Procedure to extract natural products

Details Procedure to extract natural products Procedure to extract natural products

1998-09-16

2001-12-04

Carr, Deborah D. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

Reexamination Certificate

active

06326504

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a procedure to extract organic products from vegetable or animal matrices, or their extracts, by means of high-pressure extraction using conventional liquid solvents and in the presence of small amounts of supercritical fluids.
BACKGROUND OF THE INVENTION
Several methods of extracting organic products from vegetable or animal matrices are disclosed in the prior art such as JP 02235997 (Preparation of alga aromas by extraction with supercritical or semi-critical carbon dioxide in the presence of water or alcohol), U.S. Pat. No. 4,675,198 (Extraction of aromas from vegetable products using liquid or supercritical extractors), JP 62036178 (Extraction and separation of organic compounds of grape skin), DE 2737794 (Decaffeinisation of coffee by extraction with a solvent), DE 2638383 (Elimination of caffeine from coffee). There are also a significant number of publications which disclose similar processes, although it should be borne in mind that these processes follow the strategy of using supercritical CO
2
in the presence of small amounts or organic and/or inorganic solvents.
A process for the extraction of oils from oil-containing solid vegetable material by means of a mixture consisting of a supercritical gas and a subcritical entraining agent is disclosed in U.S. Pat. No. 5,210,240, herein incorporated by reference.
There are many disadvantages with the current methods, such as the need to use large equipment and a high level of energy to produce relatively small amounts of product. This is because solvents are used with small solubilities or solvents which are not saturated when leaving the extractor as a result of the slow kinetics of extraction involved, and therefore the consumption of solvent per unit of extracted active product mass, is very high.
With current techniques, substances are being extracted from vegetable matrices with pure or modified supercritical CO
2
with a small proportion of organic solvent (ethanol, acetone, hexane, methanol, water, etc.), which is always in a proportion less than 50%.
SUMMARY OF THE INVENTION
The present invention relates to a high pressure process for extraction of organic products from vegetable or animal matrices or extracts thereof wherein the process is carried out in the presence of one or more liquid solvents and one or more supercritical fluids wherein the proportion of the supercritical fluid is less than 50% by weight of the total weight of the solvent and the supercritical fluid.
DETAILED DESCRIPTION OF THE INVENTION
The process of the invention includes macerating the initial material at pressures of between 50 and 500 bar, in a solvent such as water, hydrocarbon, alcohol, ketone, ether, carbon halide or a mixture thereof, containing a supercritical fluid (SCF) such as CO
2
, propane, ethane or mixtures thereof in a proportion of less than 50% by weight of the total weight of the solvent and the SCF. The high working pressure causes the penetration of SCF, as it reduces its viscosity and increases diffusivity. This increase in diffusivity and reduction in viscosity causes the mobility of SCF through the inside of the cells and allows substances to be extracted at a much higher speed and in greater quantities than the conventional extractions or in other existing extraction patents to data.
Apart from atmosphere extraction which avoids oxidation, it is also carried out at such moderate temperatures, slightly higher than room temperature, which drastically reduces the risk of decomposition of heat-labile products.
The extraction mechanism means that the product extracted by the SCF is solvated quickly with traditional solvent, setting a balance between solute-SCF-conventional solvent which allows extraction to be performed at all times with the same levels of effectiveness and performance as at the start of the process. There is a continuous transfer of matter from the cells to the conventional solvent, using an intermediate phase formed by the SCF.
The innovation of the process over existing processes lies in the fact that proportions between SCF and conventional solvent are inverted, meaning that the resulting mixture is not an SCF but a pressure liquid or a mixture of phases. This process means that the main solvent is not an SCF but ethanol, water or other solvents, which are found in greater proportions. The SCF does not act as a solvent but as a transport vehicle between the vegetable matrix and the solvent.
The procedure according to the invention minimizes extraction time, reduces the solvent/solute ratio and therefore reduces pumping costs, the consumption of solvent and costs for its later recuperation. As quick extraction kinetics are present, the volume of the extractor is reduced for a certain production, or the production increases for a determined volume of extraction.
This type of extraction can be applied to the extraction of organic products such as essential oils, dyes, alkaloids, lipids, oils, waxes, proteins, fatty acids, aromas, spices, isoprenoids, steroids, carotenes, or active pharmaceutical principles present in, or originating from extracts provided by the technique, such as oleoresin or adsorbate, or present in or originating from biological matrices, such as orange skin, paprika, grape skin, coffee, tea, medicinal plants, seeds, carrot or fish viscera.
The solvents that can be used in the process of the invention are those solvents that are conventionally used to extract organic products from vegetable or animal matrices or extracts thereof. Examples of such solvents include water, ethanol, and hexane. Preferred solvents are pentane, hexane, dichlorfluoromethane, chlorofuluromethane, dichloromethane, dimethylethere, ethylmethylether, diethylether, methanol, ethanol, acetone, ethyl butyl ketone, or mixtures thereof.
Preferred SCF's include carbon dioxide, carbon anhydride, methane, ethane, propane, or mixtures thereof. The proportion of SCF to solvent less than 50% by weight based on the total weight of the SCF and solvent. The proportion of SCF to solvent is preferably between about 7 to about 35% by weight, most preferably about 11 to about 26 % by weight. the higher concentrations of SCF are preferred when the animal or vegetable matrix is porous or akin. The lower concentrations of SCF are preferred if the matrix is more compact and less porous.
The process according to the invention is performed at pressures of between 50 and 500 bar, preferably between about 150 to about 280 bar. The time required to perform this operation is generally between about 0.25 and about 20 hours, preferably between about 0.5 and about 5 hours, most preferably between about 15 minutes and about 2 hours. The extraction temperature is typically less than 90° C., preferably between about 40° C. and about 80° C.
The extracted product which is dissolved in the solvent is collected after depressurization. This technique can be combined with a separation phase which allows the extract to be recuperated or fractionated. This recuperation or fiactionation can be carried out following any process offered by the technique and known in the prior art.


REFERENCES:
patent: 5110509 (1992-05-01), Peter et al.
patent: 5210240 (1993-05-01), Peter et al.

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