Evaluation of a simple and promising method for extraction of antioxidants from sea buckthorn (Hippophae rhamnoides L.) berries: Pressurised solvent-free microwave assisted extraction

The pressurised solvent-free microwave assisted extraction (PSFME) technique has been developed and optimised for extraction of antioxidants from Hippophae rhamnoides L. berries using a two-level full factorial design. The effects of factors (extraction time, irradiation power, number of cycles) and their first order interactions were evaluated from antioxidant activity of extracts using the 2,2'-diphenyl-1-picrylhydrazil (DPPH) free radical scavenging method, the ferric reducing ability of plasma (FRAP) assay, and the estimation of total phenolic content using the Folin-Ciocalteu method. The best extraction conditions were obtained, in a laboratory scale extractor of 50 mL filled with 4 g fresh berries, using a 1000 W microwave power applied during 50 s and repeated five cycles. PSFME was then compared to other common extraction techniques such as pressing, maceration and pressurised liquid extraction. It is appeared that PSFME leads to the most active and richest extract in phenolic content including molecules such as quercetin and isorhamnetin not extracted with other techniques. Furthermore PSFME respect green chemistry, it is rapid, cheap and does not need sample preparation and/or evaporation step. (C) 2010 Elsevier Ltd. All rights reserved.