Yield, composition, and antioxidant capacity of ground cumin seed oil fractions obtained at different time points during the hydrodistillation

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 EOextraction described in this study could be used by industry to reduce energy inputs and oil losses, and for fast oil extraction.