Natural and Biocompatible Optical Indicators for Food Spoilage Detection

The quality of food products is subject to changes during their cycle due to their perishable nature and to various spoilage processes which depend on the type of food and on its processing, storage, and handling conditions. Therefore, both regulatory agencies and consumers have recently invoked the adoption of higher quality and sustainability standards, full traceability, and the prediction of food shelflife. In order to fulfill such demands, food producers and suppliers need to ensure real-time capillary quality control operations applicable on a large scale throughout the entire processing and distribution cycle of food products. In this context, smart packaging and portable sensing technologies are attractive tools to monitor the food state and freshness from production to final consumption. In the present chapter, the most recent challenges and technological solutions addressing the optical and colorimetric detection of food spoilage through biocompatible and natural indicators will be discussed. These technologies rely on the interaction between functional components embedded in the packaging material and specific by-products originating from deterioration reactions in the food that give rise to a change in one or more measurable optical properties (e.g. color, spectral absorption, fluorescence) of the sensing material. In particular, the use of natural or biocompatible sensing platforms enables a real-time wireless user-friendly spectral and direct naked eye spoilage detection and, at the same time, meets the criteria for safety and sustainability, as it allows a safe on-site (on-package) integration, eliminating the toxicity risks associated with the direct contact with food.