EP0971040B1 - Process for preparing crystallized fructose - Google Patents

Process for preparing crystallized fructose Download PDF

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Publication number
EP0971040B1
EP0971040B1 EP98202278A EP98202278A EP0971040B1 EP 0971040 B1 EP0971040 B1 EP 0971040B1 EP 98202278 A EP98202278 A EP 98202278A EP 98202278 A EP98202278 A EP 98202278A EP 0971040 B1 EP0971040 B1 EP 0971040B1
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Prior art keywords
fructose
crystals
syrup
seeding
content
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EP98202278A
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German (de)
French (fr)
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EP0971040A1 (en
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Warcoing SA
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Warcoing SA
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Priority to DK98202278T priority Critical patent/DK0971040T3/en
Application filed by Warcoing SA filed Critical Warcoing SA
Priority to ES98202278T priority patent/ES2206826T3/en
Priority to DE69818023T priority patent/DE69818023T2/en
Priority to AT98202278T priority patent/ATE249524T1/en
Priority to EP98202278A priority patent/EP0971040B1/en
Priority to US09/743,157 priority patent/US6607603B1/en
Priority to JP2000559260A priority patent/JP2002520030A/en
Priority to IL14064099A priority patent/IL140640A/en
Priority to PCT/EP1999/004732 priority patent/WO2000003040A1/en
Publication of EP0971040A1 publication Critical patent/EP0971040A1/en
Priority to ZA200100133A priority patent/ZA200100133B/en
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    • C—CHEMISTRY; METALLURGY
    • C13—SUGAR INDUSTRY
    • C13K—SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES
    • C13K11/00—Fructose

Definitions

  • the present invention relates to a process for the manufacture of crystalline fructose by crystallization / solidification of a purified and concentrated fructose syrup.
  • the object of the present invention is to provide a new process for crystallizing fructose, overcoming the problems of the prior art, and thus to offer a form of crystalline fructose which can be used commercially.
  • This new process for the manufacture of crystallized fructose involving the solidification of a hot and concentrated solution of fructose following a seeding of the solution by means of fructose crystals, is characterized by the use of a fructose solution resulting from a pure fructose syrup freshly prepared by melting fructose dihydrate crystals, concentrated by evaporation under vacuum to a dry matter content greater than 96% by weight, and preferably greater than 97% by weight.
  • the fructose solution used for sowing preferably has a preferred temperature of between 50 and 100 ° C, ideally between 80 and 95 ° C.
  • the seeding is preferably done by means of 5 to 30% by weight of crystallized fructose having a particle size less than 500 ⁇ m, preferably less than 250 ⁇ m (for example 50 ⁇ m).
  • the time between the melting of the fructose dihydrate crystals to prepare the initial syrup and the concentration of this syrup with a dry matter content greater than 96% by weight, preferably greater than 97 % by weight, is preferably less than 24 hours, more particularly less than 8 hours, and ideally less than half an hour.
  • the invention relates to crystallized fructose, essentially consisting of beta-D-fructopyranose, having low contents of other tautomers of fructose, as resulting from a process for solidification of a hot and concentrated solution of fructose following sowing.
  • fructose solution used for sowing results from a pure fructose syrup freshly prepared by the melting of crystals of fructose dihydrate, concentrated by evaporation under vacuum until a dry matter content between 96 and 100% by weight
  • the fructose solution used for seeding has a preferred temperature of between 80 and 95 ° C.
  • the seeding is carried out by means of 5 to 30% by weight of crystallized fructose with a particle size of less than 500 ⁇ m, of lower preference at 250 ⁇ m
  • the time between the melting of the fructose dihydrate crystals to prepare the initial syrup and the concentration of this syrup with a dry matter content greater than 96% is less than 8 hours, preferably less than half an hour.
  • Obtaining fructose dihydrate crystals consists of a progressive cooling of an aqueous solution of glucose and fructose, the total sugar content of which is between 45 and 85% and, in the dry matter, the fructose concentration is between 60 and 100%.
  • the temperature of the mass thus grained is gradually lowered and is thus maintained in a zone of supersaturation in fructose such that the crystals present progressively grow, however limiting the appearance of new crystals.
  • the mass of syrup containing the crystals is conveyed to a continuous or discontinuous centrifuge similar to those used in sugar refinery. Any other physical method solid / liquid separation can be considered.
  • the mother liquors of crystallization consisting of water and sugars from the initial solution which have not crystallized, can be subjected to a new crystallization stage as described above.
  • the fructose dihydrate crystals thus separated, can be washed so as to eliminate as much as possible the film of mother liquor surrounding them therefore increasing the purity of the fructose to values between 90% and 100% and preferably between 97.5% and 100 %. They are then melted, preferably at temperatures above 20 ° C. If there is no addition of water during melting, the syrup obtained from properly washed crystals contains 83% sugars and 17% d 'water. The dry matter of such a syrup contains only a few traces of other sugars present in the mother liquors.
  • the 83% dry matter syrup obtained according to Example I is concentrated at temperatures of the order of 65 to 100 ° C. under pressures below 60 mm of mercury, for a period of less than 30 minutes, or even less than 15 minutes. .
  • the dry matter of the concentrated syrup varies between 96.0 and 100.0%.
  • the syrup is relatively viscous and can then be pumped for crystallization / subsequent solidification.
  • the concentrated and viscous syrup obtained in Example II is then kept in a mixer at a temperature between 80 and 95 ° C and seeded using 10 to 25% of crystallized fructose with a very fine particle size ( ⁇ 200 ⁇ m ). This seeding can be done using fructose obtained by the present process, very finely ground.
  • the medium is then agitated so as to ensure optimal dispersion of the germs within it.
  • the medium consisting of a very viscous whitish mass is then poured out of the mixer and stored in an oven whose temperature is fixed between 55 and 75 ° C. depending on the residual water content, the quantity of germs and the state of the mutarotation reaction. The residence time in the oven depends on these same factors.
  • the cistallized mass thus obtained is coarsely crushed by means of a grinder.
  • the particles obtained can then be dried between 50 and 75 ° C (preferably under a flow of dry air) in order to further decrease the water content. Fine grinding can then be carried out. If the initial mass is dry enough to be finely ground, drying subsequent to coarse grinding can be avoided.
  • the product obtained consists of particles (the particle size of which depends on fine grinding), themselves formed from small fructose crystals agglomerated together. In order to remove as much water as possible, final drying at a temperature between 50 and 75 ° C takes place after fine grinding.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Organic Chemistry (AREA)
  • Saccharide Compounds (AREA)
  • Jellies, Jams, And Syrups (AREA)

