Role of diagnostic packaging in food supply chain management
Interest in the use of intelligent packaging within supply chains has been increasing in recent years. The growth in awareness and continuing research in this area will provide better solutions and recommendations for food suppliers and retailers. This chapter focuses on two key diagnostic packaging technologies: time temperature indicators (TTIs) and freshness quality indicators (FQIs). Future developments in these technologies are discussed together with their potential impact on issues such as stock traceability, inventory management and waste production at all stages of the supply chain. This is followed by a discussion surrounding the collaboration of intelligent packaging with auto identification systems such as radio frequency identification (RFID) and the potential impact that these could have. A brief analysis is included of the benefits and limitations of these technologies and their return on investment.
Modern-day food packaging is expected to provide containment and protection for food produce whilst being informative, attractive, easy to use and environmentally friendly. Consumer demands are primarily focussed towards food products that are as-fresh and unprocessed. Retailer demands are, by contrast, focused towards cost-effective measures that meet consumer demands whilst extending product shelf lives. These requirements have lead to a rapid development of innovations within the packaging industry. There are two key emergent branches that aim to meet these demands, namely, active packaging and intelligent packaging. Although there are products and technologies already available and in use, the focus of this chapter will be on future developments and the potential convergence of these two branches.
Figure 17.1 presents an overview of active and intelligent packaging and the areas that they can potentially improve. The diagram shows the previously mentioned four key functions of packaging. The terms active and intelligent packaging are situated above the roles that they aim to enhance. For example, active packaging provides a means of improving the protection of the contents, whereas intelligent packaging enhances the communication of data to the user. It is important to note that in some cases these categories overlap since some active packaging systems also include improvements based on user convenience, such as microwave susceptors (Yam et al., 2005) which are, for example, used to allow better cooking performance in microwave foodstuffs. In the diagram, overlaps between packaging features are represented by the areas in grey.
Fig. 17.1 Model of packaging functions (adapted from Yam et al., 2005).
The focus of this chapter is towards food packaging that facilitates improved communication with the user, whether the user is a warehouse computer system or a food consumer. The information that is to be communicated will be much more than just the sell-by date, the product brand or the ingredients. With future developments in packaging technology, it is hoped that the user will be able to determine quantitatively to what extent degradation of the food has occurred and how much time is left before the food becomes spoiled.
Active packaging is defined as ‘packaging in which subsidiary constituents have been deliberately included in or on either the packaging material or the packaging headspace to enhance the performance of the packaging system’ (Robertson, 2006). The interaction of the active features can be through a chemical (modified atmosphere) or biological (antimicrobial agents) interface to provide an extended shelf life or an addition to the packaging that enhances its performance.
Examples of active technologies used in packaging are shown in Table 17.1. As previously mentioned, the underlying function of these technologies is to protect and increase the longevity of the product within the packaging. The examples given in the table act to preserve and protect the food product so that it is able to maintain the desired flavour and a customary appearance through delaying or hindering bacterial spoilage. This is achieved by modifying the atmospheric conditions of the packaging or by changing the surface of the packaging.
Examples of active packaging applications for use within the food industry (from Kerry et al., 2006)
|Absorbing/scavenging properties||Oxygen, carbon dioxide, moisture, ethylene, flavours, taints, UV light|
|Releasing/emitting properties||Ethanol, carbon dioxide, antioxidants, preservatives, sulphur dioxide, flavours, pesticides|
|Removing properties||Catalysing food components removal: lactose, cholesterol|
|Temperature control||Insulating materials, self-heating and self-cooling packaging, microwave susceptors and modifiers, temperature-sensitive packaging|
|Microbial and quality control||UV and surface treated packaging materials|
Smart or intelligent packaging is a widely used term that often covers many different branches of technology and packaging design. Although there is no formal academic definition for the terminology ‘smart/intelligent packaging’, many agree that it can be defined as any packaging that goes beyond the use of simple materials in conjunction with printed barcodes or labels (Kerry and Butler, 2008). The term ‘intelligent packaging’ is often used to describe improvements in existing materials or methods to extend shelf life by preventing microbial growth (Coma, 2008; Sivertsvik et al., 2002). Intelligent packaging is also used to illustrate additional design features to packaging that are convenient and that may enhance the usability of a product.
The less stringent definition of intelligent packaging allows for a greater scope of technologies and products. Table 17.2 below summarises the main ideas considered in this topic of research and proposes potential or available technologies that could be used.
