Imperial/Cell by Date/Specification

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  <ul>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Introduction" title=""><span>Introduction</span></a></li>
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    <li><a class="current" href="https://2007.igem.org/Imperial/Cell_by_Date/Specification" title=""><span>Specifications</span></a></li>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Design" title=""><span>Design</span></a></li>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Modelling" title=""><span>Modelling</span></a></li>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Implementation" title=""><span>Implementation</span></a></li>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Testing" title=""><span>Testing</span></a></li>
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    <li><a href="https://2007.igem.org/Imperial/Cell_by_Date/Conclusion" title=""><span>Conclusion</span></a></li>
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= Cell by Date: Specifications =
= Cell by Date: Specifications =
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We are targetting Fresh Aerobically Packed Ground Beef.
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'''Cell by Date in the Cold Chain:'''
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{|border="1"
 
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|-
 
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!Property:
 
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!Value
 
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|-
 
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|Inputs
 
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|<center>Isothermal Conditions between 0 & 40 C</center>
 
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|-
 
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|
 
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|<center>Dynamic conditions eg. steps & ramps</center>
 
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|-
 
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|Outputs
 
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|System like other TTIs should give a visual signal to indicate that the the beefs level of exposure is most likely off
 
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|-
 
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|Activation Energy
 
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|<center>System Needs to have an activation Energy 30 +/- kJ/mol</center>
 
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|-
 
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|Health Regulations
 
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|<center>System Must not be living replicating bacteria</center>
 
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|-
 
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|Response Time
 
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|<center>System needs to have a response time under 1 hour</center>
 
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|-
 
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|Lifespan
 
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|<center>System must have a shelf life of 7 days</center>
 
