RU2447086C2 - Method of producing high-purity arabinogalactan - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing arabinogalactan. The method involves aqueous extraction of arabinogalactan from resin-free larchwood while heating. The obtained extract is concentrated and subjected to ultrafiltration. Ultrafiltration is carried out using coarse-pored cellulose acetate membranes UAM-500P. The obtained concentrate is treated with aqueous solution of a cationic flocculant. The clarified concentrated is treated with aqueous hydrogen peroxide solution in amount of 0.1-0.5 mol/l concentrate in the presence of a complexing agent in amount of 0.12-5.0 mmol/l. The ready product is extracted by spray drying.

EFFECT: invention enables to obtain highly pure arabinogalactan, increases efficiency of the process by changing the sequence of process steps and reduces consumption of reactants.

4 ex

Description

The invention relates to the chemical industry and for the allocation of larch arabinogalactan (AH) from wood.

Arabinogalactan is a water-soluble plant-derived polysaccharide with high biological activity (immunostimulating, prebiotic, antimutagenic, mitogenic, hypolipidemic, etc.) and low toxicity (does not exhibit acute toxicity at a dose of 5 g / kg and chronic toxicity at a dose of 500 mg / kg per day ) In addition, AG is characterized by high membranotropy, dispersing ability, good solubility in water, low viscosity of concentrated aqueous solutions. AG is stable in an acidic environment and during heat treatment, it binds fat well and retains moisture, has no taste and smell.

The combination of these valuable properties determines the practical importance of hypertension for use in medicine, pharmaceutical, cosmetic industry, animal husbandry, as well as in the food industry for the creation of therapeutic and prophylactic foods and drinks (bakery, confectionery, sausages, fermented milk, mayonnaise, desserts, ice cream , drinks, etc.) [1-4].

Known methods for the extraction of arabinogalactan from crushed larch wood by aqueous extraction without first removing phenolic compounds from it [5-9]. A significant drawback of these methods is that the extremely valuable biologically active components of larch wood - flavonoids and resinous substances - are not used, so the profitability of processing wood raw materials is significantly reduced. In addition, the implementation of these methods requires expensive equipment (continuous centrifuges, shock acoustic and microwave installations). Isolation of AG by the method [5] additionally provides for the use of an expensive imported polyamide sorbent, the regeneration of which is time-consuming and requires large quantities of methyl ethyl ketone - a toxic, flammable and expensive organic solvent. Using the method of [8] microwave exposure will require significant labor protection costs, because It is known that microwave radiation is very harmful to the human body. In addition, the significant drawbacks of the methods [6-8] include the use of the method of planting large amounts of toxic flammable organic solvents (acetone, ethanol, dioxane) for the isolation of dry AG from aqueous extracts, which increases the fire hazard of production and requires significant material costs for regeneration solvents. Due to the noted drawbacks, these methods are low-tech and do not have a real prospect of industrial implementation.

A number of patents are devoted to methods of isolating AH from crushed larch wood after extraction of phenolic components (flavonoids, resinous substances) from it [10-12].

According to the method of [10], arabinogalactan is extracted from the crushed larch wood chips by aqueous extraction at a temperature of 80-90 ° C in a continuous circulation mode for 2 hours after removing dihydroquercetin (DHQ) from it with an organic solvent and drying the chips in a gentle mode. The aqueous extract of AG is concentrated under reduced pressure, treated with aqueous solutions of a coagulant — aluminum sulfate and Sunfloc flocculant, followed by filtration and precipitation of AG with a four-fold volume of ethyl alcohol, decantation of the supernatant, washing of the precipitate with alcohol and drying.

The disadvantages of this method are:

- high energy consumption for the concentration of the aqueous extract of AG by evaporation under reduced pressure;

- use for the deposition of AG large quantities of ethyl alcohol, requiring special storage conditions and a special mode of operation with it;

- use together with a flocculant coagulant, which increases the cost of the process and leads to contamination of the product.

