engleski

Extraction of wild thyme (Thymus serpyllum L.): supercritical CO2 vs. traditional extraction methods

Wild thyme (Thymus serpyllum L.) is a medicinal and aromatic plant native to Mediterranean region that contains valuable essential oils with endorsed therapeutic properties. In this work, wild thyme oil was extracted with supercritical CO2 as green extraction method and compared with conventional extraction methods – Soxhlet extraction with methylene chloride and hydrodistillation. Extraction parameters were as follows: pressure 100, 200 and 300 bar, which is corresponding to supercritical CO2 density of 628.7, 839.9 and 910.0 kg/m3, temperature 40°C, CO2 mass flow rate 0.192 kg/h and extraction time 4 h. The results showed that supercritical CO2 extraction parameters had a significant influence to extraction yields that ranged from 0.84 to 1.44 %. The extraction yield was improved with longer extraction time and with increase in pressure, i.e. increase in supercritical CO2 density. During the first hour of extraction, fast extraction period was noted for all extraction conditions, but the difference was noted after the first hour of extraction. At the density of 628.7 kg/m3 and 910.0 kg/m3, a slow extraction period was noted for the next hour, followed by period of fast extraction for last 2 hours of extraction. The extraction yield of the Soxhlet extraction was 3.08±0.03 % which is 2.14 times higher compared to supercritical CO2 extraction, while it was the lowest for hydrodistillation (0.08±0.03 %). In conclusion, the highest yield of supercritical extraction was obtained with 300 bar. Significantly higher yield was obtained with Soxhlet extraction, but considering the long extraction time, usage of organic and toxic solvents and inability to adjust selectivity of the Soxhlet extraction, it is not an optimal method for wild thyme extracts. Supercritical CO2 extraction is considered a green alternative extraction method that is in terms of sustainable production, meaning that environmental and health safe product are obtained with high yield of lipophilic extracts.

Thymus serpyllum L., supercritical CO2, essential oil, green extraction, sustainable production

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