Although carbon dioxide is the most popular of the supercritical fluids (SCF) on account of its low critical temperature, abundant availability, relatively low cost, and non toxic nature at low concentrations, it does have a natural limitation – it is non polar.
This means that supercritical carbon dioxide (sCO2):
- Can extract non polar phytochemicals as well as those that are volatile and of low molecular weight.
- Can even extract some polar phytochemicals located outside the cell wall.
- Cannot extract polar phytochemicals placed inside the cell wall.
In order to overcome this natural limitation of supercritical carbon dioxide, cosolvents are added. This is done using the cosolvent pump. Cosolvents enable sCO2 to extract even polar phytochemicals.
At the very outset, we have to differentiate between the cosolvent and the supercritical fluid extraction (SCF). The SCF in this case is sCO2 and the cosolvents can be:
- Ethanol
- Water
- Methanol
There are two ways of adding the cosolvent to the supercritical fluid:
- Priming the SCF pump and the cosolvent pump at the same time while maintaining the restrictor valve in the open position in order to have the correct mixing ratio.
- Adding the cosolvent in the extractor (which is already loaded with the raw material) in the exact quantity and then starting the SCF pump. The cosolvent dissolves in the sCO2 and works on the raw material extracting polar products form it.
Speaking of pumps:
- Operators go with High Performance Liquid Chromatography (HPLC) pumps for adding cosolvents to the SCF.
- Players in the dietary supplement, pharma, food, and cosmetic industries prefer Plunger Pumps of high capacity to circulate the supercritical fluid.
Plants naturally secrete phytochemicals as part of their defence mechanism to ward off diseases. Research has identified 4,000-odd phytochemicals and studied 150 of these in considerable detail. Research has also proved the utility of these chemicals in fighting a host of human conditions such as:
- Cancer
- Inflammation
- Mutation
- Oxidation
- Ageing
(CO2) supercritical fluid extraction (SCFE) is often deployed with the following method to boost the yield of phytochemical extracts:
- Ultrasound Extraction
- Microwave Radiation
- Pre-treatment with Enzymes
- Organic Co-solvents
- Solvent Modifiers
Phytochemicals are presently used in the making of:
- Functional Foods
- Pharmaceuticals
- Foods and Beverages
- Nutraceuticals
- Cosmetics
- Animal Feed
Broadly classified as carotenoids, phytosterols, and flavonoids, here are some specific examples of phytochemicals:
- Epicatechin upgrades the nutritional value of bread and is, therefore, utilized in the food and beverages industry.
- Carotenoid imparts natural color to food.