Supercritical Fluid (SCF) refers to the high density fluid above the critical temperature and pressure. Supercritical fluid has dual characteristics of gas and liquid, its density is close to liquid, its viscosity and diffusion coefficient are close to gas body, and its permeability is good.
At present, there are dozens of reported supercritical fluids, most commonly CO2 and H2O, which are cheap, easy to obtain, safe and non-toxic, and are widely used.
In recent years, supercritical fluid extraction (SFE) technology has been widely used in the purification and separation of various thermosensitive and high boiling point substances, and has made considerable progress in the application and research of chemical industry, food, medicine, perfume and chemical analysis.
Flavor extraction method
In the flavor industry, it is difficult to achieve the same level of essential aroma and fragrance in natural perfume by using the existing technology level.
Therefore, how to effectively separate and extract essential flavors and fragrances from natural raw materials has become a topic of research and development.
Because of the traditional methods of steam distillation, distillation, solvent extraction, extraction and pressing, there are many problems in the process of flavor extraction, such as thermal decomposition, solvent residue, or volatilization loss of some aromatic substances. These problems can be solved by supercritical fluid extraction, and high quality flavors and fragrances that can maintain natural color, aroma and taste can be obtained.
Supercritical CO2 extraction
The choice of supercritical fluid can be used for supercritical fluid extraction of CO2, ammonia, ethane, propane, ethylene, toluene and Freon. But the most popular fluid for supercritical extraction of natural flavors is CO2.
This is because:
- The critical point of CO2 is 31.1 ℃, 7280 KPa. The extraction temperature is generally about 40 ℃ which is especially advantageous to the thermal sensitive materials, and the aromatic components will not produce thermal decomposition.
- CO2 is an inert gas. Aromatic components are not easy to oxidize and deteriorate during the extraction of flavors and fragrances.
- The chemical performance of CO2 is stable, non-burning, non-corrosive, safe and non-toxic, easy to separate from the extract, and no residue.
In particular, CO2 has good solubility for aromatic compounds, such as esters, ketones, terpenes, etc., which have no polarity or weak polarity. They are almost insoluble to proteins, carbohydrates, glycosides and phospholipids and other polar substances, so they are especially suitable for the extraction of natural flavors and fragrances. Using supercritical CO2 fluid extraction of natural flavor and fragrance general working temperature is not high, and the working pressure is high.
Method of supercritical CO2 extraction of flavors and fragrances
At present, the batch extraction process is adopted, the equipment is generally used stainless steel pressure vessel. CO2 is compressed by a compressor through a filter and enters the extractor (several extractors can be switched in turn to improve work efficiency). It is extracted in contact with pre-loaded natural spices in the extractor. Then, the fluid containing the extract enters the separator and separates in the separator under reduced pressure.
The solute (extracted spices) decreases in the solubility of CO2, while the solvent CO2 is extracted from the top of the separator and reused in the compressor.
Supercritical CO2 extraction of natural flavors
CO2 supercritical fluid extraction of natural flavors and fragrances, people want to extract natural flavors and fragrances as much as possible to maintain their original natural aroma and natural tonal, and CO2 supercritical fluid extraction technology can ensure that the extracted flavor and fragrance retain its natural aroma and fragrance, and retain its natural color.
- For example, people have used this method to extract high-quality essential oils from lilac, rose and other fragrant flower raw materials, and from almonds, anise, mint and other edible spices to extract high-quality essential oils. Traditional flavors and fragrances are often difficult to maintain.
- For example, extracting ginger oil from ginger, the traditional steam distillation method not only has a long heating time, low oil yield and can not extract gingerol ingredients, but also can obtain volatile oil and gingerol simultaneously by supercritical extraction.
- Another example is the unique floral aroma of lilac. With the traditional steam distillation method, the essential oil can not completely reflect the fragrance of the flower because part of the fragrance is decomposed during the distillation process. Essential oils obtained by supercritical CO2 extraction have perfect flower fragrance.
Compared with the separation and extraction methods
Compared with the separation and extraction methods, supercritical fluid extraction has many irreplaceable advantages, which can meet some special requirements in many industrial fields.
However, the high pressure technology and equipment required are not conducive to its popularization and application, but it has aroused great interest in the production of high value flavors and fragrances, and has made great progress & Success.
In addition, if micropowder technology is combined with supercritical fluid extraction technology, the extraction rate can be greatly improved and the extraction time can be shortened.
Recently, the combination of electric pulse, ultrasonic wave, magnetic field and supercritical fluid extraction technology has attracted people’s attention. The research in these areas is likely to bring amazing effect, and further promote the application of supercritical fluid extraction technology in the flavor and fragrance industry.
In a word, supercritical fluid extraction is a promising technology for separation of high technology.
It has a bright prospect in the flavor and fragrance industry.