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.
Highlights
Agricultural and food sectors generated great amount of waste bio-mass
The results indicated that extraction temperature was the most significant linear term variable positive affected the total flavonoids (TF) extraction from onion processing waste (OPW), followed by methanol concentration and extraction time
The results indicated maximum total flavonoids content (TFC) of 15.54 mgQE g-1 d.w., which was achieved at extraction temperature 53oC, extraction time 66 min and 61% methanol concentration
Summary
Agricultural and food sectors generated great amount of waste bio-mass. The bio-economy concept includes the implementation of alternative strategies for the production of high value-added substances. Food waste accounts as a source of valuable nutraceuticals. Significant volume and availability of the bio-waste and their low cost and richness in bio-active substances convert them to a valuable resource for bio-refinery. There have been an increasing number of studies dealing with polyphenol extraction from plant tissue. The extraction of phytochemicals from onion waste is very limited [1, 2]
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