Microwave-assisted extraction of piperine from Piper nigrum

A novel microwave-assisted technique (MAE) for the extraction of piperine from coarsely powdered black pepper (Piper nigrum) was studied. The parameters such as nature of the solvent, microwave energy input, and solid loading were optimized. The mechanism of the enhancement of extraction rates was investigated by microscopic studies of the irradiated material. Studies have revealed that dielectric heating of the polar cellular matrix resulted in remarkable swelling and coalescence of the oil cells and other constituents. The resulting pressure, built-up within the cell, breaks open the cell, releasing the constituents and providing easy access for solvent penetration and subsequent solubilization of piperine and other substances. Because the cell wall is mainly composed of slightly ionic cellulose, there is a marked increase in the dielectric heating rates. Rapid degradation of the cellulosic cell wall occurs, thereby further increasing the permeability of the wall toward solvent penetration. Selective extraction of piperine in nonpolar solvents to the extent of 94% with a purity of 85% has been achieved. The MAE procedure is simple, rapid, and reliable.