Evaluation of solar dried thyme (Thymus vulgaris Linne) herbs

Thyme (Thymus vulgaris Linne) herbs can be dried at about 50 degrees C reached an equilibrium moisture content after 12 h and 9.5 h using the wire basket solar dryer and oven drying method respectively. The initial moisture content (wet wt. basis), (final moisture content, dry wt. basis (dwb)) determined by the Dean-Stark toluene method, oven and microwave were 75.15% (10.0%), 75.12% (11.85%) and 72.31% (12.50%) respectively. Paired t-test (alpha = 0.05, 10 degrees of freedom) showed no significant difference between the Dean-Stark toluene and the oven methods, but a significant difference between these two methods and the microwave method. The % essential oils extracted after drying by the oven and the wire basket solar methods were 0.5 and 0.6% (per 100 g dwb) respectively. The % oleoresin and ash content were 27% for both drying methods and 1.60, 2.03 and 2.25% for the fresh, oven dried and the wire basket solar dried herb respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.