Hazelnut shells, the major byproduct of the hazelnut industry, are rich in potentially health-promoting phenolic compounds. However, limited research has been conducted on techniques, such as ultrasound-assisted extraction for extracting phenolic antioxidants from hazelnut shells. As a result, the levels of phenolics and antioxidant activity of hazelnut shells are not known. In this research, the phenolic compounds in hazelnut shells were extracted by ultrasound-assisted extraction technology using an ultrasonic processor. Various parameters such as solvent type, solvent concentration, biomass to solvent ratio, extraction temperature, ultrasound time, ultrasound intensity, length of the probe tip dipped into the solvent, and duty circle were explored for the extraction of phenolic compounds. From economic viewpoint, the optimal conditions for the phenolic extraction from hazelnut shells were 0.3 g shell in 10 mL 50% (v/v) acetone in water at 50oC, 1698 W/cm2 intensity, and 66.7% duty cycle for 30 min with probe tip length of 20 mm dipped into the extracting solvent from the surface. The maximum extraction achieved under the prescribed optimum conditions was 11.15 mg GAE/g shell. In addition, the total phenolic content, DPPH radical scavenging capacity, and ferric reducing antioxidant power of the hazelnut shell extract under the prescribed optimum conditions were significantly higher than those from conventional extraction using shaking water bath under the same extraction conditions (acetone concentration, biomass to solvent ratio, extraction temperature, and time). The optimum conditions from ultrasound-assisted extraction is expected to improve the productivity of phenolic compounds from hazelnut shells.

Ultrasound-assisted extraction of phenolic compounds from hazelnut shells

249th National Meeting (2015)

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