MD961Z - Method for producing inulin and other fructan-containing products from Jerusalem artichoke - Google Patents

Abstract

The invention relates to nanotechnology for the production of biologically active substances, and in particular to a method for producing an inulin-containing solution from Jerusalem artichoke, as well as to methods for producing inulin, fructose-glucose syrup and fructooligosaccharides based on it. in the form of chips, their drying and grinding, mixing with water to obtain a suspension. Then fructosans are extracted from the suspension, after which the pulp is separated by filtration, and the resulting solution is clarified and concentrated to a solids content of 42 ... 45%. The method of producing inulin involves filtering a concentrated inulin-containing solution through nanofilters with a retention threshold of 5000 Da, then the obtained filtrate is filtered through nanofilters with a retention threshold of 6000 Da and an inulin-containing solution with a molecular weight of 5000 ... 6000 Da is separated, which subsequently crystallizes. From solutions containing fructooligosaccharides with a molecular weight of less than 5000 and more than 6000 Da, fructooligosaccharides are obtained. Fructose-glucose syrup is also obtained from a concentrated inulin-containing solution by hydrolysis and evaporation.

Description

The invention relates to nanotechnology for obtaining biologically active substances, namely to a process for obtaining a solution containing inulin from Jerusalem artichoke and to processes for obtaining inulin, fructose-glucose syrup and fructooligosaccharides based on it.

The invention can be used for the production of biologically active food additives, pharmaceutical preparations based on inulin and fructooligosaccharides as components of functional food products, as well as for use in agriculture as animal feed additives.

Inulin is a carbohydrate from the group of polysaccharides that occurs as an alternative product in the tubers and roots of plants of the Asteraceae family. More than 36 thousand different plants are known to contain the vegetable fiber inulin. The largest amount of inulin is contained in common chicory (Cichorium intylis L.) and Jerusalem artichoke (Helianthus tuberosus), also called "earth pear". The amount of inulin in Jerusalem artichoke tubers reaches 10...12%. The inulin molecule is a chain of 30...36 fructose residues in the furanose form (BSE, 3rd Ed., M, «Советская энциклопедия», v. 10, 1972, p. 344). The molecular mass of inulin is 5000...6000 Da (Dalton - a unit of measurement of macromolecular compounds, such as proteins, humic acids). Inulin is a polyfructosan that can be obtained in the form of an amorphous powder and in the form of crystals, easily soluble in hot water and poorly soluble in cold water. In addition to inulin, tubers also contain other fructosans with a degree of polymerization Gp> 2, which are called oligosaccharides.

A process for obtaining inulin from Jerusalem artichoke tubers is known, which includes its crystallization and drying. In the known process, from Jerusalem artichoke tubers, crushed by means of physical-mechanical separation of water-soluble substances from water-insoluble fibrous ones, a juice is obtained from which, by heating to a temperature of 80…85° C for 1…3 min and filtration, protein and colored substances are eliminated. At the same time, the separation of soluble substances from water-insoluble fibrous substances from the tubers is carried out no later than 5…10 min after their crushing. After this, the juice filtrate is purified from natural inulin macromolecular substances with a molecular mass greater than 6500 Da and from colloidal-dispersion substances using hollow fiber ultrafiltration. The obtained concentrate is diluted with water and subjected to diafiltration. The permeate obtained after ultrafiltration and the permeate obtained after diafiltration are combined and nanofiltration is performed with the passage of the combined solution through a semipermeable membrane with a retention threshold of 4500 Da. At the same time, inulin accumulates in this concentrate, and low molecular weight and inorganic impurities pass into the ultrafiltrate. The solution containing inulin is clarified by adding activated carbon which contacts the solution at a temperature of 50…60° C for 30…40 min. After this, the carbon is separated by centrifugation. The clarified solution is concentrated by evaporation, and inulin crystallizes from the concentrated solution at a temperature of 4° C [1].

In the known process, inulin is obtained from the juice of freshly harvested raw material (jerusalem artichoke), but this process does not allow obtaining chemically pure inulin, with a molecular mass of 5000…6000 Da, usable in pharmaceuticals and medicine.

