3.3 Fatty acid compositions
As shown in Table 2, fourteen major fatty acid components were detected and identified, including eight saturated fatty acids, four monounsaturated fatty acids and two polyunsaturated fatty acids. Comparing the composition of AEEO and SEO fatty acids, it was found that there were some differences presented in fatty acid contents, while no obvious difference in their types was detected. The results showed that the extraction method had no significant effect on fatty acid composition of oils, which was in agreement with other reports (Jiao et al., 2014; Li et al., 2013). The contents of fatty acid obtained were different from the values obtained by Trevisani Juchen et al. (2019). The difference in fatty acid contents might be attributed to the cultivars, planting regions, climate conditions, and the posttreatment process (Liu et al., 2019).
It could be observed that the preponderant fatty acid in RBO was linoleic acid (38.26%-38.84%), oleic acid (33.83%-34.31%), followed by palmitic acid (19.17%-19.87%). It also could be seen that the content of unsaturated fatty acids accounting for about 75% of total fatty acids in AEEO and SEO. Moreover, the contents of monounsaturated fatty acids and polyunsaturated fatty acids in AEEO were much higher than that of SEO. It was likely because the relatively mild extraction conditions of AEE was not easy to cause the oxidation and decomposition of unsaturated fatty acids. According to the literature, the oil contains a high level of monounsaturated fatty acid, which has a great potential to produce biodiesel (Lovato, Pelegrini, Rodrigues, Braz De Oliveira & Piloto Ferreira, 2014). The high proportion of linoleic and linolenic acids were precursors of polyunsaturated fatty acids from the omega-3 and omega-6 series and were essential for human health and disease prevention, which indicated their potential development prospects in health products and pharmaceutical industries (Chen, Luo, Qi & Wan, 2014), but also reduced oil stability and shelf life (Haiyan, Bedgood, Bishop, Prenzler & Robards, 2007). Therefore, compared with SE, AEE can reduce costs and green production, while AEEO also has health benefits.