Evaluation of in vitro Antioxidant Potential of Red Amaranth (Amaranthus tricolor) and Green Amaranth (Amaranthus viridis) leaves extracted at different temperatures and pH

Red Amaranth (Amaranthus tricolor) and green Amaranth (Amaranthus viridis) are two very important leafy vegetables consumed in most parts of India, not only for their flavours, but also for their pharmacological activities. The cooking processes are different in the different part of this country, and therefore, the present study was designed to analyze their in vitro antioxidant profile before and after thermal processing in water at different temperatures and pH. Thermal processing was done at 60C, 80C and 100C, whereas pH 5.0 and 9.0 were also used for extraction. The assays performed included DPPH radical decolorization assay, reducing power assay and assay for total phenolic contents. It was observed that the antioxidant activities and total phenolic content improved in case of the two vegetables after thermal processing and pH dependent extraction. Phenolic contents were nearly doubled after extraction at 100C and at pH 9.0, separately, probably due to better solublization of the antioxidants in hot water and different acid-base conditions. Improvement in the total phenolic contents substantiated the radical scavenging abilities of the two subject vegetables after aqueous extraction.