WO2006125286A1

WO2006125286A1 - Process for the production of pyrogen-free anhydrous crystalline dextrose of high purity from sucrose

Info

Publication number: WO2006125286A1
Application number: PCT/BR2005/000092
Authority: WO
Inventors: João Afonso FERREIRA; Cláudio Octávio TEIXEIRA; Sérgio Murilo SOARES
Original assignee: Getec Guanabara Química Industrial S.A.
Priority date: 2005-05-24
Filing date: 2005-05-24
Publication date: 2006-11-30
Also published as: BRPI0520266A2; BRPI0520266B1

Abstract

The invention relates to a process for the production of anhydrous crystalline dextrose of high chemical purity and free of pyrogen, using sugar cane sucrose as raw material, which process produces microcrystalline particles that are well defined morphologically, said particles being typical of the orthorhombic crystal system, and which exhibit a narrow size distribution with a mean diameter within the range of 100 to 400 microns.

Description

"PROCESS FOR THE PRODUCTION OF PYROGEN-FREE ANHYDROUS CRYSTALLINE DEXTROSE OF HIGH PURITY FROM SUCROSE"

The present invention relates to a process for the production of anhydrous crystalline dextrose of high chemical purity and free of pyrogen through crystallization thereof, which is accomplished by the controlled evaporation of an aqueous solution of glucose, said glucose being obtained from sugar cane sucrose. The said dextrose, prepared by the process in accordance with the invention, is composed of well-defined crystals, and is constituted of particles which exhibit a narrow size distribution with a mean diameter comprised between about 100 microns and about 400 microns. The physical and functional characteristics of the anhydrous crystalline dextrose according to the invention, such as purity, granulometric size distribution and mean diameter of the microcrystalline granules, apparent density, and dissolution time, are carefully adjusted in order to maximize its performance in applications in the food and pharmaceutical industries. The technical field of the invention is concerned with naturally occurring nutritive sweeteners, the most important of these being the sucrose, the glucose and the fructose, which are saccharides produced on a large industrial scale and widely consumed as simple sugars and as ingredients in various edible products.

Dextrose, also known as glucose, is an aldohexose having the molecular formula C₆H^Oe and a molecular weight of 180.2, broadly belonging to the class of pyranoses, and exhibiting a sweetening power approximately equivalent to 70% that of sucrose, when used on an equivalent weight basis. The crystalline form of this important monosaccharide is composed of orthorhombic crystals which are white, odorless and have a sweet taste; said crystals have an apparent density higher than 740 kg/m³ and a melting point of 146 °C, and are sparingly soluble in ethanol and highly soluble in water. For the most part, the patented processes for the industrial production of crystalline dextrose, since the end of the 195<bs and during the 1960s, have utilized starch as raw material, particularly the corn starch. In general, these industrial processes of the prior art have revealed a common technological core whose first step consists in the enzymatic hydrolysis of the corn starch, or alternatively an acid hydrolysis carried out through the use of a strong acid, followed by consecutive phases of purification, crystallization and separation of the crystals obtained (Pat. GB 837,039; Pat. GB 1,121,095; Pat. GB 1,230,545.

Employing some diversification into the strategy for obtaining the crystals of interest, by means of the evaporation under vacuum of glucose syrup followed by an isothermal crystallization (U.S. Pat. No. 4,342,603), as well as through the concentration of glucose solution so as to be processed in extrusion dies with the addition of seed (Pat. GB 2,077,270 A), the inventions developed during the 1980s continued utilizing preferably the starch hydrolysate as the main raw material for the manufacture of crystalline dextrose .

The French patent (Pat. FR 2,582,105) established in the middle of the 1980s describes another process for the preparation of anhydrous dextrose, in a continuous mode of operation, also from hydrolyzed starch, where the glucose syrup free from crystals flows through a vertical vessel, under constant agitation and subjected to a predefined thermal gradient, passing through a region where it is brought into contact with dextrose crystals in order to effect the crystallization. The crystals of anhydrous dextrose act as seeds to accomplish the crystallization.

By contrast, the French patent FR 2,595,715 describes a process for preparing dextrose using the sucrose as raw material. The said process, despite stating in its description the possibility of obtaining anhydrous dextrose, reveals only the manufacture of monohydrate dextrose in its experimental exemplifications. This said process comprises, after an initial phase of inversion of sugar, i.e. its transformation into a solution of glucose and fructose, chromatographic separation unit operations, with the reuse of the fructose stream by means of its enzymatic isomerization, purification, concentration, crystallization and centrifugation .