A process for obtaining a solution containing inulin is known, according to which Jerusalem artichoke tubers are washed in a water tank, inspected and cut into slices, which are then dried. The dried slices are ground into flour to a grinding fineness of 50…60 microns. Jerusalem artichoke flour is mixed with hot water at a temperature of 50…60°C until a homogeneous consistency is obtained, without lumps. Then, the suspension obtained with the quantitative ratio of the components of 1:4 is heated to 80…85° C and maintained in the kneading process for 1.0…1.5 hours for the extraction of fructosans. After this, the suspension is cooled to a temperature of 50° C and the solid phase (slurry) is separated from the liquid phase through a filter cloth or by centrifugation. The filtrate is purified from coloring substances by means of activated carbon mixed with perlite, in a ratio of 1:1. The processing is carried out at a temperature of 50…60° C for 0.5…1.0 hours. The coal and the used perlite are separated by means of filtration through a cloth. In order to increase the quality of the solution containing inulin, the filtrate is purified from inorganic impurities and inulides with a molecular mass of less than 4000 Da by nanofiltration, using a semipermeable membrane with a particle retention threshold of over 4000 Da. At the same time, the phase passed through the membrane - the permeate, contains impurities with a low molecular mass, and in the delayed phase - the concentrate, inulin and inulides accumulate. The inulin-containing solution thus prepared is subsequently used to obtain, by known technologies, inulin and fructose-glucose syrup [2].

According to the described process, examples of obtaining the solution containing inulin are presented both on the basis of juice with a pasty consistency, obtained by grinding freshly harvested Jerusalem artichoke tubers, and on the basis of an aqueous suspension prepared from Jerusalem artichoke flour. However, according to the known process, after clarifying the solution containing inulin, a great difficulty presents the separation of activated carbon from it, because the carbon particles pass through the filter cloth and end up in the filtrate. The solution is strongly colored, which affects the color of the finished product, and therefore the quality of the inulin obtained from the solution containing inulin. In addition, from the inulin-containing solution obtained by the known process, it is impossible to obtain chemically pure inulin, with a molecular mass of 5000…6000 Da, for its use in pharmaceuticals and medicine, because nanofiltration is performed using semipermeable polymeric membranes, which are limited by temperature and have a low potential for use, about 1 year, because they are subject to chemical degradation through hydrolysis, oxidation and microbial action.

Another known method is to obtain inulin and other inulin-containing products from Jerusalem artichoke. According to the known method, Jerusalem artichoke tubers are washed in a water tank, inspected and cut into slices, after which the slices are dried. The dried slices are ground to a grinding fineness of 50…60 microns. Jerusalem artichoke flour is mixed with hot water at 50° C until a homogeneous consistency is obtained, without lumps. The prepared suspension, with a component ratio of 1:4, is heated to a temperature of 80…85° C, kept in the kneading process for 1.0…4.5 hours to extract fructosans. After this, the suspension is cooled to a temperature of 50° C and the solid phase (meal) is separated from the liquid phase through a filter cloth or by centrifugation. The filtrate is cleaned of coloring substances using activated carbon mixed with perlite in a ratio of 1:1. The carbon and perlite used are also separated by filtration through a filter cloth, then the obtained solution is nanofiltered, which, to eliminate macromolecular inulin, is passed through a semipermeable polymeric membrane with a particle retention threshold greater than 4000 Da. From the concentrate containing macromolecular inulin, it is isolated in the subsequent crystallization process, and to obtain fructosans, the non-recyclable residues are used, in particular the permeate after nanofiltration, the fructosans solution, obtained by means of an additional extraction from the meal, with the 1:1 hydromodule, and the mother liquor. The solutions are combined and clarified with activated carbon, added to the combined solution, with its subsequent heating to a temperature of 50° C and maintaining for 1 hour with periodic mixing. After the clarification process is completed, vacuum filtration is performed, passing the clarified solution through a cloth with an adjuvant layer of perlite. The clarified solution of fructosans is concentrated by evaporation in vacuum at a residual pressure of 120 mm Hg and a temperature of 60° C, then dried in a spray dryer, obtaining a finely dispersed powder of fructosans (the content of fructosans is at least 85%) [3].

