Packaging is interdisciplinary, influencing (and being influenced by) other disciplines within an organization. An example is the interdependence among packaging, shelf-life testing, and expiration dating. Although his article pertains to food, some aspects apply to other product categories, such as drugs and medical devices. There are differences, however, such as regulations, that deserve their own article.
Shelf life starts at the time a food is packaged and ends when the food quality fails to meet consumers’ requirements. Shelf life, therefore, is a quality concept which is not to be confused with a safety concept, although the two are linked. To illustrate, it’s often the case that a food remains safe, but has lost too much of one or more characteristics valued by consumers.
Packaging protects and is one of several key factors that impacts shelf life. Another is the product’s ingredients, e.g., preservatives. Yet another factor is the type of processing, such as hot fill, aseptic, modified atmosphere (MAP), and vacuum, which are as much packaging operations as they are processing operations. A more dispersed factor is the supply chain, and specifically, its conditions of storage and handling.
The more that a company knows about shelf life, the more that company can leverage shelf life strategically. The optimal shelf life for a given product can be a thorny determination, involving a host of trade-offs. The absence or minimum use of preservatives might sway the purchase decision for certain consumers, but those same consumers might want minimum packaging, or dislike certain types of packaging, say, plastics. There also is a competitive aspect to shelf life, how that of one product compares to that of others in the same (or substitutable) category. Consumers are vested parties of that comparison, but so too, are retailers. The latter are concerned with product turnover and don’t want to be left with product that has to be discarded or donated. On a related note, retailers represent how widespread a product’s distribution is. As geographic coverage expands, the product spends a greater portion of its shelf life in transit, subtracting from the portion spent at retail.
The best way to determine a product’s shelf life is by testing. Shelf-life testing is not the same as safety testing, which should precede shelf-life testing. Safety testing measures the presence of pathogens and is an ongoing component of quality assurance (QA). Safety testing need not, and for most times is not, performed on the packaged product. Another type of testing that’s not to be confused with shelf-life testing is compatibility testing of food-contact packaging. There, the objective is to determine whether substances from the packaging migrate into the food. A company may forego compatibility testing if the packaging material’s proven history justifies.
One type of shelf-life testing is performed real-time. Its duration should include a safety buffer, a period that exceeds the targeted shelf life. The test subjects should be selected as soon they come off the packaging line. That’s contingent on all line controls having performed their tasks. After all, there’s no practicality in testing products that have been defectively packaged.
The quantity of test subjects should bear some relationship to the length of time over which the testing will be performed. An initial evaluation sometimes is performed immediately. Regardless, the testing consists of pulling packaged products at intervals and evaluating them. Changes are noted, until product quality becomes unacceptable.
Unacceptability can be product-specific. Nonetheless, with food, it will have an organoleptic component, i.e., it is perceptible through the senses. Taste, color, odor, and feel (texture) are quality cues. Regarding a compromised overall appearance, if the packaging is see-through, shelf-life affects shelf-appeal, as well.
The other type of shelf-life testing is the accelerated variety. Product is subjected to conditions that are more extreme than those used in real-time testing in order to get results quicker. Typically, accelerated testing involves elevated temperatures but also can involve other elevated conditions, such as relative humidity (RH). The results of accelerated testing need to be extrapolated to determine their relevance to anticipated conditions. Accelerated testing is not to be performed in lieu of real-time testing. Rather, there must come a time when the latter corroborates the former.
All food packagers should be able to perform real-time shelf-life testing, in-house. Because accelerated testing can require specialized environmental chambers, some food packagers outsource to laboratories.
Lastly, shelf life is communicated to consumers and retailers by expiration dating, carried on the packaging. Open dating consists of month, day, and year, interpretable by all parties. That doesn’t mean that all parties assign the same meanings to such phrases as, Best if used by, Sell by, and Enjoy by. Food packagers are free to choose any phrase, provided that it isn’t untruthful or misleading. There aren’t any federal requirements mandating that food packagers use expiration dating (except for infant formula). Food packagers use it voluntarily, believing it to be in their best interests. That’s because expiration dating is regarded favorably by the consumer and the retailer.
Sterling Anthony, CPP, consults in packaging, marketing, logistics, and human-factors. A former faculty member at the Michigan State University School of Packaging, his contact info is:100 Renaissance Center, Box-176, Detroit, MI 48243; 313/531-1875; [email protected]