Abstract

The production of crystallized fructose (A) by solidification of a hot concentrated fructose solution by adding crystal seeds of fructose comprises a fructose solution (B) for preparing crystal seeds obtained by producing a freshly prepared pure fructose syrup from melted fructose dihydrate and concentrating by evaporation under vacuum to give a solids content at least 96 wt. %. An Independent claim is also included for a crystallized fructose comprising beta -D-fructopyranose as a main constituent, obtained by the above described method.

Description

La présente invention a pour objet un procédé de fabrication de fructose cristallin par cristallisation /prise en masse d'un sirop purifié et concentré de fructose.The present invention relates to a process for the manufacture of crystalline fructose by crystallization / solidification of a purified and concentrated fructose syrup.

La préparation de fructose cristallin à partir de sirops de sucres, notamment les sirops contenant à la fois du fructose et du glucose, est connue en soi mais pose de nombreux problèmes pratiques.The preparation of crystalline fructose from sugar syrups, in particular syrups containing both fructose and glucose, is known per se but poses many practical problems.

Le brevet americain 2.588.449 décrit un procédé pour la préparation de cristaux de dihydrate de fructose C6H12O6.2H2O, par refroidissement et ensemencement ("grainage") d'une solution de fructose. Le produit obtenu, le dihydrate de fructose, n'est toutefois stable qu'à des températures relativement basses et ne peut donc pas être entreposé ni transporté sans précautions particulières pour éviter qu'il ne se liquéfie.American patent 2,588,449 describes a process for the preparation of crystals of fructose dihydrate C 6 H 12 O 6 .2H 2 O, by cooling and seeding ("graining") of a fructose solution. The product obtained, fructose dihydrate, is however only stable at relatively low temperatures and therefore cannot be stored or transported without special precautions to prevent it from liquefying.