The known process of obtaining inulin and other fructan-containing products from Jerusalem artichoke has a number of disadvantages. When washing the tubers in the water tank, due to the complicated glomerular configuration of the Jerusalem artichoke tubers, some soil remains on them, which then falls into the technological production line, thus it can also be contained in the finished product, reducing its quality. Jerusalem artichoke tubers are cut into large slices and, since the tubers contain a large amount of sugary substances (including inulin), their drying becomes very difficult because the slices stick together, requiring constant mixing, at the same time the equipment becomes more complicated, and energy consumption increases. In addition, large slices turn black due to oxidation, which requires more effort to clarify the finished product. The low extraction yield of inulin in solution is determined by the fact that the product is ground with a grinding fineness of 50…60 microns. The preparation of the suspension begins at a low temperature of 50…60° C, and for the extraction, forced heating is carried out to 80…85° C. At the same time, however, the extraction time is reduced, which is insufficient for the maximum isolation of fructosans in the solution. When filtering the suspension through textile filters, the solution is not pure enough to obtain inulin, since small pulp particles can enter the solution, the filters become clogged and their permanent replacement is necessary, which also affects the complexity of the process. In addition, after clarifying the inulin-containing solution with activated carbon, which is separated from the solution by filter cloth, fine particles of activated carbon enter the filtrate and the solution remains black. For this reason, the subsequent purification process of such an inulin-containing solution from inorganic impurities, carried out by nanofiltration, is inefficient. In addition, the use of semipermeable polymer membranes in the nanofiltration process does not provide the possibility of obtaining chemically pure inulin for medical and pharmaceutical use. In the known process, when obtaining fructosans, their content in the finished product (powder) is limited to at least 85%, since the solution, transferred to drying immediately after the evaporation concentration process, is characterized by a solids content of 25…30%.

The purpose of the claimed invention is to obtain inulin with nanoproperties and to improve the qualitative and quantitative composition of fructan-containing products.

The technical problem is solved by proposing a process for obtaining a solution containing inulin from Jerusalem artichoke, which includes washing Jerusalem artichoke tubers by periodic bubbling and mixing, keeping them in water for 2.5…3 hours, and subsequent washing in a washing plant, cutting the tubers into slices in the form of chips with a thickness of 1.0…1.5 mm, drying them, grinding them to sizes of 20…30 microns, gradually mixing the ground product with water at a temperature of 85…90° C in a ratio of 1:(5…6) respectively with obtaining a suspension. Then, for 1.5…2 hours, the fructosans are extracted, after which the pulp is separated from the suspension by filtration on continuous flow centrifuges, and the solution obtained is clarified by filtering it through a cylindrical filter with a layer of perlite and concentrated by evaporation at a temperature of 60…70°C and a residual pressure of 120…150 mm Hg, to a dry matter content of 42…45%.

At the same time, the process for obtaining inulin from the mentioned inulin-containing solution includes filtering it through nanofilters with a retention threshold of 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da, the inulin-containing solution with a molecular mass of 5000...6000 Da is separated, which is transferred through the cooling installation for crystallization, a process that is carried out for 16...18 hours at a temperature of 2...3°C; the precipitated inulin crystals are mixed with the initial inulin-containing solution and dried in a spray drying installation.

A process for obtaining fructose-glucose syrup from the inulin-containing solution is also proposed, which includes its hydrolysis with organic or mineral acid at a pH of 1.5…2.0 and a temperature of 60…70° C, then the hydrolysate is concentrated by evaporation to a content of 55% dry substances, filtered through a layer of perlite on a cylindrical vacuum filter, after which the clarified solution obtained is concentrated by evaporation to a content of dry substances of at least 70%.

A process for obtaining fructooligosaccharides from the inulin-containing solution is also proposed, which includes filtering it through nanofilters with a retention threshold of 5000 Da, with the separation of the solution of micromolecular fructooligosaccharides with a molecular mass of up to 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da with the separation of the solution of macromolecular fructooligosaccharides with a molecular mass greater than 6000 Da, unification of both fructooligosaccharide solutions and discharge through a cooling installation for crystallization, which is carried out for 16…18 hours at a temperature of 2…3°C; the precipitated fructooligosaccharide crystals are mixed with the initial solution containing inulin and dried in a spray drying installation.

