Comparison of the contents of benzo(a)pyrene, sesamol and sesamolin, and volatiles in sesame oils according to origins of sesame seeds

The objective of the present study was to compare the contents of antioxidants (sesamol and sesamolin) and benzo(a)pyrene (BaP), as well as the volatile profiles in sesame oil obtained from sesame seeds cultivated in four different areas in Korea, and those cultivated in other countries, including Ethiopia, India, and China. The sesamol content was lower in Korean sesame oils than in Ethiopian, Indian, and Chinese sesame oils, whereas sesamolin content was higher in sesame oils derived from Korea than those in sesame oils derived from other countries. There was also a difference in the contents of BaP in the sesame oils obtained from seeds in different cultivated areas. The volatiles that allowed Korean samples to be discriminated from those of other countries were mainly pyrroles and sulfur-containing compounds such as 1-ethyl-1H-pyrrole, 2-ethyl-4-methyl-1H-pyrrole, 2,4-dimethylthiazole, and 5-ethyl-4-methylthiazole.


Introduction
Benzo(a)pyrene (BaP), one of the polycyclic aromatic hydrocarbons (PAHs), is a ubiquitous environmental pollutant (Benner Jr et al. 1989). The formation of PAHs including BaP is mainly derived from both natural causes (e.g., forest fires and volcanic eruptions) and anthropogenic sources (e.g., waste incineration, automobile exhaust, and cooking), mostly by incomplete combustion of organic matter (Chen and Chen 2001;Alomirah et al. 2010). Recently, experimental animal studies revealed that BaP is carcinogenic and mutagenic to several animal species (e.g., primates, rats, and mice) with oral exposure (National Toxicology Program 2014). Accordingly, there has been growing concern regarding the presence of BaP in foods and BaP was upgraded from Group 2A (probably carcinogenic to humans) to Group 1 (carcinogenic to humans) by the International Agency for Research on Cancer (IARC 2010). The presence of BaP in foods can result from (1) environmental pollution of raw materials, (2) contamination from combustion gases during cooking (e.g., heating, roasting, grilling, and frying), and/or (3) contamination from packaging materials (Phillips 1999).
Sesame (Sesamum indicum L.) is an important oilseed crop that contains oil (42-54 %), protein (22-25 %), and carbohydrates (*13.5 %) (Orruno and Morgan 2007). Oil from roasted or unroasted sesame seeds has been mainly used for edible oil such as cooking and salad oil since ancient times. In particular, roasted sesame seed oil possesses a distinctive odor and taste notes so it has long been consumed as a seasoning ingredient in some Asian countries including Korea (Dong et al. 2012). Sesame oil is mainly produced by roasting sesame seeds at high temperatures (220-260°C), and this roasting process can lead to the generation of BaP (Seo et al. 2009). Although the mechanism of BaP formation in sesame oil has not been completely explained, its formation in edible oils is mainly related to the pyrolysis of lipids that are main constituents in oils (Masuda et al. 1967). Organic compounds such as lipids are partially broken down into small and unstable fragments (pyrolysis). These fragments, which are highly reactive free radicals, are recombined to form more stable PAHs including BaP through repeated condensation and cyclization of 2-carbon intermediates (Badger and Novotny 1963;Mastral and Callen 2000). Also, Chen and Chen (2001) demonstrated that thermal oxidation of fatty acids in lipid model system can lead to BaP formation. Besides the roasting process, the contamination of raw sesame seeds can influence the contents of BaP in sesame oil. The level of contamination is significantly affected by the location where the seeds are cultivated, because sesame seeds can be contaminated with PAHs or other pollutants such as heavy metals via deposition of airborne particles on crops or uptake from the soil (Guillen et al. 1997). According to a previous study, BaP was detected at level ranging from 0.28 to 11.05 lg/kg in various sesame oils cultivated in different areas (Alomirah et al. 2010).
The major producing countries of sesame seeds are in Asia and Africa. In Korea, the annual production of sesame seeds was approximately 12,000 tons in 2013, and sesame seeds have been cultivated mainly in two Provinces of Korea, Jeonbuk (29 %) and Gyeongbuk (22 %) (KFDA 2013). To satisfy domestic consumption of sesame seeds (about 90,000 tons), Korea imported approximately 130,000 tons of sesame seeds from other countries in 2012-2013. The major countries for importation were China and India with 38 and 51 %, respectively, of total imported seeds. Additionally, the import of Ethiopian sesame seeds has been increasing steadily (KFDA 2013). These domestic and imported sesame seeds have mostly been used for manufacturing sesame oil in Korea.
