3 – Quality of packaged foods

Publisher Summary The quality of packaged foods is a combination of attributes that determine their value as human food. These quality factors include visual appearance, texture, flavor, nutritive value, and safety. “Keeping quality” is used more commonly than “shelf life” because of consumer demand for product freshness. The deterioration of foods that occurs progressively during storage may result from physical or chemical changes in the food itself, or from the activity of microorganisms growing in or on the product. Eventually, the cumulative effect of the changes reaches a point at which the consumer rejects the product. Rejection is based on the sensory expectations and perceptions of consumers. Shelf life of a product depends on a multiplicity of variables and changes in them, including the product, the environmental conditions, and the packaging. Depending on the product and its intended application, shelf life may be dictated by microbiology, enzymology, and/or physical effects. The combined knowledge and experience of processors, and those involved in the storage, distribution, and retailing of foods enable estimates to be made of the likely shelf life of the product under specific storage conditions. In practice, however, the influencing variables that accelerate or retard shelf life are temperature, pH, water content, water activity, relative humidity, radiation, gas concentration, redox potential, the presence of metal ions, and pressure.