon gum film window and PP membrane. 18 cm length 12 cm width 4 cm depth, with a wall thickness of 0.3 mm and a total surface area of 456 cm2, which achieves an O2 permeability of 14.62×10 -16 mol S-1 m-2 Pa-1 and CO2 permeability of 53.51×10 -16 mol S-1 m-2 Pa-1 at 20 C and 90% RH were used by Li and Zhang (2015).

52 Journal of Applied Packaging Research product’s antioxidant capacity as compared to the CONCLUSION control packaging conditions. Li and Zhang (2015) investigated effects of MAP as a progressive technology, has been MAP with a silicon gum film window on the quality developed for preservation and storage of many of stored green asparagus (Asparagus officinalis L) fresh fruits and vegetables. The advantages of MAP spears. Packages of green asparagus with or without are extending the shelf-life, preserving or stabiliz- silicon gum film windows were flushed in two dif- ing the desired properties of fruits and vegetables, ferent modified systems (50 mLL-1 2 O with 100 convenience in use and distribution for sale. mLL-1 CO2 and 100 mLL-1 O2 with 100 mLL-1 Recent development achieved in packaging material

CO2, with N2 as a balance gas) and stored at 2 ± 1°C such as bio-based polymers provides feasibility of for 30 days. Figure 5 shows the package that was MAP development for new applications. Also devel- used in this research. opments in MAP claim new equipment and machin- The changes in gas headspace, sensory, respira- ery and accurate control of process. Recent advances tion rate, ascorbic acid content, soluble solid content in mechatronics and automation provides reliable and chlorophyll content were investigated. They control of all machine functions in MAP process found that, the gas exchange between packages such as temperature and gas injection. Many factors and surrounding atmosphere through the silicon should be considered to facilitate MAP process gum film windows induced an in-package optimum based on the nature of the product and the market atmosphere for green asparagus spears stored at O2 requirements. Some of these parameters are quality, above 21 mLL-1, CO2 below 157 mLL-1 and ethyl- cleanability, throughput, flexibility, operating cost, ene below 15.84 mLL-1. These packages prevented processing yield and equipment price. anaerobic respiration to get good odor score, and were able to keep a relatively low respiration rate and reduce loss of ascorbic acid. The initial atmo- sphere in packs also affected the quality attributes, where 50 mLL-1 O2 and 100 mLL-1 CO2 initial atmosphere was preferred.

Modified Atmosphere Packaging 5 3 REFERENCES [8] Burton, K. S., Frost, C. E., & Nichols, R. (1987). A combination plastic permeable [1] Abdel-Bary, E. M. (2003). Hand book film system for controlling post-harvest of plastic films. Rapra Technology Ltd., mushroom quality. Biotechnology Letters, Shawbury, Shrewbury, Shropshri, SY4 9(8), 529-534. 4NR, UK [9] Calderon, M., & Barkai-Golan, R. (1990). [2] Ahvenainen, R. (2003). Novel food pack- Food preservation by modified atmosphere. aging technology, Published in CRC Press, CRC Press, Boca Raton, FL. Boca Raton Boston, New York, Washinton, [10] Caleb, O. J., Opara, U. L., Mahajan, P. V., DC and Published by Woodhead Publish- Manley, M., Mokwena, L., & Tredoux, A. ing Ltd., Cambridge, London. G. J. (2013). Effect of modified atmosphere [3] Arvanitoyannis, I. (Ed.). (2012). Modified packaging and storage temperature on atmosphere and technolo- volatile composition and postharvest life gies. CRC Press. of minimally-processed pomegranate arils (cvs. ‘Acco’ and ‘Herskawitz’). Postharvest [4] Ashley, R. J. (1985) Permeability and plas- Biology and Technology, 79, 54–61. tics packaging. In: Comyn J (ed) permeability. Elsevier, New York, pp [11] Cameron, A. C, Boylan-Pett, W., & Lee, 269–308. J. (1989). Design of modified atmosphere packaging systems: modeling oxygen [5] Ben-Yehoshua, S., Fishman, S., Fang, D., concentrations within sealed packages of & Rodov, V. (1993, July). New develop- fruits. Journal of , 54, ments in modified atmosphere packaging 1413–1421. and surface coatings for fruits. In ACIAR PROCEEDINGS (pp. 250-250). Austra- [12] Candir, E., Ozdemir, A.E., Kamiloglu, lian Centre for International Agricultural O., Soylu, E. M., Dilbaz, R., & Ustun, Research. Berins, M. L. (1991). Plastic D. (2012). Modified atmosphere packag- engineering handbooks of the society of ing and ethanol vapor to control decay of the plastic industry, 5th edn. Chapman and ‘Red Globe’ table grapes during storage. Hall, London, UK. Postharvest Biology and Technology, 63, 98–106. [6] Blakistone, B. A. (Ed.). (1999). Principles and applications of modified atmosphere [13] Cheng, Y., Liu, L., Zhao, G., Shen, C., packaging of foods. London: Blackie Aca- Yan, H., Guan, J., & Yang, K. (2015). The demic & Professional. effects of modified atmosphere packaging on core browning and the expression pat- [7] Brody, A. L., Zhuang, H., & Han, J. H. terns of PPO and PAL genes in ‘Yali’ pears (Eds.). (2010). Modified atmosphere pack- during cold storage. LWT - Food Science aging for fresh-cut fruits and vegetables. and Technology, 60, 1243-1248. John Wiley & Sons. [14] Coles, R., McDowell, D., & Kirwan, M. J. (Eds.). (2003). technology (Vol. 5). CRC Press.

