MFT-004>>Block-1>>Unit-1>>

Unit-1:Introduction

MFT-004>>Block-1>>Unit-2>>

Unit-2:Packaging Materials and Properties of Materials

MFT-004>>Block-1>>Unit-3>>

Unit-3:Recent Trends in Food Packaging

3.0 : Objective

3.1 : Introduction

3.2 : Vacuum Package

3.3 : Gas Packaging

3.3.1 : Oxygen

3.3.2 : Carbon dioxide

3.3.3 : Nitrogen

3.4 : Aseptic packaging

3.5 : Retort packaging

3.6 : Active Packaging

3.6.1 : Ethylene scavengers

3.6.2 : Carbon dioxide scavengers and emitters

3.6.3 : Humidity regulators

3.6.4 : Oxygen scavengers

3.6.5 : Antimicrobial packaging

3.6.6 : Breathing films

3.7 : Biodegradable Packaging

3.8 : Let us sum up

3.9 : key words

3.10 : Answers to check your progress exercises

3.11 : Some useful books

3.0 : Objective

After reading this unit, you should be able to: Explain different types of packaging systems Understand the importance of packaging systems Define functions of packages Explain the relationship between food properties and properties of packaging materials Design and develop packages for different foods

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3.1 : Introduction

You have studied packaging requirement and their selection for different food products. When you go to super markets you will see newer and newer packages on the shelf quite often. The shifts in packaging trends are due to consumers demand for convenience, information, attractive display, address one or more specific needs etc. In this unit you will study recent trends in food packaging.Modern food packaging innovations have made it possible to keep the food fresh for a much longer time, without changing the taste or aroma. The goal of developing food packaging is the achievement of a more ideal match of the properties of the package to the requirements of the food. Hence it addresses one or more specific needs of the food without necessarily having any impact on other food properties. Flavour and odour absorbers like films and sachets have been introduced to reduce the transfer of aroma or flavour between components. This helps keeping food items fresh and natural for a long times. Various industries have introduced specific technologies suiting their special food type.Drip absorbing pads have been introduced for moisture control and oxygen removal systems have been used to keep egg fresh for a longer period of time in poultry industry. Digital technology has been introduced to look into the freshness of food items. Ripeness indicators have been designed recently to monitor and communicate information about food quality.Intelligent or smart packaging is designed to monitor and communicate information about food quality. Examples include ripeness indicators and radio frequency identification. These smart devices may be incorporated in package materials, attached to the inside or outside of a package, or sometimes the product itself. These smart devices can be incorporated on the food item itself. Packaging developments such as packages incorporating antimicrobials and oxygen scavengers established new precedents for prolonging shelf life and protecting food from environmental influences. Nevertheless, omnipresent global trends such as increased industrial processing of food, greater importation and exportation of food products, and less time for preparation of fresh foods compel the food and beverage packaging industry to investigate newer, more advanced packaging solutions. It is said that nano technology will produce the most remarkable new food packaging concepts. Work has already begun in the field of active and intelligent packaging, pathogen detection and creating good barriers between various food materials.Thermal processing is one of the conventional preservation methods which assures processed foods to be safe and shelf stable. Thermal processing of foods in cans and bottles is a well known technology which is a common operation in food industry. In this the product is hermetically sealed in a container and heat processed in a retort for required time to arrive at commercial sterility. It is also known as in container sterilization. Now-a-day, it has even extended for plastic based semi rigid and flexible containers known as retort trays and retort pouches respectively. Retort trays are semi rigid containers with a high barrier core layer and retort pouches are flexible packages made of multilayer films with or without aluminium foil. Aluminium foil serves as the barrier layer and is responsible for longer shelf life of over one year for the product. Silicate SiO2layer is also being used as an alternate to aluminium layer as it gives clear pouches and also has the advantage of being micro ovenable. The most important feature of these containers is that they are made of plastics amenable for processing in retorts at temperatures of about 121C. All new innovations in food packaging have some element of "green" sustainable with the criteria of 1) It has to be healthy safe and beneficial for communities and individuals throughout its lifecycle. 2) It meets market criteria for performance and cost. 3) It is sourced, manufactured, transported and recycled using renewable energy. 4) It maximizes the use of renewable or recycled source materials. 5) It is manufactured using clean production technologies and best practices. 6) It is made from materials healthy in all probable end-of-life scenarios. 7) It is designed to optimize materials and energy. 8) It is recovered effectively and used in biological and/or industrial cradle to cradle cycles.These are among the many developments emerging from research labs worldwide where food scientists, materials specialists and others continually attempt to improve current packaging materials and develop new ones with optimal barrier properties. Like food products themselves, packaging materials are constantly evolving to meet the latest demands of the marketplace. Companies have a significant interest in improving their food products. New packaging films that offer optimal barrier properties undoubtedly will help companies meet the challenge of keeping products fresh and extending their shelf life.

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3.2 : Vacuum Package

In the retail shops you will find products like dry foods such as cereals, nuts, cured meats, cheese, smoked fish, coffee etc are packed in vacuum. In this section we will find out why they are vacuum packed.

Fig 3.1 Vacuum packaged food productsVacuum packaging refers to packaging in containers (rigid or flexible), from which substantially all air has been removed prior to final sealing of the container. This method of packaging is actually a form of Modified Atmosphere since normal room air is removed from the package. Vacuum packaging helps in extending shelf life; in controlling oxidative rancidity; preventing the growth of normal spoilage bacteria; in suspending Aerobic organisms such as Pseudomonas and favouring lactic-acid bacteria. The latter can grow to high numbers without causing spoilage. Reduces moisture loss and freezer burn. Prevents movement of water out of the product into the surrounding headspace. Prevents loss of moisture at product surface and eliminates freezer burn. Requires minimal storage space Package is drawn tight around product taking up minimal space. Leakers are easily detected A small puncture or pinhole in a vacuum pack is easy to detect by looking for loose packages. This technique has been shown to help maintain the quality of various frozen products including pizza, seafood, beef and pork.

There are two forms of vacuum packaging, depending on the rigidity of the package. The first form of vacuum packaging involves a rigid package (e.g., glass jar) or a semi-rigid package (e.g., plastic container) in which most of the air is evacuated, but a headspace still remains in the package. The removal of air typically reduces the oxygen level in the headspace to as low as 1%, which significantly helps to reduce the problem of oxidation. However, frost formation and freezer burn are still problematic since the headspace exists.

