Extraction, biological activities and stability of Hylocereus polyrhizus peel extract as a functional food colorant and nutraceutical

Purpose: To study the biological effects and the stability of H.polyrhizus peel extract as a natural colorant and nutraceutical in foods Methods: Distilled water, 90 % alcohol mixed with citric acid (2 and 4 %) were used for pigment extraction. Betalain content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were determined. Cytotoxic effect against human breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (Hela), human colon adenocarcinoma (HT-29), murine leukemia (P388) and human oral cavity carcinoma (KB) were measured with MTT assay. Then, the effectiveness of different carriers for coating the pigment i.e., lactose, starch and maltodextrin were measured. The thermal and pH stabilities of pigments were determined in samples at temperatures of 50, 70 and 90 degrees C, and at pH values of 2, 7 and 12. Finally, consumer acceptance of cooled jelly containing synthetic dye and betalain pigment was assessed. Results: Distilled water was the best solvent for extraction, producing 59.9 mg/g of betalain, and 42.39 % DPPH radical scavenging activity. The betalain pigment had high antiproliferative effect against P388 cancer, with 77.50 %, cytotoxicity. The best for carriers were 10 % lactose and 10 % matodextrin (p > 0.05). The samples were unstable when adjusted pH 2 and 12 at all temperatures. Cooled jelly containing 1 % artificial dye had the highest sensory score, followed by 2.5 % natural colorant. Conclusion: H. polyrhizus pigment has promising potential for application in food products as a functional food colorant and nutraceutical. However, further studies are required the shelf life of pigment.