Multifunctional intelligent indication labels featuring antibacterial properties based on pectin/carboxymethyl chitosan incorporated with porous microspheres loaded with anthocyanins: A new approach for salmon preservation and freshness detection

Abstract

Multifunctional intelligent indication labels tend to prolong the quality guarantee period and monitor the freshness of food. In this study, indication labels were prepared with carboxymethyl chitosan (CMCS) and pectin as substrate, and porous microspheres loaded with anthocyanins (ACN@PGMs) as indicators and antioxidant as well as clove essential oil as an antibacterial agent. The interaction between pectin and CMCS and the addition of ACN@PGMs improved the physical properties and structural density of indication labels due to electrostatic complexing and hydrogen-bonding interactions, which exhibited optimal performance when the added anthocyanins equivalent was 0.25 mg/mL. Meanwhile, the water contact angle and antibacterial activity reached maximum values of 78.8 ± 2.3°, 11.8 ± 0.88 cm (E.coli), and 17.00 ± 0.71 cm (S.aureus), respectively. In addition, indication labels displayed sensitive color responses to different pH and ammonia environments. In application, labels could extend the shelf life of refrigerated salmon from 4 days to 9 days and showed significant color changes when salmon spoiled. Overall, indication labels played a positive role in extending shelf life and visual freshness detection, which could be employed in food quality evaluation and food preservation.