The claimed technical solutions ensure the quality of the products obtained by performing the following actions. First, the washing of the tubers brought from the field is carried out more thoroughly, in order to avoid soil particles entering the technological line together with the tubers: they are first placed in a tank with bubbling water, where they are kept, being periodically mixed, for 2.5…3 hours. Second, oxidation and blackening of the cut tubers in the process of drying them is prevented due to the fact that they are cut into slices of no more than 1.5 mm. Third, due to the finer grinding of the dried slices, with a grinding fineness of 20…30 microns, a high dispersion of the Jerusalem artichoke flour is ensured, from which the aqueous suspension for the extraction of fructosans is prepared. Clarification of the separated pulp solution is carried out on a cylindrical filter with an adjuvant layer of perlite.

The process is carried out as follows. Jerusalem artichoke tubers are first washed in a tank with bubbling water, being periodically mixed, kept for 2.5…3 hours to separate the soil stuck to them, then they are introduced into the washing installation. The washed tubers are transferred for inspection and waste removal and for their recycling. After that, the selected tubers are cut into slices in the form of chips with a thickness of 1.0…1.5 mm, then dried in a belt dryer. The dried Jerusalem artichoke slices are ground into flour with a grinding fineness of 20…30 microns. The ground product is packed in kraft bags which are stored in the warehouse in a dry and cool place.

The inulin-containing solution is prepared in a steam-jacketed reactor, in which the Jerusalem artichoke flour is mixed with hot water at a temperature of 85…90° C, while the water is gradually discharged, until a suspension hydromodule with a component ratio of 1:(5…6) is obtained, from which fructosans are extracted for 1.5…2 hours. At the end of the extraction process, a suspension of uniform consistency is obtained. This suspension is discharged into a continuous-flow centrifuge to separate the pulp from the inulin-containing solution. After this, the inulin-containing solution is subjected to additional purification and clarification. At the same time, the solution is directed into a single-section cylindrical vacuum filter, consisting of a rotating drum with a rotation speed of no more than 8 rpm, on which the filter cloth covered with a layer of perlite is stretched. The precipitate of suspended particles remains on the surface of the perlite and is continuously removed by scrapers. The clarified solution is pumped into a plant with a mixer, a bottom discharge outlet and a steam jacket, where it is concentrated by evaporation in vacuum at a temperature of 60…70° C and a residual pressure of 120…150 mm Hg.

To obtain inulin with nanoproperties, usable in medicine and pharmaceuticals, the solution containing inulin concentrated by evaporation is filtered through nanofilters with a retention threshold of 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da and the solution containing inulin with a molecular mass of 5000 ... 6000 Da is separated. After this, the solution containing inulin is discharged, through a continuous flow cooling installation, into a crystallizer equipped with a jacket, in which the solution is cooled to 2 ... 3 ° C and kept for 16 ... 18 hours for the precipitation of inulin crystals. The precipitated crystals are mixed with the mother solution and pumped through the bottom discharge outlet of the crystallizer into the spray dryer. After obtaining the finished product in the dryer, the macromolecular inulin is weighed and packaged.

To obtain fructose-glucose syrup, the solution containing inulin concentrated by evaporation is subjected to hydrolysis with organic or mineral acid at a pH of 1.5…2.0 and a temperature of 60…70° C, then the hydrolysate is concentrated by evaporation to a dry matter content of 55%, filtered through a layer of perlite on a cylindrical vacuum filter, after which the clarified solution obtained is concentrated by evaporation to a dry matter content of at least 70%.

To obtain fructooligosaccharides (FOZ), the concentrated inulin-containing solution is filtered through nanofilters with a retention threshold of 5000 Da, with the separation of the micromolecular fructooligosaccharide solution with a molecular mass of up to 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da with the separation of the macromolecular fructooligosaccharide solution with a molecular mass greater than 6000 Da, unification of both fructooligosaccharide solutions and discharge through a crystallization cooling installation, which is carried out for 16…18 hours at a temperature of 2…3°C; the precipitated fructooligosaccharide crystals are mixed with the initial inulin-containing solution and dried in a spray-drying installation. Then, the obtained FOZ powder is weighed and packaged.