The second form of vacuum packaging involves a flexible package (e.g., a plastic pouch) in which not only the oxygen is removed but also the headspace is eliminated. Thus both oxidation and frost formation are controlled. This form is also known as vacuum skin packaging, since the food is tightly wrapped by the package. The mechanical stress created by the vacuum also helps to remove air pockets inside the product. This technique has been widely used to package frozen meat and seafood products including meat balls, clam strips, lobster tails, salmon, and farmed rainbow trout.

Several types of materials are used for vacuum skin packaging, such as a blend of Surlyn ionomer resin with low density polyethylene (LDPE) and ethylene-vinyl acetate (EVA). Vacuum packaging requires the use of gas barrier packaging materials; otherwise, the vacuum cannot be maintained for a prolonged period of time.

Vacuum packaging, and reduced oxygen packaging, is an excellent way of preserving frozen food quality and safety. The exclusion of oxygen from the microenvironment surrounding the food has benefits to prevent the growth of aerobic microorganisms and also minimizes the effects of detrimental oxidative biochemical reactions, which would normally set a limit on the achievable quality shelf-life of the food. Vacuum packaging is also an excellent means of minimizing surface moisture loss, both in terms of dehydration during freezing and drip loss during thawing. The technology is also beneficial from a processing perspective, as the skin-tight package on the food readily allows heat transfer from the food to the freezing medium. This means that foods can be packaged prior to the freezing operation, which makes the essential requirement of good hygiene practice a little easier for the food manufacturer.

Fig 3.2 Vacuum Chamber SealersExternal Sealers

External vacuum sealers involve a bag being attached to the vacuum-sealing machine externally. The machine will remove the air and seal the bag, which is all done outside the machine.

Chamber Sealers

Chamber sealers require the entire product to be placed within the machine. Like external sealers, a plastic bag is typically used for packaging. Once the product is placed in the machine, the lid is closed and air is removed. Once the air is removed, the bag is sealed and the atmosphere within the chamber is returned back to normal. The lid is then opened and the product removed. Chamber sealers are typically used for higher-volume packaging.

We have studied the vacuum packed products. Now we will see some of the products like potato chips are packed with gases called gas packaging.

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3.3 : Gas Packaging

Gas packaging can be defined as the alteration of the proportional volumes of the gases which comprise a normal atmosphere. This type of packaging generally falls into two categories. The most commonly used gases for the packaging are CO2, N2and O2. According to EU legislation, foods packaged in modified atmospheres must be labelled with a phrase like Packaged in a protective atmosphere. Gases for the packaging of meat are seldom used alone but in mixtures, which vary according to the application.Materials used for modified atmosphere packaging are a combination of different substrates. The materials can be as simple as two-ply laminations or multi-layer coextrusions, incorporating EVOH as a high barrier substrate.

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3.3.1 : Oxygen

One of the major functions of oxygen is to maintain the red pigment, myoglobin in the oxymyoglobin state that is responsible for the bright red colour associated with freshness. Oxygen pressure levels over 240 mm are thought to greatly increase and extend the fresh appearance of meats.

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3.3.2 : Carbon dioxide

Carbon dioxide is a known inhibitor of microbial growth. Gram-negative spoilage flora of refrigerated meat is especially sensitive to CO2while lactic acid bacteria are less affected. The inhibitory effects of CO2have been attributed to alteration of the bacterial cells permeability, pH changes and enzymatic inhibition. CO2helps to increase the lag phase and generation time, which delays the overall increase of bacterial populations. Factors such as initial bacterial load, time of application, storage temperature and gas concentration will affect the desired end result. The inhibitory efficiency of CO2is increased at lower temperatures. This is thought to be due to the fact that the solubility of gases is much higher at lower temperatures; the CO2concentration in the medium will increase as the temperature is lowered.Carbon dioxide reacts with water to form carbonic acid and can actually dissolve in food products. As the gas dissolves in the water the quantity of gas within the package diminishes and a partial vacuum is generated. This may bring about the collapse of the pack.Carbon dioxide by itself already been recognized for a significant effect of inhibiting pathogens, but concentrations over 30 percent or 40 percent usually result in discoloration of fresh meat. But in combination with carbon monoxide, the colour is greatly improved. With cooked, cured, processed products, the higher levels of carbon dioxide are acceptable. It doesnt discolour those products such as ground meat or pork chops.

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3.3.3 : Nitrogen

Nitrogen is an inert gas and is abundantly available at relatively low cost, has neither colour nor odour and is chemically unreactive. It has a low solubility in both water and fat. In modified atmospheres nitrogen is used to displace oxygen in order to delay aerobic spoilage and oxidative deterioration. Another role of nitrogen is to act as a filler gas so as to prevent pack collapse. Nitrogen packaging is common for foods like potato chips, snack foods, fruits and vegetables, and many meat and seafood items.

Fig 3.3 Vacuum and Gas packaging machineCheck Your Progress Exercise 1

Note: a) Use the space below for your answer b) Compare your answer with those given at end of the unit.1. What is vacuum packaging?...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

2. How is shelf life extended under vacuum?.......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

3. What are advantages of Vacuum Packaging?...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

4. What is nitrogen or inert gas packing?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

5. Do you have to use special pouches for vacuum/gas packaging?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

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3.4 : Aseptic packaging

Aseptic packaging can be defined as the filling of a commercially sterile product into a sterile container under aseptic conditions and hermetically sealing the containers so that reinfection is prevented. This results in a product, which is shelf-stable at ambient conditions. The term aseptic is derived from the Greek word septicos which means the absence of putrefactive micro-organisms. In practice, generally there are two specific fields of application of aseptic packaging technology: Packaging of pre-sterilised and sterile products. Examples are milk and dairy products, puddings, desserts, fruit and vegetable juices, soups, sauces, and products with particulates. Packaging of non-sterile product to avoid infection by micro-organisms. Examples of this application include fermented dairy products like yoghurt.Aseptic packaging technology is fundamentally different from that of conventional food processing by canning. In canning, the process begins with treating the food prior to filling. Initial operations inactivate enzymes so that these will not degrade the product during processing. The package is cleaned, and the product is introduced into the package, usually hot. Generally, air that can cause oxidative damage is removed from the interior. The package is hermetically sealed and then subjected to heating. The package must be able to withstand heat up to about 100C for high acid products and up to 127C for low acid products, which must receive added heat to destroy heat-resistant microbial spores. Packages containing low-acid (above pH 4.5) food must withstand pressure as well. Although conventional canning renders food products commercially sterile, the nutritional contents and the organoleptic properties of the food generally suffer in the processing. Moreover, tinplate containers are heavy in weight, prone to rusting and are of high cost.

