Commercialization of time-temperature integrators for foods
Abstract:
Temperature is the main post-processing parameter that determines food quality of perishable food products. Monitoring temperature is essential for effective shelf-life management. A cost-efficient way to monitor and continuously communicate the temperature conditions of individual food products throughout distribution are time-temperature integrators (TTIs). TTIs are inexpensive, active ‘smart labels’ that can show easily measurable, time- and temperature-dependent changes that reflect the time-temperature history of the food products. Implementing a TTI-based system could lead to realistic control of the chill chain, optimization of stock rotation and reduction of waste, and efficient shelf-life management. Current TTI technology, attitudes of consumers and food industry and commercial applications of TTIs are discussed.
14.1 Introduction: active and intelligent packaging – time-temperature integrators (TTIs)
Current packaging technology aims to provide more than the protective functionality required for ensuring the safety and integrity of food products. Active and intelligent packaging imparts passive protection, contributes to shelf-life extension, and provides valuable information about the quality and safety status of food products for better management of the food chain, reduction of food waste, and increased protection of the consumer. The ‘intelligence’ of packaging refers to its ability to communicate information about the requirements known to ensure product quality, like package integrity (leak indicators) and time-temperature history of the product (time-temperature integrators, ‘TTIs’). Intelligent packaging can also give information on product quality directly. For example, freshness indicators provide a direct indicator of the quality of the product (Smolander, 2003). Thus, a signal of microbiological quality of the product could be a result of a reaction between an indicator and the metabolites produced by the growth of the microflora in the product. Such direct or indirect indicators of quality or safety of the products are based on the recognition and thorough study of the deteriorative phenomena that define spoilage processes of foods throughout their intended shelf life.
14.2 History of time-temperature integrators (TTIs) – definition and principles of operation
Perishable food products, even when they are processed and packaged with the best practices and materials currently available, have a limited shelf life. Temperature is the main post-processing parameter that determines food quality. Shelf life can be shortened considerably, if products are not distributed and stored appropriately at controlled temperatures throughout their entire life cycle, including all the way to the consumer’s table. In practice, however, temperature conditions in chilled or frozen distribution and handling very often deviate from recommended levels (Taoukis et al., 1998; Giannakourou and Taoukis, 2003; Giannakourou et al., 2005). Monitoring temperature therefore constitutes an essential prerequisite for effective shelf life management. The complexity of such a task can be fully appreciated when the variations in temperature exposure of individual products within batches or transportation subunits is considered. A cost-efficient way to monitor and continuously communicate the temperature conditions of individual food products throughout distribution would be required, in order to indirectly indicate actual state in terms of quality.
Time-temperature integrators (TTIs) could be effective tools to fulfill this requirement. Based on having available reliable models of food product shelf life and information on the kinetics of a TTI’s response, temperature can be monitored, recorded, and translated into its effect on quality, all the way from production to the consumer’s table. Implementing a TTI-based system could lead to realistic control of the chill chain, optimization of stock rotation and reduction of waste, and efficient shelf life management. TTIs are inexpensive, active ‘smart labels’ that can show easily measurable, time- and temperature-dependent changes that reflect the full or partial time-temperature history of a food product to which they are attached (Taoukis and Labuza, 1989). TTIs are based on mechanical, chemical, enzymatic, or microbiological changes that are irreversible and expressed usually as a response in a visually quantifiable identifier in the form of mechanical deformation, color development, or color movement. The rate of change in the system underlying the TTI is temperature dependent, increasing with higher temperatures, in a manner similar to the deteriorative reactions responsible for food spoilage. Overall, the visible response of the TTIs reflect the cumulative time-temperature history of the food products they accompany. TTIs are an integral part of an interactive intelligent package and can serve as part of an active shelf-life signal in conjunction with the ‘use by date’ on the label.
