A Comparative Study on Potential Antioxidants and Antioxidant Activity in Raw and Cooked Selected Locally Grown Legumes in Sri Lanka

Legumes are important crop species belonging to the family Fabaceae and constitute a significant part in the diet of Sri Lankans, as a meat substitute. The present study evaluated antioxidants and their activity in locally grown legume varieties for potential utilization as health foods. Twelve legume varieties grown in Complete Randomized Block Design (CRBD) were used for screening purpose. Results were statistically analysed using Univariate General Linear Model (SPSS Version 20) followed by mean separation Tukey HSD test. The Total Phenolics Content (TPC) of raw and cooked form of legume varieties ranged from 0.84 ± 0.04 (MICP 1) to 4.34 ± 0.15 mg (GAE)/g (ANKCP 2) and 0.30 ± 0.04 (MICP 1) to 3.71 ± 0.12 mg (GAE) /g (Dhawala) whereas Total Flavonoids Content (TFC) ranged from 0.88 ± 0.03 (ANK-Black) to 2.19 ± 0.04 mg (QE)/g (Waruni) and 0.62 ± 0.04 (Waruni) to 8.33 ± 0.16 mg (QE)/g (Dhawala) respectively. TPC and TFC were significantly differed (p < 0.05) among the varieties as well as raw and cooked form in each variety.

The significant highest (p<0.05) antioxidant activity in terms of DPPH was shown in both forms of raw and cooked in dark seed coat coloured varieties of ANK-Brown (4.95± 0.42 and 2.18± 0.45 (TE) / g ; dark brown) ANK-Black (4.11± 0.41and 3.17± 0.60 (TE) / g ; black) and Waruni (3.38± 0.18 and 1.51± 0.13 (TE) / g ; purple) respectively while the significant (p<0.05) highest ABTS and FRAP were shown in the same varieties in raw form only. Similarly, the highest results for activity for ABTS (11.74 ± 0.26 (TE) / g) and FRAP (0.32 ± 0.02 (TE) / g) were found in cooked form of variety Dhawala. Results demonstrated the varietal identification of ANK-Brown, ANK-Black, Waruni and Dhawala with a high potential in developing functional foods.