Sugar – starch – and carbohydrates – Processes – Carbohydrate manufacture and refining
Reexamination Certificate
2002-08-01
2003-03-04
Brunsman, David (Department: 1755)
Sugar, starch, and carbohydrates
Processes
Carbohydrate manufacture and refining
C426S456000, C426S471000, C426S660000, C424S441000, C424S465000
Reexamination Certificate
active
06527868
ABSTRACT:
The present invention relates to a dextrose in powder form with a high dextrose content, an essentially a crystalline form and a pronounced anhydrous nature, also having a rapid rate of dissolution in water, a particular particle size distribution and excellent flowability. The invention also relates to a dextrose in powder form of which the industrial use properties in direct compression are improved, and to a process for the preparation thereof.
Dextrose, produced industrially by hydrolysis of various starches, has been commonly used, mainly in the food industry, for numerous years.
Dextrose in powder form is used to advantage in pharmaceutical and food applications (notably in confectionery) where it is necessary to have dry products, for example, for the production of tablets or chocolate articles.
Three crystalline forms of dextrose are traditionally described, i.e. &agr; dextrose monohydrate, anhydrous a dextrose and anhydrous &bgr; dextrose.
Although numerous processes have been proposed for directly converting glucose solutions to solid materials of any crystalline form, &agr; dextrose monohydrate remains the virtually exclusive source of dextrose powder. This &agr; dextrose monohydrate is traditionally produced by slow crystallisation, by cooling supersaturated syrups with a high glucose content originating from the hydrolysis of starch.
The main advantages thereof are its flowability and its low tendency to agglomerate, its chemical or physical stability during handling, its solubility in water, its whiteness and its sweet character without an abnormal taste.
However, its water content of about 9% in the form of water of crystallisation precludes its use in fields of application where problems relating to the moisture content of the finished products must be avoided.
Anhydrous crystalline &agr; dextrose, a very pure crystalline dextrose with a low water content, was therefore chosen.
This anhydrous &agr; dextrose is generally produced by dissolving the crystals of &agr; dextrose monohydrate in water at temperatures from 60° C. to 65° C., for example, in autoclaves under a high vacuum and under carefully controlled operating conditions.
However, the anhydrous &agr; dextrose thus obtained has the disadvantages of dissolving relatively slowly in water and having a tendency to cake during dissolution. In fact, a part of the anhydrous &agr; dextrose is converted once again during this dissolution to &agr; dextrose monohydrate which agglomerates and delays the dissolution of the anhydrous &agr; dextrose accordingly.
In order to dissolve satisfactorily the two &agr; monohydrate and &agr; anhydrous forms, it is necessary, therefore, to use water at a high temperature or to add the dextrose gradually to water with stirring.
It has been proposed, therefore, to use anhydrous crystalline &bgr; dextrose which has a much better rate of dissolution compared with that of anhydrous &agr; dextrose and even monohydrate.
However, it is well known to experts in the crystallisation of dextrose that although the transition point of the crystallisation of &agr; dextrose monohydrate to anhydrous &agr; dextrose is about 55° C., that of anhydrous &agr; dextrose to anhydrous &bgr; dextrose is about 110° C.
Consequently, in order to obtain anhydrous &bgr; dextrose, it is necessary to operate at a high temperature at which dextrose is not very stable. This result limits all the more the industrial use of such a crystallisation process.
Moreover, as any dextrose in powder form composed of a single crystalline species and prepared in the traditional way is generally not very compressible, it is necessary to add maltodextrins or polysaccharides to it for the production of tablets.
However, the anhydrous products prepared in this way according to the prior art have generally been unsatisfactory because of problems of agglomeration and handling due to the maltodextrins or polysaccharides.
Patent application FR 2.398.802 describes a dextrose in powder form which has good flowability, does not agglomerate, is appreciably free from an unpleasant taste and coloured impurities but also has satisfactory compression properties.
The analysis of said dextrose in powder form reveals that it is composed of a mixture, in roughly equivalent amounts, of anhydrous &agr; and &bgr; dextrose. The process for the preparation thereof by crystallisation and granulation is, however, particularly long and tedious.
Patent application WO 94/28.181 describes a dextrose which, apart from having a particularly low moisture content and a rapid rate of dissolution in water at ambient temperature, also has compression properties which allow it to be used for the production of tablets without the need for it to undergo special additional treatments or to add a binder.
However, the dextrose in powder form thus obtained is characterised not only by a composition containing the two anhydrous &agr; and &bgr; crystalline forms with a high anhydrous &bgr; dextrose content of the order of 60 wt.% , but also by its amorphous nature, i.e. a degree of crystallinity only in the range 87% to 90%. Moreover, its dextrose content is only 94%, the remaining 6% being composed mainly of maltose and maltodextrins with a higher degree of polymerisation (DP).
It is apparent from the above that there is an unsatisfied need to obtain a dextrose in powder form with a high dextrose content and high crystalline purity and which also has excellent compression properties.
To its merit, the Applicant company has developed, after considerable research, a new dextrose in powder form.
The dextrose in powder form according to the invention is thus characterised initially in that it has:
a dextrose content at least equal to 99%,
an &agr; crystalline form content at least equal to 95%,
a water content at most equal to 1%,
a compressibility, determined by a test A, at least equal to 80 N, preferably in the range 100 N to 200 N.
The dextrose content may be measured by a conventional high performance liquid chromatography method. It is determined here at a value at least equal to 99%.
The crystallinity is a measure of the crystalline structure or otherwise of the product. This crystallinity is determined according to measurements of the latent heat of fusion carried out using a differential calorimeter. The crystallinity of the product is determined by comparing the latent heat of fusion of the product with that of crystalline references having a variable proportion of &agr; and &bgr; dextrose.
The degree of crystallinity for the anhydrous &agr; form of dextrose in powder form according to the invention is determined at a value at least equal to 95%. The anhydrous &bgr; dextrose form is therefore in a small proportion, contrary to what may be found in commercial anhydrous products which nevertheless have similar compression properties.
The moisture content of the particles is also measured by traditional methods known, moreover, to the skilled person. The water content of said dextrose in powder form is thus at most equal to 1%, indicating a pronounced anhydrous character.
According to the invention the compressibility of the dextrose in powder form is determined by test A below, described in patent EP 220.103 owned by the Applicant company. This test A consists in measuring the force, expressed in newtons, which is representative of the compressibility of the dextrose in powder form studied. This force therefore reflects here the resistance to crushing of a tablet which is cylindrical with convex sides (radius of curvature 14 mm), having a diameter of 13 mm, a thickness of 6 mm and a weight of 0.764 g, i.e. an apparent density of 1.3 g/ml.
It is particularly surprising that a dextrose in powder form can simultaneously have a high dextrose content, at least equal to 99%, of which the anhydrous &agr; crystalline form represents at least 95%, and a compressibility of at least 80 N, preferably in the range 100 N to 200 N.
In fact, it is conventionally accepted that the preparation of a dextrose in powder form having properties of high compressibility requires the mixing o
Labergerie Erik
Lefevre Philippe
Lis Jose
Moraly Franck
Brunsman David
Roquette Freres
Sturm & Fix LLP
LandOfFree
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