14.2.1 Development and application
The quest for the development of a reliable, cost-effective temperature history integrating system began when the potential for significantly improving quality and shelf life by monitoring and controlling temperature in the food cold chain was realized. Initially, interest focused on frozen foods. The first application of a ‘device’ to indicate handling abuse dates from World War II, when the US Army Quartermaster Corps used an ice cube placed inside each case of frozen food. The disappearance of the cube indicated mishandling (Schoen and Byrne, 1972). The first patented indicator goes back to 1933 (Midgley, 1933), and over a hundred US and international patents relevant to TTIs have been issued since. During the last 30 years numerous TTI systems have been proposed, of which only a few have reached the prototype, and even fewer have reached the market stage. Byrne (1976), Taoukis et al. (1991a,b), and Taoukis (2001) provided overviews of the evolution of TTIs and compiled a list of patents issued up to that time.
The first commercially available TTI was developed by Honeywell Corp. (Minneapolis, MN) and was described in detail by Renier and Morin (1962). To activate the TTI, pressure was applied to a frangible electrolyte vial that released an electrolytic solution which was absorbed by chemically treated filter paper. An electrolytic cell with the electrodes shorted was thus formed. The hydroxide ion produced at the copper cathode changed the color of the chemically treated paper from yellow to red. A sharp red boundary appeared at the leading edge of the copper electrode coinciding with the ‘0’ of the scale. The red boundary proceeded along the scale at a temperature-dependent rate. The indicator was tested by USDA at the Western Regional Research Laboratory and determined to be reliable (Guadagni, 1963), however, the device never found commercial application, possibly because it was costly and relatively bulky. By 1970 it was no longer available.
In the early 1970s, the US government considered mandating the use of TTIs on certain products (OTA, 1979), which generated a flurry of research and development activities. Researchers at the US Army Natick Laboratories developed a TTI that was based on an oxidizable chemical system (Hu, 1972). The TTI operation was based on the principle of oxygen permeation, as the extent of reaction depended on the amount of oxygen that permeated the film, to indicate the time and temperature exposure history. The solution color started as dark red and gradually turned colorless upon oxidation, to reveal a warning message like ‘Use within …’ or ‘Discard’ that was imprinted on the back surface of the pouch. The system’s response period and temperature dependence was calculated for a variety of alternative polymer films (Killoran, 1976). The system was contracted to Artech Corp. (Falls Church, VA) for commercial development.
In 1976, six companies were making temperature indicators in at least at the prototype stage (Byrne, 1976; Kramer and Farquhar, 1976). By the end of the 1970s, however, there were very few commercial applications of the TTIs. Research activity in the area of TTI subsided temporarily, as evidenced by a decrease in the relevant publications and in the types of new TTI models introduced. However, the more scientifically sound systems remained available, and their development continued with the aim toward fine-tuning their characteristics and making them more consistent with their claimed performance. In the following two decades, three types of TTIs were the main focus of both scientific and industrial trials. The 3 M Monitor Mark® (3 M Co., St. Paul, Minnesota; US Patent, 3,954,011, 1976) achieved one of the first significant applications of TTIs when it was used by the World Health Organization (WHO) to monitor refrigerated vaccine shipments. The indicator consisted of a pad saturated with a chemical mixture of fatty acid esters and phthalates (colored with a blue dye) serving as a reservoir. Layered on the pad was the end of a long porous wick, along which the chemical could diffuse, if the temperature exceeded its melting point. The time-temperature response of the indicator corresponded to the advance of the diffusing blue color front measured on an appropriate scale along the whole length of the wick. The useful range of temperatures and the response life of the TTI was determined by the type of ester used and the concentration at the origin. The first enzymatic indicator, called the I-Point Time Temperature Monitor, and later succeeded by the VITSAB Time Temperature Indicator (VITSAB A.B., Malmö, Sweden), was based on a color change caused by a pH decrease occurring from controlled enzymatic hydrolysis of a lipid substrate (US Patents 4,043,871, 1977 and 4,284,719, 1981). The Lifelines Freshness Monitor® and Fresh-Check® TTI (Lifelines Inc., Morris Plains, NJ) were based on a solid state polymerization reaction (US Patents 3,999,946, 1976 and 4,228,126, 1980) resulting in a highly colored polymer (Fields and Prusik, 1983). The response of the TTI is the color change measured as a decrease in reflectance. Further details on the principles and mechanism of operation of the above TTIs are given by Taoukis (2001).
