ES2344038A1 - Procedure for the extraction or fractionation of solid mixtures of carbohydrates with supercritical co2 in the presence of modifiers. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Procedure for the extraction or fractionation of solid mixtures of carbohydrates with supercritical co 2 in the presence of modifiers. The present invention consists essentially of the use of alcohols and alcohol-water mixtures as modifiers in the process of extracting carbohydrates by supercritical co 2 . The invention is characterized in that the process developed allows the selective extraction with high yields and in a single stage of carbohydrates present in solid mixtures with other sugars. (Machine-translation by Google Translate, not legally binding)

Description

Extraction or fractionation procedure of solid mixtures of carbohydrates with supercritical CO2 in presence of modifiers.

Technical sector

This patent is addressed to the sectors food and pharmaceutical

State of the art

Extraction with supercritical CO2 has been Widely developed in recent years for a wide variety of applications due to the low pollution it gives rise to,  to which it operates under conditions in which reactions of degradation and that its solvation power can easily be modified by changes in pressure conditions and temperature. Regarding polar compounds, their low solubility in CO_ {2} under supercritical conditions limits its application so that polar modifiers that increase the product solubility. (John M. Walsh, George D. Ikonomou, Marc D. Donohue. Supercritical phase behavior: The entrainer effect. Fluid Phase Balance 33 (1987) 295-314).

Regarding carbohydrate behavior in Supercritical CO 2, although studies on liquid-vapor balance measures in systems binaries and quaternaries (Jun-Shun Yau and Fuan-Nan Tsai. Solubilities of D (-) - Fructose and D (+) - Glucose in Subcritical and Supercritical Carbon Dioxide. The Journal of Supercritical Fluids, 7 (1994) 129-133; Alexander P. Bünz, Natasa Zitko-Stemberger, Ralf Dohrn. Phase Balance of Ternary and Quaternary Systems Containing Carbon Dioxide, Water, Isopropanol, and Glucose. The Journal of Supercritical Fluids, 7 (1994) 43-50; Oliver Pfohl, Jens Petersen, Ralf Dohrn, Gerd Brunner. Partitioning of carbohydrates in the vapor-liquid-liquid region of the 2-propanol + water + carbon dioxide system. The Journal of Supercritical Fluids 10 (1997) 95-103 .; R. D'Souza, A.S. Roof tile. High pressure phase equilibria in the system glucose + fructose + water + ethanol + carbon dioxide. Fluid Phase equilibria 39 (1988) 211-224.), none of them has directed towards the purification and / or selective fractionation of some carbohydrates of interest in solid mixtures with others Carbohydrates of a similar nature. The studies that have been carried out carried out consist of measures of carbohydrate solubility in binary systems (for example: CO 2 + fructose and CO 2 + glucose), and quaternaries (for example: CO2 + isopropanol + water + glucose) In the first of the studies, although the measure of the solubility of solid carbohydrates in CO2, not the possibility of fractioning mixtures of the neither the use of modifiers. The remaining investigations are directed to the study of solubilities of carbohydrates in aqueous solution. There is only one antecedent bibliographic that addresses the separation of glucose and fructose using supercritical fluids (W. Bracey, U. Akman, K. Sunol. High pressure adsorption and supercritical desorption of aqueous fructose-glucose mixtures. The Journal of Supercritical Fluids, 4 (1991) 60-68.) Though, to Unlike the process claimed in this patent, the described process consists of 2 perfectly differentiated stages, one of adsorption on an adsorbent as activated carbon, and another of desorption of the adsorbed compounds in the first stage. He described process is carried out from an aqueous solution of glucose and fructose, which passes through a column previously packed with active carbon. After a first stage of adsorption, which takes place at a low flow to allow the interaction between sugars and the adsorbent, the system will clean (avoiding the passage of cleaning solvents through the column) and subsequently the adsorbed compounds are desorbed using CO2 under supercritical conditions with ethanol as modifier The process, therefore, is not continuous and is based fundamentally in the well-known fractionation process of carbohydrates by adsorption on active and subsequent carbon selective desorption of them.

