1. Technical Overview

Carbon dioxide super critical fluid extraction (CO2 SCFE) is the method of choice in the herbal extract industry owing to its capacity to maintain purity of the extracted ingredient. Hydrodistillation and solvent extraction cannot retrieve ingredients in their pristine form [1].

Figure 1. Herbal tea is a popular beverage

Solvent extraction often utilizes toxic compounds which cannot be completely separated from the extracted ingredient [1]. The tedious procedure makes the process cumbersome, expensive, and unsafe. Certain solvents are not eco-friendly and create issues of waste disposal.

Many times, heat employed in the process damages temperature-sensitive ingredients. Thermal degradation is an issue also inherent in hydrodistillation that uses water and/or steam for extraction. For these reasons, CO2 SCFE is replacing [1]:

  • Solvent Extraction in seed oil separation.
  • Hyrdodistillation in essential oil extraction.

SCFE has evolved from a laboratory procedure to the industrial scale over the past two decades. Cutting energy use and employing eco-friendly solvents were the drivers behind the exploration of alternatives to the solvent extraction procedure. Examples of other environment friendly technologies for herbal extraction include [1]:

  • Microwave-assisted Extraction
  • Mechanical Pressing
  • Ultrasound-assisted Extraction
  • Detente Instantanee Controlee (DIC)


2. Global Herbal Extract & Herbal Medicine Market

2.1. From Past to Present

Estimates expect the global herbal extract market to register a 7.79% growth rate from 2019 and clock $15.09 billion by 2024 [2]. Similarly, the worldwide herbal medicine market is forecasted to be worth $129.7 billion, growing at a CAGR of 5.88% between 2019 and 2023 [3].

Herbal remedies and cosmetics have been around since ages. It is only in the recent past that they are available as tablets, capsules, solutions, powders, creams, soaps, and other such forms. In 2015, the World Health Organization (WHO) reported the reliance of 70-80% people across the world on herbal sources of medicines [3].

Sourced from various parts of plants [2], herbal extracts rich with numerous active compounds including alkaloids, flavanoids, steroids, phenols, tannins, volatile oils, and glycosides. These serve as medicines and nutritional supplements.

Basil leaves are a treasure house of iron, calcium, magnesium, potassium, and vitamins – A, C, K [4]. Antioxidant-rich leaves of basil, rosemary, aloe vera, clove, and thyme make them a prized commodity. Mint is useful for treating bowel infections, allergies, and common cold.

2.2. Market Drivers

Drivers for the herbal extract and herbal medicine markets include:

  • Expanding awareness on the health benefits of products containing herbal extracts [2].
  • Surging cognizance of the side effects of products with synthetic chemicals [2].
  • Rising demand for naturally sourced functional foods to fight various deficiencies as a result of the busy and stressful present-day lives [4].
  • Increasing promotion of herbal products by numerous governments [4].
  • Greater allocation of research funds for herbal medicines [3].

2.3. Market Segmentation & Applications

Parameter Herbal Extracts Herbal Medicines
Industrial Applications
  • Foods
  • Pharmaceuticals
  • Beverages
  • Neutraceuticals
  • Personal Care
  • Pharmaceuticals
  • Beauty Products
  • Functional Foods
  • Dietary Supplements
  • Mint
  • Thryll
  • Dill
  • Rosemary
  • Basil
  • Lavender
  • Others
  • Marrubium Vulgare
  • Echinacea
  • Camellia Sinesis
  • Aloe Vera
  • Vaccinium Macrocarpon
  • Curcuma Longs
  • Actaea Racemose

Table 1. Details of the herbal extract and herbal medicine industries

3. Supercritical Fluid Extraction (SCFE) & Carbon dioxide (CO2) SCFE

3.1. Why SCFE Use is Rising?

Regulations on toxicity, quality, safety, and residues in consumer products are getting stricter as consumers demand products with more natural ingredients in food-beverage, pharmaceutical, neutraceutical, and personal care products. SCFE is safer, more eco-friendly, and leaves behind zero or less toxic residues in the final product.

Alternative methods have drawbacks:

  • Solvent Extraction: uses toxic organic solvents whose residue cannot be completely separated from the extracted ingredient [5]. Some solvents deplete the ozone layer and create environmental issues [6].
  • Hydrodistillation: employs heat which can thermally degrade the ingredient [7].

3.2. What are Supercritical Fluids & How do they Assist with Extraction?

A fluid at above its critical pressure and temperature is a supercritical fluid. The phase boundary between its liquid and vapour phase disappears and its properties can be customized by changing the pressure and temperature.

Roughly, supercritical fluids with higher density possess greater solvent power. And because altering pressure and temperature substantially varies their density, supercritical fluids make exceptional solvents.

Figure 2. Triple Point Parameters

Supercritical fluids are excellent solvents because of their [8]:

  • Higher, Liquid-like Density: boosts solvent power.
  • Low, Gas-like Viscosity: improves mass transfer and diffusion inside porous solids.
  • Low, Gas-like Surface Tension: enables greater seepage inside porous solids.

3.3. Why Supercritical Carbon dioxide (CO2) Makes an Excellent SCFE Solvent?

Carbon dioxide and water are the most popularly utilized supercritical fluids [9]. Supercritical (CO2) is an ideal solvent for SCFE because it [8]:

  • Has a critical temperature of 31.10C, which is around the ambient temperature. Relatively low temperatures for CO2 SCFE avoid thermal degradation.
  • Has a more manageable critical pressure of 73.9 bar.
  • Is non-flammable and non-toxic.
  • Has a customizable density to upgrade its solvent power.
  • Is available in ample quantities and in pure form.
  • Has a comparatively low cost.

Although CO2 is a greenhouse gas (GHG), the SCFE process using CO2 becomes eco-friendly if the gas is captured from the atmosphere, reused, and recycled.



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  1. Supercritical Fluid Extraction: A New Technology to Herbals. Vaibhav Shinde et al. International Journal of Herbal Medicine.
  2. Global Herbal Extracts Market Research. Market Research Future.
  3. Global Herbal Medicine Market. Market Research Future.
  4. Plant Extracts Market. Markets and Markets.
  5. Fires and Explosions. Max Houck et al. Fundamentals of Forensic Science (Third Edition). Science Direct.
  6. Initial Considerations. Francisco Pena-Pereira et al. The Applications of Green Solvents in Separation Process. Science Direct.
  7. Supercritical Fluid Extraction. E. Reverchon. Encyclopedia of Food Sciences and Nutrition (Second Edition). Science Direct.
  8. Supercritical CO2: A Green Solvent. Chemical Engineering.
  9. Supercritical Fluids. LibreTexts.