Sesame oil contains high amounts of phenolic antioxidants such as tocopherols and lignans (Katsuzaki et al. 1994;Kanu et al. 2010). Antioxidants were reported to inhibit lipid oxidation during food processing and storage, because antioxidants scavenge free radicals such as hydroxyl and lipid peroxyl radicals (Choe and Min 2006). Sesamol and sesamolin are natural antioxidants that impart high oxidative stability to sesame oil in comparison with other edible oils (Namiki 1995;Shahidi and Naczk 2003). Sesamol is only present in trace amounts in raw sesame seeds, but roasted sesame oil contains higher content of sesamol than raw sesame seeds (Fukuda et al. 1986). Sesamol can be formed by the hydrolysis of sesamolin during roasting or bleaching process (Lee et al. 2010b). Sesamol is known to possess exceptionally high free radical scavenging capacity and synergistic antioxidant effect with c-tocopherol (Yoshida and Takagi 1999;Suja et al. 2004). Suja et al. (2004) showed that the rate constants of sesamol and sesamolin were 4.00 9 10 -5 and 0.13 9 10 -5 lM -1 S -1 , respectively, when these compounds reacted with DPPH radical. Although sesamolin was demonstrated to have low antioxidant capability compared to sesamol, this compound is a precursor for sesamol and is abundant in roasted sesame oil. According to a study by Lee and Choe (2006), sesamol and sesamolin reduce the autoxidation of methyl linoleate.
In general, it is known that the composition of agricultural products such as sesame seeds can be impacted by geographical conditions and abiotic factors such as growth altitude, soil moisture, temperature, sun exposure time, humidity, and rainfall (Lee et al. 2010a). Recently, several studies were conducted to investigate the contents of BaP or antioxidants (sesamol and sesamolin) in sesame oils derived from different cultivated areas (Kang et al. 2003;Jeon et al. 2013), but there is no report on the comparison of the volatile profiles. Most volatiles in sesame oil are pyrazines, pyrroles, furans, carbonyls, and sulfur-containing compounds, which are formed through complex reaction such as Maillard reaction, Strecker degradation, and lipid oxidation (Park et al. 1995;Shimoda et al. 1996). The objectives of the present study were to (1) compare the contents of antioxidants (sesamol and sesamolin) and BaP, and the volatile profiles in sesame oil obtained from seeds cultivated in different areas, and (2) investigate whether antioxidants have an effect on the BaP contents and the volatile profiles in sesame oil.

Materials
The sesame seeds were collected from seven different geographic locations, including four different areas of Korea (KOR) [Muan, Sinan, Yecheon, and Uiseong] and three different countries [Ethiopia (ETH), India (IND), and China (CHN)] in 2013.

Geographic and climatic data analysis
Information on geographic factors (latitude, longitude, and altitude) of cultivated areas of Korean sesame seeds was obtained from Google Earth (http://earth.google.com). Data on climatic conditions, including total precipitation and mean temperature, during the growing period of sesame seeds (the 5 months of May-September 2013) were collected from the Korea Meteorological Administration (http://www.kma.go.kr/). Table 1 shows the geographic and climatic conditions of four cultivated sites of Korean sesame seeds used in this study.
Preparation of sesame oil 6.5 kg of sesame seeds from different cultivated areas were washed with tap water for 5 min to remove any residual impurities. Then, these seeds were roasted in a drum roaster at 260°C for 21 min. Sesame oil extracted from roasted sesame seeds using an oil presser was stored at room temperature for 1 day prior to volatile analysis. The rest of oils were stored at 4°C in a room before the analysis of BaP, sesamol, and sesamolin. All samples were prepared in triplicate to analyze BaP, sesamol, and sesamolin, and volatiles in sesame oils.

Analysis of sesamol and sesamolin by HPLC/DAD
Standards of sesamol (100 mg) and sesamolin (1.0 g) were separately dissolved in 80 % methanol (1 mL) for using as standard stock solutions. The stock solutions were diluted with 80 % methanol to obtain sesamol solutions at the concentrations of 0.2, 0.5, 1.0, 2.0, 3.0, and 4.0 lg/mL (w/ v) and sesamolin solutions at the concentrations of 1.0, 2.5, 5.0, 10, 20, and 30 lg/mL (w/v), respectively. These six standard solutions were used to obtain calibration curves.