Examples of intelligent packaging applications for use within the food industry (from Kerry et al., 2006)
|Area of research||Application|
|Tamper evidence and pack integrity||Breach of pack containment|
|Indicators of product safety/quality||Time temperature indicators (TTI), gas sensing devices, microbial growth, pathogen detectors|
|Traceability/anti-theft devices||Radio frequency identification (RFID) labels, tags, chips|
|Product authenticity||Holographic images, logos, hidden design print elements, RFID|
The focus for this chapter will be on the development of intelligent packaging systems that can be used alongside food products to facilitate better stock management and safety within the food industry. The key driver for this technology is an improvement in food safety and food quality assurance (Ahvenainen, 2003). The improvement for better food safety directly benefits the end-consumer, however, with this technology there may also be direct benefits for food retailers and suppliers.
Sustainability of food supply chains is a topic which is generating plenty of political interest and is another driving force for the development of this technology. High levels of waste can occur within the food industry, most of which is sent to landfill (C-Tech Innovation Ltd, 2004). Guidelines issued by government and environmental departments suggest that there needs to be long-term alternatives to landfill through the reduction of waste production (DEFRA, 2007). This could potentially drive optimal technologies that could be used in supply chains to determine the cause of high wastage levels. Consumers are adding to this pressure as they are becoming more environmentally aware as well as food ‘savvy’ when it comes to selecting products based on traceability and health benefits. The ultimate aim is to produce technologies that could communicate and assure consumers about issues of traceability and safety as well as reducing waste occurrence in supply chains.
For sealed packed produce, the only source of quality assurance at present is the packaging material and its integrity. This is communicated via the branding and the information available on the label, including a sell-by date, the source of contents and location of production. With the consumer trend for fresher, less preserved foods of high quality, a potential market is emerging for an intelligent packaging that can identify food spoilage or deterioration of quality without being invasive, destructive or expensive. For the purposes of this chapter, the focus will be on the interactivity of the packaging with the consumer and the retailer and how reliable the information provided is in terms of food quality and safety, in other words, producing packaging that conveys data to the user that is both easily comprehensive and accurate.
This section will highlight the key areas in which this technology could reduce costs in the future and discuss the problems that it can help to overcome. It is anticipated that intelligent packaging will play an important role in the following areas:
These areas share similar problems that intelligent packaging can help to solve or minimise (Hurme et al., 2002). The first of these problems is the wastage of food. Intelligent packaging can aid the reduction of food waste via improved communication of food degradation to consumers and could potentially reduce the amount of food waste from poor food production and supply chain systems. In a similar vein is the issue of stock management, traceability and information flow within the food industry. Above all, consumer concerns about safety and quality must be considered, as well as overcoming confusion caused by over reliance on date codes (i.e. use-by and best-before dates).
In recent times, food wastage has become an important environmental, economical and political focal point for research and debate (BBC, 2008; Hogg et al., 2007; Ventour, 2007). WRAP (Waste and Resources Action Programme) of the UK recently reported that as much as a third of food bought by consumers is thrown away and placed into landfill (Ventour, 2007). The food, drink and tobacco industry is responsible for 11% (7.5 megatonnes) of the total industrial and commercial waste in the UK with the retail and wholesale sector being responsible for a further 19% (12.9 megatonnes) (DEFRA, 2007). There are three key stages throughout the food supply chain which can be envisaged as a supply pipeline. Figure 17.2 shows the simplified stages of food production, supply and consumption together with the waste produced at each stage. It is important to note that some waste will be unavoidable. There are many examples in this context such as, for example, banana skins from a food production facility manufacturing banana-containing goods.
A significant driver for the food industry to uptake this technology is the increase in production efficiency which in turn would aid in the reduction of production costs. As mentioned previously, governmental pressures on issues surrounding waste production and disposal are growing. Some types of wastage could be better understood if there was a more accurate means of determining their source or sources from a food supply chain. In terms of food traceability, packaging with sensors that follow a product from ‘farm to fork’ would provide key information about the producer and the route through the supply chain to the eventual sale to a consumer (Yam et al., 2005). In a situation where a product needs to be recalled, traceability would mean that less drastic measures would need to be taken to purge the supply chain. For example, if there was an emergency food recall caused by a contaminant from one factory, the information obtained from an intelligent label would prevent the waste of a whole product line and would affect only the product which had passed through that factory. Another advantage mentioned previously would be enhanced consumer confidence in knowing where the item had come from if the label was able to display such information.