Description of the invention

The present process consists in the extraction selective carbohydrates from solid mixtures with others sugars by using supercritical CO2 with alcohols as polarity modifiers. The novelty of the invention regarding the use of supercritical fluids in the carbohydrate purification is that the prior adsorption of carbohydrates in activated carbon and that the process can be carried out in a single stage requiring a system configuration simpler than previously processes described. On the other hand, the use of carbohydrates in state solid allows to reach high extraction yields and purities greater than 85%.

To carry out the process, the mixtures solid carbohydrates are introduced into an extraction cell (mixed with an inert material to promote the diffusion of solvent through the bed and avoid the formation of roads preferred) and are extracted under the conditions selected with the appropriate solvent (mixture of CO2 and alcohol or alcohol / water in the appropriate proportions). The extract, which contains the purified carbohydrate, is collected dissolved in the alcohol used as co-solvent of the extraction.

Examples of embodiment of the invention

The following examples are described without This limits the procedure.

Example 1 Obtaining Tagatose from mixtures with galactose. Use of isopropanol as a modifier

A part of a tagatose / galactose mixture in proportion 70/30 and nine parts of sea sand are introduced in the cell of an extractor with supercritical fluids. One time Operating conditions reached (300 atm pressure and 80ºC of temperature), the supercritical fluid (consisting of a mixture CO 2 with 27% isopropanol as a modifier) is made circulate through the extraction cell at a given flow during two hours. The extract is collected in a pressure manifold atmospheric Under these conditions it is possible to extract tagatose with a purity of 90% and a yield of 75%.

Example 2 Obtaining Tagatose from mixtures with galactose. Use of ethanol-water mixture as modifier

Using the same procedure as the described in Example 1 with a mixture of tagatose and galactose, in 70/30 ratio, and under experimental conditions of 300 atm., 80ºC and 16% modifier (95% ethanol, 5% water) can be extracted Tagatose with a purity of 88% and a 92% yield.

Example 3 Obtaining Lactulose from mixtures with lactose. Use of ethanol as a modifier

Using the same procedure as the described in Example 1 with a mixture of lactulose and lactose, in 70/30 ratio, and under experimental conditions of 100 atm., 100ºC and 5% modifier (95% ethanol, 5% water) can be extracted lactulose with a purity of 95% and a 45% yield.

Example 4 Obtaining Tagatose from mixtures with galactose. Use of methanol as a modifier

Using the same procedure as the described in Example 1 with a mixture of tagatose and galactose, in 70/30 ratio, and under experimental conditions of 300 atm., 80 ° C and 21% of modifier it is possible to extract tagatose with a 73% purity and with 89% yield.

Example 5 Obtaining Tagatose from mixtures with galactose. Use of propanol as a modifier

Using the same procedure as the described in example 1 with a mixture of tagatose and galactose, in 70/30 ratio, and under experimental conditions of 300 atm., 80 ° C and 21% of modifier it is possible to extract tagatose with a 90% purity and 53% yield.

Example 6 Obtaining Tagatose from mixtures with galactose. Use of butanol as a modifier

Using the same procedure as the described in example 1 with a mixture of tagatose and galactose, in 70/30 ratio, and under experimental conditions of 300 atm., 80 ° C and 21% of modifier it is possible to extract tagatose with a 90% purity and 52% yield.

Claims (6)

1. Process for carbohydrate purification from solid mixtures with other sugars by CO2 extraction under supercritical conditions (between 70 and 400 atm pressure, between 10 and 120ºC of temperature and between 0.5 and 40% of modifier) 2. Process according to claim 1 characterized by the use of ethanol as a modifier and mixtures thereof with water in the proportion of water with respect to ethanol of less than 10%. 3. Process according to claim 1 characterized by the use of methanol as a modifier and mixtures thereof with water in the proportion of water with respect to ethanol of less than 10%. 4. Process according to claim 1 characterized by the use of propanol as a modifier and mixtures thereof with water in the proportion of water with respect to ethanol of less than 10%. 5. Process according to claim 1 characterized by the use of isopropanol as a modifier and mixtures thereof with water in the proportion of water with respect to ethanol of less than 10%. 6. Process according to claim 1 characterized by the use of butanol as a modifier and mixtures thereof with water in the proportion of water with respect to ethanol of less than 10%.