Cross docking has become more popular, especially in the past 10 to 15 years, as shippers deal with shortages of drivers and equipment, and with the rising popularity of loads mixed with several different fresh produce commodities, possibly from several different growers or other entities. This increases the chances of quality problems from the heat or cold at open docks, depending upon the time of the year.
It is common for temperature recording devices to keep a record of how long that trailer door is open. It also will record the spike in temperature in the trailer due to warm weather, or the drop of temperature in colder environments.
“If you are a driver, there’s a full recording of how long that door is open and that can come back to haunt the driver at destination,” states Rich Macleod of TransFresh Corp. of Salinas, CA, whose career has been dedicated to improving in-transist issues associated with fresh produce, and how to improve upon delivering a fresh, quality product.
“If you are at an open loading dock, you need to turn your reefer unit off when the product is being loaded,” Macleod cautions.
Otherwise, a running refrigeration unit will be sucking warm air across the trailer floor and into the reefer unit. This puts exceptional demand on that reefer unit, he notes. If there is warm air coming across the unit’s coils, that results in a lot more condensation — and freezing.
“So the first thing that happens when you close the trailer doors is that unit goes into defrost So then you just further aggravate what ever break you have in the cold chain. So back up to the dock, shut off the reefer, load, and then close the trailer door and re-start the reefer unit. You will have colder loads,” Macleod relates.
One situation Macleod is noticing is when a partial load of strawberries is loaded at Watsonsville, CA and the driver proceeds to the Central San Joaquin Valley to fill out the trailer with stone fruit.
“The trucker backs up to the dock and sometimes that driver will leave the reefer unit running. then they (shipper) re-balance the load, perhaps placing the heavier commodities in the front of the trailer.. They pull the strawberries (off the truck), place them on the loading dock to move in the other product. Typically, those strawberries will start picking up temperature within 15 to 30 minutes,” Macleod says.
Of course, factors such as whether those strawberries on the dock are sitting in the shade, or sun, whether the wind is blowing, temperature, etc.
This has resulted in strawberry shippers insisting the strawberries being picked up and loaded last onto the trailer.
(This is the third in a five-part series featuring an interview with Rich Macleod, vice president, pallet division North America for TransFresh Corp., Salinas, CA. He has been with the company since 1976, and has a masters degree in post harvest science from the University of California, Davis.)