On connait d'autre part le fructose dit "anhydre" (cf. brevet américain 3.513.023). Les procédés de cristalisation de ce produit sont soit relativement complexe et coûteux, par exemple par l'utisation de solutions alcooliques (cf. brevet américain 3.607.398), soit ne s'avèrent pas efficaces dans la pratique par suite des phénomènes d'isomérisation du fructose en phase aqueuse. C'est notamment le cas pour le procédé selon le brevet américain 3.513.023 : lorsque les conditions revendiquées par ce brevet sont reproduites expérimentallement il s'avère que la "mutarotation" du fructose (réaction d'equilibre entre les cinq isomères du fructose, à savoir le beta-D-fructopyranose, le beta-D-fructofuranose, le alpha-D-fructofuranose, le alpha-D-fructopyranose et la forme cétonique non cyclique du fructose) engendre la formation d'isomères non cristallisables qui entrave considérablement la cristallisation par prise en masse.On the other hand, so-called "anhydrous" fructose is known (cf. American patent 3,513,023). The crystallization processes of this product are either relatively complex and costly, for example by the use of alcoholic solutions (cf. American patent 3,607,398), or do not prove to be effective in practice owing to isomerization phenomena fructose in the aqueous phase. This is particularly the case for the process according to American patent 3,513,023: when the conditions claimed by this patent are reproduced experimentally it turns out that the "mutarotation" of fructose (equilibrium reaction between the five isomers of fructose, namely beta-D-fructopyranose, beta-D-fructofuranose, alpha-D-fructofuranose, alpha-D-fructopyranose and the non-cyclic ketone form of fructose) generates the formation of non-crystallizable isomers which considerably hinders crystallization by solidification.

La présente invention a pour objet de procurer un nouveau procédé de cristallisation de fructose, remédiant aux problèmes de l'art antérieur, et d'offrir ainsi une forme de fructose cristallin utilisable commerciallement.The object of the present invention is to provide a new process for crystallizing fructose, overcoming the problems of the prior art, and thus to offer a form of crystalline fructose which can be used commercially.

Ce nouveau procédé de fabrication de fructose cristallisé, impliquant la solidification d'une solution chaude et concentrée de fructose suite à un ensemencement de la solution au moyen de cristaux de fructose, se caractérise par l'utilisation d'une solution de fructose résultant d'un sirop de fructose pur fraîchement préparé par la fonte de cristaux de dihydrate de fructose, concentré par évaporation sous vide jusqu'à une teneur en matière sèche supérieure à 96% en poids, et de préference supérieure à 97% en poids.This new process for the manufacture of crystallized fructose, involving the solidification of a hot and concentrated solution of fructose following a seeding of the solution by means of fructose crystals, is characterized by the use of a fructose solution resulting from a pure fructose syrup freshly prepared by melting fructose dihydrate crystals, concentrated by evaporation under vacuum to a dry matter content greater than 96% by weight, and preferably greater than 97% by weight.

Selon une caractéristique supplémentaire de l'invention, la solution de fructose utilisée pour l'ensemencement a de préférence une température de préference comprise entre 50 et 100° C, idéalement entre 80 et 95° C.
De même l'ensemencement se fait de préférence au moyen de 5 à 30% en poids de fructose cristallisé ayant une granulométrie inférieure à 500 µm, de préference inférieure à 250 µm (par exemple 50µm).According to an additional characteristic of the invention, the fructose solution used for sowing preferably has a preferred temperature of between 50 and 100 ° C, ideally between 80 and 95 ° C.
Similarly, the seeding is preferably done by means of 5 to 30% by weight of crystallized fructose having a particle size less than 500 μm, preferably less than 250 μm (for example 50 μm).

Selon une autre caractéristique supplémentaire de l'invention, le délai entre la fonte des cristaux de dihydrate de fructose pour préparer le sirop initial et la concentration de ce sirop à une teneur en matière sèche supérieure à 96% en poids, de préference supérieure à 97% en poids, est de préference inférieur à 24 heures, plus particulièrement inférieur à 8 heures, et idéalement inférieur à une demi heure.According to another additional characteristic of the invention, the time between the melting of the fructose dihydrate crystals to prepare the initial syrup and the concentration of this syrup with a dry matter content greater than 96% by weight, preferably greater than 97 % by weight, is preferably less than 24 hours, more particularly less than 8 hours, and ideally less than half an hour.

