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Use of microwave radiation in extraction of natural products is increasing in an exponential manner because of its inherent greener features. The extraction of essential oil from the leaves of lemongrass was carried out using microwave radiation and compared with hydrodistillation. The process was optimized using the Taguchi method, and the highest yield was obtained at a 200 mL volume of water, 30 min of rehydration time, and 45 min of extraction time. The extraction time was found to be the most influential parameter affecting the process. A data fit for kinetic desorption models was carried out. The biological activities of the lemongrass oil were also assessed. A microscopic study was performed to understand the extraction mechanism. A comparison showed that microwave-assisted extraction is a better alternative to hydrodistillation in terms of yield, extraction time, biological activity, energy efficiency and environmental friendliness.

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A novel technique for the extraction of citral from the leaves of Cymbopogon flexuosus (Steud.) Wats. using hydrotropic solutions (sodium salicylate and sodium cumene sulfonate) was investigated. The yield of citral was dependent on the concentration of hydrotrope, solid loading, temperature, and size of the plant material. Using the Taguchi method, the extraction was optimized, and both the hydrotropes gave the highest yield of citral at a concentration of 1.75 M, 5% solid loading, a temperature of 30 °C, and a size of 0.25 mm of the plant material. Sodium salicylate gave a better extraction yield of citral than sodium cumene sulfonate. The microscopic analysis of plant leaves provided insight into the extraction mechanism. A kinetic study was carried out to check the extraction efficiency for both the hydrotropes. The hydrotropic solution was successfully recycled. Using hydrotropic extraction, citral could be extracted under normal operating conditions, and the use of traditional organic solvents could be eliminated. As a simple and environmentally friendly technique, hydrotropic extraction could be utilized for the extraction of bioactive compounds from plants.

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