Infrared‐assisted hydrodistillation as an efficient, promising approach to the extraction of essential oil from Rosmarinus officinalis

Abstract

Herbs and raw plant materials usually contain essential oils that are extractable by a variety of methods. The quality and quantity of essential oils are largely influenced by the method of extraction, some of which have remained unexplored. Demands for environmentally-friendly extractions are increasingly becoming common. The present study used infrared-assisted hydrodistillation (IAHD) as a new extraction method that performs faster than the classical hydrodistillation (HD) method. Here, the essential oil of Rosmarinus officinalis L. (common rosemary) was extracted from the leaves by each of the two methods separately. The essential oils were evaluated in terms of extraction kinetics, antioxidant activity, and chemical composition. Compared with the HD (2.15 AE 0.01 mL/100 g, 210 min), the IAHD generated higher yields (2.17 AE 0.02-2.51 AE 0.04 mL/100 g) over shorter periods (60-120 min), depending on the power of radiation (150-375 W). The IAHD method offered important advantages over HD, such as better maintenance of antioxidant activity in the oil and higher oil quality, e.g. enhanced levels of oxygenated compounds. Thus, it can be introduced as a promising method because of its higher extraction output and simple extraction procedure. Infrared radiation extraction can be used as a valuable substitute for classical hydrodistillation when aiming to extract essential oil from R. officinalis and other aromatic plants.