Advances in food packaging

Stewart Postharvest Review An international journal for reviews in postharvest biology and technology

Advances in food packaging – a review Harleen Kour, Naseer Ahmad Towseef Wani, Anisa Malik, Rajkumari Kaul, Harmeet Chauhan, Prerna Gupta, Anju Bhat and Jagmohan Singh Division of Post Harvest Technology, Sher-e-Kashmir University of Agricultural Science and Technology, Jammu, India

Abstract Purpose of review: This article focuses on the use of active and intelligent packaging in the food industry and highlights areas where these techniques are being applied for the storage of fresh produce. Findings: Active and intelligent packaging are of great importance to the storage of fresh produce and several types of active packages are commercially available. Recent studies with strawberries have shown that active packaging, with and without CO2 absorbers, maintained fruit quality and improved storage life significantly better than controls. Assessment of fruit quality can be monitored nondestructively using FT-NIR. Intelligent packages, eg, the 3MTM MonitorMark indicator, have been developed and have had success in the food industry. Nanotechnology applications in packaging include sensors that can detect food deterioration, nanoclay-nylon coatings and silicon oxide barriers for glass bottles that impede gas diffusion, metalized films, and antimicrobials incorporated in packaging, smarter bar codes, and improved pigments, inks, and adhesives. Directions for future research: The recent advances in packaging technologies have improved things both from a consumer safety perspective and for manufactures as well. However, there are several areas which require further exploration. These include: the development of toxic free and degradable or edible packaging materials that are for humans as well as for the environment; further research into regulations governing the assessment and use of these technologies worldwide. The development of the 3MTM MonitorMark indicator and others have generated much momentum in the area of food packaging research and we believe that in the near future this will be followed by the development and widespread use of many other similar indicators. Keywords: biosensors; time-temperature indicators; oxygen scavengers; antimicrobials; active and intelligent packaging

Abbreviations MAP TTI

Modified Atmosphere Packaging Time-Temperature Indicator

*Correspondence to: Harleen Kour, Division of Post Harvest Technology, Sher-e-Kashmir University of Agricultural Science and Technology, Jammu-180018, India. Email: [email protected] Stewart Postharvest Review 2013, 4:7 Published online December 2013 doi: 10.2212/spr.2013.4.7

© 2013 Stewart Postharvest Solutions (UK) Ltd. Online ISSN:1945-9656 www.stewartpostharvest.com

Introduction In recent years packaging has developed well beyond its original function as merely a means of product protection and now plays a key marketing role in developing on shelf appeal, providing product information, and establishing brand image and awareness. The continued quest for innovation in food and beverage packaging is mostly driven by consumer needs and demands influenced by changing global trends, such as increased life expectancy, fewer organizations investing in food production and distribution [1], and regionally abundant and diverse food supply. The use of food packaging is a socioeconomic indicator of the increased spending ability of the population or the gross domestic product, as well as regional (rural as opposed to urban) food availability. Food and beverage packaging comprises 55% to 65% of the $130 billion value of packaging in the USA [2].

Kour et al. / Stewart Postharvest Review 2013, 4:7

History of packaging development Wrapping the product for the consumer in the late 1800s was not a science. Packaging was anything the seller had on hand. Newspaper and cloth sacks were best known for wrapping meat and holding flour or sugar. The paperboard box lead to the mass-marketing of many products. Canning food, to preserve it for a long period of time was invented in the early 1800s when Napoleon wanted higher quality diets for his armies. Later, the packaging world saw the introduction of other materials such as cellophane and polyethylene. Cellophane, a clear, flimsy product was used as a protective covering for food. It allowed the packager to display products in an attractive way by placing “windows” in a paper package; this type of packaging encouraged the growth of self-service stores. Polyethylene, a kind of plastic, was introduced around the time of World War II. Since the 1950s, plastics have entered the packaging scene to replace many steel, glass, and paper containers. The advantages of plastic containers are that: they are less expensive; easier to produce; lighter in weight; more resistant to breakage; and less expensive to ship.

