THE DRYING KINETICS OF MINT (MENTHA-SPICATA HUDS)

The annual consumption of medicinal and aromatic plants in France is of the order of 30 000 tonnes and is worth about one billion (10(9)) francs. Domestic production accounts for a small share (10%) and can be increased only by improving the quality of the starting material and finished product (in particular, the color). The present work examines the effect of drying conditions on drying kinetics of mint (Mentha spicata Huds.). Several parameters were studied, including humidity, drying air temperature and velocity, whether or not the leaves were blanched before treatment, as well as temperature changes during drying. The results verified, with good reproducibility, that temperature is the main factor in controlling the rate of drying, and that when blanching is limited to 15 s, drying times were divided by 5. This facilitated a study of the dynamic behavior of the dryer.