1.0 g of sesame oil sample was precisely weighed and dissolved in 5.0 mL of 80 % methanol. For extracting sesamol and sesamolin, the samples with solvents were vortexed for 3 min and then centrifuged at 3000 rpm and 25°C for 15 min. Upper methanol phase was transferred to a 15-mL falcon tube. Additional 5.0 mL of 80 % methanol was added to the remaining samples, and vortexing and centrifuging steps were repeated. All extracts were combined to obtain a final volume of 10 mL with 80 % methanol. 10 lL of combined extract was injected into the HPLC column after filtering through 0.45 lm PVDF membrane (Pall Corporation, USA). All samples were prepared in triplicate.
The analysis of sesamol and sesamolin was performed using a high-performance liquid chromatograph (HPLC, 1260 Agilent Technologies, Germany) equipped with diode-array detector (DAD, 1260, Agilent). SunFire C-18 reversed-phase column (250 mm 9 4.5 mm, 5 lm particle size, Waters, UK) was used for the separation of sesamol and sesamolin in sesame oils. Mobile phase was composed of water (solvent A) and methanol (solvent B). The flow rate of 1.0 mL/min was used for over 35 min with the following gradients: 0 min, 5 % B; 0-5 min, 5-30 % B; 5-25 min, 30-80 % B; 25-30 min, 80-100 % B; and 30-35 min, 5 % B. The sample injection volume was 10 lL and the column temperature was set at 25°C. DAD was operated at 290 nm. All the experiments were performed in triplicate.
Sesamol and sesamolin which appeared at 13.497 min and at 20.968 min, respectively, were identified by comparing the retention times of their peaks to those of sesamol and sesamolin standards. Sesamol and sesamolin were quantified based on the external standard curves at concentrations ranging from 0.2 to 4.0 lg/mL and from 1.0 to 30 lg/mL, respectively. The coefficients of correlation (R 2 ) of standard curves were 0.9997 (sesamol) and 0.9963 (sesamolin).

Analysis of BaP by HPLC/FLD
100 g sesame oil was diluted in 10 mL of n-hexane spiked with 50 lL of 3-methylcholanthrene [50 lg/kg (w/w) in ACN] as an internal standard. The SPE cartridge (Chromabond HR-P, Macherey-Nagel, Germany) was conditioned with 5 mL of n-hexane before use. After conditioning SPE cartridge, the sample solution was loaded on 0.5 g SPE cartridges and then the extracted sample was eluted with 2.5 mL toluene, which was repeated four times. The collected effluent was evaporated at 40°C with a gentle blow of nitrogen gas flow. The residue was dissolved in 1.0 mL acetonitrile prior to injection into HPLC instrument. All samples were prepared in triplicate. The analysis of BaP was carried out using a high-performance liquid chromatograph (HPLC, Nanospace SI-2, Shiseido, Japan) system with fluorescence detector (FLD,3213,Shiseido). The separation of BaP was achieved on a CapCell Pak MG II C18 column (150 mm length 9 4.6 mm ID, 5 lm particle size, Shiseido). Mobile phase was composed of 50 % ACN (solvent A) and 95 % ACN (solvent B) with the following gradients: 0-27 min, 35 % B; 27-38 min, 35-100 % B; 38-42 min, 100 % B; and 42-50 min, 35 % B. The flow rate was 1 mL/min with a sample injection volume of 5 lL and the column temperature was set at 40°C. The excitation and emission wavelengths of fluorescent detector were 294 and 404 nm, respectively. All the experiments were conducted in triplicate.
BaP was identified by comparing both the retention time and its fluorescence spectra with those of the reference standard compound. BaP was quantified based on the relative peak ratio of its peak area to that of the internal standard, 3-methylcholanthrene.

Analysis of volatile compounds by SPME and GC-MS
SPME method was used for extraction of volatile compounds in sesame oil. DVB/CAR/PDMS SPME fiber was applied to adsorb volatiles. 20 mL of sesame oils and 0.1 mL of p-cymene [1 g/mL (w/v) in paraffin oil] as an internal standard compound were put into a 60-mL amber bottle containing a stir bar. This bottle was sealed with a plastic screw cap and a PTFE/red rubber septum. The sample bottle was placed into a water bath and kept at 30°C under magnetic stirring at 400 rpm for 30 min for equilibrium. SPME fiber was manually exposed to headspace of the sample vial for 10 min for adsorption, and then the adsorbed volatiles were desorbed in GC injection port at 250°C. All the experiments were carried out in triplicate.
