Optimization of Aqueous Extraction Method for Natural Dye from Basella alba Linn. Fruits: UV-Vis Analysis and FTIR Characterization

Abstract

Natural dyes are valued for their biodegradability, non-toxic nature, and environmental sustainability. This study optimized an aqueous extraction method for dye obtained from Basella alba Linn. fruits, using water as the solvent, to develop a simple, safe, and cost-effective extraction approach. The extraction time and temperature were optimized based on UV-Vis spectroscopy analysis, while the effect on the dye was evaluated using Fourier Transform Infrared Spectroscopy (FTIR). The dye exhibited a λmax at 542nm, consistent with anthocyanin pigments, particularly malvidin. Absorbance increased with extraction time and temperature, with the highest value (1.56) recorded at 45 minutes and 90°C. The dye showed significant pH-dependent color changes, shifting from red (acidic) to purple and blue (neutral-alkaline). FTIR spectra at different pH values displayed only water-derived O-H and H-O-H bands, attributed to the low concentration of dye compounds resulting from the fruit’s high moisture content (82.5%). Lake pigments prepared using lime displayed poor stability under light exposure. Integrating findings from previous studies, this work addresses a critical gap by defining optimized aqueous extraction conditions for B. alba, thereby supporting future applications in the development of textile, cosmetic, and food colorants.