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 μg/mL, antioxidant activity
of 74% at 25 μg/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.