pH-sensitive films based on carboxymethyl cellulose/date pits anthocyanins: A convenient colorimetric indicator for beef meat freshness tracking

The pH-sensitive intelligent film is a much-awaited advancement in packaging technology, which uses visually discernible color changes to warn consumers about the freshness or spoilage of perishable food products. This study aims to develop an intelligent indicating film based on carboxymethyl cellulose (CMC), formulated with date pits anthocyanins-rich extract (DPAE) at 1.5 %. The incorporation of DPAE significantly enhanced the physical (moisture content, swelling index, water solubility and biodegradability) and mechanical (thickness, elongation at break and thickness). Developed films exhibited a higher antioxidant and antibacterial activity against food-borne pathogens. Furthermore, the inclusion of DPAE had a noticeable effect on pH-sensitive characteristics of the CMC/DPAE films. Interestingly, the CMC/DPAE film displayed a color change from yellow to dark brownish in response to changes in pH levels, covering a wide range from 1 to 13. The CMC/DPAE films were also capable of detecting ammonia at concentrations ranging from 0.125 to 1 mg/mL. In order to monitor the freshness of minced beef meat stored under refrigerated conditions at 4 °C over 14 days, CMC/DPAE films exhibited noticeable color variations corresponding to the changes in meat quality, which were assessed based on total volatile basic nitrogen, microbial count, and pH during storage. The color alteration on the packaging label shifted from yellow to dark, signifying changes in meat freshness. The obtained results stipulated that the newly developed CMC/DPAE films hold promise as innovative colorimetric pH indicators for tracking the freshness and spoilage meat-products in the food industry and supermarkets.