MXPA97005398A - New manufacturing procedure of palatini - Google Patents

Abstract

The present invention relates to a process for the manufacture of palatinitol, characterized in that - in a first step, the epimerization of isomaltose is carried out under conditions which make it possible to obtain a mixture of alpha-D-glucopyranosyl- (1- > 6) D-mannose and isomaltose, in a second stage the isomaltose is depleted of this epimerized mixture in order to obtain a new mixture containing an approximately equimolar proportion of alpha-D-glucopyranosyl- (1-> 6) -D-mannose and isomaltose, in a third stage, proceeds to the catalytic hydrogenation of this mixture approximately equimolecule

Description

NEW MANUFACTURING PROCEDURE OF PALATINITOL The present invention relates to a new process for the manufacture of palatinitol. It relates more particularly to a process for the manufacture of palatinitol from isomaltose or α-D-glucopyranosyl- (1α6) -D-glucose. Palatinitol is a low-calorie, low-cariogenic sweetener that is obtained up to now by the catalytic hydrogenation with neutral pH of isomaltulose or α-D-glucopyranosyl- (1α6) -D-fructose. Isomaltulose is obtained by enzymatic isomerization, with the aid of a sucrose glycosyltransferase of sucrose or α-D-glucopyranosyl- (1 2 2) - / 3-D-fructofuranoside. It is thus sucrose that constitutes the raw material for obtaining palatinitol, mixing in approximately equimolar proportions, of o; -D-glucopyranosyl- (1? 6) -D-sorbitol (GPS or isomaltitol) and of cc-D-glucopyranosyl - (1? 6) -D-mannitol (GPM). Palatinitol, also called isomalt, is marketed especially by the company Süddeutsche Zucker AG under the name Palatinit®. We can refer, among other documents that concern the obtaining and properties of palatinitol, to the work "Alternative Sweeteners" published in 1986 by LYN O'BRIEN NABORS, chapter 11, pages 217 to 244. Concerned about developing a procedure that allows obtaining the palatinitol from another raw material other than sucrose, the Applicant Company has found that this goal can be achieved by a process employing isomaltose or aD-glucopyranosyl- (1? 6) -D-glucose. According to the present invention, palatinitol is obtained by a process characterized by the fact that. - in a first stage the epimerization of the isomaltose is carried out under conditions that allow to obtain a mixture of α-D-glucopyranosyl- (1 6 6) -D-mannose and of isomaltose, in a second stage the isomaltose is impoverished. epimerized mixture so as to obtain a mixture containing an approximately equimolar proportion of α-D-glucopyranosyl- (1α6) -D-mannose and of isomaltose, in a third step, the catalytic hydrogenation of this mixture is carried out. If it is reasonable to imagine that palatinitol could be obtained from sucrose, the technician can not wait for this same palatinitol to be obtained from isomaltose, which is obtained from glucose and thus from various and varied starches.

«FeJiiiiii.iffiíMiyfliifcafcittiil-hrflfflM ^ < . ^^ j ^ * ^ * a i *. * i ^ > ^ t ** ^ ^ vki &? In fact, in the first case, the sucrose whose formula developed comprises a fructose motif will give, in a known manner by means of enzymatic isomerization, the corresponding ketose, that is isomaltulose. And it is known to the artisan that the hydrogenation of such a ketose leads to the formation of two corresponding itols in substantially equimolar proportions. Thus, the fact that the formula of sucrose resembles that of palatinitol allows us to presume the result. On the other hand, the process of the invention does not employ a starting product whose formula resembles that of the palatinitol sought. In fact, both isomaltose, glucose or starch have a structure that has no fructose motif and is therefore far removed from that of palatinitol. The process of the invention then makes it possible to exempt the obligation to use sucrose as a raw material in the manufacture of palatinitol since isomaltose can be obtained easily from glucose and then from various and varied starches, which have been extracted from cereals or from tubers. A method of obtaining isomaltose < _. Glucose or corn syrup is described, for example, in French patent application 2,515,186.

