Optimization of methanol extraction parameters for total flavonoids from onion processing waste

Abstract

Onion processing generates large amount of solid waste. Due to the high amount of biologically active substances the onion processing residues could be interesting source of value-added functional ingredients. In this study the response surface methodology was applied to explore the possibilities of modelling and optimization of the methanol extraction of total flavonoids from onion processing waste. The extraction temperature, time and solvent concentration were first optimized employing Box-Behnken design and then the extraction efficiency was further assessed through kinetics. The optimal extraction conditions were determined to be 53oC, 66 min and 61% of methanol concentration. Data indicated that predicted (15.54 mgQE g-1 dw) and experimental (15.58±0.03 mgQE g-1 dw) values of total flavonoids were not significant different (p > 0.05). The kinetics and thermodynamic parameters of the extraction process were determined also.