Another important driver that needs to be considered for the introduction of intelligent packaging are the requirements of the consumer. A packaging technology that could prevent consumers buying and eating unsafe or poor quality produce would show obvious benefits. Research has shown, however, that there are several potential barriers to overcome when introducing new packaging technology (Hurme and Ahvenainen, 1996). Table 17.3 shows the potential barriers and challenges that need to be overcome when introducing packaging technology to be used by the general public.
|Consumer attitude||Consumer research: education and information|
|Doubts over the performance||Storage tests before launching; consumer education and information|
|Increased packaging cost||Use in selected, high quality products; marketing tool for increased quality and QA|
|False sense of security, ignorance of date markings||Consumer education and information|
|Mishandling and abuse||Active compound/sensor incorporated into label or packaging film; consumer education and information|
|False complaints and returns of packs with indicators||Indicator automatically readable at the point of purchase|
|Difficulty of checking every indicator at point of purchase||Bar code labels: intended for QA for retailers only; RFID system within stores|
(adapted from Hurme and Ahvenainen, 1996)
These solutions would require substantial investment before any real returning benefit is seen by the consumer, retailer or food producer (Han et al., 2005). The function of this technology for industrial use provides more opportunity and benefits in the short term. Using an indicator or sensor for monitoring food spoilage would require a design that integrates easily into existing supply chains and that can also interpret changes and potential hazards which the foodstuff is exposed to. The information that is obtained from the indicators has to be simple and accurate so that the data can be used to make key decisions. A sudden change in temperature in a cold chain would require a decision to be made about the safety of the food as well as an assessment of the scale of the problem.
The role of the intelligent label is to respond to changes in the external environment. The change could be a simple fluctuation in temperature along the cold chain or an increase in volume of a product owing to seasonality. Considering the example of temperature abuse, a time temperature indicator (TTI) (Taoukis and Labuza, 2003, Selman, 1995) label could be attached to a temperature-sensitive product, where a change in temperature affects the state of the TTI label. The change displayed by the TTI could then be fed into a data processing unit that could model and estimate the best business recommendations for how to manage the packaged food through the supply chain (Yam et al., 2005). Figure 17.3 shows the potential feedback loop of a TTI where once a decision has been made from the data gathered from the labels and an action has been taken in real time, the data can be matched to an appropriate model.
Fig. 17.3 Possible information flow diagram of a supply chain augmented with a FQI intelligent packaging system (adapted from Yam et al., 2005).
Although the model is simplistic, it shows the data flow from the external environment, through the labelling technology and into a management decision. In this situation an indicator, such as a TTI, could highlight areas in supply chains which are not maintained or are inefficient at keeping food items chilled. As the data is recorded in real time, companies would get warning of failure or problems and be able to cope better with managing such a problem. Another use for TTIs has been to provide evidence in insurance claims caused by logistical negligence (Tsironi et al., 2008). Transit vehicles that have failed to provide adequate temperature control for chilled products have been shown to be at fault from the data from these sensors.
This model is improved if measuring changes to the external environment is not relied upon solely. If we were able to measure directly the food and the impact of a change in external environment within the packaging, then a more robust food model could be generated and a more reliable business recommendation could be made on what decision to take. A food quality indicator (FQI) could be used in this case to measure direct food changes and spoilage in order to ascertain actual bacterial changes in the food. Figure 17.3 also shows the extra input of information into the food label. A change in temperature could be recorded (external factor) and then the spoilage of the food could also be monitored (internal factor).
The potential application of this technology, if used and harnessed correctly, is to provide a real time flow of information to food producers, retailers and consumers (Kerry et al., 2006). There are many examples of these technologies that are in current use (Hurme and Ahvenainen, 1996; Han et al., 2005; Pacquit et al., 2008). In the literature there are also countless examples of sensors and indicators that are being developed (Adhikari and Majumdar, 2004; Butler, 2001; Connolly, 2007). The next section will examine the impact of TTIs and FQIs as intelligent food labels and compare the two technologies.