The three main advantages of using aseptic packaging technology are: Packaging materials, which are unsuitable for in-package sterilisation can be used. Therefore, light weight materials consuming less space offering convenient features and with low cost such as paper and flexible and semi-rigid plastic materials can be used gainfully. Sterilisation process of high-temperature-short time (HTST) for aseptic packaging is thermally efficient and generally gives rise to products of high quality and nutritive value compared to those processed at lower temperatures for longer time. Extension of shelf-life of products at normal temperatures by packing them aseptically.Besides the features mentioned above, additional advantages are that the HTST process utilises less energy, as part of the process-heat is recovered through the heat exchangers and the aseptic process is a modern continuous flow process needing fewer operators. Figure shows schematic representation of aseptic packaging process. Different methods based on physical process, chemical sterilisers and radiations are used for sterilisation of packaging materials.

Fig 3.4: Schematic diagram of Aseptic packaging processFunctional requirements1. High impermeability to water vapour, zero WVTR for prolonged storage. 2. Very low permeability to gases especially oxygen since its interaction leads to chemical and biological deterioration.3. Aroma barrier property to preserve odours and freedom from external taints.4. Inertness with the product packed, sterilizing treatments, imparted-heat, chemicals or radiations.5. Perfect package and closure integrity.6. Capacity to form well on operating machinery.7. Provide user convenience for unit and bulk packages.8. Thermal stability for both low and high temperature.9. Sufficiently robust to withstand rough treatment likely to occur during handling and transportation.10. Meet all regulatory specifications.Aseptic packaging forms: Aseptically processed foods are packed in varieties of packaging materials and forms comprising flexible, semi rigid and rigid containers. Their structure, form and application are as follows.

Flexible pouches and bags: Flat or Stand up pouches like PET/PE, met PET/PE, PET/Al foil/PE and some co-extruded film structures can be used for this. The shelf lives of aseptically processed foods are given in Table 5.

Cartons in aseptic packaging: Different types of cartons gable-top, tetrahedron and brick shape are employed for aseptic packaging. The tetrahedral shape has the advantage of minimum ratio of area to volume and employed for liquid food. Brick cartons are very popular as they facilitate easy distribution. The cartons are essentially made of PE/paper/PE/Al foil/PE with slight differences among manufacturers. Especially for aseptic juice applications, the inner most layer is PE-Ionomer co-extruded web as this eliminates PE de-lamination from the foil. A typical six layer laminate construction used in aseptic packaging is 16 m coating/ 240 gsm paper board/ 16 m PE/ 9-10 m Al foil/ 11 m Ionomer and 38 m PE. The outermost PE layer provides water vapour barrier property, paper board provides stiffness, ease of formation on automatic machines and printability. 9-10 m Al foils afford gas and water vapour barrier property, odour proofness and light protection. Ionomer eliminate seal failures and leakers and resist cracking at score lines. However it has been shown that oxygen transmission rate at the scored area would be 40-50 times higher than flat area. To eliminate the risk of contamination from the base of carton, all edges are protected.

Fig 3.5 Composition of Tetra packs Aseptic Carton.Bag in the box system: Bag in the box is high barrier multilayer bag contained in a shipping container of CFB or wooden box or metal drum. The capacity of the bag ranges between 5 liters institutional use to 250 liters (60 gallons) for industrial market (Paine 1987). Even 1135 liters (300 gallon) bulk containers are also available. Generally these bags are made of met PET/PE or PA/PE having 4 side seals of width 5-10 mm. Inclusion of a single web of inner loose liner of LLDPE provides added physical strength. High barrier Al foil laminates with PET or PA / Al foil / PE / LDPE / LLDPE are also being used for aseptic bags. The most important factor in bag design is the spout. In normal use the bag has a welded fitment which contains a rigid plastic spout which is fitted with a screw cap or pressed fit cap and some with spigots for easy dispensing. There are different types of construction of spouts with ability to maintain aseptic conditions.Bag in drum system: These are bulk metal containers used for aseptic bags. They are normally 247.5 lt electrolytically tin plated containers. The body and the components are made from electroplated 18 gauge steel with 6-10 times more tin coating than the normal tin plate cans. The drum is normally coated with a suitable food lacquer and can withstand a vacuum of 27.The aseptic packaging is very well accepted in food service applications worldwide as a safe and high-quality packaging option. Aseptic processing sterilizes food products by destroying the harmful bacteria and pathogenic micro-organisms through a tightly controlled thermal process and combines the sterile product with the sterile packaging material in a sterile environment; the end result is a shelf-stable product requiring no refrigeration. The use of plastics in the aseptic packaging significantly increases the non-refrigerated shelflife and availability of many perishable products. Today, this is readily being used in the innermost contact layers of the package, thereby protecting the quality of food.

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3.5 : Retort packaging

Retort is a cooking process that uses heat and pressure to cook food in its sealed package. Retort Packaging conditions are quite demanding with temperatures typically ranging from 120C to 130C. Different retort grade films which are laminated together to provide the strength, toughness, puncture and burst resistance that enable flexible retort packaging to withstand the strenuous retort process.

Fig 3.6 RetortRetort packaging was initially developed using glass and metal. Consumer convenience, safety concerns and cost issues served as the genesis for the development of plastic resin formulations capable of sustaining the challenging retort temperatures. The magnitude of the development challenge is proportional to the thermal and pressure history of the package in the retort. These attributes of the process are governed by the target Fo value required to achieve sterilization.

A retortable pouch is a multi-layered lamination structure designed to withstand extreme conditions, including cooking, freezing, dropping, and flexing. It can also be heated and sterilized, thereby providing for long term storage. To properly retort a pouch, temperatures can reach up to 275 F for up to 90 minutes. Many new pouches feature a clear, see-through lamination structure and, to provide added convenience, some new retort pouches feature re-closable zippers or spouts. Retorted pouches are often designed to remain stable for up to 60 months.

