DEVELOPMENT AND CHARACTERIZATION OF VALUE-ADDED FOOD COLOURANT DERIVED FROM SOLUBLE DIETARY FIBER OF POMEGRANATE PEEL AND ONION PEEL

Objective: This research focuses on effective global food waste management strategies while exploring the sustainable use of agricultural waste through the extraction of soluble dietary fiber (SDF) from onion peels (O-SDF) and pomegranate peels (P-SDF) to produce a natural food colourant with added value. Methods: Pomegranate and onion peels were harvested and pre-processed before being subjected to an alkali extraction method to extract SDF. The research employed FT-IR spectroscopy, in conjunction with evaluations of water and oil holding capacity, and assessments of total phenol, flavonoid, and tannin content, as well as DPPH radical scavenging activity, anthocyanin content analysis, and color measurements, to examine the extracted SDF. Results: The peel of pomegranates allowed the isolation of 3-4 g of SDF, but onion peels yielded only 1-2 g of SDF. The SDF derived from onion peel exhibited greater phenol content of 140.32 mg GAE/100g and flavonoid and tannin levels of 62.41 mg RE/100g and 54.67 mg TAE/100g, respectively, compared to pomegranate peel SDF, while also demonstrating superior water holding capacity at 2.95 g/g. Onion peel SDF demonstrated an IC50 value of 778.81 µg/ml, while pomegranate exhibited an IC50 value of 390.62 µg/ml for DPPH radical scavenging activity. The colour analysis revealed that both samples exhibited bright yellow colours along with identical chroma values. Conclusion: The research demonstrates potential applications for repurposing fruit and vegetable waste into natural food colourants that exhibit potent antioxidant properties. This approach enables the creation of eco-friendly food additives by converting agricultural waste into high-value products that support the circular bioeconomy and sustainable waste management systems.