Attapulgite/nanofiber composite aerogels-based 3D porous colorimetric sensor for rapid and sensitive freshness monitoring

This study presents the development and optimization of a novel colorimetric sensor for rapid and sensitive detection of freshness in aquatic products and pork. Attapulgite and polyimide nanofiber composite aerogels loaded with anthocyanin (AC@ATP/PI NFAs) were prepared and systematically characterized, revealing a 3D multi-level pore structure with high porosity and large specific surface area. The sensor demonstrated a rapid response, with color changes quantitatively measured within 30 seconds of exposure to volatile amines produced during spoilage. Sensitivity analysis indicated excellent performance, with a limit of detection and limit of quantification for trimethylamine at 2.60 ppb and 7.89 ppb, respectively, and a linear range of 10–1000 ppb with determination coefficient of 0.9983. The sensor exhibited remarkable stability, maintaining sensing ability even after 120 days of storage. Importantly, the feasibility and accuracy of established method were confirmed through comparison with the national standard method (automatic Kjeldahl nitrogen determination). This research developed AC@ATP/PI NFAs as a practical, portable, and reliable naked-eye-based colorimetric sensor for freshness detection, providing a promising strategy for food quality assessment.