In the process of the invention, it is preferred to use crystallized isomaltose although syrups very rich in isomaltose are equally convenient if it is admitted that maltitol or isomaltotriitol may be present in palatinitol. These last two compounds come from the hydrogenation of maltose or isomaltotriose, which represent the dominant impurities of the syrups very rich in isomaltose. In the process of the invention the epimerization of isomaltose can be carried out as described in the Japanese patent application 63-162698 with the aid of a metal salt and an amine but it is preferably conducted in the manner described in Japanese patent application 63-96195 and which consists of reacting with a pH comprised between 2.5 and 4, in the presence of molybdic anhydride or hexavalent molybdenum salts, at a temperature between 90 ° C and 140 ° C, an aqueous solution of isomaltose. Preferably, ammonium molybdate is used in a proportion of about 0.1 to 1.5 weight percent with respect to isomaltose. Preferably, the epimerization of the isomaltose is also carried out in the form of an aqueous sugar solution containing 10 to 70 percent isomaltose. The epimerization conditions are adjusted i. (essentially catalyst rate, duration of the epimerization and reaction temperature), in order to obtain a mixture of isomaltose and of-D-glucopyranosyl- (1? 6) -D-mannose, containing from 10 to 40 percent of this last compound. Mixtures containing less than 10 percent are not economical to treat and mixtures containing more than 40 percent contain too many impurities that form under extreme epimerization conditions. It is preferred to work under conditions that allow 20 to 35 percent of a-D-glucopyranosyl- (1? 6) -D-mannose to be obtained and more preferably from 25 to 35 percent of this compound. The mixture thus obtained is demineralized on the ion exchange resins to remove the salts that have served as a catalyst. In the process of the invention, the depletion of isomaltose of the epimerized mixture can be obtained in different ways. It is possible, for example, to subject the epimerized mixture to the action of an amyloglucosidase which has the effect of hydrolyzing the isomaltose into two molecules of glucose. It is then possible to eliminate this glucose in the form of gluconic acid by the action of a glucose oxidase which transforms this glucose into gluconic acid which is eliminated by the exchange of ions on the anionic resins.

