Effect of Pre-Treatment, Treatment, and Extraction Technologies on the Bioactive Substances of Coriander

Abstract

Herbs and spices, with their wealth of bioactive compounds, are widely used in food, medicine, and cosmetics. Among them, coriander (Coriandrum sativum L.) is particularly valued for its medicinal and culinary properties. Growing consumer and industrial interest in natural products has led to the development of modern, environmentally friendly extraction techniques designed to improve the yield and quality of extracts while reducing time, energy, and solvent consumption. These processes make it possible to obtain optimal quantities of active compounds, thereby meeting the growing demand for plant-based products. After showing evidence of coriander’s health benefits, this review summarizes research findings on the impact of some treatments and pretreatments on its phytochemical composition. After that, it summarizes different aspects of the use of conventional and non-conventional extraction techniques for coriander’s bioactive constituents, mainly polyphenols and crude and essential oils (EO). Among these methods, microwave-assisted extraction (MAE/MAHD) emerges as one of the most efficient methods, offering higher yields, better-quality extracts, and a significant reduction in energy costs.

1. Introduction

Numerous developing countries worldwide possess abundant natural resources. This valuable heritage, including medicinal plants, has been used by indigenous populations for centuries in remedies for illnesses, health care products, perfumes, aromas, sweeteners, and pest control agents [1]. Due to their widespread use as natural additives in the food, pharmaceutical, cosmetic, and feed industries, as well as in the research and development field, the production of herbs and spices has expanded globally [2], with coriander being a prime example. In fact, according to recent FAO data [3], the global production of coriander and related spices increased from approximately 299,457 tonnes in 1994 to over 2.75 million tonnes in 2022, illustrating a significant expansion in this sector.

Coriander (Coriandrum sativum L.) is native to the European–Mediterranean area and was cultivated in China in the 1st century BC [4]. Today, this herb is cultivated in a wide range of regions worldwide, such as North Africa, Russia, Central and Eastern Europe, Asia (Pakistan, India, Bangladesh, and China), and Mediterranean regions (Egypt, Morocco, and Malta) [5]. In addition to its culinary uses, coriander is appreciated for its distinctive aroma, flavor, and potential health benefits thanks to its rich chemical composition, which contributes to its bioactive potential. In recent years, there has been an increased interest in exploring the chemical composition of coriander and its potential effects on human health [6]. Therefore, various parts of this plant, including leaves, flowers, seeds, and fruits, as well as essential oils and extracts, have been studied both in vitro and in vivo for their potential biological activities [7]. In fact, its extracts and its bioactive phytochemicals have been reported for a wide range of biological activities, including antioxidant, anticancer, neuroprotective, anxiolytic, hypnotic, anticonvulsant, analgesic, anti-inflammatory, and antidiabetic activities [8].

It should be noted that the bioactive compounds of herbs can vary according to several factors, including variety, geographic area, nutritional status, harvest time, manufacturing process, and even storage method [9]. Similarly, the yield of coriander fruit is affected by abiotic stress, phenological variation and phenotypic plasticity, weather conditions, and agricultural and genetic factors [10]. For instance, drought, as a main abiotic stress, affects the physiological and biochemical processes of plants, particularly the synthesis and accumulation of secondary metabolites [11]. To mitigate these effects, the application of suitable agrotechnical practices can be useful in improving the productivity of the plants [12]. Among these practices, one of the few tactics that has lately seen commercial use is the elicitation-based augmentation of secondary metabolites. Elicitors are substances, microbial or non-biological, which, when in contact with higher plant cells, cause them to produce more pigments, flavones, phytoalexins, and other defense-associated substances [13]. In addition, other treatments and circumstances, including disinfectant washing treatments and storage time could also, have an effect on the quality of fresh coriander, particularly on the content of bioactive compounds, which are very important in leafy greens [14]. Additionally, drying processes have a substantial impact; it was also reported that the yields of the bioactive compounds of dried herb samples were both increased and reduced via different methods, depending on the drying method, time, and temperature [15].

Along with these environmental and agricultural factors, the efficiency of phytochemical extraction methods is equally crucial in determining the composition and purity of the final product. Moreover, the extraction process is the first step in both the analysis and exploitation of plant bioactive constituents, and the most suitable method should be quantitative, non-destructive, and time-saving [16]. However, despite the diversity of extraction methods, they are all united by the requirement for meticulous and thorough execution using straightforward, quick, and workable methods that, if possible, are automated [17]. Methodologies can be classified as either conventional or non-conventional, each with its specific advantages and disadvantages [18]. Conventional methods, including soaking, maceration, water percolation, and Soxhlet extraction, rely on solvent selection and the use of heat and/or agitation to enhance the solubility of target compounds. Nevertheless, these methods often lead to heat deterioration of compounds due to prolonged extraction times and generally do not adhere to eco-extraction principles [19,20]. In contrast, numerous novel extraction techniques, such as pressured liquid extraction, pressurized hot water extraction, ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction (SFE), and subcritical water extraction (SWE), have been developed and studied [21]. These advanced methods are designed to improve solvent usage, extraction time, quality, and efficiency [22]. Nonetheless, despite the innovative approaches provided by recent technological advances, the efficiency of these extraction methods depends on various factors, including the type of samples and solvents used, as well as the pH, temperature, light, duration of extraction, particle size, solvent/sample ratio, and extraction procedure [17,23]. The literature indicates that no review has yet been conducted on the methods of extracting bioactive components from Coriandrum sativum (L.) or its antioxidant capacity. Therefore, after reporting the outstanding multidisciplinary areas of application of this culinary herb or spice, this work aims to provide a comprehensive review of the conventional and innovative extraction methods of main phytochemical (polyphenols, and crude and essential oils (EO)) from different parts of coriander (Coriandrum sativum L.). It is focused on the discussion of the advantages and disadvantages of these processes, while encompassing the set of pretreatments affecting the content of its active compounds. We first document pre-harvest treatments used in the field; then, post-harvest treatments, which refer to the storage period prior to further usage, are documented (Figure 1). This review is intended as a comprehensive reference for researchers and practitioners interested in exploiting the bioactive properties of coriander, highlighting the most effective processes for maximizing its antioxidant potential for possible application in the food and pharmaceutical industries.

2. Overview on Coriander and Areas of Its Application (Traditional Uses)

Coriander (Coriandrum sativum L.) is a member of the Apiaceae family and an annual herbaceous plant [24]. Its name is in fact derived from the Greek word, “Korion”, which means bug [25]. Although this plant is native to the Mediterranean region, it is widely grown for culinary and medicinal purposes across North Africa, Central Europe, and Asia. Moreover, it grows well under a variety of circumstances [24]. Depending on the agroclimatic circumstances, the plant’s height might vary from 20 to 140 cm. The various parts of coriander (

Table 1. Description of coriander different parts [25].