Examples of implementation

The harvested Jerusalem artichoke tubers, in the amount of 3200 kg, are loaded into a container with bubbling water, kept stirring periodically for 2.5 hours and then placed in a washing plant. After washing and inspection, with the removal of waste, the tubers with a total weight of 3000 kg are cut into slices (chips) and directed to a belt dryer, where they are dried in several stages at an air temperature of 120 to 150° C, until the moisture content of the dried product does not exceed 6%. The dried product is ground into flour with a grinding fineness of 20…30 microns. After drying and grinding, 780 kg of Jerusalem artichoke flour is obtained. In a reactor equipped with a mixer and a steam jacket, 100 kg of Jerusalem artichoke flour are loaded and 500 l of water with a temperature of 85…90°C is gradually added to obtain a suspension hydromodule with a component ratio of 1:5. Being constantly mixed, a homogeneous suspension is obtained. For 1.5 hours, the fructosans are extracted in the suspension hydromodule. After the extraction is completed, the suspension is discharged into a centrifuge, where the suspended solids are separated from the solution containing inulin and fructooligosaccharides. At the output, 470.5 l of inulin-containing solution containing fructooligosaccharides and 125.3 kg of pulp are obtained. The pulp is sent for processing, and the solution, having a temperature of 50…60° C, is subjected to additional clarification and purification. Further clarification and purification of the solution is carried out on a cylindrical vacuum filter with a drum rotation speed of 8 rpm. The cylindrical vacuum filter used is equipped with a drum with a perlite adjuvant layer 60 mm thick and with scrapers with transverse movement of 0.2…0.8 mm. The filtrate in the amount of 435.0 l and with a solids content of 14.2% is fed into the vacuum evaporation plant MZS-320 (VNIIKP-2), where at a temperature of 70° C and a residual pressure of 120…150 mm Hg the solution is concentrated by evaporation to a volume of 141.8 l. In the indicated volume the solids content is 42…45%.

To isolate inulin with nanoproperties, the concentrated solution by evaporation with a volume of 141.8 l is transferred to dynamic nanofiltration through ceramic membranes. After interaction with ceramic nanofilters, the solution containing micromolecular fructosans with a molecular mass of less than 5000 Da is first separated. Then the rest of the solution is again sent to dynamic membrane nanofiltration, in the process of which the solution containing fructooligosaccharides with a molecular mass of more than 6000 Da is separated. As a result of nanofiltration, an inulin solution with a molecular mass of up to 6000 Da is obtained. The volume of the inulin solution separated in the nanofiltration process is 42.5 l, and the inulin contained in it has a molecular mass of 5000…6000 Da and a chain length of 1.48 nm. This solution is transferred through the continuous flow cooling system into a crystallizer equipped with a water jacket and a bottom drain. Water is fed into the reactor jacket at a temperature of 2…3° C. Crystallization is carried out for 16…18 hours. Then, the precipitated inulin crystals are mixed with the mother liquor using a mixer and passed into the spray dryer. After drying, a quantity of 9.21 kg of macromolecular inulin powder is obtained, with a molecular weight of 5000…6000 Da and a chain length of 1.48 nm, usable in medicine and pharmacy. The good quality product constitutes 48.6%.

The solution containing fructooligosaccharides with a molecular weight greater than 6000 Da and the solution containing micromolecular fructooligosaccharides with a molecular weight less than 5000 Da, isolated by nanofiltration of the solution containing inulin concentrated by evaporation with a volume of 141.8 l are combined, then cooled in the continuous flow cooling installation and discharged into the crystallizer where they are maintained at a temperature of 2…3° C for 16…18 hours. After the precipitation of fructooligosaccharide crystals, they are mixed with the mother solution using a mixer and dried in a spray dryer. The finished product is crystalline fructooligosaccharides (FOZ) in an amount of 30.7 kg, usable in the food industry. The good quality product is 92%, the degree of polymerization >2.

