The project was designed to study the ability of RFID sensor tags to track the temperatures of fresh legs of lamb as they were transported by truck from slaughterhouse to distribution center.
By Claire Swedberg
Dec. 2, 2011—The practice of super-chilling food products below the freezing point to stop bacteria growth is fairly commonplace with fish, according to Geir Vevle, the CTO of technology provider Hrafn, based in Norway. Although the same process could also stop bacteria growth in meat products (thereby extending the meat's shelf life by weeks), few meat producers or companies in the supply chain super-chill meat, he says, because the temperature threshold is very tight. Temperatures must remain colder than 0 degrees Celsius (+32 degrees Fahrenheit), but not fall below -1.7 degrees Celsius (+28.9 degrees Fahrenheit), Vevle explains, or the quality of the fresh meat could degrade. Ensuring that temperatures stay within those perimeters can be difficult, he adds. Therefore, Hrafn, along with slaughterhouse Fatland Ølen and research organization Sintef, recently tested the use of RFID technology to track the temperatures of super-chilled meat products being transported from an abattoir to a distribution center in Norway.
The pilot was funded by a Norwegian government research council, as part of Norway's KMB Lønnsom foredling (profitable processing) project, to improve and secure marine and agricultural food processing within that country. The KMB project includes plans to use technology to improve hygiene, cold chains and fresh-food traceability.
The temperature-tracking system, with RFID technology developed for Sintef by Hrafn, included RFID temperature sensor tags, passive ultrahigh-frequency (UHF) EPC Gen 2 RFID tags and 2-D bar-coded labels, as well as software based on EPCglobal's EPC Information Services (EPCIS) standard. The test was intended to investigate whether regular temperature measurements could be transmitted in real time via RFID and a cellular connection from a truck transporting products from the slaughterhouse to the DC. The study found, in fact, that the information could be collected by an EPCIS system, but that most RFID sensor tags were not read by the interrogator, because their signals were unable to pass through the meat packed densely within the truck.
After Fatland slaughters and processes lamb at its Ølen facility, the company super-chills the meat prior to shipping it to its Trondheim distribution center. For the pilot, Hrafn equipped one truck with an RFID reader cabled to a computer equipped with a GPS unit and a GSM radio that could transmit data via a cellular connection to Hrafn's EPCIS-based software. The goal, the company reports, was to test the sensor tags' ability to verify that the meat was stored at the desired temperature (between 0 and -1.7 degrees Celsius) within the refrigerated truck for the duration of the 14-hour journey to the Trondheim DC.
Hrafn and Sintef spent two months studying the meat-chilling and transportation processes, testing the placement of tags in meat and within the truck, and establishing the EPCIS data-management application. The group selected RFID hardware from CAEN RFID, including two models of semi-passive UHF EPC Gen 2 sensor tags—the A927Z, a temperature logger with 16 kilobytes of memory (sufficient to record 8,000 temperature readings), and the A927ZET, which has an external probe so that it could be used to measure the internal temperature of a leg of lamb. For the test, carried out on Nov. 23, the truck was chilled using two cold-air blowers. Hrafn deployed nine A927Z RFID temperature sensor tags around the vehicle's interior (one on the ceiling and four on each sidewall), in order to detect whether temperatures differed in various areas located either near or farther away from those blowers. Hrafn also inserted the probes of four A927ZET tags into four legs of lamb, in order to test any temperature fluctuations within the meat itself.
with pallets of lamb at the slaughterhouse, and again when the meat was received at the DC. In this way, the EPCIS system would retain a timestamp indicating when the product left the facility and when it was received. The researchers could have utilized the RFID tags to record these events, Vevle says, but they instead opted to use bar codes, which would enable staff members to read an ID number via a mobile phone rather than requiring handheld interrogators.
The truck's reading unit, known as the Hrafn Online Container, consisted of a CAEN A941 reader and an Owasys GPS- and GSM-enabled industrial computer powered by an automotive battery. The reader was intended to capture each tag's unique RFID number, as well as temperature sensor data, every 10 minutes. To accomplish this goal, the unit was placed within the truck, on the floor, in the space in which a pallet would have been loaded. The solution was designed so that whenever the reader captured data from the tags, the Owasys computer then forwarded that information, along with the truck's GPS coordinates, to the EPCIS system on a standalone back-end system, via a GSM cellular radio, transmitting through the truck's fiberglass walls.
Once the product was delivered to the Trondheim DC the following morning, the tags were removed from the product and truck, and were brought to Sintef's Fisheries and Aquaculture lab. According to the company, the test results are still being analyzed.
The test experienced hardware-related problems, Vevle says. Only three of the 13 temperature sensor tags transmitted data to the reader during transport. The failure of 10 tags out of 13 to transmit, he explains, resulted from difficulty transmitting through all that meat densely packed into truck. The tags, however, acted as data loggers, recording every temperature reading taken throughout the trip. Once the equipment and the sensors were removed from the vehicle at the Trondheim DC, the RFID equipment was set up again at the Sintef lab, to retrieve all of the temperature data, including the tags that did not transmit to the reader while the meat was in transit.
Moreover, the Hrafn Online Container's GPS equipment also could not operate during transport, because signals from GPS satellites were blocked by the truck's cargo of densely packed meat. Therefore, the EPCIS system was unable to include data regarding the truck's location throughout the journey.
In January 2012, Vevle says, Hrafn plans to participate in a second study, intended to track the temperatures of bakery items as they are shipped in chilled containers from a bakery to distribution centers
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