Perishable foods are frequently exposed to temperature abuse during transportation and
distribution. The use of traditional data loggers do not permit the instantaneous data transmission that radio frequency technology offers. Temperature has a major impact on food
quality and safety, particularly when long transit times are imposed. Consequently, using
radio frequency identification (RFID) to track and monitor temperature in perishable shipments will bring significant benefits to the cold chain. The goal of this study was to determine the optimal RF antenna placement to achieve full RFID tag readability inside a sea
container. Testing was made at two different frequencies (915 and 433 MHz) while the
refrigeration unit was running at À25 °C and the container was fully loaded with frozen
bread. The sea container was instrumented with eight RFID antennas, three of which were
tuned for 433 MHz and five for 915 MHz. All antenna wires exited the container via the forward drain holes. The RFID readers were outside the container and connected to their
respective antennas, one at a time. Thirty eight RFID tags were evenly distributed onto
the pallets of frozen bread. All RFID tags were active tags capable of reading and recording
temperature. Results at 915 MHz showed readability levels between 47% and 79%, with an
average of 68.4%, whereas 433 MHz demonstrated 100% readability at all antenna positions. In conclusion, the 433 MHz RFID system appears suitable for real time temperature
monitoring of frozen bread inside a sea container. This technology could be applied to
other food items similar to frozen bread.
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