Time-Temperature Integrators

Commercial dextrins are specifically the oligomers of starch. White dextrins, so called because of their visual appearance, are produced from a 30-40% suspension under the mildest possible hydrolysis conditions (79-120°C for 3-8 h in 0.2-2% H2S04 or HC1). Yellow dextrins and British gums are the partial hydrolysates at higher time-temperature integrals. Maltodextrins, dextrose equivalent20 5-19, derive from controlled enzyme or acid partial hydrolysis of gelatinized corn starch. The 20-24 dextrose equivalent hydrolysates tire com syrups (Appi, 1991). 

Two different types of enzymatic time-temperature integrators are described. The first, under the tradename of I-point, is based on a lipase-catalyzed hydrolysis reaction (125). The lipase is stored in a nonaqueous environment containing glycerol. The indicator contains two components that are mixed when the indicator is activated. The operating principle is as follows Upon activation, two volumes of reagents are mixed with each other. Lipase is thereby exposed to its substrate, here a triglyceride. At low temperatures there will be almost no hydrolytic reaction. As the temperature increases, hydrolysis accelerates and protons are liberated. A pH indicator is dissolved in the system. The indicator is selected to shift color after a certain amount of acid has been liberated by the enzyme-catalyzed process. Since the catalytic activity is influenced both by temperature and time, this indicator strip is said to be a time-temperature integrator. 

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... 

Smith, S.E., Orta-Ramirez, A., Ofoli, R.Y., Ryser, E.T., and Smith, D.M. 2002. R-phycoerythrin as a time-temperature integrator to verify the thermal processing adequacy of beef patties. Journal of Food Protection 65 814-819. 

CavaUini, M. Calo, A. Stoliar, R Kengne, J. C. Martins, S. Matacotta, F. C. Quist, F Gbabode, G. Dumont, N. Geerts, Y. H. Biscarini, F Lithographic alignment of discotic liquid crystals a new time-temperature integrating framework. Adv. Mater. 2009, 21, 4688 691. 

CHEMOMETRIC APPLICATIONS OF THERMALLY PRODUCED COMPOUNDS AS TIME-TEMPERATURE INTEGRATORS IN ASEPTIC PROCESSING OF PARTICULATE FOODS... 

Maesmans,G. Hendrickx, M. De Cordt, S. Van Loey, A. Noronha, J. Tobback, P. Evaluation of process value distribution with time temperature integrators. Food Research Inti. 1994, 27, 413—423. 

Time-Temperature Integrators in Aseptic Processing of Particulate Foods 91 H.-J.KimandY-M. Choi... 

Recently, our group reported a new application of dewetting of polymer thin films as time-temperature integrator. The idea stems from the knowledge that dewetting of a solid film is an irreversible process exhibiting an activation energy and whose characteristic... 

Figure 14.19 Time-temperature integration functionality (a] Scheme of the irradiated zones of a PIB thin film. The gray level is proportional to the electron dose the number indicates the exact doses expressed in pC-cm . ...

A. Cal6, P. Stoliar, F. C. Matacotta, M. Cavallini, and F. Biscarini, Time-temperature integrator based on the dewetting of polyisobutylene thin films, Langmuir, 26, 5312-5315, [2010]. 

Giannakourou, M. C., Koutsoumanis, K., Nychas, G. J. E., and Taoukis, P. S. Field evaluation of the application of time temperature integrators for monitoring fish quality in the chill chain. Int. J. Food Microbiol., 102, 323-336 (2005). 

Taoukis, P. S. Application of time-temperature integrators for monitoring and management of perishable product quality in the cold chain. J. Kerry and P. Butler (Eds.), Smart Packaging Technologies, John Wiley Sons, Ltd., West Sussex, pp. 61-74(2008). 

Chemical markers can mimic other processes. Chemical reactions taking place in foods can be used to mimic an entirely different process taking place in the vicinity of the site where the chemical measurements are made. An interesting example is the use of chemical markers to determine lethality within a food particulate where direct temperature measurement is not practical (Chapter 6). It appears that chemical reactions can mimic bacterial destruction, and are potentially useful time-temperature integrators in the continuous thermal processing of foods. 

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