next sealed tightly. The presence of oxygen in the packaging results in many adverse changes, eg: autoxidation of fats (rancidity); changes of taste and aroma; oxidation of pigments, vitamin C, vitamin E, beta-carotene and certain amino acids; as well as the development of aerobic microflora, particularly moulds. For this reason removing oxygen from the medium can inhibit the development of aerobic bacteria, as well as yeasts and moulds, which cause food spoilage [5]. In this paper will examine some advances in active and intelligent packaging, with emphasis on such methods as: oxygen scavengers, carbon dioxide absorbers and emitters, moisture control agents, antimicrobials and ethylene absorbers and emitters.

Active and intelligent packaging Production of high quality food with an extended shelf life, which is safe for consumer health is a task faced by producers. Advanced packaging systems have been developed in order to protect the product and extend its stability. These technologies are known as active packaging and intelligent packaging [6].

The importance of packaging The principal function of packaging is protection and preservation from external contamination [3]. This function involves: retarding deterioration; extending shelf life; and maintaining the quality and safety of packaged food. Packaging protects food from environmental influences such as heat, light, the presence or absence of moisture, oxygen, pressure, enzymes, spurious odours, microorganisms, insects, dirt and dust particles, gaseous emissions, etc. Secondary functions of increasing importance include traceability, tamper indication, and portion control [4]. Different types of packaging methods have evolved with need. The packaging of food in modified atmospheres is a well-known and proven method. In the beginning only nitrogen and carbon dioxide were used as single gases for processing and packaging of coffee and cheese, among other goods. The main gases used for modified atmosphere packaging (MAP) are nitrogen, carbon dioxide and oxygen. However, argon, carbon monoxide, helium and other gases are defined as permitted gases for MAP by the European Community. The door for MAP was opened in principle, by the needs of the customer. People want fresh, attractive and high quality food at any time in any place. To fulfil these expectations the manufacturer or trader has to solve great logistic problems. Transport over long distances assumes high stability of the goods. In addition, the packed food has to look attractive enough to be bought. Consistent quality (taste, freshness, etc) is absolutely necessary for strong customer loyalty. Another form of packaging which took a lead is controlled atmosphere packaging in which the atmosphere of the food is continuously monitored and controlled. It involves mainly the control of oxygen, carbon dioxide, relative humidity, temperature etc. Vacuum packaging, which also has widespread use, consists of the removal of air from the packaging, which is

Active packaging Active packaging materials are designed to actively maintain or improve the condition of the food either by eliminating unwanted components from the package headspace and/or from the food itself or by releasing active components into the food or its surroundings. Such actions result in an extension of shelf life, improved safety and sensory attributes and the maintenance of product quality [7]. Unlike traditional packaging, active packaging plays a dynamic role in food preservation. The main applications have mostly focused on delaying oxidation and controlling moisture migration, microbial growth, respiration rates, volatile flavours and aromas. Active packaging technology can manipulate permselectivity, which is the selective permeation of package materials to various gases. Through coating, micro perforation, lamination, co extrusion, or polymer blending, permselectivity can be manipulated to modify the atmospheric concentration of gaseous compounds inside a package, relative to the oxidation or respiration kinetics of foods. Certain nanocomposite materials can also serve as active packaging by actively preventing oxygen, carbon dioxide, and moisture from reaching food. . Today more and more studies are being conducted on the application of active packaging studies in postharvest technology. For example, Aday et. al [8] have investigated the use of alternative packaging approaches to maintain the quality and extend the shelf life of strawberries. The methods studied were active packaging, using chlorine dioxide (ClO2) and ethylene moisture sachets. The quality properties of four groups of samples were measured over 3 weeks at 4°C. Groups were: control, active packaging without ClO2 treatment, active 2


packaging with low-dose (5 ppm) ClO2 treatment and active packaging with high-dose (10 ppm) ClO2 treatment. Measured properties were weight loss, gas concentration, pH, titratable acidity, soluble solids content, texture profile and colour. Active packaging with low-dose (5 ppm) ClO2 treatment was found to be the most effective method for retaining titratable acidity and for maintaining (L) brightness values. The control group showed the largest total soluble solids reduction from 7.60 to 6.57. Active packaging without ClO2 treatment showed the lowest weight loss (0.33%), while the control group showed the highest (1.86%) at the end of the storage [6]. These data have shown that active packaging can be beneficial for the storage of postharvest produce.