For many food products, retortable pouches have already replaced a metal can. Two prominent examples include tuna fish and moist pet food. These products are readily found today on store shelves in pouch form. Also found on store shelves in retortable packages are: seafood, precooked meats, rice, sauces, soups, stews, and many others.

Retort pouch packaging has superior barrier and printing qualities and can be supplied as stand-up, flat or in roll form. Flexible retort packaging offer a variety of additional benefits over rigid packaging to both retailers and consumers that include : Superior taste due to reduced retort time. Extended shelf life in retort packaging. Reduced storage space in retort packaging, both in warehouse and pantries. Reduced transportation costs. Easier and safer tear-open/disposal consumer experience. Microwave convenience retort packaging

Retort packaging and packaging are available in two variants one is aluminium foil laminated and another transparent see through retort packaging .

Common flexible retort packaging structures include the following:

PET / FOIL / Nylon / CPP PET / Nylon / FOIL / CPP PET-SiOX or AlOX / Nylon / CPP

Due to retort packaging have their thinner dimensions; it takes less time to cook food in a flexible retort packaging than in other forms of rigid packaging such as cans and jars. This reduced retort time results in foods that have superior taste in retort pouches.

Fig 3.7 Retort pouchesSuitable semi rigid containers for thermal processing are

1. Injection moulded multiple pocket plastic trays of construction PP/ PVDC(or EVOH)/ PP2. Al Foil based trays made of Body- Epoxy resin / 100-150 m Al Foil / 50 m PP3. Lid - Epoxy resin / 50- 100 m Al Foil / 50 m PP

Fig 3.8 High barrier polypropylene retort tray

Fig 3.9 Lid material for trayCheck Your Progress Exercise 2

Note: a) Use the space below for your answer b) Compare your answer with those given at end of the unit.

1. What are the benefits of aseptic packaging to the consumer?............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................2. What is aseptic packaging?..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

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3.6 : Active Packaging

Active packaging is an emerging and exciting area of food technology which can confer many preservation benefits on a wide range of foods. The aim of active packaging is to match the properties of the package to the more critical requirements of the food. Adoption of some of these methods will require changes in attitude to packaging and a willingness to address regulatory issues where chemical effects are used. Application of these and other emerging technologies offers the prospect of greater satisfaction in India as these are relatively new concepts, and that we are maximising the benefits from some of our traditional agricultural industries.

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3.6.1 : Ethylene scavengers

Ethylene (C2H4) acts as a plant hormone that has different physiological effects on fresh fruit and vegetables. It accelerates respiration, leading to maturity and senescence, and also softening and ripening of many kinds of fruit. Furthermore, ethylene accumulation can cause yellowing of green vegetables and may be responsible for a number of specific postharvest disorders in fresh fruits and vegetables. Although some effects of ethylene are positive such as degreening of citrus fruit, ethylene is often detrimental to the quality and shelf life of fruits and vegetables. To prolong shelf life and maintain an acceptable visual and organoleptic quality, accumulation of ethylene in the packaging should be avoided. Most of these absorbers are supplied as sachets or integrated into films. Potassium permanganate (KMnO4), oxidizes ethylene to acetate and ethanol. In this process, colour changes from purple to brown indicating the remaining C2H4scavenging capacity. Products based on KMnO4cannot be integrated into food-contact materials, but are only supplied in the form of sachets because KMnO4is toxic and has a purple colour. Typically, such products contain 4 to 6% KMnO4on an inert substrate with a large surface area such as perlite, alumina, silica gel, vermiculite, activated carbon or celite. CFTRI Mysore has developed KMnO4and activated brick power based ethylene scavengers in sachet for storage and transportation and refill for refrigerators respectively. Rengo Co. (Japan) developed `Green Pack', a sachet of KMnO4embedded in silica. The silica adsorbs the ethylene and the permanganate oxidizes it to acetate and ethanol. The technology of C2H4scrubbing has also been transferred to household refrigerators in USA. Systems containing a zeolite coated with KMnO4are now available and are meant to be used in consumer refrigerators e.g. Mrs Green's Extra Life cartridges from Dennis Green (USA) and Fridge Friend TM sachets from Ethylene Control.

Furthermore, the adsorbing capacity is often lost when incorporating these minerals into a polymer matrix. Commercially available examples of these mineral containing materials are the Orega plastic film (Cho Yang Heung San Co., Korea), Evert-Fresh (Evert-Fresh Co., USA), Peakfresh TM (Peakfresh Products, Australia), BO film (Odja Shoji Co., Japan) and ProfreshTM Europe). PeakfreshTM is a mineral impregnated film that is FDA approved and complies with current EU directives. C2H4scavengers are not yet very successful, probably because of insufficient adsorbing capacity. A large proportion of the fresh fruits and vegetables harvested each year are lost due to fungal contamination and physiological damage. The C2H4adsorbing packaging concepts could possibly contribute to an increase in the internal trade as well as export of fresh produce.

Fig 3.10 Ethylene scavenger

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3.6.2 : Carbon dioxide scavengers and emitters

CO2is formed in some foods due to deterioration and respiration reactions. The produced CO2has to be removed from the package to avoid food deterioration and/or package destruction. CO2absorbers might therefore be useful. The active compound Ca(OH)2of FreshLock reacts at sufficiently high humidity with the CO2to produce CaCO3. A CO2absorbent sachet includes porous envelope containing CaO and a hydrating agent such as silica gel on which water is absorbed.In some cases, however, high CO2levels (10-80%) are desirable for foods such as meat and poultry because these high levels inhibit surface microbial growth and thereby extend shelf-life. Fresh meat, poultry, fish and cheese can benefit from packaging in a high CO2atmosphere. Removal of O2from a package by use of O2absorbers creates a partial vacuum which may result in a collapse of flexible packaging. Also, when a package is flushed with a mixture of gases including CO2, the CO2dissolves partly in the product and creates a partial vacuum. In such cases, the simultaneous release of CO2from inserted sachets which consume O2is desirable. Such systems are based on either ferrous carbonate or a mixture of ascorbic acid and sodium bicarbonate. The O2absorbers/CO2generators are mainly used in products where package volume and package appearance are critical.

