The effect of drying methods on the concentration of compounds in sage and thyme
2017
Sadowska, Urszula | Kopeć, Aneta | Kourimska, Lenka | Zarubova, Lena | Klouček, Pavel
The aim of the study was to evaluate effects of three drying methods of thyme and sage. Collected herbs were dried: under natural conditions, at temperature of 35 °C/40 °C, and freeze‐dried. The material was tested on the essential oil content using Clevenger apparatus; chemical composition was determined using gas chromatography coupled to mass spectrometry (GC‐MS). Antioxidant activity was analyzed by determining the ability to neutralize the free radical 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) with simultaneous measurement of phenolic compounds content. Most oils were isolated from herbs dried at 35 °C, but the largest amount of thymol in thyme and thujone in sage leaves was determined at 40 °C. The highest content of polyphenols for thyme was found at 35 °C and for sage in lyophilized leaves. The lyophilized material was characterized by the largest ability of free radical (ABTS) elimination. PRACTICAL APPLICATIONS: Drying as a method of preservation of herbal plants, like food preservation, is a necessary process of maintenance, especially in temperate climates. The way in which thyme and sage leaves are dried, has a significant influence on their chemical composition, and thereby the properties of the received raw material. Therefore, there is a possibility of programming their composition according to the needs. Owing to appropriate technological treatment it is possible to obtain the substances which are helpful in the prevention of civilizational diseases. Nowadays thyme and sage are widely used. The presented research results are useful not only in the process of obtaining dried leaves from thyme and sage but also in isolating the essential oil with the desirable chemical composition, for further use and development of functional food.
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