Temperature excursions during refrigerated food transportation reduce product shelf life. Maintaining the integrity and quality of refrigerated cargo is paramount to preventing these issues. Stakeholders, from fleets that transport food to distribution centers and manufacturing facilities, follow industry standards to ensure food safety.
As an ecosystem, it’s vital that all involved in the food transportation and storage cold chain understand these procedures. Temperature-controlled vessels transport perishable cargo. Consistent temperatures preserve the integrity of the product to prevent spoilage, and fleets maintain a tight temperature band with minimum variations to ensure the product has the longest possible shelf life. In addition to standard food safety procedures, fleets can follow food transport best practices to ensure the product quality and longest shelf life while realizing fuel savings.
The Pre-Trip Inspection
The first step to ensure optimal food quality is to perform a pre-trip inspection of the transport refrigeration unit (TRU) and the trailer. Manufacturers should set pre-trip inspection requirements that include clearing previous alarm codes or addressing and mitigating existing alarms. Drivers should perform a visual inspection of the trailer to ensure the unit isn’t physically compromised in any way. Lastly, drivers should ensure there’s enough fuel onboard to operate the unit for the expected duration of the trip.
Pre-cooling the trailer ensures that cargo doesn’t reach inappropriate temperatures during or immediately after loading. The same standards apply regardless of the starting and final trailer temperature to ensure temperatures are within food safety guidelines.
Fleets begin the pre-cooling process by setting the TRU setpoint at the manufacturer’s desired temperature. Some air will escape the unit during loading, so some manufacturers prefer the temperature to be set below the set point. Distributors of the product in transport generally set the pre-cooling guidelines.
Protocol dictates that those pre-cooling conditions are met before operators load pallets onto the truck or trailer. For example, a manufacturer of ice cream might want to pull down the temperature to -20 degrees Fahrenheit before loading, while others may prefer to load at -10 degrees Fahrenheit. The key is keeping within the product’s tolerance range to maintain the its integrity.
Single-temperature refrigeration units pull down the temperature of the truck or trailer to the desired temperature. Typically, refrigeration units utilize a high speed to pull down to the setpoint quickly. Pulling the trailer temperature down at a low speed may take longer, but it’s a worthwhile consideration, as it can equate to significant savings in fuel costs.
Maintain Precise Temperature Control During Refrigerated Transport
Fleets can optimize the refrigeration unit and trailer to maintain desired temperature control, ensuring product integrity and negating potential losses from temperature variations. Airflow is one of many important factors in reducing temperature excursion risk. Here are four ways to improve airflow within the trailer:
1. Install Door Switches. It’s a best practice to turn off the trailer before opening doors to load cargo. Hot air will be pulled into the trailer if the unit is running when trailer doors are open. In food distribution with multiple stops throughout the day, drivers may forget to turn off the unit before unloading cargo, which repeatedly increases the overall trailer temperature. Trailers with door switches will automatically turn the unit off when the driver opens the doors. This process protects the integrity of the cargo throughout the loading and unloading process.
2. Stimulate Airflow and Circulation. Consistent airflow and circulation from the front of the trailer to the back helps maintain appropriate temperatures throughout the trailer. This is key to minimize the risk of hot spots, especially around temperature-sensitive cargo. An air chute distributes cold air to the back of the trailer before it cycles back toward the front, which reduces risk of short cycling.
Effective loading significantly improves airflow throughout the trailer. These configurations are best for palletized products, which should be placed away from walls and doors so air can flow freely around the load. The air acts as an insulator to protect pallets from hot or cold conditions outside the trailer and to maintain the set temperature inside.
3. Understand the Impact of “Off Time” in Start/Stop Operation. A unit in start/stop operation can significantly impact overall temperature variations within the trailer. Fleets benefit from understanding when to run continuous or start/stop mode based on the type of cargo in transport.
Carriers generally run a start/stop operation when transporting frozen products because frozen cargo isn’t as sensitive to temperature variations. Frozen cargo tolerates mild temperature variations of a few degrees without risk of spoilage. However, with temperature-sensitive fresh products, the temperature variations from the front to the back of the trailer can be significant. Small changes in the restart temperature could mean wild fluctuations in the actual trailer temperature, leading to cargo degradation and shorter shelf life.
4. Achieve Quality Assurance with Telematics. With telematics solutions, fleets open a window into their real-time operations and have critical visibility for temperature-sensitive cargo and equipment. In the past, drivers were alerted to alarm codes when they viewed a flashing remote status light on the side of the truck from their side mirror. This practice took driver’s eyes off the road and only alerted drivers to low fuel, temperature status or if an alarm was triggered, but not the nature of the alarm. Drivers would then have to pull over to the side of the road and look at the Human Machine Interface (HMI) to investigate further.
Today, telematics automates sensors and alarms to notify drivers and fleet managers of a potential problem before spoilage occurs. Drivers and fleet managers receive notifications straight to their smartphones with Bluetooth systems or via an app that makes equipment monitoring and remote diagnostics easier and more accessible. With state-of-the-art telematics solutions, fleets monitor cargo integrity, improve fleet uptime, and manage fleet operating and maintenance costs more effectively.
Telematics programs send instant notifications of problems within the unit so fleet managers can diagnose the issue and formulate a solution without disrupting the cargo temperature. Real-time remote monitoring mitigates potential issues like compromised load integrity or disrupted delivery schedules before they occur. Fleets improve uptime and drivers can keep their eyes on the road.
Integrating telematics is a process of continuous improvement. Fleets that are just beginning to utilize telematics typically start by installing door switches to ensure the unit turns off during deliveries, while fleets that take an all-inclusive approach to telematics implement driver training, change loading practices, adjust pre-cooling procedures, and more.
Kampf is the product manager for trailer and rail refrigeration units at Thermo King. Reach him at Tom_Kampf@irco.com.