L'invention concerne également un procédé global de fabrication de fructose cristallisé à partir d'un sirop contenant du fructose et eventuellement d'autres substances (par exemple d'autres sucres, des protéines, etc.), impliquant les étapes successives suivantes :

  • ensemencement au moyen de cristaux de fructose dihydrate de la solution aqueuse de fructose ayant une teneur totale en sucre comprise entre 45 et 85% en poids et une teneur en fructose supérieure à 60% en poids de la matière sèche, à une température entre 10 et - 10° C,
  • maintien de la solution dans une zone de sursaturation en fructose par abaissement progressif de la température jusqu'à obtention de cristaux de taille souhaitée, et séparation des cristaux obtenus de la solution mère de manière à obtenir des cristaux de fructose dihydrate ayant une teneur en fructose comprise ente 95 et 100% en poids de matière sèche;
  • fonte des cristaux récoltés en un sirop ayant une teneur d'environ 83% en poids de sucre et environ 17% d'eau; concentration du sirop ainsi obtenu, par évaporation d'eau sous une pression réduite, de préference une pression inférieure à 60 mm de colonne de mercure, jusqu'à une teneur en matière sèche supérieure à 96% en poids, de préference entre 97 et 100% en poids;
  • ensemencement du sirop ainsi obtenu au moyen de 5 à 30% en poids de fructose cristallisé, de préference à une température comprise entre 80 et 95° C,
  • maintien de la masse obtenue à une température entre 55 et 75° C jusqu'à obtention d'une masse non collante et cassante, et
  • concassage, séchage et broyage de cette masse en particules formées de cristaux de fructose agglomérés.
The invention also relates to a global process for the manufacture of crystallized fructose from a syrup containing fructose and possibly other substances (for example other sugars, proteins, etc.), involving the following successive steps:
  • seeding by means of fructose crystals dihydrate of the aqueous fructose solution having a total sugar content of between 45 and 85% by weight and a fructose content greater than 60% by weight of the dry matter, at a temperature between 10 and - 10 ° C,
  • maintaining the solution in a fructose supersaturation zone by gradually lowering the temperature until crystals of desired size are obtained, and separation of the crystals obtained from the mother solution so as to obtain fructose dihydrate crystals having a fructose content between 95 and 100% by weight of dry matter;
  • melting the crystals collected in a syrup having a content of about 83% by weight of sugar and about 17% of water; concentration of the syrup thus obtained, by evaporation of water under reduced pressure, preferably a pressure less than 60 mm of mercury column, up to a dry matter content greater than 96% by weight, preferably between 97 and 100 % in weight;
  • inoculation of the syrup thus obtained by means of 5 to 30% by weight of crystallized fructose, preferably at a temperature between 80 and 95 ° C.,
  • maintaining the mass obtained at a temperature between 55 and 75 ° C until a non-sticky and brittle mass is obtained, and
  • crushing, drying and grinding this mass into particles formed of agglomerated fructose crystals.

Il est à noter que l'ajout éventuel d'eau lors de la fonte des cristaux de fructose dihydrate, et l'élimination consécutive de cette eau ajoutée lors de l'étape de concentration du sirop jusqu'à une teneur en matière sèche entre 96 et 100% en poids, est absolument équivalente au procédé impliquant la fonte des cristaux tels que récoltés, pour autant que le délai entre la formation du sirop et sa concentration soit le plus court possible (en particulier inférieur à 24 heures).It should be noted that the possible addition of water during the melting of the fructose dihydrate crystals, and the subsequent elimination of this water added during the syrup concentration step up to a dry matter content between 96 and 100% by weight, is absolutely equivalent to the process involving the melting of the crystals as harvested, provided that the time between the formation of the syrup and its concentration is as short as possible (in particular less than 24 hours).