Applications of active packaging Oxygen scavengers The presence of oxygen in a package can trigger or accelerate oxidative reactions that result in food deterioration. Oxygen facilitates the growth of aerobic microbes and moulds. Oxidative reactions result in adverse qualities such as offodours, off-flavours, undesirable colour changes, and reduced nutritional quality. Oxygen scavengers remove oxygen (residual and/or entering), thereby retarding oxidative reactions. They are supplied in various forms; sachets in headspace, labels, or direct incorporation into package material and/or closures. Oxygen scavenging compounds are mostly agents that react with oxygen to reduce its concentration. Ferrous oxide is the most commonly used scavenger. Others include ascorbic acid, sulphites, catechol, some nylons, photosensitive dyes, unsaturated hydrocarbons, ligands, and enzymes such as glucose oxidase. To prevent scavengers from acting prematurely, specialised mechanisms can trigger the scavenging reaction. For example, photosensitive dyes irradiated with ultraviolet light activate oxygen removal [11]. Oxygen scavenging technologies have been successfully used in the meat industry. Chemical substances are contained in a small bag, which is placed in the packaging or they may be incorporated in plastic materials (components of a low molar mass are dispersed in plastic during production or this plastic may be laminated with an absorber carrier) [12]. Kartal et al. [13] have studied the effectiveness of two biaxially-oriented polypropylene and four biaxially-oriented polypropylene microperforated films of different transmission rates (7 and 9 holes) with and without oxygen scavengers, on storage stability of fresh strawberries. The gas concentration in trays, pH, total soluble solids, surface colour (L* and a*), electrical conductivity, sensory acceptance, texture profile and FT-NIR analyses were measured during storage at 4oC. The microperforations and oxygen scavenger significantly affected the maintenance of an optimum gas composition within the package for increasing strawberry storage life and quality [13]. The authors found that, in general, packages

with oxygen scavengers had better results than controls in terms of preservation of the biochemical parameters measured. Commercial oxygen scavengers Several oxygen scavengers are available commercially and are briefly discussed below. Ageless® absorbers / scavengers This scavenger is one of the most often referred to and widely used. It may be supplied in different formats: sachet, to be placed in the primary package, pressure-sensitive label to be affixed in the internal surface of the package or card for product support. The substances used are iron powder and ascorbic acid, although the iron powder is more widely used. Several types and sizes of sachets are commercially available and are applicable to many types of foods of different moisture contents. The main types of absorbents are types Z, S, FX, E and G, although other types are available in Asian markets Types Z, S and FX are based on iron and are single function. Type E contains, besides iron, Ca(OH)2, which is responsible for carbon dioxide scavenging. Type G is based on ascorbic acid and generates an equal volume of carbon dioxide to the oxygen volume scavenged. FreshPax® absorbers / scavengers This product significantly inhibits the growth of moulds in high and moderate barrier packaging. It also reduces the formation of n-hexanal and other volatile compounds in fat rich foods which are sensitive to oxidative rancidity. Atco® absorbers / scavengers This product is available in the form of sachets. It absorbs oxygen in the packaged material, by reduces the level of atmospheric oxygen from 20.9% 0.01%. It prevents the oxidation in the product by absorbing the oxygen, as well as prevents bacterial growth. O-Busters® absorbers / scavengers This product removes the oxygen content inside the packaged environment. The unique O-Busters® blend of absorbents can pick up approximately three times its weight in oxygen, preventing the harmful effect of moulds, mildew, bacteria, colour change, taste change, insects and toxins. It is mostly used in baked products, rice noodles, dried fruits and vegetables. Cryovac® OS2000™ polymer-based O2 scavenging film This product helps in protecting the nutrients, colour and flavour components in food while reducing or eliminating the formation of oxidative by-products. Carbon dioxide absorbers and emitters Carbon dioxide may be added to packages for beneficial effects, for example, to suppress microbial growth in certain products such as fresh meat, poultry, cheese, and baked goods. Carbon dioxide is also used to reduce the respiration 3