17.3 Diagnostic packaging: time temperature indicators (TTIs) versus freshness quality indicators (FQIs) and new technologies
Indicators can be defined as devices or substances that inform the user about the presence, absence or concentration of another substance. They can also indicate the extent of a reaction between substances by means of a distinctive change, such as colour. They are said to differ from sensors as they do not require a receptor or transducer and can impart information through a direct change or reaction (Kerry and Butler, 2008). The subtle difference between TTIs and FQIs is what each one interacts with. A thorough overview of TTIs is presented elsewhere (Taoukis and Labuza, 2003) and several authors have discussed their reliability and function (Selman, 1995; Taoukis et al., 1991; Singh and Wells, 1985). There are also several examples of FQIs in the literature (Kerry and Butler, 2008; Hurme et al., 2002; Kerry et al., 2006; Pacquit et al., 2008; Smolander, 2003). Figure 17.4 shows the distinction between TTIs and FQIs when used as intelligent labels. TTIs rely on modelling and predictive behaviour of microbial growth when temperature abuse occurs. FQIs on the other hand, interact with the metabolites caused by microbial growth and do not require microbial growth models.
Fig. 17.4 Comparison of the information obtained by FQI and TTI labels (adapted from Smolander, 2003).
Here, the focus is on freshness quality indicators (FQI) and time temperature indicators (TTI) as methods for determining food spoilage and estimating shelf lives of differing products. As mentioned previously, FQIs provide direct food quality information by reacting to changes taking place within the foodstuff. These changes can be due either to the external or the internal environment. Internally, these changes are caused by chemical degradation or microbiological activity and metabolism as the food perishes. TTIs on the other hand monitor the temperature and time lapse over a predetermined amount of time so that they are able to estimate how degraded food items changed due to an external environment variation, which in this case would be temperature. For example, if a sensor is set to measure an item that is to be stored for 5 days at 7 °C, then it would indicate when 5 days had elapsed. If this item had been subjected to a higher temperature then the indicator would behave differently and would react quicker to inform the user that the food has degraded sooner.
Temperature is deemed to be the most important external factor controlling food spoilage. Storage temperature has a direct influence on the kinetics of the chemical and biological changes that occur in food products. Currently there are three types of commercially available TTIs which are critical temperature indicators, partial history indicators and full history indicators (Singh, 2000). There has been extensive review of these indicators throughout the literature (Taoukis and Labuza, 2003; Selman, 1995; Taoukis et al., 1991; Singh and Wells, 1985; Claeys et al., 2002; Smolander et al., 2004). Although the technology has been available for over 20 years, the rate of adoption or implementation has been very slow. This has been a result of the high cost of the technology and the lack of supportive information technology that will allow appropriate utilisation (Yam et al., 2005). The information that is obtained by these sensors is also deemed to be limited, especially in the context of cheaper FQI technologies becoming available (Kerry and Butler, 2008).
Most FQIs respond to changes in the gaseous headspace of the packaging. Several techniques exist which correlate changes in certain gases to microbial growth or chemical spoilage. This technology is usually concerned with items such as meat and fish which give rise to distinctive aromas once they spoil or become unsafe to eat. There are also examples of this technology in use with other items such as fruit and vegetables, in addition to materials that are sensitive to changes in concentrations of oxygen and carbon dioxide (Ahvenainen, 2003). Mostly they are concerned with food that has an extremely short shelf life. Table 17.4 summarises some of the points that have been raised by previous research (Hurme and Ahvenainen, 1996).
(adapted from Pacquit et al., 2008)
The main issue with both technologies is the limitated concern over food safety. In both cases the indicators are there to measure food spoilage which is followed as the food degrades and spoilage bacteria populations increase to unsafe levels. This does not take account of the situation where a small number of pathogenic bacteria are sourced onto the foodstuffs (e.g. Salmonella or E. coli; Hurme et al., 2002). The presence of a very small count of these bacteria makes the food unsafe. A TTI is concerned only with the external environment and so it has no method of detecting the bacteria, whereas a FQI may not have the sensitivity or ability to detect such small populations especially if produced commercially on a small budget. Another potential pitfall of these technologies is their sensitivity to spoilage. If the lower limit of detection of spoilage is too high, then users may already be able to determine if the food is spoiled by visually checking it. On the other hand if the limit is too low, then food that is edible would be deemed by the sensor to be unfit for consumption. An advantage is that TTIs and FQIs allow certain levels of tailoring for the levels of detection as there are different standards of spoiled food throughout the world (Singh, 2000).
