What Is a Cold Chain?

A cold chain is a series of controls on production and distribution of products to keep them within a safe temperature range from production to end consumer. Food, certain chemicals, medications, and perishable products like film all rely on cold chains to retain their integrity through the shipment process. There are a number of tools manufacturers and shippers can use to maintain safe temperatures and monitor goods throughout the shipping process for signs of dangerous increases in temperature.

In production facilities, a cold chain includes refrigeration for goods in the facility, along with cool working environments, if necessary. The producer may package products in insulated containers for added protection before sending them out for shipping. The insulation is useful for if the cold chain fails, as well as for when it is necessary to transfer goods between vehicles and they may be exposed in warm conditions. Refrigerated trucks, rail cars, and shipping containers are also useful for protecting the integrity of goods during shipment.

Cold chain monitoring is an important part of the process. Refrigerated units usually have thermometers and may sound alarms if the temperature gets too high. Packaging can have specialized stickers that react to excessive temperatures by changing color. The color change will alert shippers to the fact that the goods may have been compromised in shipping. If the product is particularly sensitive, it may be discarded, or the company can test it to see if the temperature increase damaged it.

For health and safety reasons, it is especially critical that food and medicine be shipped via cold chain if they are perishable. Vaccines are a classic example. Vaccines are very fragile, and if handlers expose them to temperatures that are too high, they may be damaged and become ineffective. This can be a significant problem in developing countries in the tropics, where access to refrigeration is limited. Safety procedures in these areas may involve tools like coolers packed with ice and brought to a vaccination center for immediate use, as it may not be possible to safely store vaccines in a rural clinic.

The military is one of the leaders in cold chain technology, as it needs to meet the needs of large numbers of personnel on the move, often in hostile conditions. Military inventors have created a variety of monitoring and backup methods to limit disruptions to the supply chain. This ensures that members of the military have access to safe, fresh food along with medications while they are on duty. Some of this technology has spilled over into the civilian world, where military inventions like heat-sensitive adhesive tape are standard on some cold chain products.