Closest to the proposed is a method for producing arabinogalactan [11], which consists in the extraction of larch wood in the form of crushed technological wood chips after removing from it DKV and other monomeric extractive substances with an organic solvent (ethyl acetate). The extraction is carried out with water (hydraulic module from 1: 1.5 to 1: 3.6 to the mass of absolutely dry raw materials) at a temperature of 80-90 ° C in continuous circulation for 2 hours. The aqueous extract, without cooling, is treated with stirring with an aqueous solution cationic flocculant, filtered, then the concentration and additional purification of the extract by ultrafiltration using industrial cellulose acetate or polysulfonamide membranes is carried out, and the powdery target product is isolated from the concentrate by spray drying.

The filtrate passing through the ultrafiltration membrane is mixed with fresh water without additional treatment and reused for extraction.

This method eliminates the need for expensive sorbents and equipment, reduces energy costs, eliminates the use of toxic flammable solvents, provides closed water circulation, which reduces water consumption and significantly reduces the amount of wastewater.

Membrane methods, such as ultrafiltration, are promising for concentration and purification, because They are distinguished by universality, simplicity of equipment design, low power consumption, and the possibility of carrying out the process at ambient temperature. The use of ultrafiltration in combination with spray drying in AG separation technology makes it possible to abandon the use of large quantities of organic precipitants, which leads to the creation of environmentally friendly, resource-saving and waste-free production.

AH aqueous extract contains mechanical and finely divided high molecular weight impurities (lignin substances, tannins) that cannot be removed by conventional filtration. Therefore, ultrafiltration of the crude extract using finely porous membranes UAM-150, as in the prototype, proceeds at a low speed, the membrane is rapidly blocked and requires frequent regeneration or replacement. In the prototype method for removing high molecular weight impurities before ultrafiltration, the extract is treated with solutions of industrial synthetic cationic flocculants. Obtained by the prototype AG method is suitable for use in the pharmaceutical industry for the production of biologically active food additives.

The disadvantage of the prototype method is the low productivity of the process, as well as the insufficiently high degree of purity of the product, which is due to the presence in it of the residual amount of high molecular weight phenolic impurities complexed with arabinogalactan and therefore not removed by the used cleaning methods. This does not allow the use of the resulting AH to create drugs that require high purity of the substance.

The objective of the invention is to improve the process of obtaining arabinogalactan when used as a raw material for production of DHQ by intensifying the process, reducing material costs and increasing the degree of purity of the product by changing the sequence of technological stages and additional purification of the product from high molecular weight phenolic impurities.

The problem is solved in that the extraction of larch wood in the form of crushed technological wood chips after removing from it DHQ and other monomeric extractives with an organic solvent (ethyl acetate) is carried out with water (hydraulic module from 1: 1.5 to 1: 3.6 to the mass of absolutely dry raw materials ) at a temperature of 80-90 ° C in continuous circulation for 2 hours. The resulting aqueous extract containing 4-8% solids after removal of mechanical impurities using a polypropylene filter is first fed to an ultrafiltration unit tanovka with an industrial membrane UAM-500P (pore size 0.03 μm), where it is concentrated to a solids content of 15-25% and is cleaned of low molecular weight impurities. The filtrate passing through the ultrafiltration membrane is diluted with fresh water and returned to the extraction.

The concentrate is treated with a 0.1% aqueous solution of a cationic flocculant at a flow rate of 0.04-0.1 g / l with stirring for 0.5-2 hours, then it is freed from the cake formed by decantation, followed by filtration.

Changing the sequence of technological stages has become possible due to the use of larger pore ultrafiltration membranes, for example, UAM-500P (pore size 0.03 μm), compared with UAM-150 (pore size 0.01-0.015 μm).

Additional purification of the clarified concentrate from high molecular weight phenolic impurities complexed with arabinogalactan and therefore not removable by flocculation is carried out by treating it with an aqueous solution of hydrogen peroxide in the presence of a complexing agent that prevents unproductive consumption of hydrogen peroxide and the destruction of arabinogalactan macromolecules. The consumption of H ₂ O ₂ depending on the amount of phenolic impurities remaining in the extract is 0.1-0.5 mol / L. As the complexing agent, for example, disodium salt of ethylenediaminetetraacetic acid (EDTA, Trilon B) is used, the flow rate of which is 0.125-5.0 mmol / L. A powdered commercial product is isolated from the purified concentrate by spray drying.