L'invention concerne du fructose cristallisé, essentiellement constitué de beta-D-fructopyranose, ayant de faibles teneurs en autres tautomères de fructose, tel que résultant d'un procédé de solidification d'une solution chaude et concentrée de fructose suite à l'ensemencement de la solution au moyen de cristaux de fructose, dans lequel la solution de fructose utilisée pour l'ensemencement résulte d'un sirop de fructose pur fraîchement préparé par la fonte de cristaux de dihydrate de fructose, concentré par évaporation sous vide jusqu'à une teneur en matière sèche entre 96 et 100% en poids,
la solution de fructose utilisée pour l'ensemencement a une température de préference comprise entre 80 et 95° C, et l'ensemencement se fait au moyen de 5 à 30% en poids de fructose cristallisé de granulométrie inférieure à 500 µm, de préference inférieure à 250 µm, et
le délai entre la fonte des cristaux de dihydrate de fructose pour préparer le sirop initial et la concentration de ce sirop à une teneur en matière sèche supérieure à 96% est inférieur à 8 heures, de préférence inférieure à une demi heure.The invention relates to crystallized fructose, essentially consisting of beta-D-fructopyranose, having low contents of other tautomers of fructose, as resulting from a process for solidification of a hot and concentrated solution of fructose following sowing. of the solution by means of fructose crystals, in which the fructose solution used for sowing results from a pure fructose syrup freshly prepared by the melting of crystals of fructose dihydrate, concentrated by evaporation under vacuum until a dry matter content between 96 and 100% by weight,
the fructose solution used for seeding has a preferred temperature of between 80 and 95 ° C., and the seeding is carried out by means of 5 to 30% by weight of crystallized fructose with a particle size of less than 500 μm, of lower preference at 250 µm, and
the time between the melting of the fructose dihydrate crystals to prepare the initial syrup and the concentration of this syrup with a dry matter content greater than 96% is less than 8 hours, preferably less than half an hour.

Les exemples ci-après serviront à illustrer l'invention et à en préciser certains détails et modes de réalisations préférés, sans toutefois en limiter la portée telle que définie dans les revendications qui suivent.The examples below will serve to illustrate the invention and to specify certain details and preferred embodiments, without however limiting its scope as defined in the claims which follow.

EXEMPLE IEXAMPLE I Purification d'une solution de glucose et de fructose : obtention de cristaux de dihydrate de fructose C6H12O6.2H2OPurification of a glucose and fructose solution: obtaining crystals of fructose dihydrate C 6 H 12 O 6 .2H 2 O

L'obtention de cristaux de fructose dihydrate consiste en un refroidissement progressif d'une solution aqueuse de glucose et de fructose dont la teneur totale en sucre est comprise entre 45 et 85% et, dans la matière sèche, la concentration en fructose est comprise entre 60 et 100%.Obtaining fructose dihydrate crystals consists of a progressive cooling of an aqueous solution of glucose and fructose, the total sugar content of which is between 45 and 85% and, in the dry matter, the fructose concentration is between 60 and 100%.

Au cours du processus de refroidissement, quand la concentration de saturation du fructose dihydrate est atteinte, des cristaux de fructose dihydrate, apportés de l'extérieur, sont introduits dans la masse de sirops. Cet apport de cristaux extérieurs, appelé grainage, a lieu à une température variant de 10 à - 10° C suivant la concentration en matière sèche et suivant la composition de la matière sèche.During the cooling process, when the saturation concentration of fructose dihydrate is reached, crystals of fructose dihydrate, brought from the outside, are introduced into the syrup mass. This supply of external crystals, called graining, takes place at a temperature varying from 10 to -10 ° C. depending on the concentration of dry matter and on the composition of the dry matter.

Après grainage, la température de la masse ainsi grainée est abaissée progressivement et est ainsi maintenue dans une zone de sursaturation en fructose telle que les cristaux présents croissent progressivement en limitant toutefois l'apparition de nouveaux cristaux.After graining, the temperature of the mass thus grained is gradually lowered and is thus maintained in a zone of supersaturation in fructose such that the crystals present progressively grow, however limiting the appearance of new crystals.

Lorsque les cristaux ont atteint la taille souhaitée, la masse de sirop contenant les cristaux est véhiculée vers une centrifugeuse continue ou discontinue semblable à celles utilisées en sucrerie. Toute autre méthode physique de séparation solide/liquide peut être envisagée.When the crystals have reached the desired size, the mass of syrup containing the crystals is conveyed to a continuous or discontinuous centrifuge similar to those used in sugar refinery. Any other physical method solid / liquid separation can be considered.

Les eaux mères de cristallisation, constituées de l'eau et des sucres de la solution initiale qui n'ont pas cristallisé, peuvent être soumises à une nouvelle étape de cristallisation comme décrite ci-avant.The mother liquors of crystallization, consisting of water and sugars from the initial solution which have not crystallized, can be subjected to a new crystallization stage as described above.