In view of the above considerations, it is possible to note that the aforesaid processes of the prior art for the production of crystalline dextrose use almost exclusively corn starch as a basic raw material and, in their vast majority, are directed towards the preparation of a monohydrate product. The typical constituent steps of the said processes, which comprise the extraction of starch from the corn, the enzymatic hydrolysis of this starch to form the glucose, the purification of the solution thus formed, the concentration and crystallization thereof and the subsequent separation, washing and drying of the crystals, involve various physical, chemical and physicochemical operations, thereby requiring the application of a considerable amount of scientific and technical knowledge.

The present invention embraces distinguishing characteristics in introducing a technology which is distinct from those of the prior art, by combining the sugar cane sucrose as the source of raw material and an integrated processing route which is original and economical for producing the pyrogen-free anhydrous dextrose.

As regards the process for the manufacture of crystalline dextrose, the present patent application exhibits several features that are significantly different from those of all the other processes revealed in the literature of the prior art, possessing a high degree of inventiveness. Such inventiveness, besides embodying a focus on the production of a dextrose that is simultaneously anhydrous and free of pyrogen, is unique owing to its various technical improvements and innovations that combine to form a simple and effective processing route which comprises the following steps:

(a) enzymatic treatment of a sucrose solution with an amylase at a mean temperature comprised between 78 °C and 82 ⁰C for about 45 minutes, followed by filtration;

(b) chemical hydrolysis of the sucrose solution resulting from step (a) by employing an acid selected from the group consisting of inorganic acids, having the pH controlled in the range of

1.9 to 2.1;

(c) neutralization of the solution resulting from step (b) with sodium hydroxide, followed by its deionization at a temperature lower than 50 ⁰C; (d) chromatographic fractionation of the solution of glucose and fructose carried out at a temperature of the feed to the column in the range of 58 ⁰C to 62 ⁰C;

(e) treatment of the glucose solution with active charcoal, followed by deionization conducted in a battery of decolorizing, cationic, and anionic beds;

(f) treatment for eliminating pyrogen;

(g) elimination of particles by means of filtration of the charcoal, followed by a further filtration carried out in a battery of low- porosity filters;

(h) concentration of the glucose solution;

(i) crystallization of the dextrose from the syrup resulting from step (h) ;

(j) centrifugation, washing, drying and screening of the dextrose. Notwithstanding the irrefutable originality found in the sequencing of the unit operations employed according to the present patent, the process conceived herein contains further specific innovations such as the elimination of the residual starch existing in the sucrose, through the insertion of an enzymatic treatment at the beginning of the process, and the strategic inclusion of purification modules in subsequent steps which render it possible to obtain the final product free from pyrogen, according to the market requirements, and with a high degree of purity.

The elimination of the residual starch that is present in the sucrose is of fundamental importance to the success of the subsequent operations employed in the production of dextrose. The commercially available sucrose is usually contaminated with starch with various concentrations. In case such sucrose is processed directly without the previous elimination of this residual starch, the preparation of the final product will be harmed due to the formation of several contaminants that interfere with the dextrose crystallization. In the execution of the industrial process, these contaminants impair the quality of the finished product and the process yield, and may even completely inhibit the crystallization of the final product.

Thus, the anhydrous dextrose produced by the process in accordance with the invention has a high degree of purity, which is quantified by glucose content higher than 99.70%. The excellent purity of the dextrose crystals, their very well defined shapes which are typical of the orthorhombic crystal system, and the great uniformity of their sizes, which are features resulting from the process according to the invention, reveal an optimum stability of the crystalline product.

The economic and technical studies conducted by the Applicant Company demonstrated, unequivocally, that the raw material which combines, advantageously, the strategic and commercial characteristics and allows the establishment of a technological route which is more simple, efficient and productive, thereby meeting all the criteria specified in the inventive concept, is the sucrose obtained from the sugar cane. It should be noted that, in Brazil, the sucrose from sugar cane is a feedstock which is available on a large scale, is subject to few seasonal fluctuations in its demand, supplied regularly with a good product quality by a great number of producers and, furthermore, it has been historically cheaper than starchy raw materials. These features reinforce the perfect adequacy of the sucrose to be used as an excellent feedstock for the process in accordance with the invention.

Figure 1 shows schematically the process for the manufacture of pyrogen-free anhydrous crystalline dextrose of high purity from sucrose.