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3.6.3 : Humidity regulators

This approach allows the food packer to reduce the surface concentration of water in a food by reducing the in-pack relative humidity. This can be done by placing one or more humectants between two layers of a plastic film which is highly permeable to water vapour. An example of this type of product is "Pitchit" manufactured by Showa Denko in Japan. The film duplex is described as containing an alcohol, as propylene glycol and a carbohydrate, both of which are humectants. A different approach to humidity buffering is being developed for use in the distribution of horticultural produce which is normally distributed in fibreboard cartons, usually with a polyethylene liner or made from very expensive waxed fibreboard without a liner. A recent development has been the water-barrier coating of the inside of fibreboard cartons to allow moist produce to be placed directly into the carton. Besides the introduction of liquid water with the produce, packing into closed spaces allows the build-up of water vapour. Since temperature cycling is very difficult to avoid during handling there is every likelihood of condensation and with this the growth of microorganisms on fruits and vegetables.Two widely different approaches have been taken to buffering the humidity in the cartons in order to prevent condensation while not concurrently causing desiccation of the produce. One is to include microporous bags or pads of inorganic salts and the other is to line the carton with a protected layer of a solid polymeric humectant.The most recent alternative involves the use of the carton as the active package rather the use of an insert. This approach lends itself to combination with EMA generation less readily as the humidity is buffered at the interface with the fibreboard. The designs of Patterson and Joyce involve a) an integral water vapour barrier layer on the inner surface of the fibreboard, b) a paper-like material bonded to the barrier and which acts as a wick, and c) a layer highly permeable to water vapour (but unwettable) next to the fruit or vegetable. The latter layer is spot welded to the layer underneath. Accordingly the multilayer of material on the inside of the carton is able to take up water in the vapour state when the temperature drops and the RH rises. When the temperature rises the multilayer releases water vapour back into the carton in response to a lowering of the RH. The condensation control system therefore acts as an internal water buffer. The critical characteristic of the system is the capacity of the wick layer for water. For dried food applications, desiccants such as silica gel, molecular sieves, CaO and natural clays (e.g. montmorillonite) are often contained within TyvekTM sachets. Examples where these compounds are used include the sachets MINIPAX and STRIP-PAX and the moisture absorbing label DesiMax (United Desiccants, USA) and the sachets Desipak, Sorb-it , Tri-sorb and 2-in-1TM(Multisorb technologies, USA).

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3.6.4 : Oxygen scavengers

Oxygen is such a broadly effective agent of deterioration in foods that a substantial industry has been established to provide a wide range of alternative means of oxygen removal from package headspaces to reduce chemical deterioration. The choice of method of oxygen removal depends upon both economic factors and upon the properties of the particular food. In practice the application of a short inert-gas flush coupled with use of a scavenger is likely to be an attractive combination. The performance of oxygen scavenging sachets depends strongly on the equilibrium relative humidity of the food and the range of sachets available. The inclusion of iron-based scavenging compositions in sachets has been improved by development of adhesive scavenging labels for the inner wall of packages.

Iron based oxygen scavenger

Sachet Based should be Permeable to O2& H2O; 1gm absorbs ~300 cc of oxygen; LD50 = 16mg/kg body wt.

Fig 3.11 Oxygen scavenger pouchScavenging mechanism:Fe Fe+2+ 2e1\2 O2+ H2O + 2e- 2OHFe+2+ 2OH- Fe(OH)2Fe(OH)2+ 1\4 O2 Fe(OH)3Technologies for thin films typically used in MAP systems need an additional feature to prevent premature reaction if they are to provide maximum scavenging capacity. The transition-metal-catalyzed (optionally light-activated) process patented by W.R. Grace, Inc. approaches this by pre-planned activation involving generation of full capacity by consumption of antioxidants. This type of film, involving side-chain oxidation of a polydiene, appears to be designed as a permeation barrier for chilled, short shelf life processed meats. Amoco Chemicals have reported some performance data for their Amosorb, water-activated, masterbatch for blending into a variety of plastics. No compositional detail is yet provided but the masterbatch and plastics incorporating it are stable at relative humidities below 40%.The development of yellow colour or fluorescence in an oxygen scavenging plastic film has been proposed as a means of monitoring the initial scavenging capacity of such films or as a heat seal leakage indicator in filled packages.The oxygen scavengers were incorporated in LLDPE film fo increase the shelf life of bread and bun(CFTRI). Ageless (Mitsubishi Gas Chemical Co., Japan) is the most common O2scavenging system based on iron oxidation. The sachets are designed to reduce O2levels to less than 0.01%. A rule of thumb is that 1g of iron will react with 300 cc of O2. When the initial O2Concentration at the moment of packaging and the O2permeability of the packaging material is known, an absorber can be chosen. However, a potential risk could be accidental ingestion of a large amount of iron, in spite of the label `Do not Eat'. Other iron-based O2absorbent sachets are the ATCO O2-absorber (Standa Industrie, France), the Freshilizer Series (Toppan Printing Co., Japan), Vitalon (Toagosei Chem. Industry Co., Japan), Sanso-cut (Finetec Co., Japan) and Freshpax (Multisorb Technologies Inc., USA).An alternative to sachets is the incorporation of the O2scavenger into the packaging structure itself. Low molecular weight ingredients may be dissolved or dispersed in a plastic or the plastic may be made from a polymeric scavenger. An example is Oxyguard (Toyo Seikan Kaisha, Japan), an iron-based absorber which can be incorporated into a laminate. The main alternative to dispersal of iron in plastics is organic reactions of plastics themselves. Oxbar is a system developed by Carnaud-Metal Box (UK) which involves cobalt-catalysed oxidation of a nylon polymer blended especially in PET-bottles for plastic packaging of wine, beer, sauces and other beverages. It should be noted that the speed and capacity of O2scavenging films are considerably lower compared with iron-based O2scavenger sachets. Other recent developments include inserts in the form of flat packets, cards or sheets, as well as O2scavenging adhesive labels, like Freshmax (Multisorb technologies, USA) and the ATCO labels (Standa Industrie, France).Ascorbic acid is another O2scavenging component which can be used. The Pillsbury Co. holds a 1994 patent that also utilizes ascorbic acid as reducing agent. A transition metal, copper, is used to catalyse the oxidation reaction. The product, referred to as Oxysorb can be included inside a pouch or may be incorporated into the packaging. Another O2scavenging technique involves sealing of a small coil of an ethyl cellulose films containing a dissolved photosensitive dye and a singlet O2acceptor in the headspace of a transparent package. Due to illumination of the film with light of the appropriate wavelength, excited dye molecules sensitize O2molecules, which have diffused into the polymer, to the singlet state. These singlet O2molecules react with acceptor molecules and are thereby consumed.