rate of fresh produce and to overcome package collapse or partial vacuum caused by oxygen scavengers. Carbon dioxide is available in various forms, such as moisture-activated bicarbonate chemicals in sachets and absorbent pads. Conversely, high levels of carbon dioxide resulting from food deterioration or oxidative reactions could cause adverse quality effects in food products. Excess carbon dioxide can be removed by using highly permeable plastics whose permeability increases with higher temperatures. Calcium hydroxide is a typical absorber of carbon dioxide used in the form of sachets [5]. The use of carbon dioxide absorbers is exemplified in a study by Aday et al. [15], who investigated the effect of active modified atmosphere packaging on the quality of fresh strawberries. Strawberries were treated with one oxygen and two different carbon dioxide scavengers throughout storage at 4°C for 4 weeks. The effect of active packaging was assessed by comparing gas concentrations, pH, electrical conductivity, total soluble solids, surface colour, decay incidence, texture profile analysis, sensory analysis, and FT-NIR analysis values. pH values were significantly higher in the controls (package without absorbers) during storage compared with other treatments. The package headspace with CO2 absorbers, had the lowest CO2 accumulation, and O2 absorbers produced constant O2 levels (5 kPa) during storage. Total soluble solid contents of all treatments were between 10.34% and 7.7% except for the control, which had a value of 6.94% at the end of storage. This study shows that CO2 absorbers are effective for maintaining some biochemical parameters. Electrical conductivity was also lowest with CO2 absorbers throughout storage and colour was better maintained in all treated fruit. Firmness values of the controls were significantly lower than those of the treatments. Results of sensory evaluation showed that the controls had the lowest scores for all attributes. Moisture control agents For moisture-sensitive foods, excess moisture in packages can have detrimental results: for example, caking in powdered products, softening of crispy products such as crackers, and moistening of hygroscopic products such as sweets and candy. Conversely, too much moisture loss from food may result in product desiccation. Moisture control agents help control water activity, thus reducing microbial growth; remove melting water from frozen products and blood or fluids from meat products; prevent condensation from fresh produce; and keep the rate of lipid oxidation in check. Desiccants such as silica gels, natural clays and calcium oxide are used with dry foods while internal humidity controllers are used for high moisture foods (for example, meat, poultry, fruits, and vegetables). Desiccants usually take the form of internal porous sachets or perforated water-vapour barrier plastic cartridges containing desiccants. They can also be incorporated in packaging material. Humidity controllers help maintain optimum in-package relative humidity (about 85% for cut fruits and vegetables), reduce moisture loss, and retard excess moisture in headspace and interstices where