In accordance with the process of the present invention, initially, the crystalline sucrose, received from the suppliers with a minimum purity of 99.5% by weight, on a dry solids basis, is dissolved in process water, thereby forming an aqueous solution having a concentration of about 60% by weight, and is then subjected to an essential and innovative enzymatic treatment accomplished with an amylase, for about 45 minutes at a mean temperature of between 78 °C and 82 ⁰C, preferably at 80 ⁰C, said treatment not being found in the technical documents of the prior art, aiming at the convenient elimination of any residual starch that may exist in the medium and that could seriously hinder the filterability of the final product.

Subsequently, this sucrose solution, after occasional impurities have been removed by means of a filtration operation using a filter aid, undergoes a hydrolysis reaction catalyzed by hydrochloric acid, or by another inorganic acid, which is added as an aqueous solution in order to maintain the pH within the range of 1.9 to 2.1, thereby resulting a solution of fructose and glucose having a dry solids concentration of between 58% and 62% by weight, preferably of 60% by weight, and a maximum admissible glucose content of 1.5% by weight.

Upon completion of this acid hydrolysis, the resultant solution is neutralized with sodium hydroxide and purified by deionization, at a temperature never higher than 50 ⁰C, in an ion exchange unit whose purpose is the removal of all the cations and anions that could contaminate, in the subsequent step, the resin which constitutes the packing material of a chromatographic separation column, which forms an integral part of the process, what would cause a significant reduction in the level of performance of the column operation.

In accordance with the present invention, in the chromatographic step of the process the partial separation of the glucose from the fructose takes place, where the glucose-enriched fraction is concentrated in order to obtain a glucose-rich syrup, which also contains minute amounts of fructose. To achieve this aim, the aqueous solution of fructose and glucose having a dry solids concentration comprised between 58% and 59% by weight, obtained previously just after the deionization operation, and at a temperature comprised between 58 ⁰C and 62 ⁰C, is fed into a chromatographic column containing a packed bed formed by a cation-exchange resin which adsorbs the fructose to a greater degree than it adsorbs the glucose, thereby resulting, as a consequence of this selective retention of the fructose in the resin, a partial fractionation of these two isomers. Afterwards, a certain volume of elution water, which has been deoxygenated and deionized in a special ion exchange unit, is introduced into the chromatographic column to effect the desorption of fructose from the resin, thereby forming a fructose stream with a dry solids concentration comprised between 22% and 26% by weight, and having a fructose content comprised between 84% and 90% by weight, on a dry solids basis, preferably comprised between 86% and 88% by weight, and which stream is employed in the production of sorbitol in association with mannitol, such compounds being polyols which have a wide range of industrial uses, and, moreover, a glucose stream, said stream being the main focus of the present invention, having a dry solids concentration of between 22% and 26% by weight, and a glucose content of between 94% and 97% by weight, on a dry solids basis, preferably of greater than 95.5% by weight, on the dry basis, thereby allowing the formation of dextrose crystals with a very good quality in the last step of the process. This glucose solution, whose temperature is adjusted to a value within the range of 57 ⁰C to 61 ⁰C, preferably within the range of 58 ⁰C to 60 ⁰C, and having a pH of about 3.5, is then subjected to a treatment with active charcoal in an approximate proportion of between 0.1% and 0.3% wt/vol, preferably of between 0.1% and 0.2% wt/vol, for about 45 minutes, in order to remove color from the product, after which there is accomplished the filtration of the stream using a filter aid to separate both the charcoal and the impurities adhered to its surface. Thereafter, the glucose syrup, which has already been cooled so that it does not reach a temperature higher than the limit of 50 °C, is fed into a battery of decolorizing, cationic and anionic beds wherein it is clarified and deionized until its color and resistivity satisfy entirely the requirements represented by the predefined process parameters.

With the purpose of removing the undesirable pyrogen which exists in the solution, such removal being an extremely important aspect which not only differentiates positively this invention from all of the other technologies found in the documents of the prior art, but also extends the use of the anhydrous dextrose, according to the invention, to many other notable commercial applications in the pharmaceutical sector, the stream is subjected to a second treatment with active charcoal, said charcoal having smaller particle sizes and higher specific surface area when compared to the first one, in the approximate proportion of between 0.1% and 0.3% wt/vol, preferably of between 0.1% and 0.2% wt/vol, at a temperature adjusted within the range of 65 °C to 70 ⁰C, and having the pH adjusted in the range of 3.0 to 4.0, preferably in the range of 3.3 to 3.6, followed by the filtration of the solution employing a filter aid so as to remove the charcoal and all the impurities adsorbed on it.