Another important aspect is the contrast between the kind of produce the user is labelling. The technology in a TTI label functions primarily with foodstuffs that have to be kept at a low and constant temperature. It is only when there are deviations from this temperature that the indicator behaves differently to one that has been attached to a correctly stored item. There is also the issue that the reliability of the indicator increases with the amount of time it is set to measure. This limits the use of TTIs to mainly chilled or frozen long-life goods (Singh and Wells, 1985; Riva et al., 2001).
FQIs solely rely upon the change in headspace gas of the food. The data that they collect relies heavily on the bacterial growth and the metabolites that are produced. The gas has to be of the correct type and concentration to react effectively with the sensing element. This limits the deployment of this kind of food monitoring technology to aromatic and perishable foodstuffs. This is the main reason that research in this area focuses on meat, fish and other short-shelf life food (Kerry et al., 2006; Pacquit et al., 2008).
As previously stated, one of the main barriers preventing the integration of TTIs into supply chains over the last 20 years has been the cost and the requirement for a data and information handling system. Over recent years, production costs of TTIs and FQIs have been reduced and now it is almost unheard of to not have a data base or computing network setup for supply chain management purposes. These two factors have enabled a route to commercialisation for these products. There are still however intrinsic problems that exist when introducing and producing new products and services like these, together with attributing costs and reliance to the present system. A dramatic shift from one labelling type to another may be required in order to provide a pathway for either technology.
RFID (radio frequency identification tags) has long been heralded as ‘the next big thing’ in supply chain management and as the solution to a lot of inventory management problems. In this section, a consideration of a system that has benefited from RFID technology will be discussed. Comparisons between this case study and the food industry will then be drawn to demonstrate the potential impact of RFID technology in collaboration with smart packaging technology. This chapter will not discuss the working of or technical aspects of RFID in detail. An excellent overview has been written elsewhere which explains the workings and limitations of the technology (Clarke, 2008) and the reader is also referred to Chapter 21 of this book by Katerina Pramatari and co-authors.
RFID permits the transfer of electronic data and is therefore classified as a separate intelligent device and does not fall into either the sensor or indicator categories. The concept is that tags are attached to items (ranging from cattle, containers, pallets, individual packets etc) to give the user a real-time collection of data. This data is transmitted to an information system and allows analysis and tracking of the object to which the tag is attached. For some, RFID technology is seen as the natural evolution of the barcode in that it gives objects identification as well as a potential array of other information.
A case study of Marks and Spencer (Stafford, 2008) shows how RFID technology can be transferred to a clothing department. The original technology was used in the food supply chain as a measure of volume and inventory management. In the case study, intelligent labels were attached to individual items of clothing that were then tracked and registered during their journey through the supply chain. When transferring the technology from food to clothing, some of the key benefits were deemed to be:
In this case the tags were only used as a stock control and were unable to emit signals without the correct interrogating signal. This meant that they were able to avoid the issue of breaching customer privacy. An intelligent label used as a food monitoring device would need to be able to communicate with the user at any point to highlight any problems. This is a potential hurdle in light of the recent bad press that RFID has received for being a technology that intrudes into consumer privacy. Another problem is the cost of an integrated label which would require adequate power to monitor food and signal any problems if necessary. This would require a reliable power source and could place the cost of the technology out of the range of potential users.
It is often said that retail is detail. RFID technology in the first instance acts as a descriptor of what it is attached to. Consider a plastic tray in a food depot containing packaged portions of chicken breast; a written tag on the side of the tray would be able to confirm what the contents were and a few more key pieces of information (weight, date and place of origin etc) which would then be manually entered onto a stock management system. A barcode could provide a method of relaying this information, and maybe more, to a stock management system. If a real time device, such as an RFID tag with an attached FQI, were to be attached to the tray, much more information could be ascertained. This information could include more data on the source of the meat, the route taken so far by the tray through the supply chain pipeline, the predicted remaining shelf life of the meat and so forth.
For many, the idea of an RFID tag attached to an individual item, such as a single piece of chicken, for the purposes of stock management in the food industry, would be complex and expensive. If the tag were to provide more information about the remaining shelf life and possible contamination, the cost and information trade off would be better balanced. Figure 17.5 shows a simple model of a supply chain using RFID technology in conjunction with a FQI tag. The route that the RFID chip has taken and its location is updated upon entry and exit at every stage of the diagram. A remote reading could be taken of the state of the foodstuff to which it is attached.
Fig. 17.5 Simplified map of a supply chain and how an intelligent tag could be used for stock control and product monitoring (adapted from Stafford, 2008).
