Time-temperature indicators

Figure 8.37. Burial history plot for Helderberg Group rocks and other strata. Helderberg Group is shaded, whereas the base of Ordovician strata, base of Silurian strata and base of Mississippian strata are shown as thin lines marked O, S and M. Dashed lines are time-temperature indices of maturity (TTI see Waples, 1980). The oil generation window represents the necessary conditions of time and temperature for potential oil generation. The 50° oil preservation deadline is the upper TTI limit for occurrence of oil with API gravity of 50°. (Modified from Dorobek, 1987.)...

The second time-temperature indicator is based on the use of horseradish peroxidase in liquid and solid paraffin (126). The enzyme is deposited onto non-porous glass beads md mixed with melted paraffin containing the substrate. The suspension is mixed well and quickly cooled in a dry ice/acetone bath. When the enzyme is stored in solid paraffin, the activity is extremely slow. But when the temperature increases, the paraffin may melt and thereby make the enzyme reaction a millionfold faster than in the solid hydrocarbon phase. This time-temperature integrator is based on the same concept as the I-point, but here the... 

A minimum durability date should be provided and for highly perishable foodstuffs a use by date should be given. This latter requirement is a hindrance to the use of a time temperature indicator (TTI). A use by date should also cover foreseeable incorrect storage conditions, e.g., during transport. Therefore use by dates are set on a very safe (short) period. By use of appropriate TTIs the total safe consumption period could be used for the benefit of both the consumer and the manufacturer or retailer. It is assumed that further effort by TTI manufacturers may result in a legal recognition of TTI as a replacement for use by dates. 

The color change associated with diacetylene polymerization is useful as a time-temperature indicator (M), and a system using this technology has recently been commercialized. 

Galagan, Y., Su, W J., 2008. Fadable ink for time-temperature control of food freshness novel new time-temperature indicator. Food Research International 41 (6), 653—657. 

Time-temperature indicators are used for products where the storage and transport in appropriate conditions is very important. This indicator informs on the difference between the optimal temperature and the actual temperature and how long a product was exposed to inappropriate temperature conditions. An indicator must be able to monitor one or more conditions chill temperature, frozen temperature, temperature abuses, partial, or full history. The principle operation is based on the polymerization reaction or enzymatic fat hydrolysis or diffusion of the chemically modified dye from encapsulation layer. i Color change must be correlated to food shelf-life. The time-temperature indicator could be placed as a label or as a small packaging in shipping containers (Figure 61.3). 

FIGURE 61.3 Schematic of time-temperature indicator created by The OnVu . (From http //www.onvu. de/ page id=25.)... 

The second category of intelligent devices is approximately subdivided in four subclasses with concern to the particular information. In detail, the group is often confused with the so-called time-temperature indicators or TTI. In recent times, researchers have studied possible applications and real benefits of TTI in terms of food safety and hygiene [10]. At the same time, the detractors of intelligent devices have always preferred to attack the whole category targeting TTI. 

For tunnel pasteurisers time temperature indicators that travel through the tunnel recording the temperatures that containers are subjected to, and for what time, can be used to monitor the process. 

Figure 12.3 illustrates data from a time temperature indicator showing the temperature profiles during low (10.8 PU) and high (36.8 PU) levels of pasteurisation. 

Temperature indicators give a visual signal at a specified temperature, while time-temperature indicators give signal when a specified temperature deviation over time has been recorded throughout the shipment. Time-temperature indicators can be... 

The thermally induced solid-state polymerization of diacety-lene exhibits a marked change in color as the monomer is polymerized. This behavior has been taken advantage of in the fabrication of a time-temperature indicator [181]. 

The active or intelligent packaging has various modes of action such as removal, Oj barrier, water removal, gas indicator, ethylene removal, CO release, antimicrobial properties, and so on. Recently, new films known as time temperature indicators have also been introduced for commercial application. 

EC considers intelligent materials and articles materials and articles which monitor the condition of packaged food or the environment surrounding the food . The present literatme review outlines the IP concepts including integrity indicator (II), freshness indicator (FI) (that is food spoilage indicator (FSI), ripeness indicator (RPI), and rancidity indicator (RCI)), time-temperature indicator (TTI) and radio frequency identification (RFID). 

Temperature is a crucial factor affecting the quality and safety of food products diuing both distribution and storage. The difficulty in controlling and monitoring the temperature history of food products makes it difficult to precisely predict shelf life. Time-temperature indicators (TTIs) provide a visual summary of a product s accumulated chill-chain history, recording the effects of both time and temperatme. 

Koutsoumanis, K., Taoukis, P. S., and Nychas, G. J. E. Development of a safety monitoring and assurance system for chilled food products. Int. J. Food Microbiol., 100, 253-260 (2005). Kreyenschmidt, J., Christiansen, H., Hiibner, A., Raab, V., and Petersen, B. A novel photochro-mic time-temperature indicator to support cold chain management. Int. J. Food Sci. Technol.,... 

Nopwinyuwong, A., Boonsupthip, W., Pechyen, C., and Suppakul, P. Response modeling for polydiacetylene/silica nanocomposite as time-temperature indicator. The Book of Abstracts of the 5th Shelf Life International Meeting 2012. May 30 June 1, 2012. Changwon, South Korea, (2012(b)). 

Patel, G. N. and Yee, K. C. Diacetylene time-temperature indicators. United States Patent Publication US 4228126 (1980). 

Kinami, M., Crenshaw, B.R., and Weder, C. (2007) Time-temperature indicators. US Patent Application 2007/0158624. 

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