Separation of curcuminoids enriched fraction from spent turmeric oleoresin and its antioxidant potential

The rhizomes of turmeric are processed to obtain oleoresin and subsequently curcuminoids are isolated. The mother liquor, after partial isolation of curcuminoids, known as spent turmeric oleoresin (STO), is considered as industrial waste. Curcuminoids enriched spent turmeric oleoresin (CSTO) is prepared by removal of nonantioxidant constituents, and investigated for its antioxidant potential using in vitro methods, and also the total curcuminoids and phenolic contents were determined. CSTO has a total phenolic content of 267.27 +/- 5.75 mg GAE/g that is almost double the amount present in STO (118.3 +/- 3.0 mg GAE/g). The total amount of curcuminoids in CSTO is found to be 39 +/- 1.2%, whereas STO had 15 +/- 2.0%. CSTO possessed radical scavenging activity of 84% at 50 microg/mL, antioxidant activity of 74% at 25 microg/mL, high antioxidant capacity, and moderate total reducing power. These results provide scope for utilization of CSTO/STO as natural antioxidant/preservative as well as colorant in various foods.