Characterization of Edible pH‐Responsive Ink Based on Carboxymethyl Chitosan and Purple Potato Anthocyanin/Curcumin for Monitoring Pork Freshness

ABSTRACT This study developed an edible indicator ink based on purple potato anthocyanins and curcumin for monitoring the freshness of pork. By utilizing dual colourants and adjusting the pH value of the ink matrix, the pH and ammonia sensitivity of the ink were significantly enhanced. The FT‐IR analysis reflected that the composite pigments were successfully integrated into the ink. To assess its practicality, the ink was used to monitor the freshness changes of pork stored at 4°C for 7 days. The colour change of ink was positively correlated with the degree of pork spoilage, indicating that the ink can accurately reflect the freshness of pork. The ink provided an intuitive detection effect, further enhancing the application value of natural pigments in the packaging industry.