To obtain fructose-glucose syrup (GFS), the entire volume of the inulin-containing solution concentrated by evaporation in the amount of 141.8 l is transferred to the hydrolysis reactor. The volume of the reactor, equipped with a mixer, a bottom drain and a heating jacket, is 1.6 m3. The hydrolysis of inulin and fructooligosaccharides is carried out at pH 1.5…2.0, its level being established with citric acid at a temperature of 60…70° C. As monosaccharides and oligofructosans accumulate in the solution, the hydrolysis is completed. After that, the obtained solution, in the volume of 141.0 l, is concentrated by evaporation to a solids content index of 55%. Next, the obtained sugar-containing solution, in the amount of 102.6 l, is clarified on a cylindrical vacuum filter through an adjuvant layer of perlite. The clarified solution, in an amount of about 98 l, is concentrated by evaporation (boiling) in a vacuum evaporation plant until, after evaporation, the index of solid particles content in the syrup reaches at least 70%. Then the finished syrup, with a mass fraction of fructose and glucose of at least 70%, pH 7.5…8.5, clarity of 1…2 cm, is packaged. The product is usable in the food and functional food industries.

By implementing the invention, the quality and quantity of the extraction of finished products are improved, while the energy costs and the complexity of the processes are reduced by 2.5...3 times. The finished inulin powder, obtained by the claimed invention, has the characteristics of chemically pure inulin, which allows its use both in medicine, especially in the pharmaceutical industry, and in the preparation of animal and poultry feed.

1. RU 20148588 C1 2000.05.10

2. RU 22281291 C2 2006.08.10

3. RU 2009111945 A 2010.10.10

Claims (4)

1. Process for obtaining the inulin-containing solution from Jerusalem artichoke, which includes washing the Jerusalem artichoke tubers by bubbling and periodic mixing, keeping them in water for 2.5…3 hours and subsequent washing in a washing installation, cutting the tubers into slices in the form of chips with a thickness of 1.0…1.5 mm, drying them, grinding them to sizes of 20…30 microns, gradually mixing in a steam-jacketed reactor the ground product with water at a temperature of 85…90° C in a ratio of 1:(5…6) respectively with obtaining a suspension, then for 1.5…2 hours the fructosans are extracted, after which the pulp is separated from the suspension by filtration on continuous flow centrifuges, and the solution obtained is clarified by filtering it through a cylindrical filter with a layer of perlite and concentrated by evaporation at a temperature of of 60…70°C and residual pressure of 120…150 mm Hg, up to a dry matter content of 42…45%. 2. Process for obtaining inulin, which includes obtaining the solution containing inulin according to the process defined in claim 1, filtering it through nanofilters with a retention threshold of 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da and the solution containing inulin with a molecular mass of 5000 ... 6000 Da is separated, which is transferred through the cooling installation to crystallization, which is carried out for 16 ... 18 hours at a temperature of 2 ... 3 ° C; the precipitated inulin crystals are mixed with the initial solution containing inulin and dried in a spray drying installation. 3. Process for obtaining fructose-glucose syrup, which includes obtaining the solution containing inulin according to the process defined in claim 1, its hydrolysis with organic or mineral acid at a pH of 1.5…2.0 and a temperature of 60…70° C, then the hydrolysate is concentrated by evaporation to a dry matter content of 55%, filtered through a layer of perlite on a cylindrical vacuum filter, after which the clarified solution obtained is concentrated by evaporation to a dry matter content of at least 70%. 4. Process for obtaining fructooligosaccharides, which includes obtaining the solution containing inulin according to the process defined in claim 1, filtering it through nanofilters with a retention threshold of 5000 Da, with the separation of the solution of micromolecular fructooligosaccharides with a molecular mass of up to 5000 Da, then the filtrate obtained is filtered through nanofilters with a retention threshold of 6000 Da with the separation of the solution of macromolecular fructooligosaccharides with a molecular mass greater than 6000 Da, unifying both fructooligosaccharide solutions and passing through a cooling installation for crystallization, which is carried out for 16…18 hours at a temperature of 2…3°C; the precipitated fructooligosaccharide crystals are mixed with the initial solution containing inulin and dried in a spray drying installation.