Microwave Exposure Sensitive Response of Antioxidant Properties of Nelumbo nucifera rhizome at Various Levels of Extraction and Analysis.

Effect of microwave treatment on phytochemical composition and free radical scavenging capacity of Nelumbo nucifera rhizome was determined. Paste of fresh rhizome and powder were treated with microwave (MW) radiation for different time periods 0, 4, 8, 12, 16, 20 minutes at medium low intensity. Total phenolic content (TPA), Linoleic acid reduction capacity (LARC), β-carotene bleaching assay (BCBA), DPPH radical scavenging capacity and Superoxide radicals scavenging activity (SORSA) was found to be decreased and total antioxidant activity by Phosphomolybdenum assay (TAOA), reducing power (RP) and iron chelation activity (ICA) is increased in response of increased microwave treatment. TPA content of fresh and dry samples ranged from 4.38±0.13 to 4.67±0.14 and 4.35±0.11 to 4.72±0.14 g/100g extract respectively. TAOA and RP (absorbance at 700 nm) content of fresh and dry samples ranged from 1.91±0.33 to 9.08±0.34 and 2.83±0.22 to 8.58±0.34 g/100 extract and from 0.72±0.04 to 1.29±0.02 and 0.73±0.05 to 1.29±0.02 respectively. ICA of fresh and dry samples ranged from 6.51±0.13 to 8.90±0.17 and 6.31±0.11 to 8.99±0.13 g/100 g extract respectively. BCBA values ranged from 4.69±1.02 to 16.19±1.16 and 2.60±1.08 to 15.56±1.41 %. DPPH and SORSA content of fresh and dry samples has significant values. It is therefore concluded that the microwave treatment has a significant effect on the antioxidant properties of N.nucifera rhizome. The data would be useful for the researches concerning with the analysis of effect of microwave treatment on the antioxidant activity of N. nucifera rhizome. [ABSTRACT FROM AUTHOR]