According to the sequence of operations for the purification of the glucose, the syrup passes through a battery of low-porosity filters in series, before being concentrated to the content levels required in the crystallization cycles. In order to achieve this aim, the solution is fed into a multiple-effect evaporator so that its concentration is increased from the initial range of 22% to 26% by weight until it reaches the final condition considered to be ideal for storage in the crystallizer, more specifically in the range of 76% to 80% by weight, preferably in the range of 78% to 80% by weight.

The final steps in the sequence of the process operations in accordance with the present invention comprise the crystallization of the anhydrous dextrose, the recovery of the dextrose crystals through the centrifugation of the massecuite, and the washing and drying of such crystals. This crystallization of anhydrous dextrose, said crystallization being a central point in this last series of operations, has its success heavily dependent on the previous unit operations, especially those concerned with the purification of the glucose solution, inasmuch as the shape, the size and the granulometric characteristics of the crystals thus generated are factors which are greatly influenced by contaminants that exist in the aqueous medium where the appearance and the growth of the crystal nuclei take place. In view of what it has been discussed, it becomes obvious that the processing techniques adopted in all the past phases of the technology, as well as, naturally, the crystallization proper, determine the quality of the final product and, thus, the possibilities for its employment in all the intended industrial applications, besides being parameters which determine the process yield, that is, the percentage of transformation of raw material into the anhydrous dextrose according to the desired specifications .

The crystallization of the glucose by the evaporation of its syrup, in accordance with the invention, is then initiated by storing the product obtained in the preceding phase, with a concentration being preferably in the range of 78% to 80% by weight and at a temperature of between 60 ⁰C and 63 ⁰C. During the first stage, under a vacuum in the range of approximately 640 to 660 mm Hg, the medium is subjected to a controlled heating that results in an hourly elevation of the concentration in the range of 0.8% to 1.0%, thereby causing this variable to reach the predefined level of between 81% and 82% by weight. In a second instance, after the addition of seed crystals to an ethanol solution, there is initiated a new stage of concentration elevation, but now under a vacuum in the range of 650 to 670 mm Hg, at the rate of between 0.2% to 0.4% an hour, until the profile reaches the final concentration within the range of 87% to 88% by weight, at which point the content of crystals in the massecuite, in this process according to the invention, attains a value of between 40% and 42%.

Proceeding to the third stage, the crystals are separated by centrifugation, washed with process water at a temperature in the range of 60 ⁰C to 65 °C and discharged from the automatic centrifuges as a cake having a moisture content of between 1% and 5%, preferably between 2% and 3%, whereas the mother liquor is used directly as raw material for the associated production of sorbitol, after having been conveniently hydrogenated.

The moist crystals are then transferred to the drying system and brought into contact with an air stream which has been filtered through absolute filters and preheated to a temperature in the range of 125 °C to 135 ⁰C, there being important to point out that, during the course of this operation, the product temperature is monitored so as not to exceed the upper limit of 45 ⁰C, otherwise a degradation of the dextrose could occur.

With a moisture content lower than 0.5%, the mass of crystals is screened for the separation of occasional agglomerates and, finally, after having been weighed, it is packed into adequate containers in order to be transported to the economic market.

Lastly, it is important to notice that the crystallization step, according to the invention, exhibits yields of recovery of anhydrous dextrose in the crystalline form, based on the mass of dextrose contained in the feed syrup, comprised between about 40% and about 44%, preferably comprised between 42% and 43%, said yields demonstrating the great efficiency of this novel technology.

The purity of the crystals produced by the process in question is excellent, being manifested by a content of glucose always higher than 99.70% by weight, on a dry solids basis, and a content of fructose, which is virtually the sole residual impurity in the crystalline product, lower than 0.30% by weight, on a dry solids basis. Moreover, these microcrystalline particles exhibit a considerably narrow granulometric distribution with a mean diameter comprised between about 100 microns and about 400 microns, and possess a residual moisture content lower than the predetermined upper limit of 0.5% by weight. The technical specifications of the final product obtained, particularly its chemical purity, meet all the international standards for the anhydrous crystalline dextrose required by the market.

