## 4 Extraction Methods for Coriander Bioactive Compounds
### Conventional Extraction Methods
#### 4.1.3 Hydrodistillation  
Hydrodistillation extraction methods use water as the solvent (Figure 2), and their mechanism is similar to that of the Soxhlet extraction process. These two methods are currently employed to isolate the volatile and non-volatile polar components of aromatic plants [111]. The study by [PERSON], [PERSON] [91] aimed to characterize the composition of volatile and non-volatile compound fractions of coriander seeds and leaves using gas chromatography (GC). The results indicated a difference in the yields of volatile compounds, with seeds yielding 1.1% and leaves only 0.1%. There was also a notable difference in the major compounds identified in the seeds and leaves. Furthermore, the major volatile compounds in coriander seed essential oil were linalool, \(\gamma\)-terpinene, \(\alpha\)pinene, camphor, decanal geranyl acetate, limonene, geraniol, camphene, and D-limonene, while the major volatile compounds identified in coriander leaves essential oil were (E)-2-decanal, linalool, (E)-2-dodecenal, (E)-2-tetradecanal, 2-decenen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2-hexadecenal, pentadecenal, and \(\alpha\)-pinene. Additionally, the antioxidant and reducing power abilities of coriander seeds and leaves exhibited concentration-dependent inhibitory effects, with essential oil (EO) showing stronger results in the seeds compared to the leaves. Interestingly, non-volatile extracts from the leaves demonstrated higher potency than those from the seeds, particularly medium-polarity compounds, despite their relatively low overall antioxidant contribution. Furthermore, the study conducted by [PERSON] [90] on the extraction of EO via hydrodistillation found variable yields of oils, ranging from 0.17 to 0.29 mg/100 g, depending on the developmental state at the time of harvest. Identification via GC/MS led to the recognition of 61 and 65 compounds for the generative and vegetative phases, respectively. Meanwhile, [PERSON], [PERSON] [92] investigated the effect of distillation time on the yield, composition, and bioactivity of coriander EO obtained via hydrodistillation. Their results showed a proportional relationship between EO yield and distillation time, with maximum yields achieved between 40 and 160 min. They also noted that the concentration of the main constituent, linalool, increased with longer distillation times, while low-boiling constituents like \(\alpha\)-pinene, camphene, \(\beta\)-pinene, myrcene, para-cymene, limonene, and \(\gamma\)-terpinene decreased with extended distillation. In their work, [PERSON], [PERSON] [82] utilized the hydrodistillation process to extract the total oil of coriander, achieving a total yield of 96.81%, with major compounds including trans 2-dodecenal and dodecanal. This EO contains various oxygenated compounds that may be beneficial for the food and pharmaceutical industries. Additionally, [PERSON], [PERSON] [26] conducted a study on coriander EO extracted via hydrodistillation, correlating chemical composition and thermal behavior through GC/MS, differential scanning calorimetry, and thermogravimetry. They found that the evaporation process of coriander EO occurred in a single step, and their chromatogram analysis revealed the presence of 38 different compounds, with linalool being the predominant component (64.04%). Lastly, [PERSON], [PERSON] [89] investigated the biochemical and bioactive properties of four different varieties of coriander from Turkey, noting differences in crude oil content, fatty acid profiles, and mineral compositions, with the Gamze variety exhibiting the highest crude oil and mineral content. Finally, to sum up, hydrodistillation and Soxhlet extraction methods, which use water as a solvent and operate at high temperature, are commonly used to isolate volatile and non-volatile polar components from aromatic plants. Although hydrodistillation is effective, it also co-extracts fibers. Studies show that yields of compounds vary according to plant parts, solvents, and extraction conditions.