Traditional packaging for food offers containment and protection; nevertheless it does not provide information about the product degradation. Thus, in recent years the concept of intelligent packaging has emerged that can sense environmental changes and notify consumers that the product to be consumed is in a harmful condition. Different technologies have been employed to produce intelligent packaging, the foremost being the encapsulation of sensors/indicators. Among them, indicators sensitive to pH alteration, caused by degradation of food products, such as, acid or alkaline gases, are the most promising ones. Examples of pH indicators, free or encapsulated in silica-based materials, are discussed and exemplified. Legal aspects dealing with the regulation of the use of such devices in food are also discussed.
