Preparation and Application of pH-Sensitive Film Containing Anthocyanins Extracted from Lycium ruthenicum Murr.

Abstract

A new pH-sensitive film was developed using Artemisia sphaerocephala Krasch. gum (ASKG), soybean protein isolate (SPI), and natural anthocyanin extracted from Lycium ruthenicum Murr. The film was prepared by adsorbing anthocyanins dissolved in an acidified alcohol solution on a solid matrix. ASKG and SPI were used as the solid matrix for the immobilization of the Lycium ruthenicum Murr. anthocyanin extract, which was absorbed into the film as a natural dye using the facile-dip method. Regarding the mechanical properties of the pH-sensitive film, the tensile strength (TS) values increased approximately 2–5-fold, but the elongation at break (EB) values decreased significantly by about 60% to 95%. With the increase in anthocyanin concentration, the oxygen permeability (OP) values first decreased by about 85%, and then increased by about 364%. The water vapor permeability (WVP) values increased by about 63%, and then decreased by about 20%. Colorimetric analysis of the films revealed variations in color at different pH values (pH 2.0–10.0). Fourier-transform infrared (FT-IR) spectra and XRD patterns indicated compatibility among ASKG, SPI, and anthocyanin extracts. In addition, an application test was conducted to establish a correlation between film color change and carp meat spoilage. At storage temperatures of 25 °C and 4 °C, when the meat was totally spoiled, the TVB-N values reached 99.80 ± 2.53 mg/100 g and 58.75 ± 1.49 mg/100 g, and the film’s color changed from red to light brown and from red to yellowish green, respectively. Therefore, this pH-sensitive film could be used as an indicator to monitor the freshness of meat during storage.

Development of Environmentally Friendly and Intelligent Food Packaging Bio-Nanocomposite Films

“…Films containing anthocyanins are generally pH-sensitive: changes in the anthocyanin structure with pH manifest as a change in the film color (Zeng et al, 2022). Figure 4 shows there were no significant color changes in the CH/ PSPS film (control) with pH because no anthocyanin was added to the film; thus, CH was the dominant component of the film, which therefore appeared yellow (Zhao et al, 2023). By contrast, remarkable color variations were observed for the films with added PSPE anthocyanin in various pH buffers.…”

Research Progress on Active Ingredients and Product Development of Lycium ruthenicum Murray

“…Furthermore, a novel pH-sensitive membrane gel incorporating Artemisia Sphaerocephala Krasch (ASKG), Soybean Protein Isolate (SPI), and LRM anthocyanins was developed. This membrane, prepared by impregnating solid ASKG and SPI substrates with anthocyanidin from LRM dissolved in an acidified alcohol solution, serves as an indicator for monitoring meat freshness during storage [77,78].…”