engleski

Solid-Liquid Extraction of Total Polyphenols and Proanthocyanidins from Solid Residue of Grape Seed after Supercritical Fluid Extraction of Oils

Grape seed are a waste byproduct obtained after wine or juice making and present a good source of functional compounds, such as phenolic compounds. Supercritical fluid extraction (SCFE) with carbon dioxide is a powerful technique for extraction of active compounds from natural sources. In this work grape seed oil extracts that reached by SCFE under different conditions (300 and 450 bar ; 40 and 60°C) were poor with phenolic compounds. So, the phenolic compounds were extracted from solid grape seed residue (four different samples) after SCFE and the influence of used SCFE regime on their extractability by solid- liquid extraction using 70% of aqueous ethanol was studied. The total phenolic content (TPC) in extract was determined by spectrophotometric Folin Ciocalteau method at 765 nm. The proanthocyanidins (PAC) were determined by spectrophotometric method based on acid hydrolysis and formation of red colour at 540 nm. Antioxidant activity of grape seed extract was evaluated using DPPH· radical scavenging method. All applied SCFE regimes had the positive effect on TPC and PAC in ethanol extract from solid residue in addition to raw material before SCFE. That was detected as increase yield of above mentioned compounds in solid-liquid extract for 6.63% and 17.74% in average, respectively. The results of statistical analysis were showed significant influence of grape seed sort and pressure, as well as their interaction on extractability of phenolic compounds. The assessment of the antioxidant activity showed there is a very strong correlation with TPC (R=0, 899) while correlation with PAC was not significant.

supercritical fluid extraction; solid-liquid extraction; 70% of aqueous ethanol; phenolic compound; antioxidant activity

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