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3.6.5 : Antimicrobial packaging

The surfaces of plastics can be made not only sterile but also capable of having an antimicrobial effect on the packaged food or beverage. This type of effect has already been achieved in outer layers of laminates by use of modified printing presses. Horseradish extract on a cyclodextrin carrier has been used in a drip sheet for fish or in a film wrap for lunches in Japan. Approaches to antimicrobial packaging can be classified as either of two types. The first consists of binding an agent to the surface of packages and this would require a molecular structure large enough to retain activity on the microbial cell wall even though bound to the plastic. Such agents are likely to be limited to enzymes or other antimicrobial proteins. The second approach involves the release of agents into the food or beverage or localized removal of a food ingredient essential for microbial growth.Release of antimicrobial agents will be restricted by regulatory approval as intended food additives. This is not necessarily a serious restriction as the goal of the approach is merely to maintain an appropriate concentration of the agent on the surface of the food which may have been effectively inoculated with microorganisms due to cutting or slicing. This concept has been advanced in the case of an edible coating. An alternative approach which has been developed in Japan by Mitsubishi is based on the inclusion of zeolite particles in the surface of the food-contact layer in laminates. The zeolite has some of its surface atoms replaced by silver which appears to release silver ions as aqueous solution from the food enters the exposed cavities of the porous zeolite structure. The extent of food contact depends upon the zeolite particles having a diameter greater than the thickness of the layer in which they have been embedded. The water then appears to leach traces of silver from the particles giving the highly efficient antimicrobial activity of this ion. The effect is unlikely to be as great in foods where there is a substantial content of amino acids capable of reacting with silver ion. These include acids such as cysteine. The use of edible coatings to apply relatively constant concentrations of permitted antimicrobial agents at the food surface has been developed. The relative rates of diffusion within the coating and within the food itself are very important. Such a process could be important where antimicrobial, such as sorbate, are lost by degradation. Application of antimicrobial via edible coatings appears likely to gain importance with minimally processed foods distributed under MAP conditions.To control undesirable microorganisms on foods, antimicrobial substances can be incorporated in or coated onto food packaging materials. The principle action of antimicrobial films is based on the release of antimicrobial entities, some of which could pose a safety risk to consumers if the release is not tightly controlled by some mechanisms within the packaging material. The major potential food applications for antimicrobial films include meat, fish, poultry, bread, cheese, fruits and vegetables.Several other compounds have been proposed and/or tested for antimicrobial activity in food packaging including organic acids such as sorbate, propionate and benzoate or their respective acid anhydrides, bacteriocins e.g. nisin and pediocin, enzymes such as lysozyme, metals and fungicides such as benomyl and imazalil. A film contains a natural antimicrobial compound derived from grape- fruit seed. A rarely mentioned possibility for manufacturing antimicrobial films is to incorporate radiation-emitting materials into films. However, little direct evidence for the efficiency of this technology has been published in the scientific literature. Many of the incorporated antimicrobials are not yet permitted for food use. The choice of the antimicrobial is often limited by the incompatibility of the component with the packaging material or by the heat liability of the component during extrusion. One per cent potassium sorbate in a LDPE film inhibited the growth of yeast on agar plates. The LDPE resin and potassium sorbate powder can be mixed, extruded and pelletized to produce a masterbatch. These pellets can be added to LDPE resin. The masterbatch should be produced at low temperature to prevent heat decomposition of the potassium sorbate. Another study, however, found the relatively polar sorbate, benzoate and propionate to be incompatible with the apolar LDPE. Acid anhydrides were thought to be more compatible than free acids and their salts because of their lower polarity. Two commercial biocidal films are currently marketed. One is composed of a chlorinated phenoxy compound and the other consists of chlorine dioxide. A commercial antifungal coating containing chitosan is also sold as a shelf-life extender for fresh fruit. Specific trade names or effectiveness of these commercial products were not mentioned. An interesting commercial development is the recent marketing of food-contact approved Microban (Microban Products Co., USA) kitchen products such as chopping boards, dish cloths, which contain triclosan, an antimicrobial aromatic chloro-organic compound, which is also used in soaps, shampoos, etc. In EU countries, however, the use of triclosan for food-contact applications is not allowed and the SCF (Scientific Committee for Food) has currently major objections against the use of triclosan in food contact materials.Another compound that exhibits antimicrobial effects is ethanol. Spraying ethanol onto foods prior to packaging can be applied, but another option is to use sachets generating ethanol vapour. Ethicap or Antimold from Freund Industrial Co. (Japan) consists of a 55%/10% ethanol/water mixture adsorbed onto silicon dioxide powder (35%), contained in a sachet of a laminate of paper/ethyl vinyl acetate copolymer. Ethicap acts by absorbing moisture from the food and releasing ethanol vapour. Using Ethicap ,yeast growth was suppressed completely in all packages during 21 days at 200C. Negamold (Freund Industrial Co.), scavenges O2as well as generating ethanol vapour. Other ethanol generators are Oitech TM(Nippon Kayaku, Japan), Ageless type SE (Mitsubishi Gas Chemical Co.) and ET Pack (Ueno Seiyaku, Japan). Ethanol vapour generators are widespread in Japan and are mainly used for high moisture bakery goods, fish products and cheese. A major disadvantage of ethanol vapour is its absorption by the food product. In some cases the ethanol concentration in the product might cause regulatory problems. If the product is heated prior to consumption the accumulated ethanol may evaporate. Another drawback is the cost of the sachets, which limits their use to products with higher profit margins.

