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): a-pinene (0.2% to 2.1%), b-pinene (5% to 35.8%), mycrene (0.3% to 1.7%), para-cymene (12.0% to 26.4%),g-terpinene (4.8% to 25.9%), cumin aldehyde (3.8% to 51.1%), a-terpinen-7-al (0.2% to 11.2%), and g-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), a-terpinene (0.889) and g-terpinene (0.717), which suggest that these compounds in cumin oil may be responsible for themeasured 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. Themethod for cumin seed grinding andEO extraction described in this study could be used by industry to reduce energy inputs and oil losses, and for fast oil extraction. Cumin (C. cyminum L.) is one of the important aromatic plants belonging to Apiaceae family. It has an ancient history of use as medicinal and spice plant since the Roman times (Stojanov, 1972). Cumin seed was used for the treatment of toothache, diarrhea, and epilepsy in Iranian ancient medicine (Zargari, 1989). It is also used in traditional ayurvedic medicine as a stimulant, carminative, astringent and as a remedy against indigestion, flatulence and diarrhea (Ani et al., 2006). According to Derakhshan et al. (2008), cumin EO reduces the virulence of Klebsiella pneumoniae, one of the bacteria responsible for nosocomial infection in human. Iacobellis et al. (2005) demonstrated that EO obtained from cumin seed can control phytobacterial diseases like Clavibacter, Curtobacterium, Rhodococcus, Erwinia, Xanthomonas, and Agrobacterium. Currently, cumin is a highly valuable spice, EO crop, and medicinal plant grown from India and China, Russia, Africa, Eastern and Western Europe to America (Atanassova and Nedkov, 2004; Azeez, 2008; Deepak, 2003; Gohari and Saeidnia, 2011). The EO of cumin seed may be extracted by steam or hydrodistillation (Atanassova and Nedkov, 2004; Beis et al., 2000; Topalov, 1962). However, since the EO is synthesized and stored inside the seed in special canals called vitae, steam distillation of the whole seeds may take several hours and may require substantial energy input (Atanassova and Nedkov, 2004). None of the literature reports had provided the optimal duration of cumin seed distillation yet. According to our experience, grinding of the cumin seed before the EO extraction may result in much faster oil extraction. However, as most EO, it doesn’t dissolve in water, and evaporates quickly. Our preliminary unpublished studies ascertained that cumin seed could be ground in water and then hydrodistilled, without loss of EO. In addition, the oils distilled from ground cumin seed and captured at different timeframes, had different color and aroma. Recent reports on the effect of HDT on crushed dill (Anethum graveolens L.) (Sintim et al., 2015), coriander (Coriandrum sativum L.) (Zheljazkov et al., 2014), and fennel (Foeniculum vulgare Mill) (Burkhardt et al., 2015) demonstrated different oil constituents eluted at different distillation times. Since dill and coriander belong to the same family as cumin and have similar morphological structures (vitae) to store EO, we hypothesized that by capturing the oil fractions eluted at different times, these fractions would have dissimilar composition and possibly bioactivity, which in turn could have different research or industrial applications. These oil fractions could be exploited to produce a diversity of products. Materials and Methods Hydrodistillation and HDT. This experiment was carried out at the Sheridan Research and Extension Center, University of Wyoming, in 2013. In this study, we used one batch of certified bulk seed (fruits) of cumin, originated from India, and marketed by Starwest Botanicals (Rancho Cordova, CA). The EO from all cumin seed samples was extracted via hydrodistillation in 2-L steam hydrodistillation units (Heartmagic, Rancho Santa Fe, CA). Several preliminary experiments were conducted to optimize cumin seed grinding parameters (such as duration of grinding, the amount of water needed to wash the blender, and the water to cumin seed ratio) before this hydrodistillation experiment. Consequently, in this study we used the optimized Received for publication 9 Mar. 2015. Accepted for publication 9 June 2015. This research was supported in part by Department of Plant Science funds and the Outreach School of the University of Wyoming awarded to Dr. V.D. Zheljazkov (Jeliazkov). We thank J. Vardiman and E.A. Jeliazkova for help with the extraction and measuring of the cumin essential oil. Corresponding author. E-mail: valtcho.jeliazkov@ oregonstate.edu or valtcho.pubs@gmail.com. HORTSCIENCE VOL. 50(8) AUGUST 2015 1213 | POSTHARVEST BIOLOGY AND TECHNOLOGY