The utilization of natural pigments from agricultural crops via fermentation as functional food colorants: a review 

Growing consumer awareness regarding food safety and health has intensified the demand for natural alternatives to synthetic food colorants, which are associated with potential adverse health effects and strict regulatory limitations. Tropical agricultural commodities offer abundant and diverse sources of natural pigments, including anthocyanins, carotenoids, chlorophylls, and betalains, which also exhibit functional bioactivities such as antioxidant and antimicrobial properties. However, challenges related to pigment stability, bioavailability, and efficient utilization of agro-industrial waste remain significant. This review aims to evaluate the potential of natural pigments derived from tropical agricultural commodities and their enhancement through fermentation processes for application as functional food colorants. The study was conducted through a comprehensive literature review of recent scientific publications focusing on pigment classification, sources, biochemical characteristics, and fermentation-based improvement strategies. The findings indicate that fermentation using microorganisms such as bacteria, yeasts, and molds plays a crucial role in modifying pigment structure, enhancing stability under various environmental conditions, and increasing biological activity through enzymatic bioconversion. Furthermore, the utilization of tropical agro-waste materials, including fruit peels and processing residues, provides an opportunity for sustainable pigment production while supporting waste valorization. Fermentation also contributes to improved pigment extractability and functionality, making it suitable for incorporation into food systems. Overall, the integration of tropical agricultural resources with fermentation technology presents a promising approach to develop safe, sustainable, and functional natural food colorants. Future research is needed to optimize fermentation conditions and scale up production processes for industrial applications.