engleski

Polyphenolic compounds in olive (Olea europea) leaf extracts upon used method

Olive tree (Olea europaea) leaves are agricultural and industrial by-product accumulated by olive trees pruning, olive fruit harvesting and olive oil production. They are considered as cheap, renewable and abundant source of polyphenols, compounds know to possess antioxidative, antiinflammatory, antimicrobial and anti-viral properties. Therefore, polyphenols extraction could represent an interesting mean of increasing olive leaves value. In the present study, high hydrostatic pressure assisted extraction (HHPE) and conventional extraction (CE) of polyphenols from olive tree leaves were investigated. This study aimed to examine the effect of HHPE parameters such as pressure (300, 500 MPa), time (1, 5.5, 10 min) and sample mass (1.5, 3 g), and CE parameters such as number of cycles (2, 3), time (10, 20, 30 min) and sample mass (1.5, 3 g) on concentration of each identified compound as well as to compare those two techniques. HPLC analysis showed that composition of identified polyphenols remained unchanged for both techniques, including six compounds: oleuropein, verbascoside, hydroxytyrosol, rutin, caffeic acid and chlorogenic acid. The most abundant compound was oleuropein with the average concentration of 69.23 mg/g d.w. by HHPE and 67.05 mg/g d.w. by CE. Concentrations of all identified compounds were very similar for both extraction techniques but there was significant reduction of time when using HHPE (1 and 5.5 min) compared to CE (2 cycles of 20 or 30 min). Higher concentration of most of the compounds in both techniques was achieved with 1.5 g of sample in 100 mL of solvent (50 % ethanol). Sample mass played more important role then pressure and time in HHPE and number of cycles and time in CE. In HHPE oleuropein and verbascoside concentrations were significantly higher at 500 MPa, while rutin and chlorogenic acid concentrations were significantly higher at 300 MPa. Along with being safe, more environmentally friendly, less labor intensive and consuming less energy, results of this study showed that HHPE is suitable for fast extraction of polyphenols from olive leaves.

olive leaf, high hydrostatic pressure assisted extraction, conventional extraction, polyphenols, oleuropein

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