Coriander Parts	Leaves	Stems	Flowers	Seeds
Description	Leaves are oval, slightly lobed, and sections of the upper leaves are linear and more divided.	The stem is erect, thin, sympodial, monochasial. and branched, with several side branches at the basal node, and each branch ends with an inflorescence.	The flowers are small, shortly stalked umbels, pinkish and whitish in color. The fruits are globular or ovate, consisting of two pericarps, with a diameter up to 6 mm.	The seeds are almost ovate, globular, and have a mild, sweet, and slightly pungent citrus- like flavor with a hint of sage. The most important constituents of its seeds are the EO and fatty oil.
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) are employed for useful purposes. However, only the tender leaves—ternate–pinnate leaves that have not split into tiny, linear segments yet—are utilized in Mexican, Chinese, and Indian curries and sauces. The distinctive “bug” odor of the plants is attributed to the EO of the seeds, which are located inside the convex longitudinal vittae. As a plant reaches maturity, its various sections have drastically varied odor profiles. Greenery and immature seeds smell different than ripe fruits [25]. The most important part of this plant is its seed, which is the main reason for its wide exploration [26]. About 0.9% of EOs (volatile oils) and about 28% of vegetable oils are present in the seed. Important substances included in these two oil fractions include linalool, which makes up about 70% of each oil fraction, and petroselinic acid, which is present in vegetable oil [27,28]. This dissimilarity in the composition of the different phytoconstituents could be used for various applications such as health supplements and pharmaceuticals. Above all, this plant has significant commercial value since it has been utilized as a flavoring agent in food goods, cosmetics, and perfumes. As a medicinal plant, coriander has been credited with a wide range of therapeutic applications [29]. In addition to the applications mentioned above, several studies have shown a wide range of biological activities: antioxidant, antimutagenic, antidiabetic, anthelmintic, anticonvulsant, sedative–hypnotic, and diuretic activities, a protective role against lead toxicity, cholesterol lowering, antifungal, anticancer, antifeeding, anxiolytic, antiprotozoal, and hepatoprotective activities, post-coital anti-fertility, antiulcer activities, and heavy metal detoxification [30]. Hence, coriander is considered a distinguished functional food of interest due to its therapeutic qualities and easy integration into daily life. In particular, the potent antioxidant properties of coriander extracts and its main compound, linalool, play a crucial role in mediating these medical benefits [8]. Some of its biological effects and uses are summarized in

Table 2. Biological effects and application of coriander products in different forms.

Nature of Active Compounds/Extracts	Biological Effect and Application	References
Essential oil	Antioxidant activity in Italian salami	[31]
Essential oil	Antioxidant and antifungal activities in cake for 60 day storage at room temperature	[32]
Essential oil	Antibacterial activity against Acinetobacter baumannii	[33]
Essential oil	Anti-Campylobacter activity	[34]
Essential oil	As natural food additive to improve the quality and safety of cooked pork sausages with different nitrite levels	[35]
Essential oil	Antioxidant towards DPPH radical, antimicrobial, and antibiofilm activity against Stenotropomonas maltophilia and Bacillus subtilis	[36]
Essential oil	Antioxidant and anti-inflammatory activity, innate immune responses, and resistance to Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus)	[37]
Essential oil	Anesthetic effects on rainbow trout	[38]
Essential oil seeds of nine coriander populations	Antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa	[39]
Volatile oil	Cognitive-enhancing and antioxidant activities in amyloid beta (1–42) rat model of Alzheimer’s disease	[40]
Volatile oil	Anxiolytic–antidepressant-like behaviors and decreased oxidative status in beta-amyloid (1–42) rat model of Alzheimer’s disease	[41]
Essential oil incorporated in dextrin-derived nanosponges	Antimicrobial activity against foodborne pathogens	[42]
Vegetable oil	Can replace ionophore salinomycin in the diet of early lactating Friesian cows	[43]
Seeds powder	In vivo antioxidant and antidiabetic effects	[44]
Seeds powder	Used to improve the fatty acid composition of breast meat of quails	[45]
Seeds powder	Coriander seed powder supplementation improved growth performance and carcass traits of Koekoek chickens.	[46]
Seeds powder	Coriander seed powder supplementation improved the fermentation process and modified the quality of beer	[47]
Leaf powder	Antioxidant and antiarthritic activities in vivo via the administration of coriander leaf powder (5 g/day) to selected osteoarthritis patients for 60 days	[48]
Hexane and methanolic extracts of raw and roasted seeds	Antioxidant, anti-inflammatory, and human tumor cell proliferation inhibitory effects	[49]
Hexane, chloroform, ethyl acetate, methanolic and total methanolic extracts of coriander spice	The antimicrobial, antibiofilm, anti-quorum sensing, and antiswarming properties	[50]
Leaves water extract	Proteolytic activity, antioxidant, and α-Amylase inhibitory activity of yogurt enriched with coriander	[51]
Seeds aqueous extract	Anxiolytic activity on chronic-restraint-stressed mice and effect on brain neurotransmitters	[52]
Nanoemulsion of ethanolic seed extract	Bacteriostatic action against Staphylococcus aureus, Escherichia coli, and Aspergillus flavus	[53]
Four novel compounds of fruits	Anti-inflammatory activity	[54]
Isolated eight compounds from the water-soluble extract of leaves, petioles and stems	In vivo anti-degranulation activity	[55]
Coriander straw fiber	Reinforced filler in polypropylene and biobased low-density polyethylene composite materials	[56]
Silver nanoparticles based on fresh leaves	Antimicrobial activity mainly against Staphylococcus aureus, S. epidermidis, and S. pneumoniae; antioxidant effect towards superoxide and hydroxyl radicals; anticancer effect on the MCF-7 cell line	[57]

.

3. Treatments and Pretreatments Affecting Coriander Antioxidants

Physiological, genetic, and agronomic factors (such as the cultivar, soil composition, agronomic treatments, meteorological conditions, and pre- and post-harvest treatments) all affect the phytochemical compounds’ contents [58]. Among these factors, several pre- and post-harvest treatments have been applied to plant matrices to overcome the occurrence of freezing injury, sustain product quality throughout storage, and conserve the bioactive ingredients, among other reasons [59]. Therefore, it is crucial to administer pretreatment or treatment that maintains or enhances the functional and nutritious substances [60], whose role has the greatest significance and a major influence on the quantity and quality of target compounds [61] (Table 3).

Applied pretreatments and treatments to plant crops could be any of the following:

(1)

Before/or during their harvest: application of bioinoculants [62] or application of some foliar fertilizers and biostimulators [12];

(2)

During storage: drying methods effect [15] and/or storage conditions [63];

(3)

During extraction processes preparation: washing treatments [14] and the type of whitening [64].

However, less information is available on the effects of treatments and pre-treatments applied to the coriander crop, particularly on its bioactive compounds (including its polyphenols, EO, and crude oil).

Table 3. Main treatments and pretreatments affecting coriander components.

Classification of Treatments and Pretreatments	Nature of Treatments and Pretreatments	Affecting the Compounds	Main Findings	References
Before /or during their harvest	- Malic acid (MA); - Oxalic acid (OA); - Acetylsalicylic acid (ASA).	- TPC.	+ + +	[13]
	- 1-methylcyclopropene (1-MCP).	- Volatile oil and chlorophyll.	+	[65]
	- 500 mg/kg of Pb.	- TPC and antioxidant capacity.	+	[66]
	- Cadmium levels (Cd); - Lead levels (Pb).	- EO content, TPC, and total flavonoids.	+ +	[67]
	- Rhizobacteria; - Mycorrhizae; - Rhizobacteria and mycorrhizae combination.	- EO yield and profile.	+ + +	[62]
	- Mycorrhizal fungi (Glomus intraradices).	- EO yield and composition.	+	[68]
	- Silicon (Si); - Nanoparticles of Silicon (Si-NPs).	- TPC, total flavonoid, and EO.	+ +	[11]
	- Benzyl adenine (BA); - Salicylic acid (SA).	- Total antioxidants content; - Antioxidant capacity.	+ +	[69]
	- Salinity.	- EO; - TPC.	+ −	[70]
	- Salt stress.	- Saturated fatty acids; - Monounsaturated fatty acids; - Polyunsaturated fatty acids. - Unsaturated fatty acids.	+ − − −	[4]
	- Silicon (Si) and salinity.	- EO yield and composition.	+	[4]
	- Masterblend; - Fertigrain.	- EO.	+ +	[12]
	- Ultraviolet (UV-C) radiation.	- TPC, flavonoids, and antioxidant activity.	+	[71]
	- Spectral quality under the photoselective red and pearl nets.	- Total phenols, flavonoids (quercetin), and antioxidant activity.	+	[72]
	- Effect of amino acids.	- EO.	+	[73]
	Fertilization systems and sowing rates	- EO content and yield.	+ with an optimal yield observed at a sowing rate of 2.5 million seeds/ha	[74]
During storage	- Microwave drying - Convective drying	- TPC; - TFC; - Antioxidant activities.	- Microwave drying was the best	[75,76,77]
	- Drying: - In sunlight; - Shade; - Mechanical ovens (40 and 60 °C); - Microwave oven (500 and 700 W); - Freeze-drying.	- EO.	- Freeze-drying was the best	[15]
	- Microwave drying	- TPC; - TFC; - Antioxidant activities.	+	[78]
	- Spray-drying:	- EO.	+	[79]
	Effect of drying temperature, particle size, and propane extraction.	- Volatile composition; - Oil content; - Fatty acid composition.	- Volatile compounds were best preserved at 60 °C; - Propane extraction led to a decrease in volatile composition, oil content, and fatty acid composition.	[63]
	- Storage: - In the freezer; - In the fridge; - At room temperature; - At high temperature.	- Volatile composition during prolonged storage.	- Volatile compounds were best preserved when cilantro samples were dried at 60 °C, extracted with propane, and stored in refrigerator or in freezer.	[63]
During extraction processes preparation	- Dehulling of coriander fruit	- Oil content.	+	[80]
	Washing: - Sodium hypochlorite (SH, 100 mg/L); - Chlorine dioxide (CD, 10 mg/L); - Sodium butyl p-hydroxybenzoate (SBPH, 12 mg/L); - Tap water.	- TPC and ascorbic acid (VitC).	− − − −	[14]
	- Steam blanching; - Water blanching.	- TPC and antioxidant capacity.	+ +	[64]

