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An intelligent pH indicator film was prepared by mixing cassava starch, polyvinyl alcohol (PVA), and natural anthocyanin extracted from grape skin (GSE) and mangosteen rind (MRE). The effects of GSE and MRE on the physical, structural, and pH‐sensing performance of composite films were studied. Scanning electron microscope results showed that the microstructure of film had little difference when the anthocyanin extracts were incorporated into the polymer matrix. A significant (p <.05) effect of GSE and MRE on the tensile strength, moisture content, and elongation at the break of the films were observed. The two indicator films could respond to different pH values and showed good color stability. During the storage of pork, the cassava starch/PVA/GSE film showed a visible color variation from pink, blue, purple to yellow, while the cassava starch/PVA/MRE film showed color variation from light yellow, bright yellow, green to dark green. The result indicated that the two films could be used to monitor pork freshness for intelligent pH indicator packaging. Novelty impact statement: Using fruit waste to extract anthocyanin.Indicator film has good color stability, and the color change was obvious at different pH values.The color of the indicator film changed obviously in the process of indicating the freshness of pork. [ABSTRACT FROM AUTHOR]

A novel antimicrobial packaging system was prepared by incorporating TiO2 or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO2, and PLA/TiO2 + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO2 and PLA/TiO2+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO2 or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days. Practical applications Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5-7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO2 or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation. [ABSTRACT FROM AUTHOR]