Synergetic effect of ultrasound and hydrodistillation for extraction of patchouli oil: Screening, optimization and comparison

Abstract

Patchouli oil is highly recommended in fragrance and cosmetic industries. Patchouli alcohol is the main component as well as the prime reason for the classical aroma of the oil. An intensified concept of aiding hydrodistillation with sonication, a green concept, has been incorporated to maximize the yield of patchouli oil. With the help of Taguchi method, the screening of extraction parameters, viz., extraction time, solid loading, particle size, heating mantle power, sonication amplitude and pulse ratio was carried out while optimization was accomplished by Box-Behnken design. The highest yield (2.05%, w/w) was acquired under optimum conditions, i.e., 30% amplitude, 500 W power and 20 g solid loading. A comparative study of different techniques as well as parts of plant suggested sonohydrodistillation to be the suitable option for isolating the oil from the leaves of patchouli. GC–MS has shown the oil to be a combination of number of sesquiterpenes hydrocarbons as well as oxygenated compounds. The morphological changes in the plant material were studied using scanning electron microscope. Eventually, sonohydrodistillation has reduced the extraction time and improved the yield while maintaining the quality of the oil, hence a symbiotic effect of hydrodistillation with ultrasound was achieved. Furthermore, an evaluation of the electricity consumption and the environmental impact of sonohydrodistillation method for the extraction of the patchouli oil from the patchouli leaves indicated that the method can be considered as a green technique.