Les cristaux de fructose dihydrate, ainsi séparés, peuvent être lavés de façon à éliminer au maximum la pellicule d'eaux mères les entourant donc à augmenter la pureté du fructose à des valeurs comprises entre 90% et 100% et préférablement entre 97.5% et 100%. Ils sont ensuite fondus, de préference à des températures supérieures à 20° C. S'il n'y a aucun ajout d'eau durant la fonte, le sirop obtenu à partir de cristaux correctement lavés contient 83% de sucres et 17% d'eau. La matière sèche d'un tel sirop ne contient que quelques traces d'autres sucres présents dans les eaux-mères.The fructose dihydrate crystals, thus separated, can be washed so as to eliminate as much as possible the film of mother liquor surrounding them therefore increasing the purity of the fructose to values between 90% and 100% and preferably between 97.5% and 100 %. They are then melted, preferably at temperatures above 20 ° C. If there is no addition of water during melting, the syrup obtained from properly washed crystals contains 83% sugars and 17% d 'water. The dry matter of such a syrup contains only a few traces of other sugars present in the mother liquors.

EXEMPLE IIEXAMPLE II Concentration d'un sirop de fusion de cristaux de dihydrate de fructose.Concentration of a syrup for melting fructose dihydrate crystals.

Le sirop à 83% de matière sèche obtenu selon exemple I est concentré à des températures de l'ordre de 65 à 100° C sous des pressions inférieures à 60 mm de mercure, durant un délai inférieur à 30 minutes, voire inférieure à 15 minutes. Plus la pression de concentration est faible, plus la température maximum requise sera faible réduisant ainsi les risques de coloration du sirop concentré.The 83% dry matter syrup obtained according to Example I is concentrated at temperatures of the order of 65 to 100 ° C. under pressures below 60 mm of mercury, for a period of less than 30 minutes, or even less than 15 minutes. . The lower the concentration pressure, the lower the maximum temperature required, reducing the risk of coloring the concentrated syrup.

En fonction de la température, de la pression et du temps concentration, la matière sèche du sirop concentré varie entre 96.0 et 100.0%. A une température de sortie de l'ordre de 90° C, le sirop est relativement visqueux et peut alors être véhiculé par pompage pour la cristallisation/prise en masse consécutive.Depending on the temperature, pressure and concentration time, the dry matter of the concentrated syrup varies between 96.0 and 100.0%. At an outlet temperature of around 90 ° C, the syrup is relatively viscous and can then be pumped for crystallization / subsequent solidification.

Remarque :Note :

Dans les cristaux de dihydrate de fructose, de même que dans ceux de fructose, la molécule de fructose se trouve uniquement sous forme de beta-D-fructopyranose. En revanche, en solution aqueuse, le fructose subit le phénomène de mutarotation. A l'équilibre, la solution contient les 5 isomères suivants :

  • le beta-D-fructopyranose, le beta-D-fructofuranose,
  • le alpha-D-fructofuranose, le alpha-D-fructopyranose et la forme cétonique non cyclique du fructose (les 2 dernières formes étant largement minoritaires). Seul le premier de ces isomères est susceptible d'entrer dans l'édifice cristallin du fructose, les autres devant être considérés comme des impuretés dans le contexte de la cristallisation.
Pour éviter au maximum la formation des ces isomères non cristallisables, il convient de concentrer rapidement les sirops (obtenus par fusion des cristaux de dihydrate) jusqu'à une teneur en matière sèche de préference supérieure à 96.0%, idéalement jusqu'à une teneur en matière sèche supérieure à 97.0%. La mutarotation s'effectue de manière d'autant plus lente que la teneur en eau de la solution est faible. Si le temps compris entre la fusion des cristaux et la concentration du sirop est trop important, la teneur en isomères non cristallisables peut atteindre des valeurs de l'ordre de 25 à 30% ce qui entrave considérablement la cristallisation du beta-D-fructopyranose.In fructose dihydrate crystals, as well as in fructose, the fructose molecule is found only as beta-D-fructopyranose. On the other hand, in aqueous solution, fructose undergoes the phenomenon of mutarotation. At equilibrium, the solution contains the following 5 isomers:
  • beta-D-fructopyranose, beta-D-fructofuranose,
  • alpha-D-fructofuranose, alpha-D-fructopyranose and the non-cyclic ketone form of fructose (the last 2 forms being largely in the minority). Only the first of these isomers is capable of entering the crystal structure of fructose, the others having to be considered as impurities in the context of crystallization.
To avoid as much as possible the formation of these non-crystallizable isomers, it is advisable to quickly concentrate the syrups (obtained by melting the dihydrate crystals) up to a dry matter content preferably greater than 96.0%, ideally up to a content of dry matter greater than 97.0%. The mutarotation takes place the more slowly the lower the water content of the solution. If the time between the melting of the crystals and the concentration of the syrup is too long, the content of non-crystallizable isomers can reach values of the order of 25 to 30%, which considerably hinders the crystallization of beta-D-fructopyranose.

