Subcritical Water Extraction

24-September-24

A successful Prototype Equipment for SUBCRITICAL WATER EXTRACTION was tested at the fabricator’s workshop before being dispatched to the customer.

Here is a technical description of the Subcritical Water Extraction (SWE) process applied to extract polyphenols from Cinnamomum zeylanicum (Ceylon cinnamon).

Subcritical Water Extraction (SWE) involves using water as the solvent to extract polyphenols from Cinnamomum zeylanicum under controlled temperature and pressure conditions, below the critical point of water (Tc = 374°C, Pc = 221 bar).

Process Parameters:

Temperature: 130 -150°C (below the critical point)
Pressure: 3 to 4 bar (sufficient to maintain water in a liquid state)
Flow rate: 5 – 10 Lt/min
Extraction time: 30-60 minutes
Water quality: Deionized water

Process Steps:

Pre-treatment: Cinnamomum zeylanicum bark is dried, ground, and sieved to a uniform particle size. The client supplied tea-cut material.
Extraction: The ground cinnamon is loaded into an extraction vessel, and subcritical water is pumped through the vessel.
Concentration: The extracted polyphenols are concentrated using vacuum evaporation or freeze-drying.

Mechanism:

Subcritical water extraction uses hot water to solubilize and extract polyphenols from the cinnamon bark. The subcritical conditions allow for efficient extraction while minimizing the degradation of thermally sensitive polyphenols. The process exploits the increased solubility of polyphenols in water at elevated temperatures and pressures.

Polyphenol Yield:

The yield of polyphenols extracted from Cinnamomum zeylanicum using SWE can vary depending on the process parameters and starting material quality. Typical yields range from 5-15% (w/w) of the dry bark weight.

Here’s a brief comparison of Subcritical Water Extraction (SWE) and Supercritical Fluid Extraction (SCFE) technologies, including their pros and cons based on the properties of the target ingredients:

(Supercritical Fluid Extraction (SFE) is a solvent-free extraction process that utilizes a supercritical fluid, typically carbon dioxide (CO2), as the extraction solvent. The process involves subjecting plant-based ingredients to high pressure and temperature conditions, above the critical point of the fluid, to create a supercritical state.)

SWE:

Pros:

Higher solubility of polar compounds
Lower equipment costs
Easier operation and scaling up
Water is a green solvent

Cons:

Limited selectivity for non-polar compounds
Longer extraction times
Higher water usage

SCFE:

Pros:

Higher selectivity for non-polar compounds
Faster extraction times
Lower solvent usage
Ability to tune extraction conditions

Cons:

Higher equipment costs
More complex operation and scaling up
Requires high pressure and temperature control

Target Ingredient Properties:

Polar compounds (e.g., polyphenols): SWE is generally preferred due to higher solubility and easier extraction.
Non-polar compounds (e.g., essential oils): SCFE is often preferred due to higher selectivity and faster extraction times.
Thermally sensitive compounds: SWE is generally preferred due to lower temperature requirements.

Note: The exact process parameters and yields may vary depending on the specific SWE equipment and experimental conditions. These are general guidelines, and the optimal extraction technology depends on the specific properties of the target ingredients and the desired outcomes.