microorganisms can grow. Purge absorbers remove liquid squeezed or leaking from fresh products and can be enhanced by other active additives such as oxygen scavengers, antimicrobials, pH reducers, and carbon dioxide generators. Examples here include packaging composed of an outer layer (eg, polyethylene or polypropylene), constituting a barrier for moisture from the outside, and an active inner layer (with microchannels), made from polyethylene glycol [15]. Antimicrobials Antimicrobials in food packaging are used to enhance quality and safety by reducing surface contamination of processed food; they are not a substitute for good sanitation practices [17]. Antimicrobials reduce the growth rate and maximum population of microorganisms (spoilage and pathogenic) by extending the lag phase of microbes or inactivating them. Antimicrobial agents may be incorporated directly into packaging materials for slow release to the food surface or may be used in vapour form. Research is underway on the antimicrobial properties of the following agents [17]: • Silver ions – silver salts function on direct contact, but they migrate slowly and react preferentially with organics. Research on the use of silver nanoparticles as antimicrobials in food packaging is ongoing, but at least one product has already emerged: FresherLongerTM storage containers allegedly contain silver nanoparticles infused into polypropylene base material for inhibition of growth of microorganisms. • Ethyl alcohol – ethyl alcohol adsorbed on silica or zeolite is emitted by evaporation and is somewhat effective but leaves a secondary odour. • Chlorine dioxide – chlorine dioxide is a gas that permeates through the packaged product. It is broadly effective against microorganisms but has adverse secondary effects such as darkening meat colour and bleaching green vegetables. • Nisin – nisin-coated films were stored at room temperature (21°C) and at 4°C and analysed weekly for 12 weeks. Antimicrobial activity of the different nisincoated films against a nisin indicator strain, Lactococcus lactis subsp. cremoris ATCC 14365, and against Listeria monocytogenes ATCC 19115 was assessed using an inhibition zone assay. Nisin has been found to be most effective against lactic acid and Gram-positive bacteria. It acts by incorporating itself in the cytoplasmic membrane of target cells and works best in acidic conditions [16]. • Organic acids – Organic acids such as acetic, benzoic, lactic, tartaric, and propionic are used as preservative agents [18]. • Allyl isothiocyanate – allyl isothiocyanate, an active component in wasabi, mustard, and horseradish, is an effective broad spectrum spectrum antimicrobial and antimycotic. However, it has strong adverse secondary odour effects in food. • Spice-based essential oils – Spice-based essential oils have been studied for antimicrobial effects: for example, 4


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oregano oil in meat and mustard oil in bread [19. Metal oxides – nanoscale levels of metal oxides such as magnesium oxide and zinc oxide are being explored as antimicrobial materials for use in food packaging [20].

Ethylene absorbers and adsorbers Ethylene has long been recognized as a problem in postharvest handling of horticultural products. It is responsible for a wide variety of undesirable effects: it accelerates the respiration of fruits and vegetables, as well as softening and ripening, and it is responsible for a number of specific postharvest disorders. The removal of this as from storage chambers and packages of fruits and vegetables is, therefore, of the utmost importance, and it is done as a regular practice in the case of chambers, although is only more recently being done in the case of removal from the packages. Ethylene is a very reactive compound that can be altered in many ways, such as chemical cleavage and modification, absorption, adsorption, etc. This creates a diversity of opportunities for commercial applications for the removal of ethylene [22]. Examples of ethylene absorbers include:Potassium permanganate-based scavengers Scavengers based in potassium permanganate are available in sachets for packages or blankets for storage chambers. They are not incorporated into food contacting materials because of its toxicity. The KMnO4 is immobilized in an inert substrate such as alumina or silica gel, among others, in a percentage of around 4 – 6%. The performance and useful life of the scavengers depend on the substrate surface area and the content in permanganate. Formulations differ in density and surface area of substrate and permanganate content [22]. Activated carbon-based scavengers Ethylene can be removed by a system using various metal catalysts on activated carbon. This type of scavenger is more popular in Japan. Examples include the Sendo Mate from Mitsubishi, which is based on a palladium catalyst, Hato fresh System from Honshu Paper, which is based on activated carbon impregnated with bromine-type inorganic chemicals and Neupalon from Sekisui Jushi (Japan) [22]. Activated earth-based scavengers Nowadays several packaging products can be found on the market claiming ethylene adsorption. In most cases, the products consist of finely dispersed clay embedded in polyethylene films or bags that are used for fresh produce. Different minerals are referred to, often local kinds of clay: Oya stone, coral sand, etc. Apparently, there is no scientific evidence of the effectiveness of these films in adsorbing ethylene. Although the finely divided minerals may adsorb the ethylene, they also open pores within the plastic layer, which alter the gas exchange properties of the bag. Because ethylene will diffuse much more rapidly through open pore spaces within the plastic than through the plastic itself, it should be expected that ethylene will diffuse out of these bags faster than through pure polyethylene bags. In addition, carbon dioxide

will leave these bags more readily and oxygen enters more readily than is the case of a comparable polyethylene bag. These effects can improve the shelf-life and reduce headspace ethylene concentrations independently of any ethylene adsorption [22].