+: positive effect; −: negative effect.

Table 3. Main treatments and pretreatments affecting coriander components.

Classification of Treatments and Pretreatments	Nature of Treatments and Pretreatments	Affecting the Compounds	Main Findings	References
Before /or during their harvest	- Malic acid (MA); - Oxalic acid (OA); - Acetylsalicylic acid (ASA).	- TPC.	+ + +	[13]
	- 1-methylcyclopropene (1-MCP).	- Volatile oil and chlorophyll.	+	[65]
	- 500 mg/kg of Pb.	- TPC and antioxidant capacity.	+	[66]
	- Cadmium levels (Cd); - Lead levels (Pb).	- EO content, TPC, and total flavonoids.	+ +	[67]
	- Rhizobacteria; - Mycorrhizae; - Rhizobacteria and mycorrhizae combination.	- EO yield and profile.	+ + +	[62]
	- Mycorrhizal fungi (Glomus intraradices).	- EO yield and composition.	+	[68]
	- Silicon (Si); - Nanoparticles of Silicon (Si-NPs).	- TPC, total flavonoid, and EO.	+ +	[11]
	- Benzyl adenine (BA); - Salicylic acid (SA).	- Total antioxidants content; - Antioxidant capacity.	+ +	[69]
	- Salinity.	- EO; - TPC.	+ −	[70]
	- Salt stress.	- Saturated fatty acids; - Monounsaturated fatty acids; - Polyunsaturated fatty acids. - Unsaturated fatty acids.	+ − − −	[4]
	- Silicon (Si) and salinity.	- EO yield and composition.	+	[4]
	- Masterblend; - Fertigrain.	- EO.	+ +	[12]
	- Ultraviolet (UV-C) radiation.	- TPC, flavonoids, and antioxidant activity.	+	[71]
	- Spectral quality under the photoselective red and pearl nets.	- Total phenols, flavonoids (quercetin), and antioxidant activity.	+	[72]
	- Effect of amino acids.	- EO.	+	[73]
	Fertilization systems and sowing rates	- EO content and yield.	+ with an optimal yield observed at a sowing rate of 2.5 million seeds/ha	[74]
During storage	- Microwave drying - Convective drying	- TPC; - TFC; - Antioxidant activities.	- Microwave drying was the best	[75,76,77]
	- Drying: - In sunlight; - Shade; - Mechanical ovens (40 and 60 °C); - Microwave oven (500 and 700 W); - Freeze-drying.	- EO.	- Freeze-drying was the best	[15]
	- Microwave drying	- TPC; - TFC; - Antioxidant activities.	+	[78]
	- Spray-drying:	- EO.	+	[79]
	Effect of drying temperature, particle size, and propane extraction.	- Volatile composition; - Oil content; - Fatty acid composition.	- Volatile compounds were best preserved at 60 °C; - Propane extraction led to a decrease in volatile composition, oil content, and fatty acid composition.	[63]
	- Storage: - In the freezer; - In the fridge; - At room temperature; - At high temperature.	- Volatile composition during prolonged storage.	- Volatile compounds were best preserved when cilantro samples were dried at 60 °C, extracted with propane, and stored in refrigerator or in freezer.	[63]
During extraction processes preparation	- Dehulling of coriander fruit	- Oil content.	+	[80]
	Washing: - Sodium hypochlorite (SH, 100 mg/L); - Chlorine dioxide (CD, 10 mg/L); - Sodium butyl p-hydroxybenzoate (SBPH, 12 mg/L); - Tap water.	- TPC and ascorbic acid (VitC).	− − − −	[14]
	- Steam blanching; - Water blanching.	- TPC and antioxidant capacity.	+ +	[64]

+: positive effect; −: negative effect.

4. Extraction Methods for Coriander Bioactive Compounds

Phytochemical analyses have highlighted that coriander parts are rich sources of bioactive compounds [24]. In order to improve the coriander practicality, and in particular, to increase the availability of health promoting molecules, various extraction methods have been exploited to maximize the extraction of the active ingredients of this herb (Figure 2). This section will discuss the conventional and state-of-the-art techniques applied to obtain bioactive compounds from coriander.

4.1. Conventional Extraction Methods

Numerous studies have demonstrated the wide range of conventional extraction techniques, such as maceration [81,82,83,84,85,86,87,88], hydrodistillation [26,82,89,90,91,92], and Soxhlet extraction [93,94,95,96], that are available for obtaining phytochemical components from plant materials, including coriander. These methods often involve applying temperature treatment and using various solvents dependent on the components that need to be removed or extracted more effectively [97]. Furthermore, the organic solvents used in the extraction will need to be removed from the final product by evaporation, posing both economic and environmental risks [98].

4.1.1. Maceration

A conventional procedure such as maceration (Figure 2), which has been used for a long time, is still relevant even if it is often criticized for its extraction time (few hours) and high temperature (above 80 °C). Some authors continuously refine this method by adjusting the extraction parameters (solvent type, liquid to solid ratio, etc.) to shorten the extraction period and lower the temperature [99]. Many studies have been devoted to the extraction of secondary metabolites from the coriander plant by this method. Indeed, the study by Arjun, Semwal [82] was the first study using fresh coriander leaves to assess the total phenolic content (TPC) and the antioxidant activity of the acetone extract. The study concluded that coriander is a rich source of antioxidants and TPC and thus could be used as a potent nutraceutical agent in daily foods. In addition, the study conducted by Nathenial, Fatima [86] on the phytochrome of the acetone extract of dried coriander seeds revealed the presence of many secondary metabolites, including flavonoids, which were present in a very high concentration, while tannins, alkaloids, quinines, terpenoids, cardiac glycosides, and phlobatannins were present in low amounts, and saponins were not identified. Moreover, the study conducted by Verma, Dhanik [88] aimed to investigate and compare the genotypic variations and similarities existing among the seventeen genotypes of coriander leaves and seeds collected from the Tarai and Kumaun areas of Uttarakhand state in India. Phytochemical screening revealed the presence in their methanolic extracts of many constituents, including alkaloids, saponins, phytosterols, fixed oils, phenols, tannins, and flavonoids, but the absence of resins and triterpenes. The types of phytoconstituents in the leaves and seeds of the different genotypes were not similar.