14.3 State of the art time-temperature integrator (TTI) technologies
The ideal TTI should be applicable to the targeted food product, practical as a shelf life management tool, and cost effective (Taoukis and Labuza, 2003). Such a TTI should:
• Be based on a continuous time-temperature dependent change that is expressed in a response that is easily measurable and irreversible.
• Have a response rate and identifier that mimics or closely correlates to the food’s extent of quality deterioration and residual shelf-life.
• Be reliable and reproducible, to give consistent responses when exposed to the same or equivalent temperature conditions and temporal profiles.
• Be flexible, adaptable to various temperature ranges (e.g., frozen, refrigerated, room temperature) with adjustable temperature sensitivity, and be useful for response periods of a few days up to several months.
• Be small, easily integrable as part of the food package and compatible with a high speed packaging process.
• Have a long shelf life before activation for use and be easily activatable.
• Be unaffected by ambient conditions other than temperature, such as light, RH, and air pollutants.
• Resist normal mechanical abuses and have a response that is unalterable by mishandling or tampering.
• Be nontoxic and pose no safety concern in the unlikely situation of contact with product.
• Be able to transmit in a simple, clear way the intended message to its targets, including distribution handlers, inspectors, retail store personnel, or consumers.
• Have a response both visually understandable and adaptable to measurement by electronic equipment for easier and faster information, acquisition, storage, and subsequent use.
Systems that are currently available commercially and striving to fulfill these requirements, while based on different principles of operation, are the following:
The Checkpoint® TTI, (VITSAB A.B., Malmö, Sweden) is an enzymatic system. This TTI is based on a color change caused by a pH decrease which is the result of a controlled enzymatic hydrolysis of a lipid substrate. Different combinations of enzyme-substrate and concentrations can be used to give a variety of response lives and temperature dependencies. Upon activation, the enzyme and substrate are mixed by mechanically breaking a separating barrier inside the TTI. Hydrolysis of the substrate (e.g., tricaproin) causes acid release (e.g., caproic acid), and the corresponding pH drop induces a color change of a pH indicator from deep green to bright yellow to orange red (Fig. 14.1, not shown here in color). A visual scale of the color change facilitates visual recognition and evaluation of the magnitude and significance of the color change. The continuous color change can also be measured with instrumentation and the results can be used in a shelf life management scheme.
The Fresh-Check® TTI (Temptime Corp., NJ, USA) (successor to Fresh-Check of Lifelines) are based on a solid state polymerization reaction. The TTI function is based on the property of disubstituted diacetylene crystals (R–C = C–C = C–R) to polymerize through a lattice-controlled solid-state reaction, resulting in a highly colored polymer. The response of the TTI is the color change as measured in terms of a decrease in reflectance. The color of the ‘active’ centre of the TTI is compared to the reference color of a surrounding ring (Fig. 14.2, not shown here in color). Before using the indicators, which are active from the time of their production, the TTIs have to be stored at deep frozen temperatures, where change is very slow.
The OnVu™ TTI (Ciba Specialty Chemicals & Freshpoint, SW) is a newly introduced solid state reaction-based TTI. It is based on the inherent reproducibility of reactions in crystal phase. Photosensitive compounds such as benzylpyridines are excited and colored by exposure to low wavelength light. This colored state reverses to its initial colorless state at a temperature-dependent rate (Fig. 14.3, not shown here in color). By controlling the type of photochromic compound and the time of light exposure during activation, the length and the temperature sensitivity of the TTI can be set. This TTI can take the form of a photosensitive ink and be very flexible in its application.
