Chitosan-based intelligent freshness indicators for monitoring food quality: A comprehensive review.

Ensuring food safety and reducing food waste has become serious impediments in the field of modern food industry. In response to the trending need for sustainable and intelligent food packaging solutions, biopolymers have garnered significant attention due to their biodegradability, biocompatibility as well as functional versatility. Among the biopolymers, chitosan-based intelligent freshness indicators (FFI) have emerged as innovative solutions for real-time monitoring of food quality. This review delves into the development and application of chitosan-based FFI, emphasizing their role in detecting spoilage markers such as carbon dioxide, volatile base nitrogen (VBN), sulfides, ethylene, microbial metabolites, bioluminescence, enzyme activity, and electrochemical changes. It also describes various food freshness indicators, including natural pigment-based, chemical chromogenic dye-based, and data carrier-based systems, highlighting the integration of natural pigments like anthocyanins, curcumin, betalains along with the study of different chemical chromogenic pigments into chitosan matrices. The review also highlights effective application of FFI across various food categories like fruits and vegetables by detecting ethylene and acidity changes, signaling ripeness and spoilage; in meat and seafood by sensing total volatile nitrogen compounds; in dairy products by monitoring pH fluctuations associated with microbial activity.