Publication: Microwave drying kinetics, hypericin content, effective moisture diffusivity and activation energy of hypericum perforatum L.
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Date
2016-02-23
Authors
Alibaş, İlknur
Kaçar, Oya
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Volume Title
Publisher
Taylor & Francis
Abstract
St. John's Wort (Hypericum perforatum L.) flowers with 25 g weight and 2.92 moisture on dry basis were dried in microwave oven using 1000, 850, 750, 650, 500, 350, 160 and 90 W microwave output powers and natural drying as a control, until the moisture fell down to 0.07 on dry basis. Drying processes were completed between 2 and 36 min depending on the microwave powers. The values measured were compared with the obtained data using Page's semi-empirical equations. By increasing the microwave output powers, the effective moisture diffusivity values ranged from 2.70 10-09m2s-1 to 1.54 10-10 m2 s-1. Energy consumption remained constant within the power range of 1000-650 W, whereas 500 and 90 W resulted in significant increase in energy consumption. Mean hypericin content values between natural drying and microwave drying with different microwave power varied between 0.241-0.280 %. Maximum hypericin content was observed natural drying (0.280 %), microwave drying of 850 W (0.278 %) and 750 W (0.277 %). The best quality in terms of hypericin content (0.278 %) was obtained in the drying period with 850 W. Microwave power of 850 W for 150 s which were produced the least energy consumption was only 0.06 kWh.
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Keywords
Plant sciences, Effective moisture diffusivity, Activation energy, St. John's wort, Hypericin, Microwave drying, St-Johns-wort, Leaves, Tolerability, Hyperforin, Mechanism, Stress, Plants
Citation
Alibaş, İ. ve Kaçar, O. (2016). "Microwave drying kinetics, hypericin content, effective moisture diffusivity and activation energy of hypericum perforatum L.". Journal of Essential Oil Bearing Plants, 19(2), 454-465.