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|}
 
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==How i arrived at above specifications :==
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[[Image:cbd.png|800px]]
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===1. Our Target : Beef===
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We all know that beef goes off.  The dominant organisms leading to the spoilage of beef depend of the beef's composition and the environmental conditions under which the beef is stored.  For refrigerated packaged beef Pseudomonas spp. were dominate areobically while Lactobacillus was dominant anaerobically. [[IGEM:IMPERIAL/2007/Cell By Date/References|(12.Labuza,1993)]] Because bacteria are responsible for the spoilage of beef it is unwise to use a bacteria based device eg. by using e.coli/yeast as a chassis as this would further add to the spoilage.
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{|
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|-valign="top"
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|width=10%|[[Image:CBDthermometer.gif|center]]<br><br><br><br><br><br><br><br>[[Image:CBDCartoonHamburger1.png|center]]<br clear ="all"><br><br><br><br><br><br>[[Image:CBDQuestionMarkCartoon.png|center]]<br>
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|width=30%|[[Image:CBDSpecs.png]]
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|width=60%|
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*'''Input: Isothermal & Dynamic conditions, eg. steps & ramps between 0-40 &deg;C'''
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Temperature is considered to be the major factor in beef spoilage and although the meat industry tries to keep temperature low during transportaion temperature conditions higher than 10&deg;C are not unusual during transport<sup>[[#References |3]]</sup>. It is therefore important that our that we look at the performance of our system in isothermal conditions eg. in the cold chain, and dynamic temperature scenarios eg. a break in the cold chain.
 +
*'''Output: Visible Signal'''
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Several Technologies already exist which address the problem of monitoring the thermal exposure of products in the cold chain.  One particular family are Temperature Time Integrators (TTIs).<sup>[[#References |5]]</sup><br>
 +
The key aspect of a TTI is that they are based on a phenomenon which can act as a signal to a consumer for example, eg. a colour change.  For Cell By Date we would like a visible signal that tells the consumer that as a result of the thermal history of the beef it is not fit for consumption e.g. it's been left out of the fridge for too longTo Determine the point at which ground beef is not good to eat we have to look at the biology of the spoilage process.The dominant organisms leading to the spoilage of beef depend of the beef's composition and the environmental conditions under which the beef is stored.  For refrigerated packaged beef Pseudomonas spp. were dominate areobically while Lactobacillus was dominant anaerobically.<sup>[[#References |1]]</sup>
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There also seems to be a general rule for beef that when the bacterial count reaches 10^7cm^-2 , off odours and slime production occour and the beef is considered off. [[IGEM:IMPERIAL/2007/Cell By Date/References|(13.Food Hygiene,Microbiology and HACCP)&(10.Leak,1999)]] For controlled isothermal conditions in a laboratory environment the time taken for beef to reach this spoilage point seems to be at most 7 days.(Koutsoumanis 2005)  This Implies that the shelf life of our system needs to be at least 7 days aswell.
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*'''Lifespan : 7 days'''
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There also seems to be a general rule for beef that when the bacterial count reaches 10<sup>7</sup> cm<sup>-2</sup>, off odours and slime production occur and the beef is considered off. <sup>[[#References |2]]</sup> For controlled isothermal conditions in a laboratory environment the time taken for beef to reach this spoilage point seems to be at most 7 days.<sup>[[#References |3]]</sup> This implies that the shelf life of our system needs to be at least 7 days.
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The Gompertz's model is widely used when considering beef spoilage as it has been shown to fit growth data very well[[IGEM:IMPERIAL/2007/Cell By Date/References|(12.Labuza,1993)]].  Using the Gompertz model we can get the specific growth rate, Lag phase duration (LPD) and maximum population density (MPD) for bacterial growth at a  particular constant temperature.  And then using these we can determine the Activation Energy Ea, for the beef spoilage rxn.  For U2 grade Argentinian beef stored in polyethylene and SARAN PVC the Ea ranged from 80kJmol^-1 to 220kJmol^-1 for a range of bacteria. [[IGEM:IMPERIAL/2007/Cell By Date/References|(11.Giannuzzi,1997)]]
+
*'''Health & Safety : Non-living , non-infectious'''<br>
 +
Because bacteria are responsible for the spoilage of beef it is unwise to use a bacteria based device eg. by using e.coli/yeast as a chassis as this would further add to the spoilage.
-
One contary value for the Ea of the beef spoilage rxns is given by Leak [[IGEM:IMPERIAL/2007/Cell By Date/References|(10.Leak,1999)]] who calculated Ea=30kJmol^1.  The difference between Leak's value and that of Giannuzzi probably lies in their packaging methods, i do not know Leak's packaging methods so this is just a guess.  I'm assuming that Leak's packaging method is the one of interest, aerobic, for the sake of this project.
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*'''Activation Energy : 30 +/- 20 kJ/mol'''<br>
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===2. Our System : a Time Temperature Integrator===
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The Gompertz's model is widely used when considering beef spoilage as it has been shown to fit growth data very well. <sup>[[#References |1]]</sup>  Using the Gompertz model we can get the specific growth rate, Lag phase duration (LPD) and maximum population density (MPD) for bacterial growth at a particular constant temperature.  And then using these we can determine the Activation Energy (Ea) for the beef spoilage reaction.  For U2 grade Argentinian beef stored in polyethylene and SARAN PVC, the Ea ranged from 80kJ mol<sup>-1</sup> to 220kJ mol<sup>-1</sup> for a range of bacteria. <sup>[[#References |4]]</sup>
-
Temperature is considered to be the major factor in beef spoilage and although industry tries to keep temperature low during transportaion exposure of the beef to 10 degrees celcius are not unusual. It is therefore important that our that we look at the performance of our system in isothermal conditions eg. in the cold chain, and dynamic temperature scenarios eg. a break in the cold chain.
+
One contrary value for the Ea of the beef spoilage reactions is given by Leak <sup>[[#References |2]]</sup> who calculated Ea = 30kJ mol<sup>-1</sup>. The difference between Leak's value and that of Giannuzzi <sup>[[#References |4]]</sup> probably lies in their packaging methods, which is of importance as the project aims to target aerobically fresh gound beef.<br>
-
Several Technologies have already been developed to addressed the problem of monitoring the heat exposure of products in the cold chainOne particular family of these products are called Temperature Time Integrators (TTI).[[IGEM:IMPERIAL/2007/Cell By Date/References|(2.Labuza,2006)]]
+
In order for Cell by Date to act as a TTI & accurately report the spoilage rxn of beef, the activation energy of the two rxns needs to be similarFor example a difference between the two Ea's less than 20kJ mol<sup>-1</sup> would result in the TTI estimating the thermal history of the beef to be within 1&deg;C of the actual history.<sup>[[#References |6]]</sup>  For Cell by Date we would like our Activation Energy of our system to be 30 +/- 20 kJ mol<sup>-1</sup> to yield an accurate thermal history of the most sensitive spoilage rxn found by Leak, which is most likely for aerobically fresh beef.
 +
 
