Solid Agarwood Oil? Unveiling the Mystery of SFE CO2 Extracts

It was a chilly and humid Sunday night, and the clock had just struck 6 PM. The weekend was winding down, and I was preparing to wrap up for the evening. The cool breeze outside hinted at the early onset of winter, making the air feel crisp and the night unusually serene. I had been fullfilling on my usual orders of agarwood oils. One of it was the Triple Happiness, meticulously extracted using the Supercritical Fluid Extraction (SFE) CO2 method. As I was about to get the oil out from the bottle, I noticed the Triple Happiness - Supercritical Fluid Extraction (SFE) CO2 extracted agarwood oil has solidified, while my Misty Forest -water distilled agarwood essential oil remains in a liquid state. So I turn these two bottles upside down to show you how they look. What an interesting phenomenon !

 Why one solidified and the other remains its liquid state?

The Extraction Processes: SFE CO2 vs. Water Distillation

Supercritical Fluid Extraction (SFE) with CO2:

• Method: SFE utilizes carbon dioxide in a supercritical state, which means it is at a temperature and pressure where it behaves as both a liquid and a gas. This method is highly efficient for extracting a wide range of compounds, including both volatile and non-volatile components.
• Temperature and Pressure: The process occurs at relatively low temperatures and adjustable pressures, allowing for the preservation of delicate compounds that might degrade under high heat.
• Extract Composition: SFE CO2 extracts tend to contain a broader spectrum of compounds, including heavier, more complex molecules such as waxes, resins, and lipids that are often left behind in traditional distillation methods.

Water Distillation:

• Method: This traditional method involves passing steam through plant material, causing the volatile compounds to evaporate. These vapours are then condensed back into liquid form and collected.
• Temperature: This method involves higher temperatures, typically around the boiling point of water (100 degrees Celsius), which can cause some heat-sensitive compounds to degrade.
• Extract Composition: Water distilled essential oils primarily contain volatile compounds, which are generally lighter and have lower melting points compared to the compounds found in CO2 extracts.

Why Does SFE CO2 Extracted Agarwood Oil Solidify at 15 Degrees Celsius (approxiately as it could be a bit higher or lower)?

Heavier Compounds:

• The SFE CO2 extraction method captures a wider range of compounds, including heavier molecules such as long-chain hydrocarbons, waxes, and resins. These components have higher melting points and can solidify at lower temperatures compared to the lighter, more volatile compounds found in water distilled essential oils.

Molecular Structure and Intermolecular Forces:

• The molecular structure of the compounds in the SFE CO2 extract allows them to pack closely together, leading to stronger intermolecular forces. These forces require more energy (in the form of heat) to break apart, meaning the oil will solidify at a higher temperature.

Purity and Concentration:

• The purity and concentration of specific compounds in the SFE CO2 extract can also influence its solidification point. Highly pure extracts with significant amounts of heavier compounds are more likely to solidify at higher temperatures.

Observations and Practical Implications

As observed in the provided images, at 15 degrees Celsius (it could be lower or higher as I do not know the exact value, 15 degree was my room temperature at that time), the SFE CO2 extracted agarwood oil has solidified, indicating the presence of a significant amount of heavier compounds with higher melting points. On the other hand, the water distilled essential oil remains in a liquid state due to its composition of lighter, more volatile compounds.

This phenomenon highlights the differences in extraction methods and their impact on the physical properties of the resulting oils. For practical purposes, understanding these properties is crucial for storage, usage, and application in various products.

For instance, SFE CO2 extracts may require special handling and storage conditions to maintain their liquid state, especially in cooler environments. Knowing this can help in designing appropriate packaging and determining the best usage scenarios to ensure the oil retains its desired properties.

Fun fact: in winter, it is very hard for us to get these oils out of the bottle. Thank you for your patient.