In summary, this invention, by choosing the sucrose obtained from sugar cane and by innovating the technological route for the production of anhydrous crystalline dextrose, constitutes an industrial alternative which makes it possible to achieve a combination of strategic, technical, economic, and commercial factors which is distinctly different from and much better than those employed by the prior art. Furthermore, the technical novelties and improvements incorporated into the process in accordance with the invention give rise to important technical effects, of which stand out the elimination of the residual starch contained in the sucrose and the purification of the glucose solution in order to render it free from pyrogen, thereby becoming relevant, with the purpose of providing a better understanding of its component phases, to illustrate it by means of the following preparation example, which does not limit the scope thereof.

EXAMPLE

Production of an anhydrous crystalline dextrose of high purity and free of pyrogen according to the invention.

An aqueous solution of sucrose having a purity of 99.8% by weight, on a dry solids basis, and a dry solids concentration of 59% by weight, was subjected to a purification treatment with an amylase-type enzyme to remove the residual starch, for 44 minutes and at a temperature of 81°C; thereafter, this sucrose, which had already been filtered, underwent a hydrolysis catalyzed by an aqueous solution of hydrochloric acid having a pH equivalent to 2.1, thereby forming a solution of fructose and glucose, also known as invert sugar, and still having a dry solids concentration of 59% by weight and a sucrose content of 0.8%.

Upon completion of the acid hydrolysis, the said solution of fructose and glucose, having already been neutralized and deionized, was then fed into a chromatographic separation column, with a dry solids concentration of 58% by weight and at a temperature of 59 °C. After having been completed the separation in question, elution water, which had been previously deoxygenated and deionized in an ancillary system, was introduced into the chromatographic column, thereby effecting the desorption of fructose from the resin, in order to permit, as a consequence, the formation of a main solution of fructose and glucose having a concentration of 24% by weight and a glucose content of 96% by weight, on a dry solids basis, in addition to another stream, which stream does not belong to the focus of interest of the present invention, with a broadly similar concentration and a fructose content of about 87% by weight, on the dry basis. The aforesaid glucose-rich solution, whose temperature was maintained at 60 ⁰C, and at a pH equivalent to 3.6, was subjected to a first treatment with active charcoal in the exact proportion of 0.1% wt/vol for 40 minutes, followed by the filtration of the stream to remove the charcoal and the impurities adsorbed on it and, after accomplishing the cooling of the stream to 44 °C, to the deionization of the syrup carried out in decolorizing, cationic and anionic beds .

In the sequence of the process in question, the said glucose solution, with the specific aim of removing any occasional pyrogen that might have been carried by it, was subjected to a second treatment with active charcoal, in the same proportion of 0.1% wt/vol, at a temperature of 68 ⁰C and having the pH adjusted to the value of 3.5, followed by a filtration operation to separate the charcoal and the impurities adsorbed on it.

After having been led to pass through a battery of low- porosity filters, the glucose syrup which had been exhaustively purified, with a concentration of 23.5%, was fed into a triple-effect evaporation unit, wherein its dry solids concentration increased to the level of 78%.

At a temperature of 63 ⁰C and under a vacuum of 650 mm Hg, the medium had its dry solids concentration raised at a rate of 1.0% an hour, until it attained a value of 81%. After having been accomplished the seeding of the medium, its concentration was raised once again, but now at a rate of 0.4% an hour, under the same vacuum, thereby attaining a content of crystals of 42% at the exact point when its concentration reached a value of 88%.

The recovery of the dextrose crystals was effected by means of centrifugation of the massecuite, followed by the washing of the said crystals in the automatic centrifuge proper, with process water at a temperature of 60 ⁰C, and subsequently by the drying through direct contact with dry air at a temperature of 130 ⁰C. By means of this unit operation, the material obtained attained a final moisture content of 0.4% by weight, and was then ready to be screened and packed in an environment with controlled conditions.

Furthermore, the anhydrous crystalline dextrose of high purity and free of pyrogen produced by the process according to the invention exhibited a glucose content of 99.85% by weight, on a dry solids basis, a fructose content of 0.15% by weight, on a dry solids basis, a mean diameter of 290 microns, and a granulometric distribution with about 80% of its particles comprised in the range of 100 to 400 microns, in consonance with the market demand.

