Optimization of solid–liquid extraction of antioxidants and saccharides from black mulberry fruit by response surface methodology

The aim of this study was to examine the influence of solvent composition (ethanol/water, 40–80% (v/v)), temperature (40–80 deg C) and time (20–60 min) on the extraction yield of phenolic compounds, flavonoids, saccharides and antioxidant activity of black mulberry (Morus nigra L.) fruit. Experimental values of total phenolic content were in the range from 15.38 g to 18.43 g of chlorogenic acid equivalents per kilogram of dry extract, and total flavonoids in the range from 7.74 g to 12.33 g of rutin eqivalents per kilogram of dry extract. Antioxidant activity expressed as IC50 value was in the range from 0.02 g to 0.04 g of mulberry extract per litre. The saccharide contents were in the range from 465.5 g to 502.2 g per kilogram of dry extract. Response surface methodology was used to determine the optimum extraction conditions and to investigate the effect of different variables on the properties of mulberry fruit extract. Optimal conditions within the experimental range of the studied variables were: solvent composition 58.7%, temperature 58.1 deg C and extraction time 46.9 min. The experimental values agreed with those predicted, thus indicating suitability of response surface methodology for optimizing the extraction conditions.