• Food Science of Animal Resources
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• v.29 no.3
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• pp.349-355
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• 2009

The temperature dependence of time temperature integrator (TTI) was investigated in terms of the Arrhenius activation energy (Ea) to determine TTI requirements to accurately predict meat quality during storage. Mathematical simulation was conducted using a numerical analysis. First, using Euler's method and MS Excel VBA, the TTI color change was kinetically modeled and numerically calculated under several storage conditions. From the TTI color variable profiles calculated from the storage time-temperature profiles, $T_{eff}$, which is a constant temperature representing the whole temperature profiles, was calculated. Upon predicting Pseudomonas spp. concentrations (one of the meat qualities) from $T_{eff}$, it was found that if $Ea_{microbial\;spoilage}=Ea_{TTI}$ be true, then Pseudomonas concentrations were calculated to be constant with the same TTI color values, regardless of time-temperature profiles, whereas if $Ea_{microbial\;spoilage}{\neq}Ea_{TTI}$ then Pseudomonas concentrations varied even with the same TTI color values. This indicates that each TTI color value represents its own fixed degree of meat quality, only if $Ea_{meat\;qualities}=Ea_{TTI}$.

• Food Science of Animal Resources
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• v.32 no.5
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• pp.598-603
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• 2012

Beef qualities which can be properly predicted by time-temperature integrator (TTI), a chromatic indicator, were selected in terms of its similarity of temperature dependence between beef qualities and TTI, denoted by Arrhenius activation energy ($E_a$). The high similarity is required to afford accurate prediction. A devised enzymatic TTI based on laccase (an oxidase), which catalyses the oxidation on 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) producing color development, was applied. The factors of beef quality, such as volatile basic nitrogen (VBN), pH, color (CIE $L^*$, $a^*$), Warner-Bratzler shear force (WBSF), Pseudomonas spp. count, and lactic acid bacteria (LAB) count were considered for the selection. $E_a$ (55.48 kJ/mol) of the TTI was found to be similar to those of the beef qualities (all referred) in the order of LAB count (53.54 kJ/mol), CIE $a^*$ value (61.86 kJ/mol), pH (65.51 kJ/mol), Pseudomonas spp. Count (44.54 kJ/mol), VBN (67.98 kJ/mol), WBSF (40.67 kJ/mol), and CIE $L^*$ value (33.72 kJ/mol). The beef qualities with more similar $E_a$ to that of the TTI showed less difference between real and TTI predicted levels. In conclusion, it was found out that when applying TTI to food packages, their $E_a$ similarity should be checked to assure accurate estimation of food quality levels from TTI response.

• Food Engineering Progress
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• v.14 no.3
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• pp.229-234
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• 2010

The applicability of a commercial enzymatic time-temperature integrator (TTI) for monitoring spoilage of ground beef was investigated under isothermal storage condition at different temperatures. The volatile basic nitrogen (VBN) value was used as a spoilage index for ground beef. The time taken to reach the spoilage of ground beef stored at 4, 10, 15, 20, and ${25^{\circ}C}$ were 168, 114, 60, 48, and 24 hrs, respectively. However, these quality losses of beef were not coincided with the endpoints of the three different C-type TTIs (C-1, C-4, and C-7). In order to match the TTI response to the quality loss of beef, some ingredients such as enzyme and substrate solutions were extracted from C-1TTI and remixed with different amount of them in the tubes to constitute the modified TTIs. The responses of the modified CM-1 TTI were very close to the quality loss of beef stored at 20 and ${25^{\circ}C}$, but not at other temperatures tested. The response of the other modified CM-2 TTI was only matched to the quality loss of beef stored at ${15^{\circ}C}$. Therefore, systematic kinetic studies of food spoilage and the TTI response are required to apply the TTI as a quality indicator for a specific food.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.2
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• pp.49-56
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• 2018

A novel printable time-temperature integrator (TTI) composed of a natural coloring matter, anthocyanidin, was developed. The anthocyanin was biochemically modified to change in color over week scale, compared to the original anthocyanin over month scale change. The anthocyanin extracted from strawberry was converted to its aglycone, anthocyanidin, by the treatment with ${\beta}-glucosidase$. The print paste was composed of the freeze-dried powder of anthocyanidin, pullulan, glycerol and distilled water, which was screen-printed. The TTI performance were examined in terms of kinetics and temperature dependency. The activation energy of anthocyanidin TTI was 86.92 kJ/mol. Compared with the activation energy of foods, the applicable food groups were found. Applicable food groups were chilled meat products and fish. The major benefits of the TTI were the printability to be practical in use and the eco-friendliness with the natural pigment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.91-96
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• 2014

TTI was applied to monitor the quality changes of fish displayed at a mock store. Chilled fishes were displayed with TTI on a styrofoam box filled with crushed ice. The ice was periodically refilled to maintain the fish freshness. The color of TTI and the qualities of mackerel and Alaska pollack were measured during displaying. VBN and Pseudomonas spp. were used as the quality factors of mackerel and Pollack, respectively. The spoilage time was regarded as when the factors reached their critical levels. The fishes were spoiled when the color of TTI reached an end-point. It was therefore found out that it is possible to predict the fish spoilage by observing the TTI color change.

