Optimization of extraction yield of carthamine and safflower yellow pigments from safflower (Carthamus tinctorious L.) under different treatments and solvent systems

Safflower (Carthamus tinctorious L.) florets contain valuable red and yellow pigments and are used in food, textile dying, and pharmaceutical industries. Red carthamine pigment is formed from a yellow precursor, precarthamine, through an oxidation reaction at the end of flowers' maturation stage. The present study was conducted to find out the most effective procedure for extraction and purification of yellow and red pigments from safflower florets.

Two different experiments were designed to assess the suitability of oxidant reagents (KMnO4 and H2O2) on the reddening of florets and different alkaline and organic solutions were used as the solvents (KNO3, Na2CO3, ethanol/hexane, methanol, and NaOH) in order to extract and purify the pigments. All obtained pigments were characterized chromatographically and spectrophotometrically for calculating the yield and evaluating purity of the extracted materials.

The results showed that KMnO4 and H2O2 treatments were significantly effective for increasing carthamine yield from safflower; but KMnO4 decreased the amount of yellow pigment extraction during the washing process of treated petals before extraction. Ethanol/hexane demonstrated to be effective in the extraction of yellow pigments, but it was not a good solvent for carthamine extraction. Except for the degassed bicarbonate which showed a high pigment yield, the other three solvents especially KNO3 did not appear to be of practical use for red pigment preparation.

The present results showed that pretreatment of petals with hydrogen peroxide and then extracting by degassed solvents resulted in higher yield of red carthamine pigment, and also using reconditioned cellulose or cotton, instead of fresh cellulose, would reduce the cost.