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  • Author or Editor: Vicki Schlegel x
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Oregano (Origanum vulgare L.) is an important medicinal, culinary, and essential oil plant. Oregano essential oil is extracted from either leaves or shoots through steam distillation. Researchers and industry in various countries reported different distillation times (DTs) for oregano; however, there are no reports on optimum DT. This study evaluated the effect of DT (1.25, 2.5, 5, 10, 20, 40, 80, 160, 240, 360 min) on essential oil yield, composition, and antioxidant activity of the oregano essential oil. In general, the concentration of the low boiling essential oil constituents (alpha-thujene, alpha-pinene, camphene, l-octen-3-ol, myrcene, alpha-terpinene, paracymene, beta-phellandrene/limonene, gamma-terpinene, cis-sabinene hydrate, terpinolene) were highest at the shortest DT (1.25 or 2.5 min), reduced with increasing DT up to 40 min, and then stayed the same. However, the concentration of the major oil constituent, carvacrol, was lowest at the shortest DT of 1.25 min (18%) and increased steadily with increasing DT up to 40 min, where it leveled at 80% to 82%. The concentration of other higher boiling constituents (borneol, 4-terpineol, beta-bisabolene, beta-caryophylenne) was maximum at 5 to 20 min DT. Maximum yield of the low boiling constituents was achieved at relatively short DT, at ≈20 min DT, and peaked again at 240 min DT. Maximum yields of alpha-terpinene, beta-phellandrene/limonene, and gamma-terpinene were reached at 240 min DT. Maximum yields of paracymene cis-sabinene hydrate, terpinolene, and transsabinene hydrate were also achieved at 240 min DT, but yields at 20 min DT were not different. Yields of borneol, 4-terpinenol, carvacrol, beta-caryophyllene, and beta-bisabolene also were highest at 240 min DT. Distillation time at 20, 80, or 360 min did not alter antioxidant or antimicrobial activity of oregano oil. The relationship between the concentration and yield of the constituents with DT was adequately modeled by the asymptotic and Michaelis-Menten nonlinear regression models, respectively. Results demonstrated that 1) DT can be used to obtain oregano essential oil with differential composition; 2) maximum essential oil yield of steam-distilled oregano leaves could be obtained at 240 min DT; and 3) reports on oregano essential oil yield and composition using different DTs may not be comparable. Results from this study will aid in comparing published reports on oregano essential oil that used different lengths of DT.

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This study evaluated the effect of distillation time (DT; 1.25, 2.5, 5, 10, 20, 40, 80, 160, 240, and 360 min) on essential oil yield, composition, and the antioxidant activity of ponderosa pine essential oil. Pine essential oil yield increased with length of the DT and reached maximum at 160 min DT. The major oil constituents were alpha-pinene and beta-pinene, ranging from 17% to 40% and from 21% to 29%, respectively, of the total oil. Overall, the concentration of alpha-pinene and beta-pinene was high at the initial DT (5–20 min) and decreased with increasing DT. The concentration of myrcene (range, 0.9% to 1.5%) was lowest at 5 min DT, then increased at 10 min DT, and did not change with longer DT. Overall, the concentrations of most other constituents (delta-3-carene, limonene, cis-ocimene, alpha-terpinyl acetate, germacrene-D, alpha-muurolene, gamma-cadinene, delta-cadinene, and germacrene-D-4-ol) were low at the initial DT and increased with increasing DT. Total yields (a function of oil yield and the concentration of individual constituents) of all constituents were generally the lowest at 5 min DT, increased with increasing DT, and reached maximum at 160 min DT. The antioxidant capacity of the pine oil in this study varied between 7.0 and 14.5 μmole Trolox/g and was unaffected by DT. This study demonstrated that DT can significantly modify the essential oil yield and composition of ponderosa pine needles. Furthermore, DT could be used to obtain pine oil with targeted chemical profiles. This report can also be used as a reference point for comparing literature reports, in which different DTs are used to extract essential oil of ponderosa pine.

