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Consumers are now looking for natural products, concerned in consuming cosmetics and fragrances closer to plants and respectful of health and the environment.
The challenge is posed to stakeholders who turn to technological tools that preserve the components and benefits of the natural product without damaging it. At the same time, they met with hardened regulations (in terms of allergens, for example), restrictions linked to pesticides, bans on certain raw materials, etc. In this context, supercritical CO2 technology appears as an ideal extraction solution to preserve the original characteristics of plant elements and as complementary technological tools.
Today, ecology, respect for the environment, health, become essential principles. The 12 principles of green chemistry and the 6 principles of eco-extraction are directly respected by supercritical technology.
When chemistry turns to ecology
The twelve principles of green chemistry
- Prevention
It is better to avoid producing waste than to treat or dispose of it.
- Atomic economy
Implementation of synthesis methods that incorporate in the final product all the materials entering the process.
- Design of less dangerous synthetic methods
Whenever possible, synthetic methods should use and produce substances with little or no toxicity to humans and the environment.
- Safer chemicals design
Development of chemicals that achieve the desired properties while being as no-toxic as possible.
- Solvents and auxiliaries less polluting
Do not use synthetic aids (solvents, release agents, etc.) or choose harmless auxiliaries when they are needed.
- Energy efficiency research
The energy expenditure required for chemical reactions must be examined from the point of view of its impact on the environment and the economy, and be kept to a minimum. Whenever possible, synthesis operations should be performed under ambient temperature and pressure conditions.
- Use of renewable resources
Use a natural resource or renewable raw material rather than fossil products, as far as technology and economy permit.
- Reduction of the number of derivatives
Avoid, if possible, the unnecessary multiplication of derivatives by minimizing the use of blocking radicals (protectors / deprotectants or temporary modification of physical or chemical processes) because they require a surplus of reagents and can produce waste.
- Catalysis
The use of catalytic agents (as selective as possible) is preferable to that of stoichiometric processes.
- Design of products for degradation
Chemicals must be designed so that at the end of use they break down into harmless, biodegradable waste.
- Real-time observation to prevent pollution
Observation methods need to be refined to allow real-time monitoring and control of ongoing operations and their monitoring prior to any formation of hazardous substances.
- A fundamentally more reliable chemistry
Substances and their physical state entering a chemical process must be chosen to prevent accidents such as dangerous emanations, explosions and fires.
Source: Paul T. Anastas and John C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, New York, 1998.
The six principles of eco-extraction:
1.
Enhancing innovation through variety selection and the use of renewable plant resources,
2.
Use alternative solvents,
3.
Reduce energy consumption by supporting innovative technologies and promote energy recovery
4. 
Promote the creation of co-products instead of waste to integrate the path of the bio- or agro-refinery,
5. 
Reduce unit operations through technological innovation and promote safe, robust and controlled processes,
6. 
Privilege an undenatured, biodegradable and contaminant free product.
Supercritical CO2 extraction.
CO2 becomes supercritical when its pressure and temperature exceed the critical point. The increase in pressure will increase the density of CO2, and thus its solvent power. Supercritical CO2 has a high coefficient of diffusivity. The viscosity of CO2 in the supercritical state is close to that of the gas. Thanks to these properties, supercritical CO2 enters the heart of the material to extract the compounds of interest. The variation of the operating parameters of the extraction makes it possible to play on the solvation power of CO2 and thus choose molecules or compounds extracted according to their chemical nature.
A certain orchestration of flow rate, pressure and temperature parameters modifying the properties allows a selective and precise extraction in the plant matrix. CO2 is a green solvent (inexpensive, low pollutant, recyclable) which has a major advantage: the CO2 reaches the supercritical threshold at a temperature of 31.1 ° C and a pressure of 73.8 bar. For comparison the water reaches the supercritical state at 374 ° C and 220 bar. Thanks to these attainable measurements, CO2 has the advantage of respecting and not destroying heat-sensitive molecules. To increase the prism of possibility of extraction it is possible to couple the supercritical CO2 to a co-solvent. CO2 is very miscible with organic solvents such as ethanol.
In perfumery, the use of supercritical CO2 for the extraction and the fractionation makes it possible to obtain scented extracts from fresh flowers. This supercritical CO2 extraction makes it possible to obtain extracts different to extracts obtained based on hexane. The market players are more and more numerous to turn to CO2 extracts that have different organoleptic properties. Blauer's Jungle Essence in 2019 uses in the composition of its fragrance range the CO2 extract of cardamom.
Supercritical CO2 extraction technology is a viable and economically viable technology.
(According to the article published on L'ACTUALITÉ CHIMIQUE N° 444-445, sheet 70, prepared by Cyrille SANTERRE (csanterre@isipca.fr)1-2, Nadine VALLET 1 and David TOUBOUL2 (1ISIPCA, Institut Supérieur International du Parfum, de la Cosmétique et de l'Aromatique alimentaire, Versailles; 2ICSN, Institut de Chimie des Substances Naturelles,CNRS, Gif-sur-Yvette).)