It is possible to consume this glucose with the help of yeasts or bacteria. It is preferred, however, to proceed to the depletion of isomaltose of the epimerized mixture by chromatographic route. Generally, when a chromatographic step is used, the separation of two components of a binary mixture must be carried out. The chromatography is conducted in such a way that the two components are separated as completely as possible, that is, in order to obtain a fraction A which contains only very little component B and a fraction B which contains only very little component A. In the process of the invention, the depletion of the mixture epimerized in isomaltose is conducted, on the contrary, in a obtain a fraction containing an approximately equimolar ratio of isomaltose and aD-glucopyranosyl- (1? 6) -D-mannose, the other fraction consisting of very pure isomalt. By approximately equimolecular, it is understood from 40 to 60 percent and more preferentially, from 45 to 55 percent of one of the two compounds with respect to the total mass of the two compounds. This way of doing so has the advantage of directly obtaining a mixture which after hydrogenation will provide the two components of palatinitol, namely, isomaltitol and oD-glucopyranosyl- (1? 6) -D-mannitol in approximately equimolar proportions and this , without having to resort to remixes of pure fractions. Advantageously, the isomaltose fraction is recycled, the richness of which is currently between 85 and 95%, the rest being mainly aD-glucopyranosyl- (1-6) -D-mannose, at the level of the epimerization stage. This way of making it possible to obtain yields close to 100 percent of palatinitol obtained with respect to the isomaltose used and then constitute the preferred embodiment of the process of the present invention. This chromatographic step is carried out very easily on an industrial scale by applying the epimerized mixture on a column charged with cation exchange resins of the sulfonated polystyrene type crosked to divinylbenzene. These resins, in order to adapt to the chromatography, must have a very fine and very homogeneous granulometry, advantageously comprised between 150 and 400 microns, and for their use, they are exchanged under the alkaline or alkaline-earth form. The mixture applied on the column is then fractionated by washing the resin with water. It is then surprisingly found that although isomaltose and α-D-glucopyranosyl- (1? 6) -D-mannose have analogous structures and strictly identical molecular weights, a much faster migration of isomaltose to the resin. It is sufficient after decanting the resin at the start of the washing cycle, the amount of isomalt strictly necessary to carry in an approximately stoichiometric proportion the components of the mixture subjected to the chromatography. This step of chromatography can be carried out discontinuously on a single column of resin or on many columns operating in parallel, but it is more conveniently conducted on the systems of multiple columns branched in curl, operating according to the principle of movable bed simulated . These systems have the advantage of producing better resin yields and continuous operation. In general, to obtain the best yields of the chromatography resins, it is preferred to perform this chromatography at a temperature comprised between 60 and 90 ° C. It is preferred to chromatograph the cured mixtures having a dry material comprised between 7 and 70 percent, preferably between 10 and 50 percent. As already stated above, the fraction excluded at the beginning of the washing cycle, rich in isomaltose, is advantageously recycled in the epimerization stage. The adsorbed fraction, which represents the end of the wash cycle and which contains in approximately stoichiometric proportions the rest of the isomaltose and oi-D-glucopyranosyl- (1-6) -D-mannose, is then concentrated in a dry material from about 30 percent to 60 percent for its catalytic hydrogenation under economic conditions. This hydrogenation is carried out in known manner, continuously or batchwise, under a hydrogen pressure of 30 to 200 bar, at a temperature of 80 to 150 ° C in the presence of a nickel or ruthenium-based catalyst and at a pH close to neutrality. . A hydrogenation conducted at a pH below 4.0 would result in partially hydrolyzing isomaltose in glucose and α-D-glucopyranosyl- (1α6) -D-mannose in glucose and mannose with the occurrence of sorbitol and mannitol in palatinitol. A hydrogenation at a pH greater than 9 would result in changing the stoichiometry between the two components of palatinitol. In general, hydrogenation is pursued until the content of reducing sugars, measured by the Bertrand method, becomes less than 1 percent and preferably less than 0.5 percent. After the hydrogenation step, the syrups obtained are purified to remove the catalyst, by filtration then demineralization on ion exchange resins. The hydrogenated and purified syrups are then concentrated, crystallized and dried to provide a commercial powder of palatinitol which is in fact a mixture in approximately equimolar proportions of crystals of anhydrous isomatitol and a-D-glucopyranosyl- (1-6) -D dihydrate. -manitol The present invention is illustrated by the following example and which is not limiting, the Applicant has no other purpose than to expose what appears to be one of the best means of employing the method of his invention.

EXAMPLE First stage: 36 grams of water, 4 grams of crystallized isomalt, as well as 16 milligrams of ammonium molybdate (NH4) M0O24, or 0.4 percent by weight with respect to isomaltose, is then added to the solution. this solution to 3.5 with the help of hydrochloric acid. This solution is immediately taken at 130 ° C for 15 minutes. After cooling, this solution is demineralized on a mixed bed of strong cationic and anionic resins which provide an epimerized mixture whose resistivity is greater than 2.10 ohms.cm.

HPLC chromatography of this epimerized mixture reveals the presence of 35 percent ot-O-glucopyranosyl- (1? 6) -D-mannose and 65 percent isomaltose. The presence of glucose and mannose is also observed, although in a trace state. Second stage: In a glass column with a double-cover thermostat at 85 ° C, of a height of 2 meters and with an internal diameter of 15 millimeters, 340 cubic centimeters of the resin marketed under the brand name PCR 532 is introduced by the PUROLITE Company. This resin has the following characteristics: skeleton: sulfonated polystyrene crosslinked with divinylbenzene - crosslinking rate: 5 percent granulometry: 180 to 280 microns ionic form for use: Ca ++ It is introduced at the top of the resin, 2.5 cubic centimeters of the mixture epimerized with 10 percent of dry material that percolates through this resin and that is pushed with water, at an expense of 210 cubic centimeters per hour. After having washed 140 cubic centimeters of water, a fraction of isomaltose representing 27 cubic centimeters is collected.