Intelligent packaging Intelligent or smart packaging is designed to monitor and communicate information about food quality [10]. This branch of packaging was developed simultaneously with active packaging. These smart devices may be incorporated into packaging materials or attached to the inside or outside of a package. Examples include time-temperature indicators (TTIs), freshness indicators, biosensors and radio frequency identification. Intelligent packaging refers to a packaging system that is capable of carrying out intelligent functions (such as detecting, sensing, recording, tracing, communicating, and applying scientific logic) to facilitate decision making to extend shelf life, enhance safety, improve quality, provide information, and warn about possible problems. We believe that the uniqueness of IP is in its ability to communicate: because the package and the food move constantly together throughout the supply chain cycle, the package is the food’s best companion and is in the best position to communicate the conditions of the food. Intelligent packaging, especially when integrated with science-based principles, is a useful tool for tracking products and monitoring their conditions, facilitating real-time data access and exchange, and enabling rapid response and timely decision making. These qualities are essential for any food safety or biosecurity strategy. One of the key benefits of intelligent packaging is that it informs the consumer of the condition of the product during transport and storage without the need to open the package [9]. Intelligent packaging usually contains quality indicators, TTIs and/or gas indicators. Temperature is usually the most important environmental factor influencing the kinetics of physical and chemical deteriorations, as well as microbial growth in food products. TTIs are typically small selfadhesive labels attached onto shipping containers or individual consumer packages. These labels provide visual indications of temperature history during distribution and storage, which is particularly useful for warning of temperature abuse for chilled or frozen food products. They are also used as “freshness indicators” for estimating the remaining shelf life of perishable products. The responses of these labels are usually some visually distinct changes that are temperature dependent, such as an increase in colour intensity and diffusion of a dye along a straight path. There are 3 basic types of commercially available TTIs: critical temperature indicators, partial history indicators, and full history indicators. Recently, attempts have been made design intelligent packaging with biosensors - “intelligent” devices comprising a bioreceptor recognizing an enzyme, antigen, microorganism, 5


hormone or nucleic acid and a transductor (of the electrochemical, optical or acoustic type), closely related to the specific character of the measured parameter. Self-heating packaging employs calcium or magnesium oxide and water to generate an exothermic reaction. It has been used for plastic coffee cans, military rations, and on-the-go meal platters. The heating device occupies a significant amount of volume (almost half) within the package. Self-cooling packaging involves the evaporation of an external compound that removes heat from contents (usually water that is evaporated and adsorbed on surfaces). More details are available at http://www.prdc.dost.gov.ph/tutorial/tutorial_materials/ antimicrobial_food_pkg.PDF.

Applications of intelligent packaging In this section we briefly highlight some of the ways in which intelligent packaging has been applied in recent years. 3MTM MonitorMark The 3MTM MonitorMark is an indicator that has two versions, one intended for monitoring distribution – the threshold Indicator for industry, and other intended for consumer information – the Smart Label. The former is an abuse indicator, which means that it yields no response unless a predetermined temperature has been exceeded. It is based on a special substance having a selected melting point and blue dye. The heart of the indicator is a porous wick layer over a reservoir pad containing the blue dye. A film strip separates the wick from the reservoir that is removed at the activation stage. At this point, the porous wick, white in colour, is shown in the window. Upon exposure to a temperature exceeding the critical temperature, the substance melts and begins to diffuse through the porous wick, causing a blue colouring to appear. There are available indicators with different critical temperatures from –15ºC to 26ºC. The consumer label is a partialhistory integrator that changes colour when exposed to higher than recommended storage temperature and will also change as the product reaches the end of its shelf-life. The working principle is based, as above, on the melting and diffusion of a dye [22]. Colour changing disposable beverage lids The smart lid is infused with a colour changing additive which allows it to change from a coffee bean brown to a bright red colour when exposed to an increase in temperature. If the red colour is too intense, it indicates to consumers that the coffee in the cup is too hot for comfortable drinking . If the lid is cocked and not positioned correctly, the brown colour will not be distributed evenly and this will indicate that a potential for spillage exists. The change in colour starts at 38ºC and it reaches full intensity at 45ºC. This colour changing additive is safe in food contact surfaces since it meets the requirements of the United States Food and Drug Administration (FDA) regulations relating to direct food contact materials additives. This innovation has won several awards including a “WorldStart Packaging Award” in 2008 and the “Best of Show” Award at the Ameristar Awards Ceremony in