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3.6.6 : Breathing films

Permeability regulations via. Thermally sensitive packaging materials.A significant development is that of side-chain-crystallisable (SCC) polymers with the ability to effectively and reversibly melt as the temperature increases and thus foster increased gas transmission through them. SCC polymers are acrylics with side-chains independently of the main chain. By varying the side-chain length, the melting point can be altered. By making the appropriate copolymers, it is possible to produce any melting point from 0 to 68C., well within the extreme distribution temperature range of minimally processed foods. When elevated to the switch temperature, SCC polymers become molten fluids which are inherently high in gas permeability. The permeation properties may be modified by inclusion of other polymers to change the carbon dioxide to oxygen permeability ratios, for example. The resulting materials can permit the packaging technologist to achieve the lowest oxygen concentration without going anaerobic within the package. Thus, the optimum gas concentration may be employed from the outset of distribution with minimum concern for elevated temperatures. In addition to the reversible temperature sensitivities, the materials are generally capable of 100 times greater oxygen permeability than mainstream polyethylene films without compromising the carbon dioxide to oxygen permeability ratio. This is accomplished by coating a porous substrate with a proprietary SCC polymer and applying the membrane as a package label over an aperture on an otherwise reasonably well sealed package. Membranes with high carbon dioxide to oxygen ratio selectivity are best for products with carbon dioxide sensitive contents to allow the carbon dioxide to escape at rate faster than oxygen can enter. Conversely, membranes with low ratios are more applicable to products in which high carbon dioxide values can inhibit microorganisms. Thus, the materials can be tailored to the exact requirements of the package contents. These SCC materials are manufactured by Landec Corp. Menlo Park, California.Check Your Progress Exercise 3Note: a) Use the space below for your answer b) Compare your answer with those given at end of the unit.1. What an oxygen absorber is made of?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................2. Why use oxygen absorber?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................3. What are the benefits of using O2absorbers?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................4. What is Intelligent Packaging?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

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3.7 : Biodegradable Packaging

Biodegradable plastics are plastics that will decompose in natural aerobic (composting) and anaerobic (landfill) environments. Biodegradation of plastics can be achieved by enabling microorganisms in the environment to metabolize the molecular structure of plastic films to produce an inert humus-like material that is less harmful to the environment. They may be composed of either bio plastics, which are plastics whose components are derived from renewable raw materials, or petroleum-based plastics which utilize an additive. The use of bio-active compounds compounded with swelling agents ensures that, when combined with heat and moisture, they expand the plastic's molecular structure and allow the bio-active compounds to metabolize and neutralize the plastic.

ASTM International defines appropriate testing methods to test for biodegradable plastic, both anaerobically and aerobically as well as in marine environments. The specific subcommittee responsibility for overseeing these standards falls on the Committee D20.96 on Environmentally Degradable Plastics and Biobased Products . The current ASTM standards are defined as standard specifications and standard test methods. Standard specifications create a pass or fail scenario whereas standard test methods identify the specific testing parameters for facilitating specific time frames and toxicity of biodegradable tests on plastics.

Examples of biodegradable plastics

Most aliphatic polyesters are biodegradable due to their potentially hydrolysable ester bonds: Naturally Produced: Polyhydroxyalkanoates (PHAs) like the poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxyhexanoate (PHH); Renewable Resource: Polylactic acid (PLA); Synthetic: Polybutylene succinate (PBS), polycaprolactone (PCL), Polyanhydrides, Polyvinyl alcohol, Most of the starch derivatives and Cellulose esters like cellulose acetate and nitrocellulose and their derivatives (celluloid).

Fig 3.12 Utensils made from biodegradable plastic.Advantages and disadvantagesUnder proper conditions biodegradable plastics can degrade to the point where microorganisms can metabolise them. Degradation of oil-based biodegradable plastics may release previously stored carbon as carbon dioxide. Starch-based bioplastics produced from sustainable farming methods can be almost carbon neutral but could have a damaging effect on soil, water usage and quality, and result in higher food prices. There are concerns over "Oxo Biodegradable (OBD)" plastic bags. These are plastic bags which contain tiny amounts of metals such as cobalt, iron or manganese. They degrade in the presence of sunlight and oxygen, but there are concerns about the metals leftover and the time it takes for the plastics to degrade in certain circumstances. Microbial consumption of polymers are available through addition of hydrophilic type additives onto the surface of the polymer chains. These types of additives are readily available and are used worldwide. The advantages of using these types of materials are heat stability, methane capturing and product performance.

Check Your Progress Exercise 4

Note: a) Use the space below for your answer b) Compare your answer with those given at end of the unit.

1. What are the main types of biodegradable plastics and how do they differ?......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

2. What are the end products of biodegradation and do they have any harmful effect on the environment?.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

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3.8 : Let us sum up

Convenience is the latest word in the food packaging industry with consumers on the constant look out for ready to eat meals. In recent times, food packaging innovations have made it possible to preserve the food fresh with good shelf life without changing the quality of the packaged food. Rising income, changing lifestyles and technology, as well as the widespread popularity of microwaveable foods is driving the use of portion and plastic packaging. In the future, partnerships between the food processor and the packaging industry are likely to be a crucial step toward more rigid, stable, and resalable packages. Development in commonly used packaging materials such as glass, plastics, light metals, and paperboard throws light on certain food packaging techniques namely aseptic packaging, retort packaging, active packaging, controlled atmosphere storage, and modified atmosphere packagingVacuum packaging is removes all headspace air from the package before final sealing of the container/ pouch. This helps in extending the shelflife. It requires gas barrier packaging material. Gas packaging is another way of extending of shelf life of different foods. For the fresh meat oxygen is required to maintain the red colour. CO2is used to inhibit the microbial growth and nitrogen is used as inert gas to displace O2is order to delay oxidative deterioration of foods.Aseptic packaging is a presterilization of food and packaging in sterile package and sealing hermatically to prevent the reinfection of the foods. Basically the processes used in dairy products, fruits and vegetables and juices.Retort packaging is cooking process of foods inside package itself at higher temperature and pressure. packaging requires strength toughness, puncture and burst resistance. Materials used are glass metal- cans and thermally stable multilayer pouches.Active packaging is another emerging area where the extra properties are provided from the package by incorporation of active ingredients package material. Ethylene scavengers are necessary to delay the ripening of fruits and vegetables. KMnO4 is used to oxdise ethylene, Ca(OH)2is used as active compound to react with CO2formed due to respiration of fresh produce, Humectent are used to reduce surface water by reducing the pH in pack. Iron based O2scavenger are used to reduce the O2level less than 0.01% are highly O2sensitive foods.The food package industry is realizing that with the increasing health consciousness among consumers, understanding the interactions between the food, package, and the environment are essential for more efficient food packaging solutions. Multidimensional functionality is the key goal in the packaging industry today, Packaging is now more inclined toward aspects such as increasing shelf life, ensuring food safety through control of the environment within the package, and minimizing damage resulting from microbial attack.