The study conducted by Al-Juhaimi and Ghafoor [81] highlighted the variability of TPC depending on the coriander part. They observed that the extract of coriander leaves contained a higher amount of TPC and presented higher antioxidant activities than the extract of stem parts. Nevertheless, they reported that the leaves and stems of coriander grown in Saudi Arabia contained good amounts of total phenols (>1.02 mg gallic acid equivalent/100 mL) and showed a free radical scavenging activity higher than 18.3%. In the study conducted by Msaada, Jemia [85] on the methanolic extracts of three coriander fruits, they reported variability in polyphenol, flavonoid, and tannin contents and antioxidant activity among Tunisian, Syrian, and Egyptian varieties. In addition, the study conducted by Tang, Rajarajeswaran [87] revealed a variability in TPC according to the type of extraction solvent: hexane, dichloromethane, ethyl acetate, methanol, and water. Indeed, the best content was attributed to the extract obtained by ethyl acetate. A more recent study conducted by Demir and Korukluoglu [84] tried to contrast the phenolic profile composition and antioxidant activity of ethanolic and methanolic extracts of coriander seeds. The results showed that the best polyphenol content and antioxidant capacity were obtained with the methanolic extract and 22 phenolic compounds were identified and quantified. The results obtained by these authors can be explained by the fact that good solvent system allows for the optimal extraction of desired compounds without modifying their chemical nature [100], and generally, polar organic solvents are the most effective in bioactive substances solubilizing from plant tissues [101]. The study conducted by Barros, Dueñas [83] brings the information that the vegetative parts showed hydroxycinnamic acids derivatives and flavonol derivatives (quercetin and kaempferol derivatives) as the main phenolic compounds. Otherwise, the fruits revealed the occurrence of only phenolic acid derivatives, with caffeoyl N-tryptophan hexoside being the most abundant. In vitro samples also yielded a wide range of polyphenols, with C-glycosylated apigenin being the main compound.

Hence, even though maceration is an ancient extraction process, it showed that coriander could be a source of polyphenols diversity and other phytochemicals, connected to its potent antioxidant action and its application in indigestion, rheumatism, and shielding against lipid peroxidation damage [83].

In conclusion, although maceration is a traditional method with advantages and disadvantages, continuous improvements and adjustments to this method can make it more effective for extracting bioactive compounds from coriander. Future studies should focus on optimizing these parameters to maximize the quality and quantity of extracts, while exploring alternative methods for more specific applications.

4.1.2. Soxhlet Extraction

Soxhlet seems to be the most adapted technique for extracting the aerial parts of plants in terms of yield (Figure 2). However, it should be emphasized that this extraction technique is conducted at high temperature and allows fibers to be co-extracted [102]. Moreover, the different solvents used can modify the yield of the extraction process [103].

Although Soxhlet extraction is effective at the lab scale, it has major drawbacks: it requires large volumes of solvents, consumes high energy, and is therefore not attractive for industrial applications [104]. In contrast, unconventional methods, such as microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE), have recently attracted growing interest in both academic and industrial fields [105]. These processes are faster and more efficient than conventional methods, saving energy and reducing extraction costs [106]. In addition, several studies have confirmed these advantages, showing that MAE [107,108,109] and UAE [102,110] outperform Soxhlet extraction in terms of efficiency, with higher yields, shorter extraction times, and reduced energy consumption, making these techniques more suitable for industrial applications.

The study conducted by Wong and Kitts [96] on the methanolic and aqueous extracts of coriander polyphenols found that the aqueous extract contained the highest levels of polyphenols compared to the methanolic one. Nevertheless, the best antioxidant activities were attributed exclusively to the methanolic extract. On the other hand, most of the investigations using the Soxhlet extraction method were dedicated to the extraction of apolar compounds, mainly oils from coriander seeds. So, the coriander seed powder phytochemicals EO was also obtained via the Soxhlet extraction method using different solvents (water, ethanol, petroleum benzene, methanol, chloroform). Phytochemical analysis revealed the presence of bioactive compounds such as flavonoids, phenols, terpenoids, and alkaloids in all extracts. While the chloroform extract at different concentrations (20, 30 and 40 μL) was tested for its antibacterial activity, it was found to have an inhibitory effect on Escherichia coli and Pseudomonas aeruginosa but not on Staphylococcus aureus [95]. Moreover, the study conducted by Balbino, Repajić [93] revealed that coriander seeds have a substantial oil yield (12.30%) and C18:1 fatty acid content (sum of petroselinic and oleic acid), but the lauric acid content was low. It was also found to have a high level of sterols and significant levels of the triterpenes α- and β-amyrin. On the other hand, when evaluating the effectiveness of the extraction methods (Soxhlet extraction, shaking-assisted extraction, and pressurized liquid extraction (PLE) at 25 and 100 °C) in terms of seed oil yield and bioactive compounds content, the results revealed that the highest oil yields were obtained via the conventional methods (Soxhlet extraction and shaking-assisted extraction at room temperature). Meanwhile, the highest contents of total sterols and triterpenes were obtained via PLE at 100 °C.

The Soxhlet extraction process was also applied to extract oil from coriander to study oil accumulation and fatty acid composition during fruit development (from flowering to maturity) and the effects of climatic conditions on these characteristics during two growing seasons. The results showed that in 2010, compared with 2011, the fruit contained 2% more oil, while the opposite was true for petroselinic acid (PA) content. Thus, these results imply that higher PA concentrations can be obtained by harvesting the fruit before full maturity [94].

The above studies highlight the Soxhlet extraction technique for aerial plant parts, emphasizing its efficiency in terms of yield despite high temperatures and the co-extraction of fibers. This method is particularly useful for extracting apolar compounds such as coriander seed oils. However, although the Soxhlet extraction method is effective in obtaining high yields of plant extracts, it presents challenges in terms of temperature conditions and choice of solvents. Optimization of these parameters and comparison with other modern methods could further improve the efficiency and quality of the extracts obtained.

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 Shahwar, El-Ghorab [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, γ-terpinene, α-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-decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2-decen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2-hexadecenal, pentadecenal, and α-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 Nurzynska-Wierdak [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, Zheljazkov, Astatkie [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 α-pinene, camphene, β-pinene, myrcene, para-cymene, limonene, and γ-terpinene decreased with extended distillation.

In their work, Arjun, Semwal [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, Micić, Ostojić [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, Beyzi, Karaman [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. Optimizing extraction parameters, such as distillation time and choice of solvent, is crucial to improving the efficiency and quality of extracts. For example, increasing the distillation time improves the yield of coriander essential oil and the concentration of its main constituents, such as linalool. In conclusion, although these methods are effective, they present challenges that require adjustments to maximize the quality of bioactive compounds, taking into account variations between plant parts and growing conditions.

4.2. Non-Conventional Extraction Methods

One of the main challenges to technological innovation in the direction of “Green chemistry” is the creation of new extraction techniques [112]. An appreciable number of innovative extraction techniques have been developed to extract bioactive compounds or secondary coriander metabolites, but the most exploited are microwave-assisted extraction, ultrasound-assisted extraction, supercritical fluid extraction, and subcritical water extraction. MAE and UAE are both aligned with the principles of green chemistry, reducing the use of solvents and energy consumption. Together, these techniques represent major advances in the search for efficient, environmentally friendly extraction methods [112]. Microwaves are generally superior to ultrasound in cases where higher yields, shorter extraction times, and uniform heating are required, particularly for more complex or dense matrices [113,114,115].

4.2.1. Microwave-Assisted Extraction

Because it has a higher extraction efficiency than other conventional extraction techniques, microwave-assisted extraction, or MAE (Figure 2), is a relatively novel technique that is being utilized extensively to extract active components from a variety of plant materials [116]. MAE turned out to be far more efficient and cost-effective. Similar to classical solvent extraction, MAE involves the target compounds migrating out of the matrix through the solvent as the solvent diffuses into the sample matrix and removes the components via solubilization [116]. By combining an extraction method with microwave heating, MAE is a potential technology for the extraction of bioactive chemicals from vegetal material. The basis for microwave heating is the way that ionic conduction and dipole rotation cause the microwaves to interact with the molecules of the substance [117]. In addition to producing heat quickly, the MAE system can help solvents enter raw plant material and intracellular material to enhance ingredient transfer, shorten extraction times, and increase extraction rates [9]. The liquid-to-solid ratio, extraction power, extraction time, and type of extraction solvent all affect MAE efficiency [118]. MAE has been shown to be highly effective for the hydrodistillation of EO, and it is being studied on a number of fronts, including the polyphenols extraction [19].

