Freshness indicators for food packages

Intelligent or smart packaging can give information about the quality of the packed food. The intelligence of a package can be based on the package's ability to give information about the requirements of the product quality like package integrity (leak indicators) and time-temperature history of the product (time-temperature indicators). Intelligent packaging can also give information on product quality directly. A freshness indicator indicates directly the quality of the product. The indication of microbiological quality is for example based on a reaction between the indicator and the metabolites produced during growth of microorganisms in the product. Of the indicators mentioned, time-temperature indicators and leak indicators are already commercially available and their use is increasing constantly. An indicator that would show specifically the spoilage or the lack of freshness of the product, in addition to temperature abuse or package leaks, would be ideal for the quality control of packed products. The number of concepts of package indicators for contamination or freshness detection of food is still very low, however new concepts of freshness indicators are patented and new commercially available products are likely to become available in the near future. The development and testing of intelligent packaging systems in confidential and non-confidential projects has been one of the key focuses of the packaging research at VTT Biotechnology for about ten years. Non-confidential research financed by European Commission, Finnish Ministry of Agriculture and Forestry, Association of Finnish Fish Retailers, National Technology Agency (Tekes) in Finland and industrial sponsors has been carried out. During these projects prototypes of leak indicators for modified atmosphere packaged foods and freshness indicators especially for poultry products have been developed and tested. Related to the development of freshness indicators metabolites reflecting the quality of poultry meat have been investigated. We have also carried out projects where the already commercially available indicators have been applied for the quality control of packaged, fresh fish and poultry products. In this presentation case studies related to the development of the different types of intelligent packaging systems will be described.