Claims

1. Process for the production of anhydrous crystalline dextrose of high purity and free of pyrogen, characterized by the fact that the raw material is sucrose, which process comprises the following steps:

(a) enzymatic treatment of a sucrose solution with an amylase at a mean temperature comprised between 78° and 82 ⁰C for about 45 minutes, followed by filtration; (b) chemical hydrolysis of the sucrose solution resulting from step (a) by employing an acid selected from the group consisting of inorganic acids, having the pH controlled in the range of 1.9 to 2.1; (c) neutralization of the solution resulting from step (b) with sodium hydroxide, followed by its deionization at a temperature lower than 50 ⁰C;

(d) chromatographic fractionation of the solution of glucose and fructose carried out at a temperature of the feed to the column in the range of 58 ⁰C to

62 ⁰C;

(f) treatment for eliminating pyrogen;

(g) elimination of particles by means of filtration of the charcoal, followed by a further filtration carried out in a battery of low-porosity filters; (h) concentration of the glucose solution;

(i) crystallization of the dextrose from the syrup resulting from step (h) ; (j) centrifugation, washing, drying and screening of the dextrose.

2. Process according to claim 1, characterised by the fact that the solution of sucrose resulting from step (a) has a minimum degree of purity of 99.5% by weight, on a dry solids basis, and a dry solids concentration of about 60% by weight.

3. Process according to claim 1, characterized by the fact that the inorganic acid employed in step (b) is the hydrochloric acid.

4. Process according to claim 1, characterized by the fact that the solution resulting from step (b) is a solution of glucose and fructose having a dry solids concentration comprised between 58% and 62% by weight, and exhibiting a maximum sucrose content of 1.5%.

5. Process according to claim 4, characterized by the fact that the dry solids concentration is preferably comprised between 60% and 61% by weight.

6. Process according to claim 1, characterized by the fact that the chromatographic fractionation in step

(d) produces a glucose solution with a concentration comprised between 22% and 26% by weight and a glucose content comprised between 94% and 97% by weight, on a dry solids basis, and a fructose solution with a concentration comprised between 22% and 26% by weight and a fructose content comprised between 84% and 90% by weight, on a dry solids basis.

7. Process according to claim 6, characterized by the fact that the glucose solution has a content preferably higher than 95.5% by weight.

8. Process according to claim 6, characterized by the fact that the fructose solution is employed in the production of sorbitol and mannitol .

9. Process according to claim 1, characterized by the fact that the charcoal treatment carried out in step (e) consists in treating the glucose solution with active charcoal in a proportion of between 0.1% to 0.3% wt/vol at a temperature comprised between 57 ⁰C and 61 ⁰C, at a pH of about 3.5, and for about 45 minutes, followed by filtration.

10. Process according to claim 1, characterized by the fact that in step (f) the elimination of pyrogen is effected through the treatment of the solution resulting from step (e) with active charcoal in a proportion of between 0.1% to 0.3% wt/vol at a temperature comprised between 65 ⁰C and 70 ⁰C, and at a pH adjusted to a value comprised between 3.0 and 4.0.

11. Process according to claim 1, characterized by the fact that the concentration of the glucose solution in step (h) is carried out in a multiple-effect evaporator, wherein the dry solids concentration initially comprised within the range of 22% to 26% by weight is raised to within the range of 76% to 80% by weight .

12. Process according to claim 11, characterized by the fact that the dry solids concentration is preferably comprised between 78% and 80% by weight.

13. Process according to claim 1, characterized by the fact that the crystallization of the dextrose in step (i) comprises the following stages:

(ii) the aqueous syrup resulting from (h) at a temperature comprised between 60 ⁰C and 63 °C is concentrated under a vacuum of between 640 mm Hg and 680 mm Hg and at a controlled temperature, until it reaches a concentration in the range of 81% to 82%; (i₂) addition of seed to an ethanol solution followed by a concentration under a vacuum of between 650 mm Hg and 670 mm Hg and at a controlled temperature, until it attains a concentration in the range of 87% to 88%.

14. Process according to claim 13, characterized by the fact that the concentration increment in stage (ii) is of between about 0.8% and about 1.0% an hour.

15. Process according to claim 13, characterized by the fact that the concentration increment in stage (I₂) is of between about 0.2% and about 0.4% an hour.

16. Process according to claim 13, characterized by the fact that the content of crystals in the massecuite resulting from stage (i₂) is comprised between 40% and 42%.

17. Process according to claim 1, characterized by the fact that the dextrose resulting from step (j) exhibits a minimum content of 99.70% by weight, on a dry solids basis, a maximum moisture content of 0.5%, a maximum fructose content of 0.30% and a narrow granulometric distribution with a mean diameter within the range of 100 to 400 microns.

18. Process for the purification of the sucrose characterized by comprising an enzymatic treatment of a sucrose solution with an amylase at a mean temperature of 82 ⁰C for about 45 minutes followed by filtration .