The (eO)® TTI (CRYOLOG, Gentilly, France) is based on a time-temperature depended pH change that is expressed as color changes using suitable pH indicators. The pH change is caused by controlled microbial growth occurring in the gel of the TTI (Ellouze et al., 2008). The parameters of the TTI are adjusted for select microorganisms by appropriate variations in the composition of the gel. The response of the TTI is claimed to mimic microbiological spoilage of the monitored food products, as its response is based on the growth characteristics of similar microorganisms, such as select patented strains of the micoorganisms Carbonbacterium piscicola, Lactobacillus fuchuensis, and Leuconostoc mesenteroides. The pH drop occurs with a color change of the pH indicator from green to red (Fig. 14.4, not shown here in color). A visual scale of the color change can facilitate visual recognition and evaluation of the significance of the color change. The continuous color change can also be measured instrumentally and be used in a shelf life management scheme.
The TT Sensor™ TTI (Avery Dennison Corp., USA) is based on a diffusion-reaction concept. A polar compound diffuses between two polymer layers and the change of its concentration causes the color change of a fluorescent indicator from yellow to bright pink (Fig. 14.5, not shown here in color).
The 3 M Monitor Mark® (3 M Co., St. Paul, Minnesota) is based on diffusion of proprietary polymer materials. A viscoelastic material migrates into a light-reflective porous matrix at a temperature dependent rate. This causes a progressive change of the light transmissivity of the porous matrix and provides a visual response (Fig. 14.6, not shown here in color). The TTI is activated by adhesion of the two materials that, before use, can be stored separately for a long period at ambient temperature.
14.4 Use of time-temperature integrators (TTIs) as tools for food chain monitoring and management
Despite the potential of TTIs to substantially contribute to improving food distribution, reducing food waste, and benefiting the consumer with more meaningful shelf-life labeling, their applications up to now have not lived up to initial expectations. The food producers’ reluctance to accept the benefits of the TTI have been questions of cost, reliability, and applicability. The cost is volume dependent, ranging from $0.02 to 0.20 per unit. If the other questions were resolved, the cost-benefit analysis would certainly favor the adoption of the TTI. The reliability question has its roots in the history of TTIs, due partly to exaggerated claims by manufacturers of some early models and partly on lack of sufficient data, both from studies and from the suppliers. Some of the early attempts in using TTIs as quality monitors were not well designed, not based on the fundamentals involved, and thus were unable to establish the reliability of the TTI systems in the real cold chain. Re-emerging discussions by regulatory agencies to make the use of TTIs mandatory, before the underlying concepts were understood and their reliability was demonstrated, resulted in resistance by industry, which may have hurt TTI adoption and use up to the present time. Current TTI models have achieved high standards of production quality assurance to provide reliable and reproducible responses according to required specifications. Testing standards have been issued by the BSI (BSI, 1999) and can be used by the TTI manufacturers and the TTI users.
The question of applicability has also hindered the wider adoption of TTI. Suppliers and earlier studies have been ineffective in establishing a clear methodology correlating TTI responses as measures of food quality throughout the cold chain. The most often underestimated requirement when developing and applying a TTI has been the need for acquiring systematic knowledge of the loss of quality during shelf life of the food system to be monitored, and a method for expressing quantitatively as accurately as possible with kinetics models the important quality-determining phenomena. It is not reasonable to expect the TTI monitoring ability to improve the accuracy with which we can estimate the quality and shelf life of a food exposed to fully known temperature conditions. Such exaggerated claims or expectations have slowed progress and often were responsible for reversals in the history of TTI application. A number of experimental studies, published in the literature or carried out by the industry, have sought to establish correlations between the response of specific TTIs and quality characteristics of specific products (Taoukis and Labuza, 2003). A kinetic modeling approach allows the potential user to develop an application scheme specific to a product and to select the most appropriate TTIs without the need for extensive testing of the product and the TTI (Taoukis, 2001).