The inventive method retains all the advantages of the prototype and is characterized by the following advantages:

- changing the sequence of technological stages allows you to increase productivity by 4-6 times, reduce flocculant consumption by 2 times, reduce capital costs 2-3 times;

- the use of an environmentally friendly reagent - hydrogen peroxide - allows you to effectively clean the AG of complex-bound high molecular weight impurities without compromising working conditions.

The following examples illustrate the invention.

Example 1

Extraction was carried out in a pilot plant for the production of DHQ. After extracting DHQ by extraction with ethyl acetate, 0.850 m ^{3 of} demineralized water continuously circulating at a temperature of 80-90 ° C were fed into an extractor containing 1390 kg of larch wood chips (dry matter content 44%) to simultaneously extract AG and remove the remaining ethyl acetate from the wood chips. . The treatment was carried out for 2 hours. Received 0.65 m ³ hot water extract of AG with a solids content of 5.46%. The AH content in the dry residue is 95% (33.74 kg). The obtained extract was filtered from solids on a filter with a pore size of 10 μm. The filtered AG extract was fed to an ultrafiltration unit using a UAM-500P cellulose acetate membrane. The extract was concentrated to a volume of 91 L (100 kg), the pressure drop was 2 atm. The solids content in the concentrate is 25.2%. To the obtained AG concentrate having a temperature of 70 ° C, 8 L of a 0.1% aqueous solution of the cationic flocculant Praestol 851 BC was added with stirring and left for 2 hours. The precipitate formed was filtered off. The obtained clear filtrate with a solids content of 23.24% was treated with 1.7 kg of hydrogen peroxide (H ₂ O ₂ concentration _of 37%) with constant stirring, after adding 34 g of Trilon B. After spray drying at 90 ° C, 26 kg of arabinogalactan was obtained with humidity 5% (yield 72.67% of hypertension in the initial extract). The content of the main substance in the dry product is 98.2%, no ash content.

Example 2

In the conditions of example 1 received 600 kg of AG extract having a temperature of 60 ° C, with a solids content of 6.83%. The AH content in the dry residue is 95% (38.93 kg). The obtained extract was filtered from solids on a filter with a pore size of 10 μm. The filtered AG extract was fed to an ultrafiltration unit using a UAM-500P cellulose acetate membrane. The extract was concentrated to a volume of 120 l (130 kg), the pressure drop was 2 atm. The solids content in the concentrate is 25.4%. To the obtained AG concentrate having a temperature of 70 ° C, 13 l of a 0.1% aqueous solution of the cationic flocculant Praestol 851 BC were added with stirring and left for 2 hours. The precipitate formed was filtered off. The obtained clear filtrate with a solids content of 23.05% was treated with 2.25 kg of hydrogen peroxide (H ₂ O ₂ concentration _of 37%) with constant stirring, after adding 37 g of Trilon B. After spray drying at 95 ° C, 33.7 kg was obtained arabinogalactan with a moisture content of 4.5% (yield 82.05% of hypertension in the original extract). The content of the main substance in the dry product is 98.0%, no ash content.

Example 3

In the conditions of example 1 received 600 kg of AG extract having a temperature of 70 ° C, with a solids content of 7.38%. The AH content in the dry residue is 95% (42.05 kg). The obtained extract was filtered from solids on a filter with a pore size of 10 μm. The filtered AG extract was fed to an ultrafiltration unit using a UAM-500P cellulose acetate membrane. The extract was concentrated to a volume of 130 l (140 kg), the pressure drop was 2 atm. The solids content in the concentrate is 26.2%. To the obtained AG concentrate having a temperature of 70 ° C, 14 l of a 0.1% aqueous solution of the cationic flocculant Praestol 851 BC were added with stirring and left for 2 hours. The precipitate formed was filtered off. The obtained clear filtrate with a solids content of 23.73% was treated with 2.4 kg of hydrogen peroxide (H ₂ O ₂ concentration _of 37%) with constant stirring, after adding 39 g of Trilon B. After spray drying at 90 ° C, 37.8 kg was obtained arabinogalactan with a moisture content of 5% (yield 84.6% of hypertension in the initial extract). The content of the main substance in the dry product is 98.1%, no ash content.

