Publication: Development of halochromic pva/cmc films using anthocyanins from red cabbage and dragon fruits for ph sensing applications
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Date
2025-08-08
Authors
Nur Liyana binti Yaacop
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Abstract
pH-sensitive or smart indicators, particularly those based on natural pigments and biopolymers, have been widely developed at both laboratory and industrial scales. However, most commonly used pigments are synthetic, posing potential risks to human health and contributing to environmental pollution. In this study, anthocyanins extracted from red cabbage and dragon fruit were utilized to develop eco-friendly pH-sensitive films by incorporating them into a polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) matrix. A solid-liquid extraction method was employed, with optimal extraction conditions identified as 60 °C, a 1:2 solvent ratio, and 20 minutes for red cabbage, and 50 °C, a 1:6 solvent ratio using 25% citric acid, and 10 minutes for dragon fruit. Different formulations of PVA/CMC films (100/0, 80/20, 60/40, and 40/60) incorporating the extracted anthocyanins were prepared to evaluate their color-changing behavior across a pH range of 1 to 12. The total color difference (ΔE) of the films was analyzed using color analysis software (CIE L*a*b). Additional characterizations, including FTIR spectroscopy, tensile testing, swelling tests, reusability tests, leaching tests, and food application tests, were performed to assess the films' functional properties. Based on these characterizations, anthocyanins extracted from red cabbage demonstrated superior color properties as a pH indicator compared to those anthocyanins from dragon fruit.