EXEMPLE IIIEXAMPLE III Cristallisation / prise en masse d'un sirop concentré frais.Crystallization / solidification of a concentrated syrup fresh.

Le sirop concentré et visqueux obtenu dans l'exemple II est alors maintenu dans un mélangeur à une température comprise entre 80 et 95° C et ensemencé à l'aide de 10 à 25% de fructose cristallisé d'une granulométrie très fine (<200µm). Cet ensemencement peut être fait à l'aide de fructose obtenu par le présent procédé, broyé très finement. Le milieu est alors agité de façon à assurer une dispersion optimale des germes en son sein. Le milieu consitué d'une masse blanchâtre très visqueuse est alors coulé hors du mélangeur et stocké dans une étuve dont la température est fixée entre 55 et 75° C selon la teneur d'eau résiduelle, de la quantité de germes et de l'état d'avancement de la réaction de mutarotation. Le temps de séjour dans l'étuve dépend de ces mêmes facteurs.The concentrated and viscous syrup obtained in Example II is then kept in a mixer at a temperature between 80 and 95 ° C and seeded using 10 to 25% of crystallized fructose with a very fine particle size (<200 μm ). This seeding can be done using fructose obtained by the present process, very finely ground. The medium is then agitated so as to ensure optimal dispersion of the germs within it. The medium consisting of a very viscous whitish mass is then poured out of the mixer and stored in an oven whose temperature is fixed between 55 and 75 ° C. depending on the residual water content, the quantity of germs and the state of the mutarotation reaction. The residence time in the oven depends on these same factors.

Durant cette étape, la cristallisation se déroule jusqu'à ce que, finalement, l'ensemble forme une masse non collante, rigide et cassante.During this stage, crystallization takes place until, finally, the whole forms a non-sticky, rigid and brittle mass.

Notons que si un sirop non ensemencé est traité de façon identique, il se vitrifie complètement et forme une masse amorphe (non cristalline) translucide très hygroscopique qui ne se prête ni au broyage ni au stockage.Note that if an unseeded syrup is treated identically, it vitrifies completely and forms an amorphous (non-crystalline) translucent, very hygroscopic mass which lends itself neither to grinding nor to storage.

La masse cistallisée ainsi obtenue est grossièrement concassée au moyen d'un broyeur. Les particules obtenues peuvent ensuite être séchées entre 50 et 75° C (de préférence sous flux d'air sec) afin de diminuer encore la teneur en eau. Le broyage fin peut alors être effectué. Si la masse initiale est suffisamment sèche que pour être finement broyée, le séchage consécutif au broyage grossier peut être évité.The cistallized mass thus obtained is coarsely crushed by means of a grinder. The particles obtained can then be dried between 50 and 75 ° C (preferably under a flow of dry air) in order to further decrease the water content. Fine grinding can then be carried out. If the initial mass is dry enough to be finely ground, drying subsequent to coarse grinding can be avoided.

Le produit obtenu est constitué de particules (dont la granulométrie dépend du broyage fin) elles-mêmes formées de cristaux de fructose de petite taille agglomérés entre eux. En vue d'éliminer un maximum d'eau, un séchage final à une température comprise entre 50 et 75° C a lieu au terme du broyage fin.The product obtained consists of particles (the particle size of which depends on fine grinding), themselves formed from small fructose crystals agglomerated together. In order to remove as much water as possible, final drying at a temperature between 50 and 75 ° C takes place after fine grinding.

