Smart and active packaging: leakage and freshness indicators

Smart and active packages give information to consumers based on the interaction happened between food and packaging, which triggers a modification (usually visual) in the packaging, an indicator of the quality or condition of the product.

Some of these indicators are:

Leakage indicators

Oxygen and carbon dioxide indicators can be used to monitor the quality of food. They can be used as leakage indicators or to verify the efficiency, for instance, of an oxygen scavenger. Many of these indicators acquire a colour change as a result of a chemical or enzymatic reaction. The most used stain for leakage indicators is methylene blue, whose colour change is based on an oxidation-reduction reaction). Oxygen indicators are widely used in Japan with many fresh or packaged prepared food with an oxygen absorber in a plastic or glass transparent packaging. Carbon dioxide indicators are beginning to become commercial.

Freshness indicators 

An ideal indicator for the quality control of packaged food is the one indicating a product’s deterioration or lack of freshness, in addition to the high temperatures or the packaging leakages. There are several patents wherein there are described mechanisms of freshness indication based on detecting volatile metabolites produced by food weathering, such as carbon dioxide, diacetates, (fish) amines, ammonia and hydrogen sulphide.

Other smart systems 

Other trends on smart packaging are those related to electronic components that provide information about the product identification, packaging date, cost, etc. and also time-temperature function and/or freshness indicator. Other intelligent systems that can be integrated in smart packaging are: time temperature indicators, knock indicators, RFID labels (Radio Frequency), electrochromic displays and authentication systems.