Example 4

In the conditions of example 1 received 500 kg of AG extract having a temperature of 50 ° C, with a solids content of 8.74%. The AH content in the dry residue is 95% (41.53 kg). The obtained extract was filtered from solids on a filter with a pore size of 10 μm. The filtered AG extract was fed to an ultrafiltration unit using a UAM-500P cellulose acetate membrane. The extract was concentrated to a volume of 122 l (135 kg), the pressure drop was 2 atm. The solids content in the concentrate is 28.4%. To the obtained AG concentrate having a temperature of 60 ° C, 13.5 L of a 0.1% aqueous solution of the cationic flocculant Praestol 851 BC was added with stirring and left for 2 hours. The precipitate formed was filtered off. The obtained clear filtrate with a solids content of 25.73% was treated with 2.3 kg of hydrogen peroxide (H ₂ O ₂ concentration _of 37%) with constant stirring, after adding 40 g of Trilon B. After spray drying at 95 ° C, 39.1 kg was obtained arabinogalactan with a moisture content of 4% (yield 89.4% of hypertension in the initial extract). The content of the main substance in the dry product is 98.4%, no ash content.

Obtained by the proposed method, arabinogalactan was characterized by physicochemical methods (UV, IR, ¹³ C NMR spectroscopy) as a highly pure substance that meets the requirements of the pharmaceutical industry.

Literature

1. Antonova G.F., Tyukavkina N.A. Water-soluble substances of larch and the possibility of their use // Chemistry of wood. 1983. No. 2. S.89-96.

2. Natural Products from the Chemistry of Trees / http://www.Larex.com/htm/index.html (Feb 24, 2004).

3. Babkin B.A., Ostroukhova L.A., Malkov Yu.A., Ivanova S.Z., Onuchina N.A., Babkin D.V. Biologically active substances from larch wood // Chemistry in the interests of sustainable development. 2001.Vol. 9, No. 3. S.363-367.

4. Medvedeva E.N., Babkin V.A., Ostroukhova L.A. Larch arabinogalactan - properties and prospects of use // Chemistry of plant raw materials. 2003. No1. S.27-37.

5. Kislitsyn A.N., Zhukova I.P., Puzanova V.Yu., Trofimov A.N., Oganina N.V., Ryzhova E.S., Povarov A.A., Savelyev S.P. The method of obtaining arabinogalactan // RF patent No. 2002756. 1993. BI No. 41-42.

6. Tyukavkina N.A .; Kolesnik Yu.A.; Naumov V.V .; Rulenko I.A .; Gavrilova T.F .; Khvostova A.I. / The method of obtaining arabinogalactan // RF patent 2040268. 1995. BI No. 21.

7. Kuznetsova S.A., Kuznetsov B.N., Mikhailov A.G., Skvortsova G.P. / A method of obtaining arabinogalactan // RF patent 2273646. 2006. BI No. 10.

8. Kuznetsova S.A., Kuznetsov B.N., Skvortsova G.P. / The method of obtaining arabinogalactan // RF patent 2280040. 2006. BI No. 20.

9. Babkin D.V., Ugreninov A.A. / A method of obtaining arabinogalactan // Application of the Russian Federation 2008120252/13. 2010. BI No. 9.

10. Babkin V.A., Ostroukhova L.A., Medvedeva S.A., Babkin D.V., Malkov Yu.A., Alexandrova G.P., Antonova L.I. A method of obtaining a high purity arabinogalactan. RF patent No. 2143437. 1999. BI No. 36.

11. Babkin V.A., Kolzunova L.G., Medvedeva E.N., Malkov Yu.A., Ostroukhova L.A. The method of obtaining arabinogalactan // RF patent №2256668. 2005. BI No. 20.

12. Malchikov E.L. The method of obtaining arabinogalactan // RF patent 2384587. 2010. BI No. 8.

Claims (1)

A method of obtaining high-purity arabinogalactan, including aqueous extraction of AG by heating from pre-tarred larch wood, characterized in that the extract obtained is first concentrated and purified from low molecular weight impurities by ultrafiltration using large-porous cellulose acetate membranes UAM-500P, then the concentrate is treated with an aqueous solution of cationic floc purified from high molecular weight phenolic impurities by treating the clarified concentrate with peroxide in portly at a flow rate of 0.1-0.5 mol / l in presence of a complexing agent at a flow rate 0,12-5,0 mmol / l, and the desired product is isolated by spray drying.