Optimizing Basil Essential Oil Yield: A GC-MS–Based Harvest Study

A joint study conducted by researchers at Dicle University (Diyarbakir, Turkey) and Kahramanmaras Sutcu Imam University (Kahramanmaras, Turkey) aimed to determine the optimal harvest time for maximum essential oil and linalool yields from basil. The dried leaves of gathered plant samples were hydrodistilled for extraction of essential oil, which was subjected to gas chromatography-mass spectrometry (GC-MS) analysis to determine the variance in chemical compounds composition. A paper based on this research was published in Annals of the Brazilian Academy of Sciences (1).

A member of the Labiatae family, sweet basil (Ocimum basilicum L.) is a tender summer and annual condimental herbaceous plant (2,3). Widely used in a variety of foods as a flavoring agent (4), essential oil extracted from basil is of strongly aromatic odor because of presence of monoterpenes, sesquiterpenes. and phenylpropanoids presents. The main components of the oil (such as linalool, methyl chavicol, eugenol, 1,8-cineole, geranial, neral, and methyl cinnamate [5]) display a variety of antioxidant and antimicrobial activities (6,7).

The researchers worked with two plant ecotypes, Dicle and Silbe, planted in Medicinal Plants Collection Garden, of Dicle University, which grew in hot Southeast Anatolian conditions of Turkey. The plants were harvested at five intervals of three hours duration from 6:00 am to 6:00 pm. Their dried leaves were hydrodistilled for extraction of essential oil, which was subjected to GC-MS analysis to determine the variance in chemical compounds composition (1).

The results of the study showed significant variations in essential oil contents, which fluctuated due to diurnal changes in temperature and humidity. The highest essential oil content for the Dicle ecotype was determined at 12:00 in the first harvest period and at 9:00 in the second harvest period. The highest essential oil content for the Silbe ecotype was obtained at 06:00 in the first harvest period and at 12:00 in the second harvest period. The interaction between harvest times and ecotypes significantly affected oil yields. It was determined that both ecotypes contained linalool as the major component, and the linalool content varied between 27.41-59.38% in the Dicle ecotype and 19.97-49.49% in the Silbe ecotype. Linalool content showed a gradual increase towards noon in both ecotypes, and a decrease from afternoon to evening (1).

“The study underscores the responsible factors in maximizing basil essential oil,” wrote the authors of the study. “It also indicated presence of 50-65% linalool and methyl chavicol in essential oil analyzed from the two O. basilicum ecotypes.” The authors recommend that “future studies should focus on herb yield, harvest time and chemotype of sweet basil for inclusion in variety breeding programs.” (1)

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References

1. Kizil, S.; Toncer, O.; Ipekesen, S. et al. Day-Time Variations in Essential Oil Contents of Sweet Basil (Ocimum basilicum L.) Ecotypes in Semi-Arid Climatic Conditions. An. Acad. Bras. Cienc. 2025, 97 (s4), e20250116. DOI: 10.1590/0001-3765202520250116
2. Akgul, A.A. Spice Science and Technology; Turkish Association Food Technologists; 1993. P. 110.
3. Chang, X.; Alderson, P. G.;Wright, C. J. 2009. Variation in the Essential Oils in Different Leaves of Basil (Ocimum basilicum L.) at Day Time. Hortic. J. 2009, 2, 13-16. DOI:10.2174/1874840600902010013
4. Ozcan, M.; Chalchat, J. C. Essential Oil Composition of Ocimum basilicum L. Czech J. Food Sci. 2002, 20 (6), 223-228. DOI: 10.17221/3536-CJFS
5. Nurzynska-Wierdak, R.; Borowski, B.; Dziba, K. et al. Essential Oil Composition of Sweet Basil Cultivars as Affected by Nitrogen and Potassium Fertilization. Turk. J. Agric. For. 2013, 37, 427-436. DOI: 10.3906/tar-1203-43
6. Javanmardi, J.; Stushnoff, C.; Locke, E. et al. Antioxidant Activity and Total Phenolic Content of Iranian Ocimum Accessions. Food Chem. 2003, 83 (4), 547-550. DOI: 10.1016/S0308-8146(03)00151-1
7. Telci, I.; Elmastas, M.; Sahin, A. Chemical Composition and Antioxidant Activity of Ocimum minimum Essential Oils. Chem. Nat. Compd. 2009, 45, 568-571. DOI: 10.1007/s10600-009-9369-z