Following this simplified diagram, a generic meat product (here named ‘product code 4’) is followed from producer to point of sale. The emphasis here is on the different routes the product could take through a supply chain and the breakdown of original produce to the final finished product. The wealth of information that could be obtained from a system like this would help to find weakness in efficiency throughout the chain as well as helping manage inventory levels and supply. In the case of Marks and Spencer, there is already an RFID framework set up to work with food inventory management. Adding a sensor to estimate product safety and condition to this existing framework, would enhance the ability for managers to make stock management decisions.
Improvements in food packaging could potentially solve some key problems for retailers and food suppliers. These include understanding the process efficiency of food production, as well as monitoring high volumes of produce as it passes through from production to sale. Issues that have been raised about food waste in the current economic and environmental climate have highlighted potential uses for technologies that can have an impact on food safety and food wastage. Over the past 20 years, supply chain management approaches to inventory management have evolved to allow integration of information technologies. This has emphasised the importance of information sharing and keeping low inventories.
This chapter has only highlighted two potential products from the growing field of smart packaging. The breadth of research is providing substantial improvements and has already seen commercialisation of a number of products. The main hurdle is to provide a cost effective yet reliable sensor so that the benefits and the value of the information retrieved obtained far outweighs the initial cost of implementation.
One of the main reasons why sensors have not been more heavily promoted is due to the lack of cross collaboration on the technology functions that are presently available. RFID has been successfully rolled out in some form into various supply chain situations. A less costly route to sensor integration might include using an RFID network to display the data that the sensor acquires. Therefore the strategy of any food sensor company should be to work with an existing system to reduce the cost of initial implementation.
BBC. Stop wasting food, Brown urging. available at: http://news.bbc.co.uk/1/hi/uk_politics/7492573.stm, 2008. [accessed 07/07].
Clarke, R. The influence of product and packaging characteristics on passive RFID readability. In: Kerry J.P., Butler P., eds. Smart Packaging Technologies for Fast Moving Consumer Goods. 1st edition. Chichester, UK: John Wiley and Sons; 2008:167–195.
Hurme, E., Ahvenainen, R. Active and smart packaging of ready made foods. In: Ohlsson T., Ahvenainen R., Mattila-Sandholm T., eds. Minimal Processing and Ready Made Foods. 1st edition. Goteburg: SIK; 1996:169–182.
Hurme, E., Sipilainen-Malm, T., Ahvenainen, R. Active and intelligent packaging. In: Ohlsson T., Bengtsson N., eds. Minimal Processing Technologies in the Food Industry. 1st edition. Cambridge UK: Woodhead Publishing; 2002:87–123.
Kerry, J.P., O’grady, M.N., Hogan, S.A. Past, current and potential utilisation of active and intelligent packaging systems for meat and muscle-based products: A review. Meat Science. 2006; 74(1):113–130.
Pacquit, A., Crowley, K., Diamond, D. Smart packaging technologies for fish and seafood products. In: Kerry J., Butler P., eds. Smart Packaging Technologies for Fast Moving Consumer Goods. 1st edition. Chichester UK: John Wiley & Sons ltd.; 2008:75–98.
Sivertsvik, M., Rosnes, J.T., Bergslinen, H. Modified atmosphere packaging. In: Ohlsson T., Bengtsson N., eds. Minimal Processing Technologies in the Food Industry. 1st edition. Cambridge, UK: Woodhead Publishing; 2002:61–86.
Smolander, M., Alakomi, H., Ritvanen, T., Vainionpää, J., Ahvenainen, R. Monitoring of the quality of modified atmosphere packaged broiler chicken cuts stored in different temperature conditions. A. Time–temperature indicators as quality-indicating tools. Food Control. 2004; 15(3):217–229.
Stafford, J. How Marks & Spencer is using RFID to improve customer service and business efficiency: A case study. In: Kerry J.P., Butler P., eds. Smart Packaging Technologies for Fast Moving Consumer Goods. 1st edition. Chichester, UK: John Wiley and Sons; 2008:167–210.
Tsironi, T., Gogou, E., Velliou, E., Taoukis, P.S. Application and validation of the TTI based chill chain management system SMAS (Safety Monitoring and Assurance System) on shelf life optimization of vacuum packed chilled tuna. International Journal of Food Microbiology. 2008; 128(1):108–115.