54 Journal of Applied Packaging Research [15] Couzens, E. G., Yearsely, V. E. (1956). [23] Fonseca, S. C., Oliveira, F. A. R., Lino, I. Plastic in service of man. Penguin Books B. M., Brecht, J. K., & Chau, K. V. (2000). Ltd., Harmondsworth. Modeling O2 and CO2 exchange for devel- [16] Crosby, N.,T. (1981). Food packaging mate- opment of perforation mediated modified rials—aspect analysis and migration of atmosphere packaging. Journal of Food contaminates. Applied Science Publisher Engineering, 43, 9–15. Ltd., London, UK. [24] Ghidelli, C., Mateos, M., Argudo, C. [17] Das, H. (2005). Food processing operations R., & Pérez-Gago, M. B. (2015). Novel analysis. Asian Books Private Limited, approaches to control browning of fresh- New Delhi. cut artichoke: Effect of a soy protein-based coating and modified atmosphere packag- [18] Del Nobile, M. E., Licciardello, F., Scrocco, ing. Postharvest Biology and Technology C., Muratore, G., & Zappa, M. (2007). 99, (2015) 105–113. Design of plastic packages for minimally processed fruits. Journal of Food Engineer- [25] Ghidelli, C., Mateos. M., Argudo, C. R., & ing, 79, 217–224. Pérez-Gago, M. B. (2014). Extending the shelf life of fresh-cut eggplant with a soy [19] Dhalsamant, K., Dash, S. K., Bal, L. M., & protein–cysteine based edible coating and Panda, M. K. (2015). Effect of perforation modified atmosphere packaging. Posthar- mediated MAP on shelf life of mushroom vest Biology and Technology, 95, 81–87. (Volvariella volvacea). Scientia Horticul- turae, 189, 41-50. [26] Gomes, M. H., Fundo, J. F., Poças, M. F., & Almeida, D. P. F. (2012). Quality changes [20] Elwan, M. M. W., Nasef, I. N., El-Seifi, S. in fresh-cut ‘Rocha’ pear as affected by K., Hassan, M. A., & Ibrahim, R. E. (2014). oxygen levels in modified atmosphere Storability, shelf-life and quality assurance packaging and the pH of antibrowning of sugar snap peas (cv. Super sugar snap) additive. Postharvest Biology and Technol- using modified atmosphere packaging. ogy, 74, 62–70. Postharvest Biology and Technology, 100, 205–211. [27] Gorris, L. G., & Peppelenbos, H. W. (1999). Modified-atmosphere packaging of [21] Exama, A., Arul, J., Lencki, R. W., Lee, produce. Handbook of food preservation. L. Z., & Toupin, C. (1993). Suitability of New York, USA. plastic films for modified atmosphere pack- aging of fruits and vegetables. Journal of [28] Hernandez, R. J., Selke, S. E. M., & Food Science, 58, 1365–1370. Culture, J. D. (2000). Plastics packaging: properties, processing, applications, and [22] Finnegan, E., Mahajan, P. V., O’Connell, regulations. Hanser, Munich, Germany M., Francis, G. A., & O’Beirne, D. (2013). Modelling respiration in fresh-cut pine- [29] Hintlian, C. B., & Hotchkiss, J. H. (1986). apple and prediction of gas permeability The safety of modified atmosphere packag- needs for optimal modified atmosphere ing: a review. packaging. Postharvest Biology and Tech- [30] ., 40, 70–76. nology, 79, 47–53.

