Development of a novel colorimetric pH-indicator film based on CMC/flaxseed gum/betacyanin from beetroot peels: A powerful tool to monitor the beef meat freshness

A novel indicator film based on carboxymethyl-cellulose (CMC)/flaxseed gum (FG) was developed by introducing betacyanin (BC) from beetroot peel extract. Remarkably, CMC/FG/BC film exhibited a dynamic color transition from pink to yellow in response to pH changes from 1 to 12. Beyond its pH sensitivity, the newly developed film demonstrated exceptional sensitivity to ammonia solution concentrations, detecting variation from 0.125 to 0.5 mg/mL with a significant ΔE (P < 0.05) change when a concentration of 0.5 mg/mL was added. Moreover, the inclusion of BC not only heightened the film's colorimetric capabilities but also enhanced the antioxidant, physical (moisture content, swelling index, thickness and biodegradability), and mechanical (elongation at break) properties. On the other hand, the CMC/FG/BC film's ability to provide real-time monitoring of minced beef meat quality was examined during 14 days of storage at 4 °C. The CMC/FG/BC film displayed a distinctive color change (from light pink to purple) corresponding to changes in meat samples' total volatile basic nitrogen (TVB-N) and microbial count (aerobic plate, psychrotrophic total and Enterobacteriaceae counts) during the storage period. The CMC/FG/BC film could be considered as a novel colorimetric pH indicator to monitor meat and meat derivatives' freshness. Its multifaceted properties make it valuable as an intelligent packaging used in food quality control, offering real-time insights into both pH changes and the freshness of stored meat products.