This fraction of isomaltose, shows in gas chromatographic analysis, an 89 percent isomaltose richness and 11 percent a-D-glucopyranosyl- (1? 6) -D-mannose. Immediately following this fraction of isomaltose, a 64 cubic centimeter fraction is recovered constituted by an impoverished mixture of isomaltose whose chromatographic analysis in gas phase will reveal a richness of 47 percent of isomaltose and of 52 percent of aD-glucopyranosyl- ( 1? 6) -D-mannose. This analysis also reveals traces of glucose and mannose. This step is performed 15 times to obtain an isomalt fraction of medium richness of 90 percent and a fraction of a mixture of almost equal parts of isomaltose and a-D-glucopyranosyl- (1? 6) -D-mannose. The chromatographic fraction excluded, rich in isomaltose, is concentrated under vacuum to a dry matter of 10 percent. 0.4 percent of ammonium molybdate was added again with respect to its estimated dry material and it was again subjected to epimerization under the conditions described for the epimerization step No. 1. It was still obtained once, 35 percent of aD-glucopyranosyl- (1? 6) -D-mannose. The adsorbed chromatographic fraction, which contains both isomaltose and α-D-glucopyranosyl- (1α6) -D-mannose was concentrated in a 40 percent dry material to undergo hydrogenation. This fraction, without taking into account the fraction of isomaltose recycled in the epimerization stage, represents 64% of the dry material subjected to the chromatographic fractionation. Third stage: This adsorbed fraction was introduced into a hydrogenation reactor in the presence of 5 weight percent sugars, Raney nickel. After having placed the apparatus under a hydrogen pressure of 50 bars to maintain it throughout the duration of the hydrogenation, its content is heated to a temperature of 125 ° C. The pH of the reaction medium at 8.0 is maintained in the course of this hydrogenation with the aid of a sodium bicarbonate solution. The hydrogenation is stopped after 8 hours, after the content of reducing sugars in the reaction medium, measured by the Bertrand method, becomes lower than 0.1 percent. The content of the hydrogenation reactor is then filtered to remove the catalyst then the syrup is demineralized on a mixed bed of resins, as after the first stage. A perfectly clear and colorless syrup is then obtained whose composition by gas chromatographic analysis is tested as follows: isomaltitol: 49.1 percent?! -D-glucopyranosyl- (1? 6) -D-mannitol: 49.4 percent This syrup is then concentrated so that it brings its two components to the state of crystals that are dried immediately to obtain a white and non-hygroscopic palatinitol powder that titrates 5.1 percent moisture.

Claims (5)

1. Process for the manufacture of palatinitol, characterized in that - in a first stage, the epimerization of isomaltose is carried out under conditions that allow a mixture of aD-glucopyranosyl- (1-6) -D-mannose and isomaltose to be obtained , in a second stage, isomaltose is impoverished from this epimerized mixture in order to obtain a new mixture containing an approximately equimolar proportion of aD-glucopyranosyl- (1? 6) -D-mannose and isomaltose, in a third stage , we proceed to the catalytic hydrogenation of this approximately equimolecular mixture.

2. Process according to claim 1, characterized in that the epimerization is carried out in the presence of a hexavalent molybdenum salt.

Method according to one or the other of claims 1 and 2, characterized in that the depletion of the epimerized isomaltose mixture is effected by chromatography on cationic resins in the alkaline or alkaline-earth form.

4. Process according to claim 3, characterized in that the cationic resins are in the form of calcium. Method according to one or the other of claims 3 and 4, characterized in that the fraction of isomaltose excluded from the chromatography step is recycled in the epimerization step.