Modified Atmosphere Packaging 5 5 [31] Iqbal, T., Rodrigues, F. A., Mahajan, P. V., [38] Kader, A. A., Zagory, D., Kerbel, E. L., & & Kerry, J. P. (2009). Effect of time, tem- Wang, C. Y. (1989). Modified atmosphere perature, and slicing on respiration rate of packaging of fruits and vegetables. Criti- mushrooms. Journal of Food Science, 74, cal Reviews in Food Science & , 298–303. 28, 1-30. [32] Jacxsens, L., Devlieghere, F., De Rudder, [39] Karel, M., Fennema, O.W., & Lund, D. T., & Debevere, J. (2000). Designing equi- B. (1975). Protective packaging of foods. librium modified atmosphere packages for In: Fennema OW (ed) Principle of food fresh-cut vegetables subjected to changes science. Marcel Dekker, Inc, USA. in temperature. LWT-Food Science and [40] Kartal, S., Aday, M. S., & Caner, C. (2012). Technology, 33, 178-187. Use of microperforated films and oxygen [33] Jafri, M., Jha, A., Bunkar, D. S., Ram, R. scavengers to maintain storage stability of C. (2013). Quality retention of oyster mush- fresh strawberries. Postharvest Biology and rooms (Pleurotus florida) by a combination Technology, 71, 32-40. of chemical treatments and modified atmo- [41] Kelsey, R. Packaging in Today’s Society. sphere packaging. Postharvest Biology and 3rd ed., Lancaster, PA: Technomic Publish- Technology, 76, 112–118. ing Co., Inc., 1989. [34] Kader, A. A. (1997). A summary of CA [42] Kong, D. (1997). Food packaging materi- requirements and recommendations for als. In: Brody AL, Marsh KS (eds) The fruits other than apples and pears. In: Wiley encyclopedia of packaging technol- Kader A (ed) Fruits other than apples and ogy. Wiley, New York. pears. Postharvest Hort. Series No. 17, Univ. Calif., Davis, CA, CA’97 Proc. vol 2, [43] Lange, D. L. (2000). New film technologies pp 1–36 for horticultural commodities. Hort Tech- nology, 10, 487–490. [35] Kader, A. A., & Watkins, C. B. (2001). Modified atmosphere packaging—toward [44] Li, T., & Zhang, M. (2015). Effects of mod- 2000 and beyond. Hort Technology 10, 483 ified atmosphere package (MAP) with a 486. silicon gum film window on the quality of stored green asparagus (Asparagus offici- [36] Kader, A. A., Singh, P. R. & Mannappe- nalis L) spears. LWT - Food Science and ruma, J. D. (1998). Technologies to extend Technology, 60, 1046-1053. the refrigerated shelf life of fresh fruits. In: Food Storage Stability (eds I.A. Taub and [45] Li, Y., Ishikawa, Y., Satake, T., Kitazawa, R.P. Singh).CRC, Boca Raton, FL H., Qiu, X., & Rungchang, S. (2014). Effect of active modified atmosphere packaging [37] Kader, A. A., Zagory, D., Kerbel, E. L., & with different initial gas compositions on Wang, C. Y. (1989). Modified atmosphere nutritional compounds of shiitake mush- packaging of fruits and vegetables. Criti- rooms (Lentinus edodes). Postharvest cal Reviews in Food Science & Nutrition, Biology and Technology, 92, 107-113. 28, 1-30.