The analysis of volatiles in sesame oil was performed using a 6890 N series gas chromatograph and 5975 mass selective detector (MSD) (Agilent Technologies) equipped with a DB-5MS column (30 m 9 0.25 mm I.D., 0.25 lm film thickness, J&W Scientific, USA). The carrier gas was helium at a constant flow rate of 0.8 mL/min. The oven conditions were as follows: the oven temperature was initially set at 40°C for 6 min, raised to 140°C at 3°C/min, and further raised to 200°C. The GC injector temperature was 250°C in the splitless mode with 5 min pure-off time, cryo-focusing by manually dipping the front part of GC column in liquid nitrogen. Detector transfer line temperature was 250°C. The MS was operated in the electron ionization (EI) mode at 70 eV and the mass scan parameter was in the range of 35 to 350 a.m.u.
Each volatile compound was tentatively identified on the basis of its mass spectral data using Wiley 7n mass spectral database and the relative index (RI) values from the previous literatures. The RI values of volatile components were calculated using n-paraffins from C 7 to C 22 as external standards. The volatile components in sesame oil samples were quantified by comparing their peak areas to that of the internal standard compound, p-cymene, on GC-MS total ion chromatograms.

Statistical analysis
All the results were presented as mean ± standard deviation of the triplicate determination. Analysis of variance (ANOVA) was performed using the general linear model (GLM) procedure in SPSS (version 12.0, USA) to estimate significant differences in the contents of BaP, sesamol, and sesamolin, and volatile profiles in sesame oil obtained from seeds of different origins. The significant differences (p \ 0.05) between samples were assessed using Ducan's multiple range test. Principle component analysis (PCA) was performed to the raw values (n = 3) of the relative peak areas obtained by GC-MS total ion chromatograms using SIMCA-P (version 11.0, Umetrics, Umea, Sweden) to compare volatile components in sesame oils from seeds of different origins.

Results and discussion
Comparison of the contents of sesamol and sesamolin in sesame oils according to origins of sesame seeds The contents of both sesamol and sesamolin in sesame oils derived from seeds cultivated in ETH, IND, CHN, and KOR (Sinan, Muan, Yecheon, and Uiseong) are shown in Fig. 1. The sesamol contents were in the range of 1.55-2.45 lg/mL in sesame oils obtained from imported seeds, and 1.23-2.25 lg/mL in those obtained from domestic seeds. The sesame oil obtained from ETH (2.45 lg/mL) contained the highest sesamol content, followed by Yecheon (2.25 lg/mL) in KOR, but there was no significant difference in sesamol content between the two samples. The sesamol contents of both oils were significantly (p \ 0.05) different from those of the other sesame oils. The sesamol contents in Indian and Chinese sesame oils (1.71 and 1.55 lg/mL, respectively) were slightly higher than those in Korean sesame oils including Sinan, Muan, and Uiseong (1.23, 1,24, and 1.51 lg/mL).
On the other hand, the sesamolin content was higher in sesame oils derived from KOR than in those derived from imported sesame seeds. The sesamolin contents ranged from 2.66 to 8.28 lg/mL and from 7.46 to 11.42 lg/mL in sesame oils obtained from imported and domestic seeds, respectively. Among the sesame oils obtained from imported sesame seeds, the sesamolin content in Chinese sesame oil (8.28 lg/mL) was significantly (p \ 0.05) different from those in Ethiopian and Indian sesame oils (3.31 and 2.66 lg/mL). Of the four Korean sesame oils tested, the sesame oil derived from Sinan contained the highest sesamolin content (11.42 lg/mL). The sesamolin contents in sesame oils derived from Muan and Yecheon (9.88 and 9.08 lg/mL) were significantly lower than those in the sesame oil derived from Sinan, but higher than those in the sesame oil derived from Uiseong (7.46 lg/mL). Previous studies revealed that there is a difference in the contents of sesamol and sesamolin between sesame oils obtained from different cultivated areas (Kang et al. 2003;Jeon et al. 2013).
