The use of medicinal plants and their derivatives for the treatment of diseases is an ancient practice. Currently, there is a growing demand for natural products, not only medicines, but also food and cosmetics. The peppermint (Mentha x piperita L.), in addition to being a medicinal plant, can be used for obtaining flavorings, spices and tea infusions. The drying process is necessary to increase the shelf life of the product and to facilitatg itr transport, handling and storage. For peppermint derivatives of sufficient quality, it is necessary studies on the pre- and post-harvest. The objective of this study is to identify the temperature and air velocity that minimizs the degradation of the color of the leaves with higher oil yield. PepperMint leaves were harvested manually from 7:15 to 8:00 a.m. and dried in trays in a completely randomized design in a 2 x 5 factorial design, being two air velocities (0.3 and 0.5 m.s-1) and five temperatures (30, 40, 50, 60 and 70 °C) with three replications. The dried material was analyzed for color using a colorimeter with the CIELab scale system based on a color within the DIN 6174 standards (1979). The quantification of the essential oil was performed by hydrodistillation in a Clevenger-type apparatus. The analyzes were performed in triplicate. Ws observed that the yield of essential oil of the dry leaves was highertwhan compared to the yield presented by the fresh leaves. This effect was attributed to the fact that the lower water content in the leaves enables the vapor stream generated in the extractor to promots a more effective drag of the volatile oilcompounds stored in the cells; however, a temperature exceeding 50 °C promotes a reduction in yield. The color of the leaves submitted to drying is different from the color of fresh leaves. According to the DIN 6174 standard, the color of the leaves subjected to drying at the temperature up to 40 °C is "easily distinguishable" and, for the leaves submitted to drying at temperatures higher than 50 °C, the differentiation is "too large". We conclude that to get the maximum yield of essential oil and minimal color degradation, drying should be carried out at a temperature of up to 50 °C. The rate of the drying processes in the rangeofrom 0.3 to 0.5 m.s-1 did not affect the parameters evaluated.
color; essential oil; medicinal plant
