A Review of Anthocyanin‐Based pH‐Sensitive Composite Films for Food Freshness Monitoring

Abstract

ABSTRACT With the increasing global demand for food safety and quality, pH‐responsive intelligent composite films have become a pivotal innovation in the packaging sector. Anthocyanins, as natural plant pigments, possess excellent biocompatibility and environmental friendliness and exhibit significant colour changes under different pH conditions: appearing red at pH < 3.0, purple at pH 4.0–6.0 and blue‐green at pH > 7.0. This colour difference (ΔE > 3.0) enables anthocyanins to visually reflect changes in the acid–base environment of foods, making them widely applicable in pH‐sensitive films. By combining anthocyanins with polysaccharides, proteins or lipid‐based materials, pH‐responsive intelligent films can be prepared for real‐time monitoring of the freshness of perishable food