Curcumin: A Multifunctional Molecule for the Detection of Various Adulterants, Pathogens, and Toxins in the Agro-Food Industry.

Food safety and quality are increasingly undermined by adulterants, contaminants, pathogens, toxins, and spoilage processes, necessitating rapid, sensitive, cost-effective, and environmentally sustainable detection systems. Traditional analytical methods typically depend on synthetic dyes, heavy metal salts, strong acids, and resource-intensive processes, limiting sustainability and on-site applicability. In line with green analytical chemistry and clean-label technologies, naturally derived sensing materials have gained increasing attention. Curcumin, a natural polyphenolic compound from Curcuma longa, has emerged as a safe, renewable, low-toxicity, and multifunctional alternative for agro-food safety monitoring. Its pH responsiveness, fluorescence behavior, redox activity, metal-chelation capacity, chemical reactivity, and strong binding affinity enable its function as a ligand, indicator, and active sensing agent. This review critically examines recent advances in curcumin-based detection strategies for food adulterants, pathogens, toxins, microbial spoilage, and quality deterioration, with a focus on its interaction mechanisms, colorimetric and fluorescent indicators, biosensors, smart packaging, and shelf-life monitoring. Additionally, the potential of curcumin-based indicators for detecting pesticide residues, toxic gases, and chemical residues, beyond the food sector, is also discussed. Although curcumin-based sensing systems represent a promising and sustainable approach for advancing next-generation food safety monitoring, further studies are required to improve sensor integration, stability, and selectivity to allow large-scale adoption.