This extraction method was applied by Zeković, Vladić [119], in their investigation into the process of extracting polyphenols from coriander seeds, they aimed to maximize both the yields of total phenolic (TP) and total flavonoid (TF) compounds while also maximizing the antioxidant activity, as assessed through 1,1-diphenyl-2-picrylhydrazyl and reducing power tests. A Box–Behnken experimental design applying response surface methodology (RSM) was employed for the optimization of three parameters influencing MAE, namely, ethanol concentration (50–90% w/w), extraction time (15–35 min), and irradiation power (400–800 W). The best MAE conditions for concurrently maximizing polyphenol output and increasing antioxidant activity were determined by this study to be a 19 min extraction period with 63% ethanol and 570 W of irradiation power. Hence, under these optimal MAE conditions, the predicted values were in the order of 311.23 mg gallic acid equivalent/100 g dry weight (DW) for TP, 213.66 mg catechin equivalent/100 g DW for TF, 0.0315 mg/mL, and 0.1311 mg/mL for IC₅₀ and EC₅₀, respectively. A recent investigation by Mouhoubi, Boulekbache-Makhlouf [120], consisting of a comparative study between MAE and conventional extraction (CE), used a hot maceration method, based on the yield of TPC and their profile, as well as the antioxidant activity of coriander leaves powder. During this study, a central composite design with RSM was applied for the optimization of four parameters influencing MAE, namely, ethanol concentration (%, V/V), microwave power (W), irradiation time (min), and solvent-to-solid ratio (mL/g), while CE was conducted using the classic water bath method. The study found that under the optimal conditions (50% ethanol concentration, 400 W microwave power, 2.14 min of extraction time, and a 75 mL/g liquid-solid ratio), TPC yield recovery was 37.94 mg (MAE) as opposed to 44.47 mg GAE/g DW (CE). The two extracts have a similar phenolic composition, according to the ultra-high-performance liquid chromatography (UHPLC) analysis. Moreover, no significant difference was recorded in terms of the antioxidant activity of both extracts. Therefore, these authors pointed out that there are many valuable advantages to using MAE as the processing time is short and the antioxidant activity and phenolic composition have not been affected by the extraction process. Similarly, Hihat, Touati [121] optimized the extraction of TPC and total antioxidant capacity (TAC) from coriander leaves using MAE and RSM, achieving yields of 49.63 mg GAE/g dw for TPC and 5.55 mg GAE/g DW for TAC under optimal conditions, which confirmed the effectiveness of their model.

Meanwhile, Priyadarshi, Balaraman [122] have also used an effective ionic liquid-based microwave-assisted extraction (IL-MAE) technique to recover the molecule responsible for the radical scavenging activity in coriander foliage, namely, Heneicos-1-ene, followed by its quantification via HPLC. The RSM was applied to determine the optimal levels of six parameters affecting the extraction, such as material/solvent ratio, types of IL, IL concentration, microwave power, temperature, and extraction time, to maximize yield. Using a 0.1 M solution of 1-Butyl-3-methylimidazolium tetrafluoroborate, optimal conditions were achieved at 800 W and 90 °C over 2 min at a material-to-solvent ratio of 1:10. Under these conditions, a maximum predicted yield of Heneicos-1-ene (412.8 mg/100 g), compared to 408.50 ± 1.14 mg/100 g for the experimental value, was obtained. Compared to the conventional method (69.77 ± 1.8 mg/100 g), the IL-MAE gave a 5.85 times higher yield.

Other studies, however, were conducted with the aim of comparing two extraction processes: hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). The comparison carried out by Sourmaghi, Kiaee [123] is based on the effects of microwave radiation on the amount, quantity, and antimicrobial activity of coriander fruits EOs. The yields of the extraction from HD and MAHD were 0.2% and 0.1%, respectively. The findings showed that monoterpenoids, including linalool, geranyl acetate, and γ-terpinene, dominated the two extracted oils, with linalool being the primary constituent of both extracts. Both oils also showed activities against the tested bacterial species. This study concluded that despite the decrease in oil yield and total composition when applying the innovative MAHD method, its use proved to be superior in terms of energy saving and extraction time. Similarly, the comparison led by Ghazanfari, Mortazavi [124] was based on the results of the chemical composition and TPC as well as the antimicrobial and antioxidant properties of EOs from coriander seeds. The results revealed that no significant difference (p > 0.05) was noticed between the extraction efficiency of the HD (0.31%) and MAHD (0.325%) methods. Nevertheless, they indicated that the MAHD extraction process was a better method for the separation of EOs as it had the advantage that the extraction time was shorter (60 min vs. 240 min). Furthermore, in terms of energy consumption and cost, MAHD was also more economical.

The previous paragraphs have examined the effectiveness of MAE compared with conventional extraction methods, and it can be concluded that MAE and MAHD offer significant advantages in terms of speed, energy efficiency, and the yield of bioactive compounds compared with conventional extraction methods. However, challenges remain, particularly in terms of optimizing extraction parameters and standardizing processes to ensure reproducible results. Future research should focus on improving these methods to maximize their industrial potential while minimizing costs and environmental impact.

4.2.2. Ultrasound-Assisted Extraction

One quick, easy, and inexpensive green extraction method that is gaining popularity is ultrasound-assisted extraction (UAE) (Figure 2). Its effectiveness has been proven in the extraction of bioactive chemicals, yielding greater recovery rates than traditional extraction methods while maintaining the extracts’ intended properties [125]. Thanks to its high frequency ultrasonic waves, the UAE method has been used to extract several antioxidants from the plant matrix. Plant cell walls are broken, and the solvent is helped to infiltrate by the waves’ contraction and expansion cycles and cavitation. Many variables, such as solvent concentration, solvent/material ratio, ultrasonication time, temperature, power, etc., affect the extraction rate and yield of UAE [126].

This extraction technique has been widely used for the extraction of bioactive constituents of coriander, namely, its polyphenols and EOs. During the study conducted by Zeković, Bušić [127], after extracting EOs from coriander seeds via the SFE method, the resulting raffinate (also called pellet) was subjected to the extraction of phenolic compounds via UAE using 70% ethanol and water as solvents for comparative purposes. The results of their study showed that the content of dominant compounds in these extracts increased with the reduction of the mean particle size and was significantly higher in the 70% ethanolic extracts. Furthermore, a better antioxidant activity was attributed to these ethanolic extracts than to the aqueous extracts. Another study conducted later by Zekovic, Djurovic [128] investigated the optimization of UAE of phenolic compounds from seeds using RSM, investigating the influence of three variables, namely, temperature (40–80 °C), extraction time (40–80 min), and ultrasonic power (96–216 W). The optimal conditions found are for TP (79. 60 °C, 49.20 min, 96.69 W), TF (79.40 °C, 43.60 min, 216.00 W), IC₅₀ (80.00 °C, 60.40 min, 216.00 W), and EC₅₀ (78.40 °C, 68.60 min, 214.80 W). The predicted values for TP, TF, IC₅₀, and EC₅₀ were 382.68 mg gallic acid equivalent/100 g, 216 mg catechin equivalents/100 g, 0.03764 mg/mL, and 0.1425 mg/mL, respectively. A more recent study conducted by Palmieri, Pellegrini [102] consists of a comparison of different conventional and non-conventional extraction techniques—maceration, Soxhlet, UAE, and rapid solid–liquid dynamic extraction—in terms of the extraction yield of polyphenols, antioxidant activity (FRAP, ABTS, and DPPH), and phenolic profile. The findings showed that the best polyphenol yield was attributed to UAE, while the best activities were attributed to rapid solid–liquid dynamic extraction (RSLDE). As for the phenolic profile, regardless of the extraction method, a total of ten compounds were identified, including eight phenolic acids and two flavonoids. The same study found that, except for luteolin and p-OH-benzoic acid, the RSLDE extracts had higher concentrations of gallic, p-OH-benzoic, and rosmarinic phenolic acids, as well as luteolin and apigenin. A longer extraction time was found to affect these concentrations positively. Nevertheless, the Soxhlet extracts exhibited greater amounts of chlorogenic, vanillic, and caffeic acids, alongside the existence of syringic acid, which was not spotted in the RSLDE extracts when this process was applied for either 2 h or 6 h. The same authors, Palmieri, Pellegrini [102], characterized the volatile fraction obtained by the four methods mentioned above and highlighted the presence of 18 terpenoids in coriander seed extracts, all belonging to the monoterpene class, of which the most abundant compound was linalool. However, the volatile fractions of the coriander UAE and 6 h RSLDE extracts were primarily composed of acyclic monoterpenes. Senrayan and Venkatachalam [129] studied this non-conventional method for the extraction of coriander seed oil by studying the influence of four parameters, namely, sample solvent ratio, amplitude level, temperature, and time, providing results on the influence of these parameters on the yield of oil extraction and their antioxidant activity. Based on their findings, the best extraction conditions for maximum oil yield and antioxidant activity (30.74–72.05%), respectively, were attributed to the sample–solvent ratio of 1:13 (g/mL), the amplitude level of 82 (%), under a temperature of 45 (°C) and the extraction time of 9 (min). In addition, the study conducted by Messaoudene, Palma [130] aimed to optimize an ultrasound-assisted extraction method for phenolic compounds in coriander, focusing on caffeic acid as the primary target. Using a Box–Behnken Design (BBD) with response surface methodology (RSM), the researchers identified methanol concentration as the most crucial factor for recovery. The optimal extraction conditions were determined to be 10 min, 70 °C, 50% methanol in water, and a 6.51 mL/g solvent-to-sample ratio. The method showed high repeatability and reproducibility, suggesting its potential use in quality control analyses of coriander.

