Evaluation of Antioxidant Activity and Polyphenolic Content of Commonly Consumed Egg Plant Varieties and Spinach Varieties in Sri Lanka

Aims: To evaluate the antioxidant capacity and the polyphenolic content of commonly consumed egg plant varieties and spinach varieties in Sri Lanka, in order to screen the potential for utilizing them in developing of functional food products.

Study Design: Complete randomized design was performed.

Place and Duration of Study: Department of Food Science & Technology, Faculty of Livestock, Fisheries & Nutrition, Wayamba University of Sri Lanka, between September 2020 and October 2020.

Methodology: Locally available, commonly consumed eggplant varieties Solanum torvum, Solanum macrocarpon, Solanum melongena BW 11, Solanum melongena and two spinach varieties Basella alba and Talinum paniculatum were collected, freeze dried & powdered. Methanolic extracts were prepared using 80% methanol.Total Antioxidant capacity (TAC), DPPH radical scavenging activity, Reducing power assay, Total Phenolic Content (TPC) and Total Flavonoid Content of fresh methanolic extracts were measured.

Results: S. torvum, S. macrocarpon, S. melongena BW 11, S. melongena showed more or less similar but remarkable DPPH radical inhibition activity ranging from 92.49 to 93.02%. TAC results of tested eggplant varieties ranged from 3.02to 8.98 mg AAE / g dw. From the two tested spinach varieties B. alba leaf extract had higher antioxidant activity but lower flavonoid content than T. paniculatum leaf extract. TPC of methanolic extractions of all tested vegetable sample was within the range of 2.49 to 670.00 µg GAE / g dw. There was a significant difference between the recorded TPC for all the tested samples and S. macrocarpon and two varieties of S. melongena showed much lower TPC when compared to TPC of S. torvum.

Conclusion: These are considerable sources of polyphenols and are having a remarkable antioxidant activity. The potential of them to be utilized in functional food industry is high and yet to be investigated.