The contents of sesamol and sesamolin in sesame seeds can be influenced by climatic, geographical, and growing conditions such as fertilizer, soil type, irrigation, and sun exposure (Kang et al. 2003;Kim et al. 2006;Jeon et al. 2013). Kim et al. (2006) reported that the sesamolin content in sesame seeds decreased in response to drought stress. According to a study by Kumazaki et al. (2009), the sesamolin content in sesame seeds increased under low air temperature (22/15°C). However, it was difficult to find the correlation between sesamolin contents and mean temperature in this study, because the mean temperature is very similar between the four cultivated areas (Table 1). Seed size or seeding and harvesting time can contribute to the composition of sesamol and sesamolin (Yoshida and Takagi 1999;Rangkadilok et al. 2010). Also, high temperature and high free fatty acid contents in raw sesame seeds can lead to the formation of sesamol in roasted sesame oils due to the decomposition of sesamolin (Yoshida 1994).
Comparison the BaP contents in sesame oils according to the origins of sesame seeds The BaP contents in both the imported and domestic sesame seeds and in their respective sesame oils are shown in Table 2. BaP was detected at trace level in sesame seeds cultivated in ETN, IND, and CHN. There were trace amounts of BaP in Ethiopian sesame oil, whereas BaP was detected in the sesame oils derived from seeds harvested from IND (0.16 lg/kg) and CHN (0.33 lg/kg), respectively. In the four different Korean sesame oils, trace amounts of BaP were only present in the sesame seeds harvested from Yecheon and Uiseong and in their oils. Also, BaP was not detected in sesame seeds harvested from both Sinan and Muan and in their oils. In the present study, there was a difference in BaP content between sesame oils obtained from Korean seeds and those obtained from imported seeds. These results were in agreement with previous findings (Kang et al. 2003;Jeon et al. 2013).
Overall, BaP was detected below the limit of quantification or not detected in all sesame seeds. However, it was found in sesame oils prepared from seeds grown in IND and CHN. These results could suggest that most BaP is generated during the manufacturing process, which can be affected differently according to sesame seeds of different origins. Seo et al. (2009) reported that the generation of BaP increased, according to the roasting temperature and time of sesame seeds. In the present study, all sesame oils were manufactured using the same processes. Accordingly, the difference in BaP contents in sesame oils obtained from the sesame seeds of different origins may be related to initial contamination of BaP or other pollutants as well as in their raw material compositions. For example, BaP was not detected in sesame oil prepared from seeds which were uncontaminated by BaP. It was postulated that the degree of contamination in raw sesame seeds can be influenced by environmental factors such as the distance from a city or air, soil, and water conditions near growing areas (Seo et al. 2009). In addition, BaP formation in sesame oils might be attributed to the macronutrients of the raw materials. Major fatty acids in roasted sesame oil are known to be linoleic acid (41-47 %) and oleic acid (38-45 %). According to a study by Chen and Chen (2001), the formation of PAHs in edible oils is influenced by the degree of unsaturation and the composition of fatty acids such as oleic acid, linoleic acid, and linolenic acid. They also reported that linolenic acid is especially liable to form cyclic compounds, which could result in the formation of PAHs. The composition of fatty acids in sesame seeds can be affected by geographical location and climate conditions in the cultivated areas (Lee et al. 1981;Kang et al. 2002). Lee et al. (1981) showed that there were significant differences in the increase of linoleic acid content with an inverse decrease of oleic acid content under the conditions of low temperature and high solar radiation (Lee et al. 1981). Also, the formation of BaP was related to free radical reaction by lipoid oxidation, while sesamol is known to possess hydroxyl and lipid peroxyl radical scavenging properties as well as singlet oxygen quenching ability (Suja et al. 2004;Joshi et al. 2005). However, direct correlation between sesamol contents and BaP contents in sesame oil was not found in the present study, because the formation of BaP was affected by various factors (such as pollutant degree and composition of raw material), as mentioned above.

