Vulnerability of oleoresins to heat, light, and oxidation and why SCFE is a better technique for their extraction
It is important that an appropriate method is used for oleoresin extraction and oleoresin oil extraction so that all their health benefits are harnessed.
Oleoresins are a mixture of oils and spices that occur naturally in plants. They offer multiple health benefits on account of their action that counters:
- Cancer Risk
- Muscle and Joint Ache
- Rheumatism
- Diarrhea Risk
- Flatulence
- Digestive Problems
- Infections in the Urinary Tract
Because oleoresins are vulnerable to the following agents, great care needs to be observed during their extraction:
- Heat
- Light
- Oxidation
Following methods are employed for oleoresin extraction as well as oleoresin oil extraction:
SCFE is among the better methods for it can extract oleoresins in their relatively pure form. The reason lies in the properties of the supercritical fluid (SCF). An SCF is a fluid that is at a:
- Pressure greater than its critical pressure; and
- Temperature more than its critical temperature.
At high pressure, the SCF can dissolve more of the required product (oleoresin in this case) from the raw material. This capacity – solvent power – falls with declining pressure. And, at a certain pressure, the SCF extracts:
- One particular oleoresin from the raw material.
- Very little or zero quantities of other products.
When carbon dioxide (CO2) is used as the SCF, these advantages are amplified because it has a critical temperature of 31.1 deg-Celsius. This is around the room temperature and, as a result, the process temperature also remains low. This avoids exposing the oleoresin to heat and oxidation – agents that it is vulnerable to.
On the contrary, when solvent extraction is used for oleoresin extraction and oleoresin oil extraction, it tends to contaminate the oleoresin. The process uses solvents such as hexane or acetone to first dissolve the oleoresin. The solvent and oleoresin are then separated. However, the separation is never complete and some solvent residues get attached to the oleoresin.
Moreover, solvent extraction may also use heat for better dissolution of the oleoresin from the plant raw material. As we have already seen, oleoresins are susceptible to heat and oxidation.
Some producers may also use hydrodistillation for oleoresin extraction and oleoresin oil extraction. The plant raw material is first dissolved in water. The solution is boiled and the required oleoresin condenses at a particular temperature. Here again, the use of heat can distort the chemical composition of the oleoresin and make it incapable of providing the mentioned health benefits.
