## 4 Extraction Methods for Coriander Bioactive Compounds
### Non-Conventional Extraction Methods
#### 4.2.3. Supercritical Water Extraction and Subcritical Fluid Extraction  
Due to their many benefits, high-pressure extraction technologies, particularly subcritical water extraction (SWE) and supercritical fluid extraction (SFE), have gained attention recently (Figure 2). In the process of separating and purifying crude extracts, they have been able to decrease the amount of energy used and the number of operation units while simultaneously increasing the yield of target compounds from plant material. Furthermore, one of their key benefits is the environmental aspect, given that water and CO\({}_{2}\) have little environmental impact and are safe for human health [132]. In the study conducted by [PERSON], [PERSON] [133], SWE was compared to two conventional methods, hydrodistillation and Soxhlet extraction, in terms of efficiency and EO composition. Their study revealed that although higher extraction efficiencies were obtained with the conventional methods, the SWE yielded EOs with a higher concentration of valuable oxygenated components. For their part, [PERSON], [PERSON] [134] compared the SWE method with the hydrodistillation method. It was found that the efficiency (g oil/g coriander) of SWE was higher than that provided by hydrodistillation with reduced extraction time. The main identified compounds were linalool, isoborneol, citronellyl butyrate, and geraniol. The SWE method offers the possibility to manipulate the oil composition by varying the temperature and adjusting the pressure. The use of the SWE method has therefore proven to be a good alternative for the extraction of EOs. At the time, the EO of coriander obtained via SWE (at a temperature of 65-150 \({}^{\circ}\)C and a pressure of 870-1000 psi = 60-68.95 bars) was comparable to that resulting from hydrodistillation. Furthermore, SWE allows for rapid extraction and has the advantage of being selective as it is possible to manipulate the composition of the extract under given working conditions. Moreover, the study conducted by [PERSON], [PERSON] [135], consists of the comparison of four techniques for the isolation of coriander EO (hydrodistillation, Soxhlet extraction, SFE and SWE). The comparison is based mainly on the total extraction yield as well as on the qualitative and quantitative composition. Their result led to the conclusion that Soxhlet extraction (at 40 \({}^{\circ}\)C) and SFE (at 300 bar) resulted in the highest extraction yields (see 14.45% and 8.88%, respectively). Furthermore, due to the high yield of EO obtained via SFE, this technique also allowed for the extraction of vegetable oils and polyphenols, thus increasing the sanitary value of the extracts obtained and presenting good alternatives to the traditional EO extraction technique. In a recent study, [PERSON], [PERSON] [5] compared the coriander leaves EO extracted via two techniques, namely, SFE and hydrodistillation, in terms of volatile chemical composition and biological attributes. Their study showed that a better yield of coriander EO (0.12%) is obtained via hydrodistillation, as this was slightly higher than that of SFE (0.09%). Nevertheless, GC-MS analysis showed that the oil recovered by SFE was richer in components compared to the hydrodistilled one (23 components identified against 18), where linalool was the main component, followed by phytol. Furthermore, the same authors indicate that the best activities, namely, antioxidant, antifungal, and microbial activities, are also attributed to this extraction process. Overall, their results showed that SFE is superior to hydrodistillation in isolating a better-quality coriander EO for nutritional and pharmaceutical developments. Another study conducted by [PERSON] and [PERSON] [136] was devoted to the extraction of monoterenes from coriander seeds using the SWE process. Their study proved that the extraction of monoterenes via this technique is influenced by the differences in their chemical structures and by the extraction conditions, temperature, and time.