56 Journal of Applied Packaging Research [46] Mahajan, P. V., Oliveira, F. A. R., & [53] Massey, L. K. (2003). Permeability proper- Macedo, I. (2008). Effect of temperature ties of plastics and elastomers. A guide to and humidity on the transpiration rate of packaging and barrier materials. Published the whole mushrooms. Journal of Food in the United State of America by Plastic Engineering, 84(2), 281-288. Design Laboratory/William Andrew Pub- [47] Mahajan, P. V., Oliveira, F. A. R., & lishing 13 Eaton Avenue Norwich, New Macedo, I. (2008). Effect of temperature York. and humidity on the transpiration rate of [54] Montanez, J. C., Rodríguez, F. A., the whole mushrooms. Journal of Food Mahajan, P. V., & Frías, J. M. (2010). Mod- Engineering, 84, 281-288. elling the effect of gas composition on the [48] Mahajan, P. V., Oliveira, F. A. R., Mon- gas exchange rate in Perforation-Mediated tanez, J. C., & Frias, J. (2007). Develop- Modified Atmosphere Packaging. Journal ment of user-friendly software for design of , 96(3), 348-355. of modified atmosphere packaging for [55] Montero-Calderona, M., Rojas-Graub, M. fresh and fresh-cut produce. Innovative A., & Olga, M. B. (2008) Effect of pack- Food Science & Emerging Technologies, 8, aging conditions on quality and shelf-life 84-92. of fresh cut pineapple (Ananas comosus). [49] Maier, C. (1998). Polypropylene the definite Postharvest Biology and Technology, 50, user’s guide and data book. Plastic Design 82–189. Library, Norwich, New York. [56] Oliveira, A., Alexandre, E. M. C., Coelho, [50] Mangaraj, S., Goswami, T. K., & Mahajan, M., Gomes, M. H., Almeida, D. P. F., & P. V. (2009). Applications of plastic films Pintado, M. (2015). Effect of modified for modified atmosphere packaging of atmosphere on polyphenols during storage fruits and vegetables: a review. Food Engi- of pasteurised strawberry purees. LWT - neering Review, 1, 133–158. Food Science and Technology, 60, 377-384. [51] Mannapperuma, J. D., Zagory, D., Singh, [57] Oliveira, F., Sousa-Gallagher, M.J., R. P., & Kader, A. A. (1989). Design of Mahajan, P.V., Teixeira, J.A. (2012). Devel- polymeric packages for modified atmo- opment of shelf-life kinetic model for mod- sphere storage of fresh produce. In: ified atmosphere packaging of fresh sliced Fellman JK (ed) Proceedings of the 5th mushrooms. Journal of Food Engineering, international controlled atmosphere 111, 466 – 473. research conference. Wenatchee, WA, [58] Opara, U. L., & Mditshwa, A. (2013). A USA. review on the role of packaging in secur- [52] Marsh, K., & Bugusu, B. (2007). Food ing : Adding value to food packaging—roles, materials, and environ- products and reducing losses and waste. mental issues. Journal of Food Science, 72, African Journal of Agricultural Research, R39–R54. 8, 2621-2630.