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3.9 : key words

CO2 Carbon dioxideO2 oxygenN2 NitrogenPET Polyethylene terephthalatePE PolyethyleneAL AluminiumLLDPE Linear low-density polyethylenePA PolyamideCPP Coextruded polypropyleneC2H4 EthyleneCaO Calcium oxideEMA Ethylene Methyl Acrylate CopolymerMAP Modified atomospheric pressurePLA Polylactic acidPHA PolyhydroxyalkanoatesPHB PolyhydroxybutyrateEVOH Ethylene Vinyl AlcoholHTST High Temperature Short Time

Head SpaceThe gaseous constituents of a closed space above liquids or solid in the container

Shelf lifeShelf life is the recommendation of time that products can be stored, during which the defined quality of a specified proportion of the goods remains acceptable under expected (or specified) conditions of distribution, storage and display.

ScavengersA chemical substance added to in order to remove or inactivate impurities or unwanted reaction products.

EmittersThe substance (chemical or combination of chemicals) used to give or send out required chemicals or gases

Aseptic processingThe process by which a sterile (aseptic) product (food) is packaged in a sterile container in sterile atmosphere in a way which maintains sterility.

Co-extrusionThe process of extruding two or more materials through a single die with two or more orifices arranged so that the extrudates merge and weld together into a laminar structure.

Retortan airtight vessel in which substances are heated at required temperature.

InhibitorA substance that decreases the rate of or prevents a chemical reaction.

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3.10 : Answers to check your progress exercises

Check Your Progress Exercise 1Your answer should include the following points:1. The process of removing air around a food product and then sealing the product in an impermeable package.2. Removing the air that surrounds food inhibits growth of bacteria, mold, and yeast because these and other spoilage microorganisms need oxygen to grow. Once most air is removed and the pouch is sealed, oxygen levels continue to drop while carbon dioxide levels increase. The low oxygen, high carbon dioxide environment significantly reduces the growth of normal spoilage organisms, allowing longer shelf life.3. Some of the advantages include: Vacuum packaging reduces product shrinkage. There is no moisture loss or evaporation in a sealed vacuum bag. Therefore, the weight you package will be the weight you sell. Vacuum packaging reduces trim losses by eliminating oxidation and freezer burn. Vacuum packaging can enhance product quality. Vacuum packaged meat held at 32 to 35 does not hinder aging or tenderizing. Vacuum packaging allows more efficient use of time. Food can be prepared in advance without loss of freshness, so slack times are more productive and busy times are more manageable.4. The process of controlled purging of inert gas inside a flexi pouch and sealing the mouth of the pouch with gas inside in sequence, is called inert gas packing. You can vacuummize and purge the pouch inside the INDVAC chamber type machine or you can vacuummize and purge or only purge a flexi pouch in INDVAC nozzle type machine.5. Yes, the conventional monolayer pouches are not suitable as they do not have barrier property. You need to use multi layer pouches with either polyester, nylon or aluminium foil barrier layers.Check Your Progress Exercise 2Your answer should include the following points:1. The special aseptic process yields a shelf-stable product, which can be kept in a cupboard for extended periods of time without preservatives or refrigeration. In describing their preference, consumers often point to the safety, nutrition, and ease of handling of the aseptic package. Others prefer the aseptic carton because it is shatter-proof and tamper-evident.2. Aseptically processed liquid foods and beverages are sterilized outside the package using an ultra-high temperature process that rapidly heats, then cools, the product before filling. This flash-heating-and-cooling aseptic process substantially reduces the energy use and nutrient loss associated with conventional sterilization. As a result, aseptically packaged products retain more nutritional value, and exhibit more natural texture, colour, and taste.Check Your Progress Exercise 3Your answer should include the following points:1. An oxygen absorber is made of a chemical compound, the active ingredient of which is an Iron Powder (Fe).2. When food has an oxygen environment, it can become moldy. It can oxidize, the colour can change, microorganisms can thrive, and the taste can change. With oxygen present, toxins can grow as by products of bacteria.3. It extends food shelf life. It prevents the growth of aerobic pathogens and spoilage organisms, including molds. It eliminates the needs for additives such as BHA, BHT, sulphur dioxide, sorbets, benzoates, etc. Use with gas flushing packaging to absorb virtually all oxygen and absorb any oxygen that may permeate the package.4. Intelligent packaging refers to packaging systems that influence of packaging so that the condition of food is monitored. It helps to extend the shelf life, to monitor freshness and to improve safety of the packaged product.Check Your Progress Exercise 4Your answer should include the following points:1. There are 2 main types of biodegradable plastics: oxo-biodegradable and hydro- biodegradable. Both will first undergo chemical degradation by oxidation and hydrolysis for oxo- and hydro-biodegradable plastics respectively. This results in their physical disintegration and a drastic reduction in their molecular weights. These smaller, lower molecular weight fragments are then amenable to biodegradation.2. The end products of biodegradation are carbon dioxide, water and biomass. Extensive studies and tests have been conducted by EPI with internationally recognized laboratories and institutions to confirm that they do not leave harmful or toxic residues to the environment.

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3.11 : Some useful books

1. Aaron L. Brody, Eugne R. Strupinsky, Lauri R. Kline. (2001)Active packaging for food applicationsTechnomic Pub. Co., Technology & Engineering.2. Gordon L. Robertson (2006)Food packaging: principles and practice Taylor & Francis/CRC Press, 2006 - Technology & Engineering.3. Jung H. Han (2005)Innovations in food packagingAcademic Press, - Technology & Engineering.4. David K. Platt,(2006) Rapra Technology LimitedBiodegradable polymers: market report iSmithers Rapra Publishing.5. Matche Rajeshwar S (2001)Packaging Machinery, in Handbook of Frozen Food Processing and PackagingEdited by Da-Wen Sun, Taylor & Francis/CRC Press.

MFT-004>>Block-1>>Unit-4>>

Unit-4:Packaging Machinery