Intensified extraction of valuable compounds from clove buds using ultrasound assisted hydrotropic extraction

Abstract

Essential oil and the prime compounds (eugenol and eugenol acetate) present in clove have numerous biological potentials and usages leading to the commercial importance. A symbiotic effect between sonication and the hydrotropic solution was investigated for selective extraction of valuable compounds, namely eugenol and eugenol acetate from the clove buds. The combined approach was aimed to lessen extraction time while maintaining selectivity by improving the mass transfer characteristics. Solubility study has assisted in selecting a suitable hydrotrope i.e. sodium cumene sulfonate for extraction. Using parametric study and optimization by central composite design, optimum conditions have been achieved as 38 °C temperature, 1.04 M NaCuS concentration, 8.2 g solid loading, 158 W sonication power and 30 min of extraction time with the extraction yield of 20.04 %. The prediction of the yield using models developed by the central composite design and an artificial neural network was within 5 % of the actual value, thereby providing aid for estimating the yield without experimenting. It was possible to reuse the hydrotropic solution after extraction without affecting the yield. The impact of sonication on clove buds has been assessed using the scanning electron microscope. In comparison with extraction using an open reflux system, ultrasound assisted hydrotropic extraction has tendered an eco-friendly and sustainable solution for isolating target compounds from clove buds.