On the other hand, Gallo, Ferracane [131], by comparing the efficiency of UAE to the MAE of bioactive metabolites (notably coriander polyphenols), reported that no significant difference between the two methods was found.

In closing, ultrasound-assisted extraction (UAE) appears to be a promising extraction method for bioactive compounds, with significant advantages in terms of yield and the preservation of extract properties. However, its effectiveness is highly dependent on specific extraction conditions, requiring careful optimization. Although UAE sometimes outperforms conventional methods in terms of yield, it is not always the best option for all applications, and its use should be judiciously considered according to the specific extraction objectives.

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 CO₂ have little environmental impact and are safe for human health [132].

In the study conducted by Eikani, Golmohammad [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, Saim, Osman [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 °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 Pavlić, Vidović [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 °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, Abbas, Anwar [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 Song and Ko [136] was devoted to the extraction of monoterpenes from coriander seeds using the SWE process. Their study proved that the extraction of monoterpenes via this technique is influenced by the differences in their chemical structures and by the extraction conditions, temperature, and time. Indeed, the increase in temperature and extraction time led to a decrease in the extraction efficiency of linalool and an increase in that of linalool oxide, resulting from the conversion via hydrothermal oxidation of linalool to linalool oxide. As for geraniol, having the same chemical formula as linalool, it was extracted at a high temperature (170 °C) due to the different location of the hydroxyl groups. The efficiency of the SWE process for geraniol and linalool oxide was shown by this study to be superior compared to conventional extraction methods (hexane, methanol, hot water, and hydrodistillation). Therefore, SWE can be used efficiently and selectively to extract monoterpenes by taking advantage of temperature changes in a short extraction time.

Other studies were devoted to investigating the parameters influencing the SFE and SWE processes. In fact, Zeković, Bušić [127] studied a non-conventional SFE method and the influence of particle size on the yield and chemical profile of Eos, and the result was compared to conventional techniques, namely, hydrodistillation and Soxhlet extraction. Their study showed that the SFE method has advantages over non-conventional methods in terms of oil yield and selectivity. The study conducted by Zeković, Pavlić [137] aimed at the optimization of the SFE process of EO from coriander seeds. This was carried out using the BBD in combination with the RSM, investigating the influence of three variables, namely, pressure (100, 150, and 200 bar), temperature (40, 55, and 70 °C), and CO₂ flow rate (0.2, 0.3, and 0.4 kg/h). The results allowed for the determination of the optimal conditions for extraction performance (199.50 bar, 40.15 °C, 0.396 kg/h of CO₂). Furthermore, the chemical composition study showed that linalool was the most plentiful compound in all samples, which was followed by camphor, methyl chavicol, (+) limonene, eucalyptol, eugenol, geraniol, γ-terpinene, and α-terpineol. As for the monoterpenes, the results showed that 100 bar was the best pressure for their isolation, while the targeted monoterpene class’s structure varied depending on the temperature and CO₂ flow rate. In addition, the study conducted by Zeković, Bera [138], a sequel to their work on optimization, successfully used the artificial neural network (ANN) approach to maximize the initial slope, which was applied as a new approach for the optimization of the solubility-controlled extraction period. Moreover, the ANN analysis provided information on the relative importance of the influence of the SFE parameters, with pressure and CO₂ flow rate having a positive effect on the initial slope, while temperature had a negative effect.

Another study conducted by Zeković, Kaplan [139] aimed to optimize the process of the SWE of seeds using the BBD, investigating the influence of three variables, namely, temperature (100–200 °C), pressure (30–90 bar), and extraction time (10–30 min), and choosing total extraction yield (Y), polyphenol content (PC) and total volatile compounds (TVC) as the response variables. According to their results, the optimal conditions for PC (1001 mg/100 g DW) were a temperature of 100.5 °C, a pressure of 87.6 bar, and an extraction time of 10 min. However, the TVC could not be optimized by RSM due to a disagreement between the observed results and the second-order polynomial model. Thus, it is concluded that the EO and polyphenolic compounds could be co-extracted in a good yield under optimal conditions for PC, as the highest TVC was obtained at 100 °C, 60 bar, and 10 min. HPLC-MS/MS analysis highlighted that 3,4-dimethoxycinnamic acid was the dominant polyphenolic compound of coriander with the highest yield, while the volatile compounds chemical profile was determined by GC-MS and showed that linalool is the dominant compound and the most abundant volatile compound in all extracts obtained at 100 and 150 °C; however, it was almost completely degraded at 200 °C.

High-pressure extraction technologies, in particular SWE and SFE, offer promising alternatives to conventional extraction methods, with environmental benefits and opportunities for extract customization. However, their widespread adoption requires the rigorous optimization of extraction parameters, cost assessment, and consideration of potential limitations related to volatile compound degradation and capital investment. Future research should focus on improving the accessibility and cost-effectiveness of these technologies to make them a viable solution for industry.

Table 4. Comparative overview on coriander parts of extraction methods: key aspects and findings.