 +
*'''Response Time: Less that 1 Hour'''<br>
 +
In addition, to correctly couple the Ea of our system to that of the dominant spoilage reaction in beef, we also have to consider the response time of our sytem.  Our system needs to have a rapid response time, so in other words it needs to be able to quickly switch between states eg. low output and high output.  This is so our system can capture small variations of temperature in the cold chain and report them in a meangingful way.  Specifically, a response time in the order of a few hours would ensure that if there are any problems in the cold chain this will arise in our system very quickly.
 +
|}
-
The key aspect of a TTI is that they are based on a phenomenon which can act as a signal to a consumer for example, eg. a colour change.  The rate at which this change occours needs to be temperature dependant so it can mimic the effect temperature has on the spoiling of meat eg. change happens quicker at higher temperatures.  In order for a TTI to accurate report the spoilage rxn of beef the activation energy of the two rxns needs to be similar.  For example a difference between the two Ea's less than 20kJmol^-1 would result in the TTI estimating the thermal history of the beef to be within 1 degree C of the actual history.).[[IGEM:IMPERIAL/2007/Cell By Date/References|(1.Taoukis,2006)]]
 
-
Applying this to our TTI this would mean that the Activation Energy of our system needs to be 30 +/- 20 kJ/mol if we are considering the most easily achieved activation energy found by Leak, which is most likely for aerobically packed beef.
 
-
In addition to correctly coupling the activation Energies of our system to that of the dominant spoilage reaction in beef, we also have to consider the response time of our sytem. Our system needs to have a rapid response time, so in other words it needs to be able to quickly switch between states eg. low output and high output. This is so our system can capture small variations of temperature in the cold chain and report them in a meangingful way.  Specifically I think a response time in the order of a few hours would ensure that if there are any problems in the cold chain this will arise in our system very quickly.
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<center> [https://2007.igem.org/Imperial/Cell_by_Date/Introduction << Introduction ] | Specifications | [https://2007.igem.org/Imperial/Cell_by_Date/Design Design >>]</center>
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Now with our Specifications are determined we can move onto the next stage in the engineering cycle, the design phase, in which we see how we can realise the targets set out in the specifications.
 