• Food Science of Animal Resources
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• v.33 no.4
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• pp.439-447
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• 2013

Time-temperature integrators (TTIs) are simple and cost-efficient tools which may be used to predict food quality. Enzymatic TTIs are devised to indicate food quality in the form of color alterations from green to red, based on the cumulative impacts of temperature and time period on the enzymatic reactions. In this study, the quality of ground beef patties was investigated for the parameters of pH levels, color, VBN, water holding capacity, and total microbial counts, depending on various storage temperatures (5, 15, and $25^{\circ}C$). TTIs were attached to the surface of the ground beef patties in order to evaluate the degree of correlating colorimetric changes with the determined quality parameters. Through the Arrhenius equation, activation energy and constant reaction rates of TTI, VBN, and total microbial counts were calculated as to observe the relationship between enzymatic reactions of the TTI and food spoilage reactions of the ground beef patties. VBN and total microbial counts were already increased to reach decomposition index (VBN: 20, total microbial count: 7-8 Log CFU/g) of meat at middle stage of storage period for each storage temperature. Although activation energy of TTI enzymatic reactions and food spoilage reactions of the ground beef patties were similar, the change of TTI color was not a coincidence for food spoilage at $5^{\circ}C$ and $15^{\circ}C$ of storage temperature. It was suggested that TTI should be designed individually for storage temperature, time, type of meat, or decomposition index of meat.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.97-102
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• 2014

It was mathematically analyzed at which steps to activate TTI in the cold chain for Alaska pollack, assuming that the performance of a commercial TTI product, and Fresh-check, could not always be optimized for the pollack. Three places were selected for the TTI activation, such as on fishing ship, Busan cooperative fish market, and mart. First, the kinetic and Arrhenius temperature dependent models were experimentally built under isothermal conditions. The color index of TTI and the level of Pseudomonas spp. of pollack were measured at time intervals. Second, the resultant models were used in the mathematical calculations for dynamic temperature conditions included in the cold chain. As a result, the TTI activated at the mart place showed the best agreement between the spoilage time of the pollack and the time for the TTI color to reach its end-point. It was therefore found that it is practically important to optimally select the TTI activation place or time when using a commercial TTI product.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.2
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• pp.41-48
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• 2018

A printable time temperature integrator (TTI) consisting of oxygen indicator and cover films with various oxygen permeability was developed. The printing ink contained methylene blue (oxygen indicator) which changed in color during storage. $TiO_2$ and glycerol for UV-activation of TTI and zein and ethanol for printing performance were also contained in the printing ink. The cover film on the ink was employed to control the color change rate and temperature dependency (Arrhenius activation energy, $E_a$) by using the different films (PE, PET, OPP, and LLDPE). The film properties were varied by annealing. TTI was produced by silk screen printing. As a result, the color change rates were different for the cover films, being the highest in TTI with LLDPE, followed by OPP, PE, and PET. The rate decreased with increase in the cover film thickness. The $E_a$ was the highest in TTI with LLDPE, followed by OPP, PE, and PET. The $E_a$ did not change with the cover film thickness. The annealed PVC and PET film were lower in oxygen permeability than the unannealed ones, indicating the lower color change rate.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.85-89
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• 2014

TTI is a small label of which the color changes by time-temperature history during food storage. The food shelf life (SL) was compared with that of TTI, the time for TTI to reach the end-point of its color change, for the various discrepancies in two Arrhenius activation energies (Ea), an important parameter of temperature dependence. The SL of TTI and food were mathematically simulated, based on zero-order and first-order kinetics, respectively. In the case Ea of food was smaller than that of TTI, the SL of food was larger than that of TTI, meaning TTI reaches the end-point of color change earlier even though food is still fresh. In the case of Ea of food > Ea of TTI, the food reaches the SL earlier than the TTI. In addition, the magnitude of ${\Delta}Ea$ between food and TTI led to the bigger ${\Delta}SL$. To be safe, $SL_{Food}$ > $SL_{TTI}$ would be practical although $SL_{Food}{\fallingdotseq}SL_{TTI}$ is ideal.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.101-107
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• 2021

Time-temperature integrators (TTIs) based on aqueous enzyme solutions produce transparent colors which lead to difficulty in distinguishing its color change by naked eye. In this present study, this issue has been solved by increasing the opacity of laccase-based TTI without changes in the kinetics (same zero-order reaction) and temperature dependency (similar Arrhenius activation energy values) of the color change. The opacity was increased by introducing TiO₂, latex, BaSO₄, or ZnO, in combination with a hydrocolloid (xanthan gum, acacia gum, pectin, and CMC) into the TTI system. The combination of TiO₂ and xanthan gum was the best. This finding broadened the advantages of laccase-based TTI to more practical uses for consumer convenience.