Temperature variances capable of shortening shelf life by five days or more were revealed in mid-March when the results of a cold-chain traceability study of fresh produce showed how radio frequency identification tags with sensors can help produce growers, shippers and receivers better manage shrink.

The study by Ryan Systems Inc., Canyon Lake, Calif., used TMT-8500 temperature monitoring tags from Intelleflex Corp., Santa Clara, Calif., to track fresh produce shipped to Hawaii from San Diego and Taiwan. Hawaii was chosen, according to the research report, because 85% to 90% of its food comes from outside its borders.

John Ryan, owner of Ryan Systems, oversaw the research. He said in his report the study confirmed suppliers need to resolve breaks in the cold chain, which are among their most challenging problems.

Before the study, the shippers involved assumed container temperatures were evenly maintained at about 45 degrees Fahrenheit. In reality, the Intelleflex tags in the pallets recorded temperature variations as the produce traveled to Hawaii.

The tags were placed at the top middle and bottom of pallets. Average aggregate temperatures ranged from 54 degrees to 43 degrees during early handling. Ryan reported the variations were significant, especially given the time spent during a trans-Pacific crossing. The warmer temperatures mean shorter shelf life of easily up to five days.

The Intelleflex tags used for the study communicate with readers. Data is transmitted through a wireless device that uses GPS tracking.

The GPS transmitters attach to locking bars on the containers. They are held in place by magnetism and a clamp that slides over the bar. They are set to detect tampering, and attempts to open the container door sets off an alarm and transmits the time and location the container bar was opened.

Peter Mehring, chief executive officer of Intelleflex, said the study shows how pallet-level temperature monitoring can have a quick return on investment, sometimes within the time frame of a single harvest. Mehring said continuous temperature monitoring allows produce to be routed for delivery based on remaining shelf life, thus reducing shrink.