Introduction: Changes in consumer preferences and the demand for safe and high-quality food products have led to innovative developments like intelligent packaging systems (IPs) or smart/active packages that directly communicate with consumers, providing information about the quality of packed food through visual change and aiding in the enhancement of freshness. Biopolymers play an important role in mitigating fossil fuel-based environmental concerns and reducing carbon footprint.

Methods: Thin biocomposites made of a rice starch matrix loaded with Aegle marmelos (L.) fruit extract were synthesised using the solvent casting method for the detection of freshness in dairy and seafood products through spoilage-induced pH modification. Additionally, their antimicrobial and antioxidant properties were also explored for shelf life enhancement. Material characterisation was investigated through UTM, FTIR and SEM.

Results: The results show that A. marmelos extract showed colour changes detectable both under UV and with the naked eye following pH fluctuations occurring during the spoilage of milk and prawns placed on the prepared thin sheet. SEM analysis revealed how the starch molecule absorbed the plant extract into its matrix structure, producing a neat, thin film. FTIR was also used to confirm how the plant material interacts with the starch used. UTM studies indicated that the Young’s modulus of the starch film decreased, thereby contributing to better mechanical strength.

Conclusion: This investigation produced insights into a novel, completely biodegradable, flavonoid-based pH biosensor that can successfully be used in food packages for freshness detection.