**4. Conclusions**

In this study, free anthocyanins and anthocyanin-loaded liposomes were added to carrageenan as the sensor layer of the bi-layer films, respectively, and agar was the outer protective layer. Different ratios of lecithin were used to design the butterfly bean flower anthocyanin extraction into liposomes, and their characterization was investigated. Then the structure, mechanical physical properties (such as TS, EB, and WVP), stability, pH, and ammonia sensitivity of the bi-layer films were individually analyzed with different ratios of lecithin in liposomes. The SEM and FT-IR results indicated that the bi-layer films were satisfactorily prepared via hydrogen bonding interactions. The films with anthocyaninloaded liposomes had significantly higher TS values and lower EB values than that with free anthocyanins. Importantly, the films with liposomes had a positive effect on the stability of the indicator films in high-humidity environments but slightly decreased the pH and ammonia sensitivity. Finally, the application on the shrimp verified that the bi-layer film can be used as an indicator of meat freshness. However, the encapsulation of anthocyanins by liposomes delayed the sensitivity of the film. Therefore, future exploration could focus on a higher sensitivity method based on liposomes.

**Author Contributions:** Writing—original draft and methodology: J.Z. (Junjun Zhang) and Y.Y. Formal analysis and software: J.Z. (Jianing Zhang). Validation: X.H. Investigation, visualization, and funding acquisition: X.Z. and J.S. Data Curation: L.L. and W.S. Formal analysis: Z.L. Writing—review and editing draft: M.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors were funded by the National Key Research and Development Program of China (2022YFD2100603), the Natural Science Foundation of Jiangsu Province (BK20220058), the project supported by the Jiangsu Specially-Appointed Professor Project (202074), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the National Natural Science Foundation of China (32272407), and the Natural Science Foundation of Jiangsu Province (BK20200103, BK20220111).

**Data Availability Statement:** The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.

**Acknowledgments:** The authors gratefully acknowledge the Project of the Faculty of Agricultural Equipment of Jiangsu University. The authors also appreciate the support provided by Chairman Fen XIAO (alumnus of Jiangsu University) of Shenzhen Fenda Technology Co., Ltd.

**Conflicts of Interest:** The author Jiyong Shi is employed by the Yixing Institute of Food and Biotechnology Co., Ltd. (researcher). The Yixing Institute of Food and Biotechnology Co., Ltd. is a joint laboratory of universities. All authors declare no conflicts of interest.
