Self-assembled polyacylated anthocyanins on anionic wood film as a multicolor sensor for tracking TVB-N of meat

Abstract

Available food indicator films do not have a wide color variation and have a low TVB-N carrying capacity. In this study, we generated a high TVB-N-loading multicolor sensor based on self-assembled polyacylated anthocyanins on anionic wood film for tracking meat freshness. We constructed an anionic wood film with H2O2/NaOH to fix Clitoria ternatea anthocyanins via electrostatic interactions. The maximum adsorption capacity was 0.82 mg/g at 50 °C for 4 h. The values of L* , a* and b* were 42.16, 7.30, and − 19.31, respectively. Clitoria ternatea anthocyanins-fixed wood film (CTWF) exhibited four significant color changes under different pH values with high pH-sensitivity. Furthermore, the fixation of Clitoria ternatea anthocyanins enhanced the thermal stability of the anionic wood film as the maximum decomposition temperature of CTWF increased from 323 °C to 336 °C. The water contact angles on the original wood film, anionic wood film, CTWF (Q min), and CTWF (Q max) were 84°, 75°, 55°, and 48° within 1 s, respectively. In addition, CTWF reacted with volatile amines due to its adequate hydrophilicity, changing from violet to green within 3 s at 53% RH under 7.50 mmol/L NH3, which is beneficial for monitoring meat freshness. When TVB-N of 14.56 mg in 100 g of pork approached 15 mg/100 g (GB 2707–2016), the color of CTWF (0.6 cm × 0.6 cm) changed from purple to blue. Therefore, CTWF holds potential as a smart sensor that can monitor the quality of protein-rich foods in real time.