Response Surface Optimization of Flavonoids Extraction, Beta Carotene Bleaching and Lipid-reducing Capacity of Nelumbo nucifera Seed Kernel Extracts

Aim/Background: The safe and complete extraction of flavonoids from plant material influenced by various factors has been ever challenging for the researchers. The study was planned to optimize the extraction of flavonoids from nucifera seeds and their antioxidant activity. Materials and Methods: The flavonoids were extracted at various combination of four extraction factors including particle size of the flour in terms of sieve number (SN), microwave treatment time (MTT), concentration of methanol as extracting solvent (CM) and soaking time (ST) each at five levels using a response surface central composite design. The extracts were analyzed for total flavonoid content (TFC), β-carotene bleaching capacity (BCBC) and linoleic acid reduction capacity (LARC). Results: A statistically significant (p<0.05) effect of the extraction factors was observed on TFC, BCBC and LARC. A linear positive effect of MTT and CM and a quadratic positive effect of SN and CM was observed on TFC. The BCBC and LARC were also found to be increased linearly by increasing the SN, MTT and CM. The levels of SN, MTT, CM and ST to obtain optimal value of TFC (1.468 g/100g dry weight) were found to be 132.94 meshes/inch, 1.85 min, 99.87% and 3.06 h respectively. Conclusion: The increase in TFC by increasing the MTT and CM may be attributed to the microwaveassisted release of bound flavonoids and their amphiphilic structure. The data would be a valuable guideline for the researchers regarding the extraction of plant flavonoids and their antioxidant potential.