The pH indicator film based on pomelo rind waste pectin /sodium alginate-purple corn cob extracts combined with deep learning for salmon freshness visualization and detection - Shuyang Sun; Yibing Ding; Chunjun Chen; Chanchan Sun; Xiulian Li; Hansheng Gong; Xiangquan Zeng; Handong Zhao; Jinwang Li; Xinguang Fan (Food Control, 2026)