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[[Imperial/Cell_by_Date/Design|Click Here to go the Design Page]]
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== References ==
 +
# [http://www.springerlink.com/index/G311226U2M51T844.pdf Labuza TP, Fu B. Growth kinetics for shelf-life prediction: theory and practice. J of Industrial Microbiology 1993;12:309-23.]
 +
# [http://66.102.1.104/scholar?hl=en&lr=&q=cache:thi6BTIW1YMJ:www.vitsab.com/PDF/V507.pdf+TTI+Beef+Activation+Energy Leak, F.W. (2000): Quality changes in Ground beef during distribution and storage, and determination of Time- Temperature-Indicator (TTI) charakteristic of ground beef University of Florida Institute of food and Agricultural Sciences Internet: www.vitsab.com, Stand: April 2003]
 +
# [http://aem.asm.org/cgi/content/abstract/72/1/124 Koutsoumanis K, Stamatiou A, Skandamis P, Nychas GJ. Development of a Microbial Model for the Combined Effect of Temperature and pH on Spoilage of Ground Meat, and Validation of the Model under Dynamic Temperature Conditions. Appl Environ Microbiol. 2006 Jan;72(1):124-34.]
 +
# [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7K-3S3M25D-B&_user=217827&_coverDate=01%2F06%2F1998&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000011279&_version=1&_urlVersion=0&_userid=217827&md5=80630ba21fbc6869b9f5179d334734da Giannuzzi L, Pinotti A, Zaritzky N. Mathematical modelling of microbial growth in packaged refrigerated beef stored at different temperatures. Int J Food Microbiol. 1998 Jan 6;39(1-2):101-10.]
 +
# [http://www.iaph.uni-bonn.de/Coldchain/downloads/06_Labuza.pdf Labuza 2006 : Cold Chain-Management II Time-temperature Integrators and the Cold chain: What is next? Bonn Germany 5/8/06]<br>
 +
# [http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1365-2621.2001.tb15211.x?cookieSet=1 E. Shimoni, E.M. Anderson, T.P. Labuza (2001) Reliability of Time Temperature Indicators Under Temperature Abuse. Journal of Food Science 66 (9), 1337–1340. doi:10.1111/j.1365-2621.2001.tb15211.x ]
 +
# [http://linkinghub.elsevier.com/retrieve/pii/S0168-1605(05)00067-X Giannakourou MC, Koutsoumanis K, Nychas GJ, Taoukis PS. Field evaluation of the application of time temperature integrators for monitoring fish quality in the chill chain. Int J Food Microbiol. 2005 Jul 25;102(3):323-36.]

Latest revision as of 03:22, 27 October 2007




Cell by Date: Specifications

Cell by Date in the Cold Chain:


Cbd.png


CBDthermometer.gif








CBDCartoonHamburger1.png







CBDQuestionMarkCartoon.png

CBDSpecs.png
  • Input: Isothermal & Dynamic conditions, eg. steps & ramps between 0-40 °C

Temperature is considered to be the major factor in beef spoilage and although the meat industry tries to keep temperature low during transportaion temperature conditions higher than 10°C are not unusual during transport3. It is therefore important that our that we look at the performance of our system in isothermal conditions eg. in the cold chain, and dynamic temperature scenarios eg. a break in the cold chain.

  • Output: Visible Signal

Several Technologies already exist which address the problem of monitoring the thermal exposure of products in the cold chain. One particular family are Temperature Time Integrators (TTIs).5
The key aspect of a TTI is that they are based on a phenomenon which can act as a signal to a consumer for example, eg. a colour change. For Cell By Date we would like a visible signal that tells the consumer that as a result of the thermal history of the beef it is not fit for consumption e.g. it's been left out of the fridge for too long. To Determine the point at which ground beef is not good to eat we have to look at the biology of the spoilage process.The dominant organisms leading to the spoilage of beef depend of the beef's composition and the environmental conditions under which the beef is stored. For refrigerated packaged beef Pseudomonas spp. were dominate areobically while Lactobacillus was dominant anaerobically.1

  • Lifespan : 7 days

There also seems to be a general rule for beef that when the bacterial count reaches 107 cm-2, off odours and slime production occur and the beef is considered off. 2 For controlled isothermal conditions in a laboratory environment the time taken for beef to reach this spoilage point seems to be at most 7 days.3 This implies that the shelf life of our system needs to be at least 7 days.

  • Health & Safety : Non-living , non-infectious

Because bacteria are responsible for the spoilage of beef it is unwise to use a bacteria based device eg. by using e.coli/yeast as a chassis as this would further add to the spoilage.

