Most of us can recount opening a recently purchased food product, only to find it spoiled. This firsthand experience underscores ongoing problems within the food supply chain that new technologies can solve.
Explore this issueAugust/September 2007
Maintaining proper temperature during handling is fundamental in ensuring the quality of perishable products. Exposures over and under safe temperature limits lead to spoilage or loss of freshness. Poorly handled products can result in rejected product, customer dissatisfaction, illness, and even loss of life.
A supply chain is referred to as a “cold chain” when transport of perishable products is involved. Spoilage problems faced by cold chain managers stem mainly from the fact that, at different points along a supply chain, products change hands many times; there are gaps in any one party’s knowledge of the environment the products are exposed to during transport. Many times, there is no single party to blame, nor can liability be assessed, because there is usually no recorded temperature history to tell what went wrong or when it happened.
Companies Absorb Losses
In most of the food industry today, spoilage problems remain open-ended, and companies are absorbing the losses. Perishable foods constitute the single largest category within a conventional supermarket chain, contributing to approximately 35% to 50% of sales and 40% to 55% of gross profits. Freezing conditions can also adversely affect some products and can cause a significant problem in many regions during colder months. More often, though, excessive heat leads to quality problems during food transport and storage.
As an example, the useful shelf life of fresh picked strawberries falls dramatically as temperatures increase (see Figure 1, right).
Growers and shippers go to great lengths to keep products such as strawberries close to their ideal temperature. Yet many temperature abuses occur on the trip from producer to distribution center to supermarket: A truck’s refrigerator unit may get turned off inadvertently, or a delivery gets left on a hot shipping dock before it is brought inside. Figure 2 (p. 27) shows an example of temperature history for a strawberry shipment, where the measurement is taken inside the product carton that was loaded on a pallet of product.
Note that the high and low limits are +39°F and +32°F—the recommended temperature range for handling strawberries. The chart shows that as the shipment progressed, the refrigerator unit did not maintain the product under its maximum limit—likely due to summer temperatures and pallet organization. The data show that the product was unloaded on the morning of June 9 and sat for approximately eight hours in a receiving area. Time out of refrigeration added to the already compromised condition of the product, resulting in an even shorter shelf life and lower customer satisfaction.
As products change hands on their way from production to point of purchase, each transition in the cold chain is another chance for temperature abuse, and each is cumulative. Perishable products lose shelf life in relation to time out of specification and in relation to the difference in actual versus desired temperature at any given time. The longer the time out and the farther it is out of range, the more spoilage will result.
Shipping and handling abuses are common—especially in summer—and, in many cases, abuses are far worse than the one in this example. Freezing conditions during colder months or caused by refrigerator units set too low also cause substantial losses for a wide variety of food products.
The lack of visibility into the causes of such events has been, until recently, a problem that supply chain managers have not been able to solve. Whether the problem occurs with produce, fresh prepared foods, or meat and seafood, avoiding food spoilage through proper cold chain management is crucial to maintaining quality, value, and safety. Without visibility, losses of product are substantially greater, as are the risks to product safety and brand image.