engleski

The effect of solvent and temperature on extraction yield of phenolic compounds from soybeans, antioxidant activity and colour of extracts

In this study the influence of solvent (50, 60, 70 and 80% ethanol) and extraction temperature (25, 40, 50, 60, 70, and 80 °C) on the extraction yield of total phenolics and total flavonoids from organic soybeans were investigated. The total phenolic content (TPC) in soybean extract was determined spectrophotometrically by Folin-Ciocalteu micro method at 765 nm and results were expressed as gallic acid equivalents. The content of total flavonoids (TFC) was measured also spectrophotometrically using the aluminium chloride colorimetric assay at 510 nm with (+)-catechin as standard. Antioxidant activity (AA) of soybean extracts was evaluated using DPPH• radical scavenging method. CIE L*a*b* system was used for determination of colour parameters of extracts obtained under extraction regime. The results showed the statistically significant influence of solvent and temperature on extraction of phenolic compounds. The best extraction yield of phenolic compounds was obtained by 50% ethanol at 80 °C (TPC: 4.5 mgGAE/gdb ; TFC: 2.56 mgCE/gdb). Weak correlations (ρ ≤ 0.298) were found between antioxidant activity of extracts and phenolic compounds. Furthermore, the phenolic content and total color change of extracts are not in correlation.

extraction; solvent; temperature; soybeans; total phenolics; total flavonoids; antioxidant activity; colour

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