2007. More details are available at http://www.iopp.org/files/ public/OhioStateLizanelFeliciano.pdf . Nanotechnology in packaging Incorporation of nanoparticles of clay into an ethylene-vinyl alcohol copolymer and into a poly(lactic acid) biopolymer was found to increase barrier properties to oxygen. This type of packaging may extend shelf life of food products. Polymer -silicate nanocomposites have also been reported to have improved gas barrier properties, mechanical strength, and thermal stability. Nanotechnology has modified the permeation behaviour, increased barrier properties, improved mechanical and heat-resistance properties, developed active antimicrobial surfaces and sensing as well as signalling microbiological and biochemical changes Kraft foods, along with researchers at Rutgers University in the USA have developed an “electronic tongue” for inclusion in packaging. This consists of nanosensors which are extremely sensitive to gases released by food as it spoils, causing the sensor strip to change colour as a result, giving a clear visible signal of whether the food is fresh or not. More details are available at http://iit.edu/ifsh/news_and_events/press/pdfsduncan_jcisfeature _2011.pdf. Hybrid packaging films have also been developed which are enriched with silicate nanoparticles. These films prevent the food from drying and protect them from moisture and oxygen. Organizations are looking at ways in which nanotechnology can offer improvements in sensitivity or ease by which contamination of food is detected. AgroMicron has developed the “NanoBioluminescence Detection Spray” which contains a luminescent protein that has been engineered to bind to the surface of microbes such as Salmonella and E. coli. When bound, it emits a visible glow, thus allowing easy detection of contaminated food or beverages. The more intense the glow is, the higher the bacterial contamination [23]. A novel packaging material prepared by blending polyethylene with nano powder of silver and titanium oxide was used to preserve fresh strawberry at 4oC. The decay rate was slow in nano-packaging than in normal. After 12 days storage decrease in the content of TSS, TA and ascorbic acid were significantly inhibited as compared to normal polyethylene packaging. The anthocyanin content was less in nano packaging as compared to the normal packaging material. The MDA content with nano-packaging was significantly lower than the normal [24].

Conclusion The food industry has seen great advances in the packaging sector since its inception in the 18th century with most active and intelligent innovations occurring during the past century. These advances have led to improved food quality and safety. While some innovations have stemmed from unexpected sources, most have been driven by changing consumer preferences. The new advances like active and intelligent packaging have mostly fo6


cused on delaying oxidation and controlling moisture migration, microbial growth, respiration rates, and volatile flavours and aromas. Nanotechnology has the potential to influence the packaging sector greatly. Nanoscale innovations in the forms of pathogen detection, active packaging, and barrier formation are poised to elevate food packaging to new heights. The recent advances in the packaging technologies have lead to tremendous growth, improvement and benefits to the consumers as well as manufacturers. There is need to: develop the scavengers which can act within short duration: develop toxic free and degradable or edible packaging materials that are safe for humans as well as for the environment; carry out further research into regulations governing the assessment and use of these technologies worldwide. The development of the 3MTM MonitorMark indicator and others have generated much momentum in the area of food packaging research and we believe that in the near future this will be followed by the development and widespread use of many other similar indicators.

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