The basic principles of applying TTIs to monitoring quality were developed by Taoukis and Labuza (1989). The loss of shelf life of a food is usually evaluated by the measurement of a change in a characteristic quality index, A, with time t usually expressed as
in which f(A) is the quality function of the food and k the reaction rate constant. The rate constant is an exponential function of inverse absolute temperature, T, given by the Arrhenius expression,
where kA is a constant, Ea,A is the activation energy of the reaction that controls quality loss, and R is the universal gas constant. The form of the quality function of the food depends on the reaction order of the phenomenon controlling the deterioration of the food.
The change of the value of the quality function during a known variable temperature exposure, T(t), can be calculated by integrating equation 14.1 with time. We can define an effective temperature, Teff, as the constant temperature that results in the same quality change as the variable temperature distribution, T(t). The same kinetics approach can be used to model the measurable change X of the TTI. If a response function F(X) can be defined such that F(X) = kt, with k an Arrhenius function of T, then the effective temperature concept as described above can also be used for the TTI. For an indicator exposed to the same temperature distribution, T(t), as the food product, the response function can be expressed as
in which kI and EaI are the Arrhenius parameters of the indicator. Thus from the measured value X of the TTI at time t the value of the response function is calculated, from which by solving equation 14.3, Teff is derived. With the Teff and the kinetics parameters (kA and Ea,A) of the food known, the quality function value is calculated from equations 14.2 and 14.1, and the value of index A is found. This gives the extent of the quality deterioration of the food and allows the calculation of the remaining shelf life at any reference storage temperature.
Shelf-life models must be obtained with an appropriate selection and measurement of effective quality indices and based on efficient experimental design at isothermal conditions covering the time-temperature range of interest. The applicability of these models should be validated at fluctuating, non-isothermal conditions representative of the real conditions in the distribution chain. Similar kinetics models must be developed and validated for the response of the suitable TTI. Such a TTI should have a response rate with a temperature dependence, i.e. activation energy EaI, in the range of the Ea,A of the quality deterioration rate of the food. A difference of less than 25 kJ/mol in Ea,A values will translate into a smaller error (< 1 °C) in difference of the Teff of the food and the TTI, which, in turn, will result in an acceptable estimation of quality (less than 10–15% error). The total response time of the TTI should be at least as long as the shelf life of the food at a chosen reference temperature. The TTI response kinetics should be provided and guaranteed by the TTI manufacturer as specifications of each TTI model they supply.
TTIs can be used to monitor the temperature exposure of food products during distribution, from production up to the time they are displayed at the supermarket. Attached to individual cases or pallets, they give a measure of the preceding temperature conditions at select control points. Information from TTIs can be used for continuous, overall monitoring of the distribution system, leading to recognition and correction of weak links in the chain. Furthermore, it serves as a proof of compliance with contractual requirements for handling by the producer and distributor. It can guarantee that a properly handled product was delivered to the retailer, thus eliminating the possibility of unsubstantiated rejection claims by the latter. The presence of the TTI itself could improve handling, by serving as an incentive and reminder to the distribution employees throughout the distribution chain of the importance of proper temperature control and storage.
14.5 Use of time-temperature integrators (TTIs) as shelf-life indicators for consumers
The same TTIs mentioned above can be used by consumers as readable shelf-life and end-point indicators attached to individual products. Tests using continuous instrumental readings to define the end-point under constant or variable temperature conditions showed that such end points could be reliably and accurately recognized by panelists (Sherlock et al., 1991). For an application of this kind to be successful, there is a much stricter requirement for the TTI response to match the behavior of the food. To achieve this prerequisite, the TTI end-point should coincide with the end of shelf life at one reference temperature, and the activation energies of the TTI and food should differ by less than 10 kJ/mol. In this way, TTIs attached to individually packaged products can serve as active shelf-life labeling in conjunction with open-date labeling. The TTI assures the consumer that the product was properly handled and indicates the remaining shelf life. Consumer surveys have shown that consumers can be very receptive to the idea of using TTIs on dairy products along with the date code (Sherlock and Labuza, 1992). The use of TTIs can thus also be an effective marketing tool. Diffusion-based TTIs have been used in this way by the Cub Foods Supermarket chain in the USA and polymer-based TTIs by the Monoprix chain in France and the Continent stores in Spain.
