Imperial/Cell by Date/Introduction

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Latest revision as of 03:20, 27 October 2007

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• Cell by Date
  • Introduction
  • Specification
  • Design
  • Modelling
  • Implementation
  • Testing/Validation
  • Conclusion
• Cell-Free
  • What is Cell-Free?
  • Cell-Free Vs. Cell
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Cell by Date Summary

Cell by Date is a Temperature Time Integrator, and will report when ground beef has been out of the cold chain for too long (the cold chain being the temperature controlled transport chain from abbatoire to supermarket). Cell By Date does this by exploiting the thermal dependence of gene expression systems to express fluorescent proteins at ambient temperatures above 8°C. By using simple constructs, Cell by Date allows the characterisation of the various cell-free chassis, enhancing our understanding of this foundational technology.

Cell by Date in the Cold Chain

Motivations

The hamburger has become synonymous with modern western culture. We see it in fast food chains , ready-made packages in supermarkets, and at most home barbeques - all made using ground beef. But who controls the quality of our burgers, who ensures that the burgers we eat don’t spoil the fun and make us sick?

Ensuring the Freshness of Beef

A lot of work has been carried out to study the spoilage of the beef that make up our burgers. In fact, there are professional organisations such as FDA and HACCAP that give strict regulations to ensure the quality of beef that meat industries produce so that we don't end up with burgers like the ones below !

As consumers, we can see this in our supermarkets in the form of a printed ‘sell by date’, which is based upon challenge testing - a process in which beef is put through numerous temperature scenarios and a prediction then made about how long the beef will last after it has left the factory. Due to safety reservations, this prediction made on printed sell by date often indicates that the beef is off when in may in fact have a few days left.

On the other hand, survey studies have shown that temperature conditions higher than 10°C are not unusual during transportation, retail storage, and consumer handling of beef products. Such temperature abuses during any stage of the cold chain could result in an unexpected loss of quality and a significant decrease of shelf life. Indeed, printed sell by date labels are seldom the best estimate of meat shelf-life. To combat this, the meat industry has looked into other ways of spoilage prediction and managing the cold chain.

Temperature Time Integrators

commercially available TTIs

One particular tool used to monitor the cold chain is a family of devices called temperature time integrators (TTIs). These devices try to monitor the thermal exposure of the food. When a certain level of exposure is reached, a change occurs, usually visual, which signals that the beef has gone off.

This project is concerned with the development of a TTI that is based upon synthetic biology components; exploiting the thermal dependence of gene expression of simple reporter system in a cell free extract.

With an idea of the problem we are trying to target head on to our specification page where we take the first step in our engineering cycle to ensure the quality, relevance and robustness of our solution.

Achievements

• We designed and modelled a device to indicate spoilage of meat/break in the cold chain via the thermal history of the system.
• We successfully characterised pTet GFP and pT7 GFP under isothermal conditions.
• We further characterised pTet GFP under dynamic temperature conditions.
• The results of the Cell by Date project were to characterise cell-free chassis using a resource-dependent model.

References

Food Hygiene, Microbiology and HACCP
[http://www.sensitech.nl/en/index.html Sensitech Company]
[http://www.sensitech.nl/en/coldchain_info/index.html Sensitech Cold Chain Background]
[http://www.sensitech.nl/en/products/index.html Sensitech Products]
[http://www.globalcoldchain.com/ Global Cold Chain Company]
[http://www.who.int/vaccines-documents/DocsPDF/www9804.pdf WHO : Temperature Monitors for vaccines and the Cold Chain]
[http://www.foodproductiondaily.com/news/ng.asp?id=51051-diagnostic-packaging-potential FoodProductionDaily.com Overview of Industry]
[http://www.packaging-gateway.com/downloads/conferences/PACE/PackagingBrody_Inc_Prsntation_4.pdf Brody 2006 Good overview of industry including active packaging]
[http://www.foodtechsource.com/emag/003/trend.htm Interview with Labuza about food law]
[http://aem.asm.org/cgi/reprint/72/7/4663 Ercolini,2006 : 5 Degrees Isothermal conditions varying Packaging]