Variation of the Chemical Composition of Essential Oil of<i>Mentha piperita</i>L. during the Growing Time

Abstract

Abstract This study was conducted over a period of three years. A marked inversion of the menthol/menthone ratio was observed according to harvesting time. The late blooming period gave oils rich in menthol. A second harvest gave a high-quality oil and increased overall yield. Pre-drying did not affect the chemical composition of the oil obtained but allowed larger amounts of plant material to be distilled.