When shipping fresh and frozen perishable food products, maintaining consistent temperatures throughout the cold chain journey is imperative to protecting both food quality and safety. Issues can quickly arise when temperatures deviate from their ideal setpoints. 

Frozen goods — such as meats, poultry and seafood — must stay frozen during transport, while fresh products must remain within their prescribed temperature range. In best-case scenarios, temperature abuse can quickly deteriorate the quality of frozen and fresh perishables, resulting in premature ripening, reduced freshness, shorter shelf life or unappealing product appearance. In the worst cases, temperature excursions can create conditions for the development of bacteria and/or pathogens that can cause foodborne illness.

Maintaining food quality and safety is a goal shared by all stakeholders in the perishable supply chain. From manufacturers and growers to carriers and distributors to supermarkets and restaurants, maintaining proper temperatures can help them protect their reputations and ensure the overall success of their respective businesses.

Because many things can go wrong along the journey from a farm to your favorite supermarket or restaurant, it is important to understand the risks, causes and industry best practices for preventing temperature abuse.

Cold Chain Overview

The cold chain is defined as the uninterrupted transport and storage of perishable goods under temperature-controlled conditions. In the perishable food cold chain, this primarily refers to the process of shipping goods from producers (i.e., farms) via trucks (i.e., carriers) to retail distribution centers (DCs) or facilities where they’re ultimately served or sold to consumers (i.e., fork). 

Quality is a differentiator: from farm to fork, maintained temperature consistency affects the overall quality, freshness and safety of perishable food. 

Food quality is a differentiator for producers and retailers — impacting the customer experience through the appearance, texture and taste of perishables. For example, we all know the difference between a salad or sandwich with fresh, crisp lettuce and one where the lettuce is wilted or soggy. 

In the cold chain shipping process, the margin of error contributing to lettuce quality and safety is relatively small. When iceberg lettuce is held at proper temperatures — from 33 degrees Fahrenheit to 39 degrees Fahrenheit — it has a shelf life of 15 days. When held at 47 degrees Fahrenheit, the same crop of lettuce will last only five days, while allowing for the potential for bacterial growth. 

Simply put, freshness can make or break the customer experience and temperature excursions can quickly degrade freshness and shorten product shelf life. Temperature consistency is also critical to maintaining perishable food safety. Improper processing, cross-contamination and temperature abuse are among the leading causes of foodborne illness. 

According to the Food Safety Modernization Act (FSMA), shippers (i.e., producers) and their carriers must agree to a mechanism that ensures temperature control for safety. Although the primary responsibility rests with the producers of perishable products, carriers must be able to demonstrate that they had maintained temperature conditions upon request. If an interruption in the prescribed temperature setpoint occurs — or other conditions arise that could render food unsafe — food may not be sold/distributed until a safety determination is made.

Thus, the use of a temperature monitoring and/or recording device in every refrigerated trailer has become a standard operating procedure (SOP) for many shippers and carriers. These devices provide real-time and/or historic proof of correct holding temperatures during cold chain transport.

Shipping Best Practices

Maintaining proper temperatures in trailers is an essential contributing factor for protecting food quality and safety. For stakeholders involved in the shipping process, quality control (QC) best practices can be divided into four main categories. 

1. Pre-cool temperatures prior to loading.

As a key part of the perishable food shipping process, product temperatures should be cooled down to shipping temperature setpoints prior to loading onto the trailer. For example, cooling sheds are often used to temporarily store fresh produce after it is harvested. Temperatures of all product cases and/or pallets should be checked, verified and documented during the pre-cooling process.

     2. Prepare the trailer for loading.

Before loading, the trailer should be pre-cooled and inspected per industry best practices or applicable SOPs. Make sure the trailer is pre-cooled to the designated setpoint and its controls are set to “continuous run” mode. Verify that temperatures are correct in both the front and rear of the trailer.

Inspect the trailer for any issues that could interfere with its ability to maintain proper temperatures:

• Check the walls and ceiling for any holes and/or damage.
• Ensure that floor drains are clean and operating as designed (e.g., no light visible due to missing rubber covers). 
• Verify that door seals are free of damage.
• If the trailer is equipped with an air chute, make sure it is properly attached to the front bulkhead and ceiling, and air is flowing/circulated as it was designed. 
• Thoroughly clean the trailer, removing debris and checking for odors that may affect product quality and/or safety.

     3.  Load the trailer for optimum cold chain effectiveness.

Pallets should be loaded to minimize thermal heat transfer from the outside of the trailer and maximize proper airflow. Load pallets in a centerline pattern so that they do not touch the trailer walls. Pallet height should be below red line (if present) or provide at least 12 inches of clearance from the ceiling. Apply load locks to keep pallets from shifting during transport.

     4.  Maintain and monitor shipments during transport.

Once products have been pre-cooled and loaded properly, the next step is to maintain temperature control during transport. For visibility to shipment temperatures and locations, a real-time data tracker should be loaded on every shipment, typically attached to the last pallet near the door or as determined by established SOPs.

Temperature and location data can be captured in the cloud and made available for review in the software’s dashboard. Stakeholders can receive alerts notifying them when temperatures drift from established setpoints and access historic data logs to verify temperature compliance throughout the cold chain journey.

Once shipments arrive at DCs or retail outlets, product should be quickly moved into a cold storage facility or loaded into store inventory. Data loggers and real-time trackers can help ensure that the transfer of goods has taken place quickly and according to SOPs. 

Take Control of Temperature Management

On the cold chain journey from farm to fork, proper temperature management is a key aspect of ensuring food quality and safety. Real-time trackers and related cargo software and services, combined with these four cold chain shipping best practices, are essential tools for preventing temperature abuse. Establishing SOPs and implementing industry best practices will help drive customer loyalty, protect brand reputation and maximize the quality and safety of perishable products.