Hybrid chiral nanocellulose-cyanidin composite with pH and humidity response for visual inspection and real-time tracking of shrimp quality and freshness.

• Chiral CNC-cyanidin films with multiple stimulus responses for freshness monitoring. • CNC and cyanidins are ecologically-friendly natural substances with no toxicity. • The samples with enhanced strength exhibit good flexibility under bended states. • CNC-cyanidin films displayed significant color variation over the pH range of 2–13. • The sample could be a convenient and visual diagnostic freshness monitor in real-time. Biobased multi-stimulation materials have received considerable attention for intelligent packaging and anti-counterfeiting applications. Cellulose nanocrystals (CNCs) and cyanidins are good material candidates for monitoring food freshness as they are eco-friendly natural substances. This work incorporated cyanidin with a CNC-hosting substrate to develop a simple, environment-friendly colorimetric device to visualize food freshness. Across the pH range of 2–13, the indicator exhibited noticeable color changes ranging from red to gray and eventually to orange. The CNC-cyanidin (CC) film exhibited a dramatic color change from blue to dark red and high sensitivity at a relative humidity of 30 %–100 %. In corresponding to the total volatile elemental nitrogen (TVB-N) level of shrimp, the indicator showed distinguishable colors at different stages of shrimp. The findings imply that the samples have substantial potential for use as an intelligent indicator for tracking shrimp freshness. [ABSTRACT FROM AUTHOR]