Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-05-15
2002-02-26
Riley, Jezia (Department: 1656)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S001110, C536S004100, C536S124000
Reexamination Certificate
active
06350864
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the preparation of a mixture of glucosylmannitol and glucosylsorbitol by the hydrogenation of glucosylglucosone.
The invention relates in particular to a process for the preparation of a mixture of glucosylmannitol and glucosylsorbitol by the hydrogenation of glucosylglucosone, in the presence of a catalyst, using specific hydrogenation pressure and temperature conditions for a high glucosylglucosone solids content.
The present invention relates more precisely to a process for the preparation of a mixture of glucosylmannitol and glucosylsorbitol by the continuous hydrogenation of glucosylglucosone in a fixed catalyst bed, and more particularly to the implementation of this continuous process in a succession of fixed catalyst beds arranged in series and in at least two reaction zones.
Finally, the present invention relates to a mixture of glucosylmannitol and glucosylsorbitol, especially a mixture of &agr;-1,4-linked or &agr;-1,6-linked isomers of glucosylmannitol and glucosylsorbitol, containing at least an equimolar proportion of glucosylmannitol and glucosylsorbitol.
2. Description of the Prior Art
These mixtures of &agr;-1,4-linked or &agr;-1,6-linked isomers are conventionally prepared either by mixing each of the two components in the desired proportions or by isomerizing or epimerizing specific disaccharides.
Thus glucosyl-&agr;-1,4-mannitol and glucosyl-&agr;-1,4-sorbitol (or maltitol) can be produced separately and then combined to give the expected mixture.
However, although maltitol is easy to prepare by hydrogenating a maltose syrup obtained from a starch hydrolyzate by any means conventionally known to those skilled in the art, glucosyl-&agr;-1,4-mannitol is prepared by a step involving isolation of the rare sugar glycosyl-&agr;-1,4-mannose from complex media (extracts of algae or yeasts, for example) by expensive and complex processes with very low yields, followed by a hydrogenation step.
As regards the &agr;-1,6-linked isomers, the corresponding mixture of the two components glucosylmannitol and glucosylsorbitol in equimolar proportions is known to those skilled in the art by the name palatinitol.
Palatinitol is a low-calorie bulk sweetener with a low cariogenicity; it is obtained e.g. by the catalytic hydrogenation of isomaltulose, or glucosyl-&agr;-1,6-fructose, at neutral pH.
Isomaltulose itself is obtained by the enzymatic isomerization of sucrose, or glucosyl-&agr;-1,2-fructose, with the aid of a sucrose glycosyltransferase.
Among other documents relating to the preparation and properties of palatinitol, reference may be made to the book “Alternative Sweeteners” published in 1986 by LYN O'BRIEN NABORS, chap. 11, pp. 217-244.
However, this isomerization process only affords a roughly equimolar mixture of glucosyl-&agr;-1,6-mannitol and glucosyl-&agr;-1,6-sorbitol (or isomaltitol) without the possibility of varying the relative composition of the two constituents in the mixture.
In patent applications WO 97/19093 and WO 97/19094, of which the Applicant is the proprietor, it was shown that palatinitol could also be prepared from isomaltose, or glucosyl-&agr;-1,6-glucose.
Isomaltose in turn is prepared from glucose or a maize syrup as described for example in patent application FR 2.515.186.
However, although these alternative processes make it possible to obtain palatinitol without being obliged to use sucrose as the starting material, it is nevertheless the case that this mixture of glucosyl-&agr;-1,6-mannitol and glucosyl-&agr;-1,6-sorbitol can still only be obtained in equimolar proportions.
At best the final mixture can contain a high proportion of glucosyl-&agr;-1,6-sorbitol if the chromatography techniques normally employed in the processes of patent applications WO 97/19093 and WO 97/19094 for separating the components of said mixture to give an equimolar mixture are not used.
Also, the mixture can advantageously be enriched in isomaltitol simply by adding said compound obtained elsewhere by the catalytic hydrogenation of isomaltose.
It is apparent from all the above that there is an unsatisfied need for a simple process which makes it possible in the vast majority of cases to obtain a mixture of glucosylmannitol and glucosylsorbitol, irrespective of the type of linkage isomer in question, in at least equimolar proportions and, more particularly, enriched in its glucosylmannitol component.
DETAILED DESCRIPTION OF THE INVENTION
Anxious to develop a process which makes it possible to meet practical constraints better than the processes already in existence, the Applicant found that this objective could be achieved by a process for the catalytic hydrogenation of glucosylglucosone carried out under specific temperature and pressure conditions.
“Glucosone”, also known as 2-ketoglucose or D-arabino-2-hexulosone, is understood as meaning the product resulting from the chemical treatment of glucose with hydrogen peroxide or with copper acetate or, advantageously, the product resulting from the enzymatic conversion of glucose with the aid of a pyranose-2-oxidase.
It is further known in the state of the art that pyranose-2-oxidase also has a broad spectrum of enzymatic modification.
Thus, in Med. Fac. Landbouww. Univ. Gent., 62/4a, 1997, pp. 1193-1197, HUWIG et al. show that pyranose-2-oxidase isolated from
Peniophora gigantea
is capable of reacting with isomaltose to give the oxidation product of its glucose in the terminal reducing position, i.e. glucosyl-&agr;-1,6-glucosone.
Likewise, in Arch. Microbiol., 1997, 167, pp. 119-125, VOLC et al. show that pyranose-2-oxidase isolated from
Agaricus bisporus
reacts with maltose to give glucosyl-&agr;-1,4-glucosone.
However, nowhere do these documents describe or suggest that it is possible advantageously to use these two &agr;-1,4-linked and &agr;-1,6-linked isomers of glucosylglucosone to give, by means of a specific hydrogenation process, a mixture of glucosylmannitol and glucosylsorbitol in at least equimolar proportions, and more particularly at mixture containing a high proportion of glucosylmannitol preferably equal to at least 1.5.
To its credit the Applicant therefore found a process for the preparation of a mixture of glucosylmannitol and glucosylsorbitol which is characterized in that glucosylglucosone is hydrogenated, in the presence of a catalyst, by subjecting a glucosylglucosone solution with a solids content equal to at least 10% by weight, preferably of between 20 and 50% by weight, to a pressure equal to at least 30 bar, preferably of between 30 and 200 bar, and to a temperature equal to at least 50° C., preferably of between 50 and 150° C.
In this way the Applicant found that the process according to the invention makes it possible to hydrogenate the &agr;-1,4-linked and &agr;-1,6-linked isomers of glucosylglucosone equally well.
The process according to the invention uses a glucosylglucosone solution with a solids content equal to at least 10% by weight, preferably of between 20 and 50% by weight.
Glucosylglucosone of very high purity, advantageously produced from maltose or isomaltose enzymatically by any means known per se to those skilled in the art, is chosen for the preparation of the solution to be hydrogenated. The choice of the &agr;-1,4-linked or &agr;-1,6-linked isomer of glucosylglucosone as the starting material to be hydrogenated is then based on the nature of the mixture of glucosylmannitol and glucosylsorbitol which it desired to obtain.
“High purity” is understood as meaning a glucosylglucosone content in the order of 100%.
The catalyst is selected from the group consisting of palladium, nickel, ruthenium, platinum, rhodium, cobalt, copper, zinc, chromium, manganese and tungsten and is preferably nickel.
In one preferred embodiment of the process according to the invention, in which the catalyst is suspended in the glucosylglucosone solution
Henderson & Sturm LLP
Riley Jezia
Roquette Freres
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