TTI responses are not intended to replace the open-date labeling (‘use by date’), that is mandatory on food products. Rather, the TTI response serves as a supporting time-temperature dependent ‘active’ signal whose relevance predominates only when recommended temperatures were not preserved along the cold chain. The message the consumer will read is ‘Use by date unless the color of the TTI in the form of a dot has turned from green (indicates good) to red (indicates end of shelf life).’
14.6 Factors in time-temperature integrator (TTI) commercial success – industry and consumer attitudes
As part of the multi-national European research project ‘Development and Modeling of a TTI-based Safety Monitoring and Assurance System (SMAS) for chilled Meat Products’ (project QLK1-CT2002-02545, 2003–2006; http://smas.chemeng.ntua.gr), coded SMAS, the attitude of European consumer and food industry were explored. In this study, 800 consumers in four European countries, Greece, Ireland, Netherlands, and Sweden were surveyed. Not many of the respondents had heard of the TTI concept previously. After being briefly educated on the subject, most respondents indicated that TTI labels would be easy to understand and would give additional information regarding the ‘expiration’ date. They were overwhelmingly in favor of TTI use, stating that they would prefer to buy products that contain the TTI label. Some 80% of the respondents considered the TTI response more reliable than just the expiration date. A total of 85% replied that the TTI message is easy to understand and will not be confused with the parallel use of the mandatory expiration date. About half of the consumers would be willing to pay an extra premium for the TTI label.
To communicate and receive feedback from potential end users of TTIs (food industry, retailers) in different European markets, a questionnaire on TTI labeling and its potential use was developed. The aim of the questionnaire was to inform industry and food retailers about chill chain management using TTIs and evaluate the users’ attitudes toward the TTIs as a monitoring and management tool for chilled products. In the questionnaire, respondents could find information about the TTI labelling and the SMAS project. The questionnaire was divided into three parts. The first part concerned the industry opinion about the current chill chain temperature conditions and whether there is a need for alternative monitoring tools. After informing the respondents about TTI labeling, the second part concerned industry attitudes toward TTI labeling, and the third part concerned possible reservations industry might have toward TTI use.
The questionnaires were completed by Quality Managers, R&D Managers, and Business Development Managers from potential users in four European Countries, Greece, Ireland, Sweden and UK. Overall, input from over 50 industries was obtained. The attitudes of industry representatives were more mixed than those of consumers. Industry overwhelmingly recognizes the benefits of improving the chill chain. It accepts the advantages from the use of TTIs; however, it also expresses reservations for the potential misapplication that could unfairly increase their responsibilities rather than improve the chill chain. Industry respondents agree that research can contribute to alleviate these reservations. The information given about the TTI cost, reliability, applicability, liability, and consumer acceptance from the SMAS project alleviated the reservations of more than 65% of the respondents.
14.7 Cases of time-temperature integrator (TTI) applications
As already mentioned, the first application of TTIs of significant scale has been the use on vaccines distributed by the WHO. For this application different TTI technologies have been employed. Currently the Fresh-Check® TTI are used on all of the vaccines supplied to the UNICEF Children’s Vaccine Campaigns worldwide (Fig. 14.7). Fresh-Check® TTIs have in recent years reported uses on food products by several customers including the Monoprix retail chain (France) on several of their own label perishable packed products, the Carrefour retail chain on packed fruits and salads distributed via e-shopping, and Milco® dairy and juice products.
The (eO)® TTI (CRYOLOG, France) has reported application by Monoprix on packed fresh pork products, by LECLERC retailer in Bretagne on ‘Marque Repere’ fresh packed sandwiches by Auchan, Coran and Elior.
