Processing of Flavor-Enhanced Oils: Optimization and Validation of Multiple Headspace Solid-Phase Microextraction-Arrow to Quantify Pyrazines in the Oils  
[PERSON]  
1 College of Food Science and Technology, Henan University of Technology, Lianhua Road,  
Zhengzhou 450001, China; [EMAIL_ADDRESS] (Z.X. ); [EMAIL_ADDRESS] (Y.B.) 1  
[PERSON]  
2 Wilmar (Shanghai) Biotechnology Research and Development Center Co., Ltd., 118 Gaodong Road,  
Pudong New District, Shanghai 200137, China; [EMAIL_ADDRESS] (C.Z. ); [EMAIL_ADDRESS] (H.S. ); [EMAIL_ADDRESS] (H.Z) 2  
[PERSON]  
2 Wilmar (Shanghai) Biotechnology Research and Development Center Co., Ltd., 118 Gaodong Road,  
Pudong New District, Shanghai 200137, China; [EMAIL_ADDRESS] (C.Z. ); [EMAIL_ADDRESS] (H.S. ); [EMAIL_ADDRESS] (H.S. ); wilmar-inl.com (H.S. ); wilmar-inl.com (H.S. ); w  
with [PERSON]'s notion that impressions of different flavors of roasted oils are caused by differences in the quantity rather than the quality of their key aroma-active compounds [10]. The conventional methods of extracting the aroma compounds of oils mainly include headspace solid-phase microextraction (HS-SPME), solvent-assisted flavor evaporation (SAFE), simultaneous distillation extraction (SDE), dynamic headspace (DHS), static headspace (SHS), and stir bar sorptive extraction (SBSE) [12; 13; 14; 15]. Compared to other methods, HS-SPME is a simple and easy technique, which reduces the size of extraction instrumentation and operates solvent-free [16], and has been widely used for volatiles analysis in food products, such as pasta [17], bread [18], and edible oils [19]. SPME-arrow fiber is a new device, which has 6-20 times larger than the sorbent phase of traditional SPME fiber and shows more than 10 times the sensitivities and extraction efficacies [20]. Until now, SPME-arrow fiber has been employed for the determination of volatiles of various food products, such as brown rice vinegar [21], Korean salt-fermented fish sauce [20], soy sauce [22], and milk [23]. In these studies, SPME-arrow showed higher extraction performance, such as more kinds of compounds extracted, larger extraction amount, and better reproducibility. Moreover, SPME-arrow was evaluated as more effective in extracting pyrazines in food matrixes. The HS-SPME technique is based on the distribution of target analyte in the headspace, sample matrix, and SPME fiber coating. Compared to other methods, SPME is a non-exhaustive extraction technique, which means only a small portion of target analytes can be extracted every time [16]. Previous studies have shown that flavor-enhanced oils contain hundreds of volatile compounds [1; 24; 25]. For example, [PERSON] has detected 80 peaks from the volatiles of roasted perilla seed oil [24], [PERSON] has observed 118 peaks, and identified 94 compounds from the volatiles of roasted peanut oil [1]. In the sealed vials, the distribution of volatiles is different in the three phases, which results in the selectivity of different volatiles by HS-SPME. On the other hand, non-degummed and undeodorized flavor oil is a complex sample matrix. The phospholipids, free fatty acids, and other compositions in oils will affect the volatilization and distribution of volatiles by binding, which is called the \"matrix effect\" [26]. For example, phenolic compounds were found to have an effect on the release of volatiles in virgin olive oil [27], which means the composition and property of the sample will affect the distribution of volatiles in the three phases. When there is a matrix effect, HS-SPME combined with traditional calibration methods, such as external standard and internal standard, has some limitations in the quantitation of volatiles in flavor oils. The stable isotope dilution analysis (SIDA) is a good approach that can effectively overcome the matrix effect [28]. However, the stable isotope standards are expensive and not all available commercially.