Extraction Method	Coriander Part Used	Extraction Solvent/Conditions	Findings	Characteristics (Strengths, Limitations)	References
Maceration	Fresh coriander leaves	Acetone, 1 h at 25 °C	- High TPC, oil contents, and antioxidant activity.	- Effective for antioxidant extraction.	[82]
	Dried coriander seeds	Acetone	- Flavonoids were present in very high concentration; - Tannins, quinines, terpenoids, and cardiac glycosides were present in low concentrations in the extract; - Alkaloids, phenols, phlobatannins, and carbohydrates were found to be present in the lowest concentrations; - Absence of oxalates, saponins and proteins was observed in acetone extract.	- Identification of the presence of the secondary metabolites.	[86]
	Leaves and seeds (17 genotypes)	Methanol	- Presence of alkaloids, carbohydrates, glycosides, saponins, phytosterols, fixed oils and fats, phenols, tannins, flavonoids, protein and amino acids; - Absence of resins and tri terpenes in both leaves and seeds genotypes.	- The type of phytoconstituents of leaves and seeds of different genotypes were not similar; - Genotypic variation in phytoconstituents allows for different applications.	[88]
	Leaves and stems	Diethyl ether for 30 min, under agitation at room temperature (25 °C)	- Higher TPC and antioxidant activity in leaves compared to stems.	- Effective in extracting phenols from leaves, but there is variability by part.	[81]
	Coriander fruits (3 varieties)	Methanol/stirring for 30 min	- Variability in polyphenols, flavonoids, tannins, and antioxidant activity.	- Differences across Tunisian, Syrian, and Egyptian varieties.	[85]
	Powdered roots, leaves and stems	Hexane, dichloromethane, ethyl acetate, methanol, water	- Highest TPC and antioxidant activity attributed to ethyl acetate extract.	- Solvent-dependent variability in extraction efficiency.	[87]
	Seeds	Ethanol and methanol extraction was carried out at ambient temperature for 24 h in a shaking water bath.	- Higher polyphenol content and antioxidant activity with methanol.	- Methanol more effective for polyphenol extraction.	[84]
	Vegetative parts and fruits	Methanol–water 80:20 (v/v) at room temperature, 150 rpm, for 1 h.	- Quercetin derivatives dominating in the vegetative parts and phenolic acids in the fruits. - In vitro cultures revealed a diversity of polyphenols, notably C-glycosylated apigenin and anthocyanins.	- Diverse polyphenol content based on part.	[83]
Soxhlet Extraction	Seeds	Methanol, water	- Aqueous extract: highest polyphenol content; - Methanolic extract: best antioxidant activity.	- Methanolic extract exhibits superior antioxidant activities despite aqueous extract containing more polyphenols.	[96]
	Seeds	Hexanwe extraction process was carried out for 8 h, after which the solvent was evaporated on a rotary vacuum evaporator at 40 °C.	- High oil yield (12.30%), C18:1 fatty acid content (petroselinic and oleic acid); - Low lauric acid.	- Efficient for extracting seed oil but lower in bioactive compounds (sterols and triterpenes) compared to pressurized liquid extraction (PLE).	[93]
	Seed powder	Solvents: water, ethanol, petroleum benzene, methanol, chloroform	- Phytochemical analysis showed flavonoids, phenols, terpenoids, and alkaloids in all extracts; - Chloroform extract had antibacterial activity against E. coli and P. aeruginosa, but not S. aureus.	- Strength: Identified various bioactive compounds; chloroform extract effective against certain bacteria; - Limitation: No activity against S. aureus.	[95]
	Seeds	Cyclohexane, 5 h	- Oil content was 2% higher in 2010 than in 2011; - PA content was higher in 2011; - Oil accumulation started earlier after flowering in 2011; - Higher PA was achieved before full maturity.	- Strengths: provides insights on optimal harvesting time for higher PA; - Limitations: dependent on specific climatic conditions during the growing.	[94]
HD	Seeds and leaves	Water (Clavenger type apparatus)	- Volatile compound yields: seeds (1.1%), leaves (0.1%); - Antioxidant activity is stronger in seeds than leaves; - Non-volatile extracts from leaves had higher potency despite lower overall antioxidant contribution.	- Strengths: comprehensive analysis of both volatile and non-volatile compounds; highlights concentration-dependent effects; - Limitations: variability in antioxidant activity based on extraction method and part use.	[91]
	Whole plant	HD for 3 h using Clevenger-type distillation apparatus	- Oil yield varied between 0.17 and 0.29 mg/100 g; - Identified 61 compounds (generative phase) and 65 compounds (vegetative phase).	- Variable oil yield based on harvest state; diverse compound identification.	[90]
	Fruits	Water (varying distillation times from 40 to 160 min)	- EO yield and concentration of constituents (e.g., linalool) depend on distillation time; - Maximum EO yield reached between 40–160 min; - Linalool concentration increased from 51% at 1.15 min to 68% with longer distillation time; - Inverse relationship for low-boiling constituents with increasing distillation time; high-boiling constituents showed the opposite trend.	- Highlights the importance of distillation time in EO composition analysis; - Results could vary significantly with different distillation durations.	[92]
	Fresh coriander leaves	HD for 2.5 h, using a Clevenger-type apparatus.	- Total yield of 96.81% with main compounds: trans 2-dodecenal, 2-methylenecyclopentanol, dodecanal, cyclooctane, 9-tetradecenal, decanal, 2-tridecenoic acid, 2-octenal, and 2-cyclohexen-1-ol.	- Contains various oxygenated compounds useful for food and pharmaceutical industries.	[82]
	Dried coriander seeds	Distilled with water for 2 h	- Evaporation of coriander EO completed in a single step; - 38 different compounds identified in coriander EO. - Main compound: linalool (64.04%); - Other significant compounds: α-pinene (7.31%), geranyl acetate (5.76%), γ-terpinene (5.59%), camphor (4.24%), p-cymene (3.83%), limonene (1.60%).	- Model constructed for predicting retention time values; - Correlation between chemical composition and thermal behavior.	[26]
	Fresh coriander fruits	EOs were extracted by a water vapor distillation apparatus (Clavenger aparatus) over 4 h	- Differences in crude oil content, fatty acids, EO levels, and mineral composition among four coriander varieties.	- Gamze had the highest crude oil and mineral content (Ca, Mg, S, Cu, B).	[89]
MAE	Seeds	Ethanol concentration: 63% w/w; Extraction time: 19 min; Irradiation power: 570 W	- Total phenolic (TP): 311.23 mg GAE/100 g DW; - Total flavonoid (TF): 213.66 mg CE/100 g DW; - IC50: 0.0315 mg/mL; - EC50: 0.1311 mg/mL	- Maximized yields of TP and TF; high antioxidant activity; optimized through RSM.	[119]
	Leaves powder	MAE vs. CE; MAE: 50% ethanol, 400 W, 2.14 min, 75 mL/g; CE: water bath	- MAE TPC yield: 37.94 mg GAE/g DW vs. CE TPC yield: 44.47 mg GAE/g DW; - Similar phenolic profile, no significant antioxidant difference.	- MAE is faster, retains antioxidant activity and phenolic composition despite lower yield.	[120]
	Leaves	52.62% ethanol, 452.12 W, and 150 s	- TPC: 49.63 mg GAE/g DW; - TAC: 5.55 mg GAE/g DW.	- Effective model for optimizing extraction, high phenolic and antioxidant yield.	[121]
	Foliage	IL-MAE: 1-Butyl-3-methylimidazolium tetrafluoroborate, 800 W, 90 °C, 2 min, 1:10 solvent ratio	- Maximum heneicos-1-ene yield: 412.8 mg/100g vs. conventional (69.77 mg/100g)	- IL-MAE gives 5.85 times higher yield, faster and more efficient.	[122]
MAHD vs. HD	Fruits	Distilled water	- MAHD yield: 0.1%, HD yield: 0.2%; - Linalool content similar in both; - Antimicrobial activity observed.	- MAHD proved superior in terms of energy savings and reduced extraction time, despite a decrease in oil yield and composition.	[123]
	Seeds	Distilled water	- MAHD yield: 0.325% and HD yield: 0.31%.	MAHD is a better extraction method; it has a shorter time and is more economical than HD.	[124]
UAE	Seeds	70% ethanol and water	- Dominant compound content increased with reduced particle size; - Higher yields in 70% ethanolic extracts; - Better antioxidant activity in ethanolic extracts compared to aqueous ones.	- Higher yields, better antioxidant activity.	[127]
	Seeds	Temperature (40–80 °C), time (40–80 min), power (96–216 W)	- Optimal TP: 382.68 mg GAE/100 g; - TF: 216 mg catechin/100 g; - IC50: 0.03764 mg/mL; - EC50: 0.1425 mg/mL,	- Strengths: effective optimization of extraction conditions, high yield of phenolic compounds; - Limitations: specific conditions may need careful control.	[128]
	Seeds	UAE vs. other methods (maceration, Soxhlet, RSLDE)	- UAE yielded highest polyphenols; - Best antioxidant activity from RSLDE; - Identified 10 phenolic compounds including 8 phenolic acids and 2 flavonoids.	- UAE provided the highest polyphenol yield and was effective in extracting acyclic monoterpenes, making it a strong method for maximizing antioxidant compounds in coriander seeds.	[102]
	Seeds	Sample–solvent ratio 1:13 (g/mL), amplitude 82%, 45 °C, 9 min	- Oil yield 30.74–72.05% and best antioxidant activity obtained under these conditions.	- Strengths: efficient in maximizing oil yield and antioxidant activity; - Limitations: parameters need to be optimized for best results.	[129]
	Aerial parts	50% methanol, 70 °C, 10 min, solvent-to-sample ratio 6.51 mL/g	- High recovery of phenolic compounds, particularly caffeic acid.	- High repeatability and reproducibility. - Effective for quality control analysis; - Conditions optimized using RSM and BBD.	[130]
SWE	Seeds	Water, temperature: 65–150 °C, pressure: 870–1000 psi (60–68.95 bars)	- Higher concentration of valuable oxygenated components in EO compared to conventional methods.	- Allows manipulation of EO composition through temperature and pressure adjustment, rapid, selective.	[133]
	Seeds	SWE vs. HD: Water with a static extraction time of 15 min, variable temperature, and pressure	- Higher oil extraction efficiency than hydrodistillation; - Main compounds: linalool, isoborneol, citronellyl butyrate, geraniol.	- SWE is efficient, has a reduced extraction time, and allows for customizable oil composition.	[134]
	Seeds	Water at subcritical conditions	- Lower yield compared to Soxhlet and SFE.	- Environmentally friendly; - Selective extraction by adjusting temperature and pressure; - Lower yield than Soxhlet and SFE for essential oil extraction.	[135]
	Seeds	High temperature (170 °C) and varying time	- Higher efficiency for extracting geraniol and linalool oxide compared to conventional methods. - Increased temperature and time reduced linalool extraction efficiency.	- Strengths: selective and efficient extraction of monoterpenes; - Limitations: efficiency varies based on temperature and chemical structure of compounds.	[136]
	Seeds	Temperature: 100–200 °C; Pressure: 30–90 bar; Time: 10–30 min	- Optimal conditions for polyphenol content (PC) were 100.5 °C, 87.6 bar, and 10 min, yielding 1001 mg/100 g DW; - Highest total volatile compounds (TVC) at 100 °C, 60 bar, 10 min.	- Strengths: high yield of polyphenols and co-extraction of essential oil; - Limitations: TVC optimization disagreement and degradation of linalool at 200 °C.	[139]
SFE	Seeds	CO2 at 300 bar	- High yield (8.88%); also extracts vegetable oils and polyphenols.	- Efficient in extracting both essential oils and polyphenols; - Increases the sanitary value of the extract; - High initial cost and specialized equipment required.	[135]
	Leaves	SFE vs. HD; Supercritical CO2	- Higher yield from hydrodistillation (0.12% vs. 0.09%); -SFE richer in components (23 vs. 18), with linalool and phytol as major components.	- SFE produced a higher quality oil rich in components; - It showed better antioxidant, antifungal, and microbial activities.	[5]
	Seeds	SFE vs. HD and Soxhlet extraction	- SFE provided the highest linalool content compared to conventional techniques.	- Strengths: higher oil yield and selectivity; - Limitations: requires optimization of parameters.	[127]
	Seeds	Pressure: 100, 150, 200 bar; temperature: 40, 55, 70 °C; CO2 flow rate: 0.2, 0.3, 0.4 kg/h	- Optimal extraction conditions determined: 199.50 bar, 40.15 °C, 0.396 kg/h of CO2; - Linalool was the most abundant compound, followed by camphor, methyl chavicol, (+) limonene, and others.	- Strengths: optimization using BBD and RSM; high yield of target compounds; - Limitations: specific pressure and temperature requirements for optimal monoterpene isolation.	[137]

