Refrigerated freight: what temperature-controlled loads ask of a carrier

What counts as refrigerated freight

Any load whose temperature has to be controlled in transit. Shippers group it by the range they need:

The ranges are typical guidance, not rules. The temperature for any load is whatever the shipper writes on the bill of lading and rate confirmation. Handling guides like UGA Extension's quick storage guide for vegetables and USDA's Agriculture Handbook 66 show why ranges differ: some products are hurt by cold (UGA lists tomatoes at 50-55°F), while others want to sit right at 32°F.

Temperature-controlled freight and the cold chain

Temperature-controlled freight is the industry's broader term. It covers frozen and chilled loads, plus freight that needs protection from heat or freezing rather than from warming. A reefer heats as well as cools, so in winter it keeps produce from freezing in the trailer.

The cold chain is the series of steps that keep a product in its range: cooled after harvest or production, held in cold storage, hauled in a reefer, received into a cooled dock, displayed in a refrigerated case. Cold chain freight is the transport part. It's the link with the most opportunities to break: doors open at every stop, units run on their own fuel, and the product is out of the shipper's control for days.

Frozen freight

Frozen loads are less sensitive to small temperature swings than fresh produce, but more sensitive to a unit failure, because a thawed and refrozen load is often a total loss. USDA's food safety guidance treats 0°F as the line for frozen storage. Frozen freight often runs in cycle mode, which saves fuel, if the shipper allows it.

Carrier duties under the FDA sanitary transportation rule

The FDA's Sanitary Transportation of Human and Animal Food rule, part of the Food Safety Modernization Act and codified at 21 CFR Part 1, Subpart O, sets duties for shippers, loaders, carriers and receivers. Businesses with less than $500,000 in average annual revenue are exempt, along with some specific situations. Here's what it asks of carriers, in plain words.

Vehicles and equipment (21 CFR 1.906). Trailers must be cleanable, kept in sanitary condition, and, for food that needs temperature control, able to hold the temperature that keeps the food safe. They must be stored so they don't harbor pests.

Transportation operations (21 CFR 1.908(e)). When a written agreement makes the carrier responsible for sanitary conditions, the carrier must:

• Make sure the trailer meets the shipper's specifications.
• Pre-cool each mechanically refrigerated compartment as the shipper specifies before offering it for loading.
• If the receiver asks, provide the operating temperature the shipper specified, and if the shipper or receiver asks, show the temperature was maintained during the trip.
• Have written procedures for cleaning and inspecting trailers and for meeting the temperature requirements.

Training (21 CFR 1.910). Carrier staff involved in transportation must be trained, at hiring and as needed, in sanitary transportation practices and the carrier's responsibilities, with records of who was trained, when and on what.

Records (21 CFR 1.912). Written procedures, agreements and training records are kept for 12 months after use.

The rule doesn't set a temperature for any food. It makes the shipper specify one and the carrier hold it, and it expects records that prove it.

Documentation that protects you

When something goes wrong, the carrier with records usually wins. Keep these for every load:

• The bill of lading with the setpoint and mode written on it. If it doesn't match the rate con, get it corrected before you leave the dock.
• Pulp temperatures at pickup, noted on the bill of lading when the shipper or broker asks for them.
• Seal number, photographed at pickup and delivery.
• Pre-cool confirmation: the time the trailer reached setpoint.
• The unit download, the temperature log from the reefer controller. Pull it if anyone questions the load.
• Times: arrival, loading start and end, departure, and the same at delivery. They support detention claims and show where delays happened.

For produce, timing at delivery matters too. Under PACA rules (7 CFR 46.2), a receiver generally has to reject a truck load of fresh produce within 8 hours of being notified it arrived, longer if a federal inspection is pending. Good records from pickup are what you'll rely on.

Preventing claims

Most temperature claims trace back to a handful of mistakes:

1. Wrong setpoint or mode. The unit was set from memory, or the shipper's paperwork disagreed with the rate con.
2. Warm product loaded. The product went on the truck above its target temperature, and nobody wrote it down.
3. No pre-cool, or the doors stayed open too long at the dock.
4. Blocked airflow. Pallets stacked against the front wall or tight to the rear doors, so air can't circulate.
5. Unit ran out of fuel or alarmed and nobody noticed.
6. Delays that weren't reported, leaving the carrier blamed for a late, warm load.

Insurance is the backstop when prevention fails. Cargo coverage with reefer breakdown protection is common for reefer carriers; see refrigerated truck insurance. Brokers set their own requirements on top of the rule, covered in our guide to reefer freight brokers.

For the equipment side of all this, read what a reefer truck is and how the unit works. For where these loads come from and how we book them, see reefer loads. To see which produce is shipping where this month, use the Produce Season Finder.