The Checkpoint® TTI, (VITSAB A.B., Malmö, Sweden) has reported applications on vacuum- or modified atmosphere (MA) packaged fresh seafood imported to USA by several importing companies. This is an interesting case that has been encouraged by regulation. The import of these products is covered by FDA’s Import Alert #16-125 (last publication 22 December 2009). In 1992, the National Advisory Committee for Microbiological Criteria for Foods (NACMCF) evaluated the microbiological safety issues associated with vacuum- or MA-packaged of raw fish and fishery products and found that the primary preventive measure (critical control point) against the growth and toxin production of nonproteolytic strains (those strains that grow at refrigeration temperatures) of Clostridium botulinum is temperature control. All such products are placed on detention unless importers are on the Green List. To qualify for the Green List, manufacturers, shippers, or importers should provide the information to FDA to establish that controls are in place to either prevent C. botulinum toxin formation or provide a visual indication of a potential problem. As set out in the Fish and Fishery Products Hazards and Controls Guidance, one of the potential controls acceptable by FDA is evidence that the individual products bear a validated TTI that indicates by a color or other visual change, whether the product has been exposed to a time and temperature combination that could result in an unsafe product. This application is based on the fact that potential toxin production is highly temperature sensitive. The time-temperature combinations that could result in toxin production have been illustrated in a single curve based on a set of over 1800 data points by Skinner and Larkin (1998). TTIs with responses that closely match this curve are suitable for this application. The required temperature dependence of the rate constant determining the response of suitable TTIs should be in the range of Ea = 150–200 kJ/mol. The L5-8 CheckPoint® TTI response conforms to the above requirements and is being applied for the import of fresh vacuum- or MA packaged seafood.
Another application reported by VITSAB are flight labels, TTIs used on board British Airways flights for monitoring temperature for proper handling of served meals (Fig. 14.8). The response of the TTI is checked before the serving of each meal and a simple record-keeping procedure is followed. Flight label 1 was based on enzymatic TTI Checkpoint B7-24 and was used on UK originating flights. For longer flights, Flight label 2, a diffusion-based TTI produced by Avery-Dennison and converted by VITSAB to use a manual activation system suitable for small local activation stations, was used. It is currently supplied by VITSAB for all British Airways flights.
The OnVu™ TTI is currently used on all packages of Kneuss fresh chicken produced and distributed by Ernst Kneuss Geflugel A.G. (Switzerland) (Fig. 14.9).
14.8 Future trends
The state of TTI technology and of the scientific approach with regard to quantitative safety risk assessment of foods allowed the undertaking of the next important step – the study and development of a TTI-based management system that could assure both safety and quality in the food chill chain (Koutsoumanis et al., 2005). The development and application of such a dual-purpose system coded with the acronym SMAS was the target of the aforementioned multi-national European research project. SMAS uses the information from the TTI response at designated points of the chill chain, ensuring that the temperature abused products reach consumers at an acceptable quality level. Although SMAS was developed for meat products, the same principles can be effectively applied to the management of the chill chain of all chilled perishable food products (Tsironi et al., 2008).
SMAS could replace the current ‘First In First Out’ (FIFO) practice and lead to risk minimization and quality optimization by improving distribution logistics and management of the food chill chain. It improves stock rotation in selected points of the chill chain. It ensures that the temperature-abused products are consumed before they reach unacceptable risk. When recommended chill chain conditions are maintained, SMAS practices do not differ from the FIFO practice. However, in case of incidental temperature abuse, SMAS manages the chain by diverting abused products so that the final rejection and risk is minimized.
Cold chain optimization and effective management will be a central issue in research, industrial practices, and regulatory efforts, as industry continuously strives to deliver high quality foods and other perishable items to consumers. Integrated systems, like the proposed SMAS based on the availability of quality data and temperature history of individual product units, will be applied and validated in practice, and TTIs can be combined with RFID technology to supplement the current traceability requirements mandated by regulation or developed by industry initiatives.
14.9 Acknowledgements
Part of the information contained in this chapter stems from research supported from the Commission of the European Communities, FP5 Quality of life RTD Project SMAS, QLK1-CT-2002-02545 (http://smas.chemeng.ntua.gr) and the FP6 Collective Research Project FRESHLABEL COLL-CT-2005-012371.
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