HD: hydrodistillation; MAE: microwave-assisted extraction; IL-MAE: ionic liquid-based MAE; UAE: ultrasound-assisted extraction; SWE: supercritical water extraction; SFE: subcritical fluid extraction.

provides a comprehensive overview of studies comparing the traditional and innovative extraction techniques used to recover active compounds from coriander.

5. Conclusions and Future Perspectives

According to this review, coriander, known for its medicinal and dietary benefits, was subjected to several treatments prior to the extraction of its bioactive compounds, and multiple techniques were employed for the attainment of higher yields. Thus, some general conclusions can be drawn from existing research and publications:

1.

The studies relating to the therapeutic effects and the biological activity of the different parts of coriander have revealed its bioactivity whether in vitro or in vivo, particularly that assigned to the oils extracted from its seeds (Table 2).

2.

The key treatments and pretreatments affecting the quality and quantity of coriander bioactive substances, especially phenolic and volatile compounds, are those applied to coriander either before or during their harvest, during storage, or during extraction processes preparation (Table 3), which have either positive or negative effects on its phytochemical content.

3.

Given the involvement of coriander in different fields (food, medical, cosmetic), and with the aim of replacing synthetic antioxidants and overcoming the disadvantages of conventional techniques that consume time and solvents to produce a lower yield, non-conventional extraction technologies (MAE, UAE, and SFE) have been used. So, several authors have optimized and identified the optimal technique necessary to maximize the extraction of phenolic and volatile compounds from coriander.

4.

Considering their respective advantages and disadvantages, the extraction processes presented in this article can be classified in the following order: MAE/MAHD, UAE, SWE/SFE, Soxhlet extraction, hydrodistillation, and finally maceration (

Table 5. Ranking of extraction methods according to their performance indicators and efficiency.

Extraction Method	Ranking	Efficiency	Extraction Conditions	Specific Results
MAE/MAHD	1	Highly efficient in terms of time and energy	Reduced extraction time, energy savings, optimization via RSM	High yields of phenolics and flavonoids; strong antioxidant activity
UAE	2	Very effective for maximizing polyphenols, flavonoids, and essential oils	Customizable extraction parameters; rapid processing	Maximizes antioxidant and oil yields; requires careful condition control
SWE/SFE	3	Known for selectivity and environmental friendliness	Temperature and pressure manipulation; specialized equipment	High-quality extracts; effective yields of essential oils and polyphenols
Soxhlet Extraction	4	Traditional but still effective for bioactive compounds	Lengthy processing time, lower efficiency compared to modern methods	Efficient for polyphenols and fatty acids; high antioxidant activity in methanolic extracts
HD	5	Reliable for extracting volatile compounds	Requires extended time and high energy input	Effective for isolating specific compounds like linalool
Maceration	6	Simple and effective for extracting antioxidants and secondary metabolites	Longer extraction time; lower efficiency	Less effective than UAE and MAE; lower concentrations of bioactive compounds

HD: hydrodistillation; MAE: microwave-assisted extraction; IL-MAE: ionic liquid-based MAE; UAE: ultrasound-assisted extraction; SWE: supercritical water extraction; SFE: sub-critical fluid extraction.

).

In the coming years, mastering the right conditions, as well as the involvement of green extraction methods, including MAE, UAE, and SFE, could provide an innovative approach to increasing the production of specific compounds extracted from coriander for various uses. Nevertheless, it is interesting to note that other techniques which are not cited in this review have been exploited for the extraction of the bioactive compounds of coriander. Overall, the application of novel technologies to scale-up processes is still largely constrained from an industrial perspective. The recovery of target chemicals from the extracted samples and the reuse of the used solvents present the biggest challenges. Improving solvent reusability in extraction processes presents challenges such as contamination and degradation of solvents, as well as recovery difficulties. To overcome these obstacles, several solutions can be implemented: adopting advanced separation technologies like distillation; using greener solvents, such as supercritical CO₂ or ionic liquids; and establishing rigorous purification protocols to eliminate contaminants. These practices promote more sustainable and efficient extraction while meeting the growing consumer demand for environmentally friendly methods.