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Sweet sagewort, also known as sweet wormwood (Artemisia annua L.), contains essential oil and other natural products. The objective of this study was to evaluate the effect of eight different distillation times (DTs; 1.25 minutes, 2.5 minutes, 5 minutes, 10 minutes, 20 minutes, 40 minutes, 80 minutes, and 160 minutes) on A. annua essential oil and its antioxidant capacity. Highest essential oil yield was achieved at 160-minute DT. The concentration of camphor (8.7% to 50% in the oil) was highest at the shorter DT and reached a minimum at 160-minute DT. The concentration of borneol showed a similar trend as the concentration of camphor. The concentrations of some constituents in the oil were highest at 2.5-minute DT (alpha-pinene and camphene), at 10 minutes (paracymene), at 20 minutes (beta-chamigrene and gamma-himachalene), at 80 minutes [transmuurola-4(15),5-diene and spathulenol], at 80- to 160-minute DT (caryophylene oxide and cis-cadin-4-en-ol), or at 160-minute DT (beta-caryophyllene, transbeta-farnesene, and germacrene-D). The yield of individual constituents reached maximum at 20- to 160-minute DT (camphor) at 80- to 160-minute DT [paracymene, borneol, transmuurola-4(15),5-diene, and spathulenol], or at 160-minute DT (for the rest of the oil constituents). DT can be used to attain A. annua essential oil with differential and possibly targeted specific chemical profile. The highest antioxidant capacity of the oil was obtained at 20-minute DT and the lowest from the oil in the 5-minute DT. This study suggests that literature reports on essential oil content and composition of A. annua could be compared only if the essential oil was extracted at similar DTs. Therefore, DT must be reported when reporting data on essential oil content and composition of A. annua.

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Cumin (Cuminum cyminum L.) is an important essential oil (EO), medicinal, and spice plant from family Apiaceae. Cumin seed EO has wide applications in the food, liquor, pharmaceutical, and aromatherapy industries, and is extracted via steam or hydrodistillation of either whole or ground seed. The hypothesis of this study was that by capturing oil eluted at different timeframes during the hydrodistillation process (HDP), we could obtain oils of differential composition and bioactivity. The objective was to evaluate the EO fractions captured at different timeframes of the HDP. In this study, we collected nine different EO fractions following nine hydrodistillation time (HDT) frames: 0–2, 2–7, 7–15, 15–30, 30–45, 45–75, 75–105, 105–135, and 135–165 minutes. In addition, continuous HDT of 165 minutes was conducted as a control and the complete cumin seed oil was collected at the end of this time. HDT significantly affected the concentrations of the following constituents in the oil (as percentage of total oil): α-pinene (0.2% to 2.1%), β-pinene (5% to 35.8%), mycrene (0.3% to 1.7%), para-cymene (12.0% to 26.4%), γ-terpinene (4.8% to 25.9%), cumin aldehyde (3.8% to 51.1%), α-terpinen-7-al (0.2% to 11.2%), and γ-terpinen-7-al (1.3% to 13.1%). Some of the constituents were eluted early in the HDP and were highest in the oil fraction collected at the beginning of the HDP, others were highest in the fractions collected midway in the HDP, and another group of constituents were eluted later and were the highest in the oil fractions collected during the last HDT (135–165 minutes). Due to their altered chemical composition, the oil fractions expressed different antioxidant capacities; the one eluted at 105–135 minutes HDT had the greatest oxygen radical absorbance capacity (ORAC) values. The ORAC values were positively correlated to the concentration of cumin aldehyde (0.962), α-terpinene (0.889) and γ-terpinene (0.717), which suggest that these compounds in cumin oil may be responsible for the measured antioxidant capacity. This study demonstrated that cumin oil with dissimilar chemical profile and antioxidant activity could be obtained from the same batch of seed by capturing oils at different timeframes during the same HDP. The resulting products (EO fractions) could have diverse industrial, medical, and environmental applications. The method for cumin seed grinding and EO extraction described in this study could be used by industry to reduce energy inputs and oil losses, and for fast oil extraction.

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