Modified Atmosphere Packaging 5 7 [59] Paine, F. A., & Paine, H. Y. (Eds.). (1992). [67] Renault, P., Souty, M., & Chambroy, Y. A handbook of food packaging. Springer (1994). Gas exchange in modified atmo- Science & Business Media. sphere packaging. 1: A new theoretical [60] Parry, R. T. (1993). Packaging require- approach for micro-perforated packs. Inter- ment of fruits and vegetables. In: Parry RT national journal of food science & technol- (ed) Principles and application of modi- ogy, 29, 365-378. fied atmosphere packaging of food. Blacki, [68] Sacharow, S. & Griffin, R. C. The evolu- Glasgow, UK. tion of food packaging. In: Sacharow, S. and [61] Parry, R.T. (1993). Principles and applica- Griffin, R. C., Ed. Food Packaging. West- tions of modified atmosphere packaging of port, CT: AVI Publishing Company, Inc., foods. Chapman & Hall, Suffolk. 1970, pp 1–62. [62] Phillips, C. A. (1996). Review: modified [69] Sacharow, S., & Griffin, R. C. (1980). Prin- atmosphere packaging and its effects on ciples of food packaging, 2nd edn. AVI Pub- the microbiological quality and safety of lishing, Westport, CT. produce. International Journal of Food [70] Salame, M. (1986). Prediction of gas barrier Science & Technology, 31(6), 463-479. properties of high polymers.Polymer Engi- [63] Prasad, M. (1995). Development of modi- neering & Science, 26, 1543-1546. fied atmosphere packaging system with [71] Ščetar, M., Kurek, M. & Galić, K. (2010). perm selective films for storage of red deli- Trends in Fruit and Vegetable Packaging – a cious apples. Unpublished Ph.D. Thesis, Review. Croatian Journal of Food Technol- Department of Agriculture and Food Engi- ogy, Biotechnology and Nutrition, 5, 69-86. neering, Indian Institute of Technology, [72] Selcuk, N., & Erkan, M. (2014). Changes in Kharagpur, India. antioxidant activity and postharvest quality [64] Rahman, M. S., & Ahmed, J. (Eds.). of sweet pomegranates cv. Hicrannar under (2012). Handbook of food process design. modified atmosphere packaging. Posthar- John Wiley & Sons. vest Biology and Technology, 92, 29–36. [65] Rai, D. R., & Singh, R. (2012). Package [73] Selcuk,N., & Erkan, M. (2015). The effects headspace dynamics for baby corn under of modified and palliflex controlled atmo- modified atmosphere packaging with mac- sphere storage on postharvest quality and roperforations. Journal of Food Process composition of ‘Istanbul’ medlar fruit. Post- Engineering, 35(2), 191-208. harvest Biology and Technology, 99, 9–19. [66] Rediers, H., Marijke, C., Luc, P., Willemsa, [74] Silveira, A. C., Araneda, C., Hinojosa, A., K. A. (2009). Evaluation of the & Escalona, V. H. (2014). Effect of non-con- of fresh-cut endive from farmer to plate. ventional modified atmosphere packaging Postharvest Biology and Technology ,51, on fresh cut watercress (Nasturtium offi- 257–262. cinale R. Br.) quality. Postharvest Biology and Technology, 92, 114–120.

58 Journal of Applied Packaging Research [75] Smith, S., Geeson, J., & Stow, J., 1987. Pro- [82] Zhang, M., Meng, X., Bhandari, B., Fang, duction of modified atmospheres in decidu- Z., & Chen, H. (2014). Recent application ous fruits by the use of films and coatings. of modified atmosphere packaging (MAP) Horticultural Science, 22, 772–776. in fresh and fresh-cut foods. Food Reviews [76] Talasila, P. C., & Cameron, A. C. (1997). International. Prediction Equations for Gases in Flexible Modified-Atmosphere Packages of Respir- ing Produce are Different Than Those for Rigid Packages. Journal of Food Science, 62(5), 926-930. [77] Villalobos, M. D. C., Serradilla, M. J., Martín, A., Ruiz-Moyano, S., Pereira, C., & Córdoba, M. D. G. (2014). Use of equi- librium modified atmosphere packaging for preservation of ‘San Antonio’ and ‘Banane’ breba crops (Ficus carica L.) Postharvest Biology and Technology, 98, 14–22. [78] Waghmare, R. B., & Annapure, U. S. (2013). Combined effect of chemical treat- ment and/or modified atmosphere packag- ing (MAP) on quality of fresh-cut papaya. Postharvest Biology and Technology, 85, 147–153. [79] Wang, Y., & Sugar, D. (2013). Internal browning disorder and fruit quality in modified atmosphere packaged ‘Bartlett’ pears during storage and transit. Posthar- vest Biology and Technology, 83, 72–82. [80] Willige, R. V., Linssen, J. P. H., Meinders, M. B. J., Stege, H. V. D., & Voragen, A. G. J. (2002). Influence of flavour absorption on oxygen permeation through LDPE, PP, PC and PET plastics food packaging. Food Additives & Contaminants, 19, 303-313. [81] Yam, K. L., & Lee, D. S. (1995). Design of modified atmosphere packaging for fresh produce. In Active food packaging (pp. 55-73). Springer US.

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