Extraction optimization and characterization of water soluble red purple pigment from floral bracts of Bougainvillea glabra

Recently, natural dyes and pigments gain more importance in food and textile industries because of their non toxic and eco friendly characteristics. Bougainvillea glabra floral bracts are rich in betalain pigments which can be used as a dye in sensitized solar cells, medicinal and food applications. The aim of this study was to optimize the natural pigment extraction from the floral bracts by response surface methodology. Central composite design (CCD) of response surface methodology (RSM) was applied to evaluate the optimal conditions of three process variables namely mass of floral bracts (g), extraction time (h) and temperature (°C) studied at five levels. Mass of bracts and extraction time were found statistically significant in the process and correlation coefficient (R2) value of 0.96 showed that model was well fitted with the experimental values. The optimum process conditions were found to be mass of floral bracts: 3 g, contact time: 6 h and extraction temperature: 22.5 °C with maximum absorbance of 9.18. Response surface methodology was performed well to identify the optimal levels of extraction process variables and the validation of predicted model was fitted 99.76% with the experimental results conducted at the optimum conditions. Fourier Transform Infrared Spectroscopy was also confirmed the presence of betalain pigment by identifying the major functional groups.