Abstract
A new pH-sensing film was developed by using tamarind seed polysaccharide (TSP) and natural dye extracted from litmus lichen (LLE). The addition of LLE from 0 to 2.5% decreased the tensile strength and elongation at break from 30.20 to 29.97 MPa and 69.73% to 60.13%, respectively, but increased the water vapor permeability from 0.399 × 10−9 to 0.434 × 10−9 g·s−1·m−1·Pa−1. The UV–Vis spectra of the litmus lichen extract (LLE) in the pH range of 4–10 showed that the color clearly changed from orange to blue. The characterization results showed that TSP interacted with LLE through hydrogen bonds. The color of the film varied from orange (pH 4.0) to blue-violet (pH 10.0). The full cream milk spoilage test indicated that the film is suitable for application in full cream milk spoilage detection. The developed pH-sensing film could be used as a promising diagnostic tool for the detection of food spoilage.
Highlights
To reduce white pollution, alternatives to synthetic polymer materials must be explored
A total of 8 g of Tamarind seed polysaccharide (TSP) powder were mixed with 200 mL of distilled water, and the mixture was heated to 90 ◦ C and maintained at this temperature for 2.5 h under constant stirring
In order to reduce the break to the structure of litmus lichen (LLE) and prevent the deterioration of TSP, the resulting solution was cast into a glass plate (26 cm × 26 cm × 4 cm) after removing bubbles and dried for 10 h at 80 ◦ C in a vacuum oven
Summary
Alternatives to synthetic polymer materials must be explored. PH-sensing chemical reagents such as bromocresol compounds, chlorophenol red, and cresol red have been widely used [15,16,17] These synthetic chemical dyes may contaminate the food and pose a threat to human health owing to their potential. Several studies have reported the potential use of natural pH-sensing dyes such curcumin and studies anthocyanin, which are fromof plants, intelligentdyes food toxicity [18]. TSP was used to develop a novel film material, and LLE was used as a natural pH indicator dye, which were both natural biomaterials.
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