Novel colorimetric indicators based on alginate hydrogel beads containing anthocyanin for visual freshness monitoring of shrimp and minced chicken

Abstract

Novel colorimetric indicators were developed by incorporating anthocyanins into alginate hydrogel beads through electrostatic extrusion for intelligent packaging. Two different sizes of hydrogel beads were produced and applied into shrimp and minced chicken packaging to visually detect freshness status during 4 °C storage. To assess the freshness of the products, the viable count of various types of bacteria (psychrotrophic, H2S-producing, mesophilic, and Pseudomonas spp.), total volatile basic nitrogen (TVB-N) content, pH, K-value, H-value, and biogenic amines level were analyzed. The indicators' color change (ΔE) was then correlated with these parameters. Color analysis of the indicators during storage indicated ΔE values below 10 and over 30 in the hydrogels incorporated into minced chicken and shrimp packaging, respectively. The color change of both indicators integrated into the shrimp package was strongly correlated with the change in viable counts, TVB-N, pH, K-value, and H-value (r≥0.8, p<0.016), as well as biogenic amines (r=0.7, p<0.05). The indicators applied to minced chicken packaging showed subtle color changes during storage, while those in shrimp packaging consistently reflected shelf-life variations. This innovative approach shows potential for improving food safety and quality monitoring, particularly in seafood packaging, where indicators have been effective in visually signaling product freshness.