  • Activation Energy : 30 +/- 20 kJ/mol

The Gompertz's model is widely used when considering beef spoilage as it has been shown to fit growth data very well. 1 Using the Gompertz model we can get the specific growth rate, Lag phase duration (LPD) and maximum population density (MPD) for bacterial growth at a particular constant temperature. And then using these we can determine the Activation Energy (Ea) for the beef spoilage reaction. For U2 grade Argentinian beef stored in polyethylene and SARAN PVC, the Ea ranged from 80kJ mol-1 to 220kJ mol-1 for a range of bacteria. 4

One contrary value for the Ea of the beef spoilage reactions is given by Leak 2 who calculated Ea = 30kJ mol-1. The difference between Leak's value and that of Giannuzzi 4 probably lies in their packaging methods, which is of importance as the project aims to target aerobically fresh gound beef.

In order for Cell by Date to act as a TTI & accurately report the spoilage rxn of beef, the activation energy of the two rxns needs to be similar. For example a difference between the two Ea's less than 20kJ mol-1 would result in the TTI estimating the thermal history of the beef to be within 1°C of the actual history.6 For Cell by Date we would like our Activation Energy of our system to be 30 +/- 20 kJ mol-1 to yield an accurate thermal history of the most sensitive spoilage rxn found by Leak, which is most likely for aerobically fresh beef.

  • Response Time: Less that 1 Hour

In addition, to correctly couple the Ea of our system to that of the dominant spoilage reaction in beef, we also have to consider the response time of our sytem. Our system needs to have a rapid response time, so in other words it needs to be able to quickly switch between states eg. low output and high output. This is so our system can capture small variations of temperature in the cold chain and report them in a meangingful way. Specifically, a response time in the order of a few hours would ensure that if there are any problems in the cold chain this will arise in our system very quickly.


<< Introduction | Specifications | Design >>


References

  1. [http://www.springerlink.com/index/G311226U2M51T844.pdf Labuza TP, Fu B. Growth kinetics for shelf-life prediction: theory and practice. J of Industrial Microbiology 1993;12:309-23.]
  2. [http://66.102.1.104/scholar?hl=en&lr=&q=cache:thi6BTIW1YMJ:www.vitsab.com/PDF/V507.pdf+TTI+Beef+Activation+Energy Leak, F.W. (2000): Quality changes in Ground beef during distribution and storage, and determination of Time- Temperature-Indicator (TTI) charakteristic of ground beef University of Florida Institute of food and Agricultural Sciences Internet: www.vitsab.com, Stand: April 2003]
  3. [http://aem.asm.org/cgi/content/abstract/72/1/124 Koutsoumanis K, Stamatiou A, Skandamis P, Nychas GJ. Development of a Microbial Model for the Combined Effect of Temperature and pH on Spoilage of Ground Meat, and Validation of the Model under Dynamic Temperature Conditions. Appl Environ Microbiol. 2006 Jan;72(1):124-34.]
  4. [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7K-3S3M25D-B&_user=217827&_coverDate=01%2F06%2F1998&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000011279&_version=1&_urlVersion=0&_userid=217827&md5=80630ba21fbc6869b9f5179d334734da Giannuzzi L, Pinotti A, Zaritzky N. Mathematical modelling of microbial growth in packaged refrigerated beef stored at different temperatures. Int J Food Microbiol. 1998 Jan 6;39(1-2):101-10.]
  5. [http://www.iaph.uni-bonn.de/Coldchain/downloads/06_Labuza.pdf Labuza 2006 : Cold Chain-Management II Time-temperature Integrators and the Cold chain: What is next? Bonn Germany 5/8/06]
  6. [http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1365-2621.2001.tb15211.x?cookieSet=1 E. Shimoni, E.M. Anderson, T.P. Labuza (2001) Reliability of Time Temperature Indicators Under Temperature Abuse. Journal of Food Science 66 (9), 1337–1340. doi:10.1111/j.1365-2621.2001.tb15211.x ]
  7. [http://linkinghub.elsevier.com/retrieve/pii/S0168-1605(05)00067-X Giannakourou MC, Koutsoumanis K, Nychas GJ, Taoukis PS. Field evaluation of the application of time temperature integrators for monitoring fish quality in the chill chain. Int J Food Microbiol. 2005 Jul 25;102(3):323-36.]