Bilayer TPU films integrating pH-responsive bromocresol purple–fluorescein indicators and carvacrol/tea tree oil-loaded HKUST-1@alkaline lignin: Visualization, controlled release, and meat preservation - Liuzi Du; Xiaodong Zhai; Xinyang Han; Ke Zhang; Junjun Zhang; Xiaobo Zou; Zhihua Li; Zhikun Yang; Quancai Sun; Ye Peng; Xiaowei Huang (Food Research International, 2026)