Rose hip (Rosa canina L.) oil obtained from waste hip seeds by different extraction methods

From the rose hip seed, which is generally a waste material, valuable oil can be obtained for medicinal use. Various extraction methods have been compared: traditional solvent extraction with ultrasound-, microwave-, sub- and supercritical fluid extraction (SFE). Unsaturated fatty acid (UFA: oleic-, linoleic- and linolenic acid; 16.25-22.11%, 35.94-54.75%, 20.29-26.48%) and polyunsaturated fatty acid (PUFA:linoleic- and linolenic acid) content were over 90% and 60% in the recovered oils. The oils contained different amounts of metals. The concentration of some metals, particularly iron in microwave oil (27.11 microg g(-1)) is undesirable from the aspect of stability. By traditional solvent extraction, oil was obtained in 4.85 wt/wt%. Subcritical FE appeared to be the best method for the recovery of rose hip oil with highest oil yield (6.68 wt/wt%), carotene- (145.3 microg g(-1)) and linoleic acid content (54.75%). Supercritical FE without organic solvent is suitable for mild recovery of oil. The oil was rich in UFA and PUFA (92.7% and 76.25%) and contained the lowest amount of carotene and pheophytin (36.3 and 45.8 microg g(-1)). Oil yield in most new extraction methods (microwave extraction, super- and subcritical FE) was higher than in the case of traditional Soxhlet extraction. The main benefit of supercritical FE with CO2 is the solvent free oil while in the case of other extractions evaporation of the solvent is needed. Although the content of bioactive compounds in oils was different, all oils may be appropriate for medicinal use.