Starch/ polyvinyl alcohol/Brazilein film with enhanced stability by using medium-chain triglycerides emulsion for real-time meat freshness monitoring.

Brazilein natural dye (BR) and various concentrations of medium-chain triglycerides emulsion (EM) were added to a starch/polyvinyl alcohol (S/PA) base film to monitor beef and shrimp freshness in a novel intelligent food packaging film. The color of the BR solution changed from yellow to dark red at pH levels ranging from 2.0 to 12.0. The EM demonstrated a size of 620.4 nm, a zeta potential of +34.1 mV, and a polydispersity index of 0.22, indicating that it was very stable with evenly distributed droplets. Incorporation of homogenized EM into S/PA-BR films markedly enhanced their mechanical, water barrier, and functional properties. Furthermore, the S/PA-BR-EM films showed the lowest release rate of BR and outstanding color stability for 18 days. The colorimetric films demonstrated high sensitivity to ammonia (50 mmol/L), with color changes from light orange to light red occurring within 2 min. The S/PA-BR-EM5 film degraded well with minimum environmental impact. Compared to the S/PA-BR film, the S/PA-BR-EM5 film improved color stability and dye leaching in humid packing. The findings indicated the S/PA-BR-EM5 film is a real-time indicator for beef and shrimp freshness at 4 °C and 25 °C, as it accurately correlates with the freshness levels and color change.