Top Shelf Quality: Shelf-life Crucial in Validating Quality and Safety

Knowledge of a food’s formulation and history, such as association with known illness outbreaks and/or evidence of potential growth, is essential when selecting the appropriate challenge pathogens. Information from the U.S. Food and Drug Administration’s Center for Food Safety and Applied Nutrition describes some pathogens that may be used in challenge studies for various types of foods (Table 3, above).

Costs and Resources

Shelf life and challenge studies can be costly and time consuming if not done effectively. If, for example, potential causes for spoilage are identified in the first step of the process outlined in Table 2 and can easily be overcome by a slight formulation or process adjustment, it may be better to revise the product under consideration with these adjustments prior to initiating the study. If optimal storage conditions involve freezing the product, the value of a challenge study should be questioned.

It is essential that subject matter experts in food safety, quality, formulation, and packaging help design the studies and evaluate the results. Enlisting third-party consulting resources and testing labs helps ensure the effectiveness and adequacy of these studies.

Design of experiment (DOE) is a systematic approach applicable to shelf-life studies in which planned changes are made to the input variables of the process or product. The effects of the changes are assessed to maximize information gained while minimizing resources required. DOE has more to offer than “one change at a time” experimental methods, because it judges the significance of input variables acting alone on the output, as well as input variables acting in combination with one another.

Another key to testing success is understanding the requirements and wording used when translating the shelf life determined by a study into a working shelf-life standard used for dating a food product. State and local requirements differ, as do the requirements of different countries, so this area must be fully researched for the specific product, packaging, and market area being serviced.

On an international level, the Codex Alimentarius helps define international standards and guidelines on food labeling relating to date-code marking. In the United States, there is no uniform or universally accepted system used for food dating. Although dating of some foods is required by more than 20 states, there are areas of the country where much of the food supply has some type of open date and other areas where almost no food is dated. Except for infant formula and some baby food, product dating is not generally required by federal regulations. If a calendar date is used, however, it must express both the month and day of the month (and, in the case of shelf-stable and frozen products, the year). If a calendar date is shown, a phrase explaining the meaning of the date—such as “sell by” or “use before”—must be placed immediately adjacent to the date (Table 4, p. 40).

In section 3-501.17, the 2005 Food and Drug Administration (FDA) Food Code adopted by many states identifies date-marking requirements for retail food establishments for ready-to-eat, potentially hazardous food. In some cases, selling food past the expiration date is not a violation of FDA regulations or law. The quality characteristics of foods (taste, aroma, and appearance, which are distinct from safety characteristics) often depend in large part on ideal storage conditions that rely on temperature and humidity control in the retail store and warehouse. Under optimal storage conditions, many foods are acceptable in terms of taste and other quality characteristics—and are safe to eat—for periods of time beyond the expiration date printed on the label.

Taste and other quality characteristics deteriorate more rapidly if the food is stored at elevated temperatures and in high humidity conditions, a situation that might occur if the air conditioning fails in a retail store, warehouse, or in the consumer’s home. Conversely, deterioration occurs very slowly if foods are stored under optimal conditions with correct temperatures and low humidity.