Discrimination of volatiles in sesame oils according to country of origin
Volatiles of the seven sesame oil samples prepared from seeds from ETH, CHN, IND, and KOR (Sinan, Muan, Yecheon, and Uiseong) were analyzed using SPME-GC-MS. A total of 62 volatiles, comprising 13 pyrazines, 6 pyrroles, 13 furans and furfurals, 11 sulfur-containing compounds, 10 carbonyls, 1 alcohol, 1 acid, 2 hydrocarbons, 4 benzenes and benzene derivatives, and 1 miscellaneous compound, were detected. Of the volatile compounds, pyrazines (such as acetylpyrazine and alkylpyrazines) and sulfur-containing compounds (such as thiazoles and thiophenes) can play a significant role in the characteristic sesame oil odors (Park et al. 1995;Shimoda et al. 1996). ANOVA of the GC-MS data set indicates that there were statistically significant differences (p \ 0.05) in the mean values of relative peak areas of volatile compounds among the sesame oils (Table 3).
PCA was used to analyze relative peak areas of the volatiles to determine whether sesame oils could be differentiated by the origin of their seeds. A total variance of 61.0 % was explained, comprising 40.9 % from the first principal component (PC1) and 20.1 % from the second principal component (PC2). As shown in the PCA score plots (Fig. 2), sesame oil samples made of sesame seeds harvested from different countries were clearly separated on the basis of their volatile profiles.
Overall, the sesame oil samples prepared from domestic seeds could be distinguished from those obtained from imported seeds by PC1 and PC2. The sesame oil samples obtained from CHN, ETH, and IND were positioned in the positive PC1 direction, while those derived from Muan, Uiseong, and Sinan in KOR were positioned in the negative PC1 direction. In addition, the sesame oil samples obtained from Muan, Uiseong, and Yecheon (on the positive PC2 dimension) were differentiated from sesame oil samples obtained from ETH and IND (on the negative PC2 dimension) by PC2. In addition, the sesame oil sample from Sinan (on the negative PC2 dimension) was separated from other Korean sesame oil samples, whereas the Chinese sesame oil sample (on the positive PC2 dimension) was distinguished from the other imported samples by PC2. Sesame oil samples obtained from CHN and Yecheon (on the positive PC1 and PC2 dimension) were placed close to each other in the PCA loading plot, presenting similar volatile profile patterns.
It is well known that the critical factor that impacts the volatile profiles of sesame oil is the roasting condition, especially the roasting temperature (Shahidi et al. 1997;Park et al. 2011). Also, the chemical composition (e.g., protein, fatty acids, and carbohydrates) of raw sesame seeds can influence the volatile profiles of sesame oil since volatiles are formed by Maillard reaction, lipid oxidation, and/or degradation of constituents in sesame seeds during roasting. For example, both pyrazines and thiazoles were formed via Maillard reaction between amino acids and reducing sugars. Several studies demonstrated that the chemical composition of sesame seeds is affected by climatic and geographic conditions during ripening (Kim et al. 2006;Lee et al. 2010a;Carrera et al. 2011). For example, Kim et al. (2006) reported that the content of oleic acid increased, while that of linoleic acid decreased in sesame seeds under drought stress conditions. In the protein composition of soybean, serine has a negative relationship with solar radiation, whereas cysteine showed a positive correlation with temperature (Carrera et al. 2011). In the present study, the preparation method (such as roasting temperature and time) of sesame oil was the same in all samples. Therefore, we presumed that the chemical constituents of the sesame seeds, which can be affected by different climatic and/or geographical conditions such as soil type, water, rainfall, and temperature in the cultivation areas, led to the differences in the volatile profiles of the sesame oil samples.
In conclusion, there were differences in the contents of antioxidants (sesamol and sesamolin) and BaP, and in the volatile profiles of sesame oils according to the cultivation areas of the sesame seeds. In case of the contents of antioxidants, sesamol contents were relatively lower, while sesamolin contents were higher in Korean sesame oils compared to those derived from seeds grown in the other countries. There were significant differences in BaP content between sesame oils derived from domestic and imported sesame seeds. Differences in the volatile profiles of sesame oils that originated from different geographical locations were demonstrated by PCA. Volatiles, highly associated with Korean samples, were mainly composed of sulfur-containing compounds such as 2,4-dimethylthiazole and 5-ethyl-4-methylthiazole, whereas sesame oils from the other countries consisted of pyrroles such as 1-ethyl-1H-pyrrole and 2-ethyl-4-methyl-1H-pyrrole. However, we could not find the effect of antioxidants on BaP contents and the volatile profiles in sesame oils obtained from seeds cultivated in different areas. This might be due to the fact that the formation of BaP and volatile components was affected by various factors such as pollutant degree, water contents, and/or composition (e.g., proteins, lipids, and carbohydrates) of raw materials as well as antioxidants.