A greener approach towards isolating clove oil from buds of Syzygium aromaticum using microwave radiation

The selection of suitable technique and apposite operating conditions are the key attributes for efficient extraction of phytochemicals from plant materials. Microwave assisted extraction (MAE) was incorporated to isolate essential oil from clove buds and the parameters were optimized using the grey based Taguchi method to maximize the yield of clove oil (Y, % w/w), eugenol content (y, % w/w) and bacterial inhibition. The results of single response analysis and multi-response analysis were compared. It was possible to achieve the best results (Y: 13.11%, w/w; y: 11.93%, w/w; zone of inhibition (ZOI): 24.80 mm) using the optimized conditions of multi response study viz., amount of plant material - 30 g; volume of water - 200 mL; power - 600 W and extraction time - 30 min. The wastes generated during extraction were explored for their utilization as a byproduct or raw material for other processes. Moreover, the performance of MAE was compared with that of hydrodistillation in terms of processing conditions, responses, energy and environmental impact. It was possible to reduce water usage, extraction time, energy requirement and CO2 emission while achieving the improved quantity and quality of essential oil along-with a higher ZOI using the green MAE technique.