**2.2 Intelligent packaging**

Intelligent packaging is an emerging and existing area of food technology that can provide better food preservation and extra convenience benefits for consumers [46]. Intelligent packaging provides information about the food product enclosed in them prior to provision of the natural packaging properties. They are integrated with a target-specific sensor (TSS), which can store information about the history of a quality attribute, such as freshness, gas leakage, microbial contamination, product demography and footprints, etc., and deliver this information to a consumer. Intelligent or smart packaging refers to a packaging system that senses and informs [30]. They are integrated in a packaging material with a sensing devices that are capable of sensing and providing information about the function and properties of food and assurances of pack integrity, tempering evidence, product safety and quality, and also utilized in authenticating, anti-theft and product traceability [30]. Sensing device in Intelligent packaging system include (i) Time–temperature indicators (TTI), (ii) Gas sensing dyes, (iii) Microbial growth indicators, (iv) Physical shock indicators, and (v) Tracing device such as tamper proof, anti-counterfeiting and anti-theft technologies [30]. Intelligent packaging also provide detailed information about shelf life and quality state of the food in order to ensure consumer satisfaction and safety while potentially improving logistics and minimizing the losses. Other sensing devices in Intelligent Packaging includes biosensors, Radio frequency identification (RFID) tags or electronic tracking tags that stores and wirelessly transmit information about the food packaged and ease traceability.

1.**Time–temperature Indicators:** In Time–temperatures Indicators, the shelf life of food products or their freshness is determined based on selected indicators, such as vitamins, color or flavor change, enzyme activity, etc. through predictive models which are developed based on accelerated shelf-life tests, usually on meat and meat product, fish and sea foods. TTIs sensors can either be

(i) diffusion-based (diffusion of colored esters forms color contrast alongside a reference scale), (ii) Enzymatic (certain enzymatic reaction that can change the environmental conditions, such as pH, which then causes color change), or (iii) Polymer-based (polymerization reaction forms a color contrast with a reference scale) depending on their material of formation. All TTIs commonly require an activation step to start the sensing process at the same time when the product enters the package.

