Intelligent pH-sensitive tragacanth gum-pectin nanofiber mats encapsulating Althaea officinalis extract and chitin nanowhiskers to track the freshness of chicken fillets

The pH-sensitive nanofiber mats were developed based on tragacanth gum-pectin (TG-PE) as a polymer matrix, Althaea officinalis extract (AOE, 3 g/100 mL) as a natural dye, and chitin nanowhiskers (CNW, 1 and 2 g/100 mL) as a nano-reinforcement compound to investigate their utilization for spoilage control of chicken fillets. The highest tensile strength and the lowest water vapor permeability, oxygen transmission rate, water solubility, and moisture content were found in TG-PE + AOE-3 + CNW-2 nanofiber mats, recorded by 11.65 MPa, 5.12 × 10‾4 g mm/m2 h Pa, 2.27 cm3/m2 h, 4.21%, and 2.25%, respectively. According to the thermogravimetric analysis, CNW-1, CNW-2, AOE-3, AOE-3 + CNW-1, and AOE-3 + CNW-2 improved the residual mass content of TG-PE nanofiber mats at 600 °C, determined by 15.00%, 10.80%, 12.47%, 17.07%, and 19.77%, respectively. From day 0 to day 4, the color of TG-PE + AOE-3, TG-PE + AOE-3 + CNW-1, and TG-PE + AOE-3 + CNW-2 nanofibers converted from white into chestnut brown; meanwhile, the total volatile basic nitrogen, pH, total mesophilic count, and total psychrotrophic count reached 25.28 mg N/100 g, 7.11, 7.03 log CFU/g, and 5.49 log CFU/g, respectively, suggesting that the nanofibers have the capacity to monitor the freshness of chicken fillets in immediate terms.