Claims (8)

  1. Process for preparing crystallized fructose by solidification of a hot and concentrated solution of fructose obtained by seeding the solution by means of fructose crystals, characterized in that the fructose solution used for seeding, results from a pure fructose syrup newly made by melting fructose dihydrate crystals, concentrated by vacuum evaporation until the content of dry substance exceeds 96% by weight.
  2. Process for preparing crystallized fructose according to claim 1, characterized in that the fructose solution used for seeding has a temperature ranging from 50 to 100 °C.
  3. Process for preparing crystallized fructose according to anyone of the preceding claims, characterized in that seeding occurs by means of 5 to 30% by weight of crystallized fructose having a granulometry of less than 500 µm.
  4. Process for preparing crystallized fructose according to anyone of the preceding claims, characterized in that the time between melting the crystals of fructose dihydrate in order to prepare the initial syrup and the concentration of this syrup up to a content of dry substance exceeding 96% is less than 24 hours.
  5. Process for preparing crystallized fructose according to anyone of the claims 1 to 4, characterized in that the time between melting the crystals of fructose dihydrate to prepare the initial syrup and the concentration of this syrup up to a content of dry substance exceeding 96% is less than 8 hours.
  6. Process for preparing crystallized fructose according to anyone of the claims 1 to 4, characterized in that the time between melting the crystals of fructose dihydrate to prepare the initial syrup and the concentration of this syrup up to a content of dry substance exceeding 96% is less than half an hours.
  7. Process for preparing crystallized fructose from syrup containing fructose and other substances on occasion, by purification of this solution of fructose and by its solidification by seeding by means of fructose crystals, characterized by the following successive stages:
    Seeding, by means of fructose dihydrate crystals, the fructose solution having a total content of sugar ranging from 45 to 85% by weight and a fructose content exceeding 60% by weight of the dry substance, at a temperature ranging from 10 to -10 °C;
    Maintaining the solution in a zone of supersaturation of fructose by progressively lowering the temperature until crystals of the size desired are obtained, and separating the crystals obtained from the mother solution in order to obtain fructose dihydrate crystals, having a fructose content ranging from 95 to 100% by weight of the dry substance;
    Melting of the crystals gathered in a syrup, having a sugar content of about 83% by weight and a water content of about 17%;
    Concentration of the syrup by evaporating the water at a reduced pressure up to a content of dry substance ranging from 96 to 100% by weight;
    Seeding the syrup thus obtained by means of 5 to 30% by weight of crystallized fructose;
    Maintaining the mass obtained at a temperature ranging from 55 to 75 °C, until a non-glueing and breakable mass is obtained, and crushing, drying and pulverizing of this mass into particles, formed by agglomerated fructose crystals.
  8. Process for preparing crystallized fructose according to anyone of the preceding claims, characterized in that:
    The fructose solution used for seeding by means of fructose crystals has a temperature ranging from 80 to 95 °C;
    The fructose solution used for seeding by means of fructose crystals has been concentrated by vacuum evaporation;
    The fructose solution used for seeding by means of fructose crystals has been concentrated up to a content of dry substance exceeding 96% by weight, and/or in that:
    The seeding crystals have a granulometry lower than 250 µm.
EP98202278A 1998-07-08 1998-07-08 Process for preparing crystallized fructose Expired - Lifetime EP0971040B1 (en)

Priority Applications (10)

Application Number Priority Date Filing Date Title
ES98202278T ES2206826T3 (en) 1998-07-08 1998-07-08 MANUFACTURING PROCEDURE OF CRYSTALLIZED FRUCTOSE.
DE69818023T DE69818023T2 (en) 1998-07-08 1998-07-08 Process for the production of crystal fructose
AT98202278T ATE249524T1 (en) 1998-07-08 1998-07-08 METHOD FOR PRODUCING CRYSTAL FRUCTOSE
EP98202278A EP0971040B1 (en) 1998-07-08 1998-07-08 Process for preparing crystallized fructose
DK98202278T DK0971040T3 (en) 1998-07-08 1998-07-08 Process for producing crystallized fructose
JP2000559260A JP2002520030A (en) 1998-07-08 1999-07-05 Method for producing crystalline fructose
US09/743,157 US6607603B1 (en) 1998-07-08 1999-07-05 Method for making crystallized fructose
IL14064099A IL140640A (en) 1998-07-08 1999-07-05 Method for making crystallized fructose
PCT/EP1999/004732 WO2000003040A1 (en) 1998-07-08 1999-07-05 Method for making crystallised fructose
ZA200100133A ZA200100133B (en) 1998-07-08 2001-01-05 Method for making crystallised fructose.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP98202278A EP0971040B1 (en) 1998-07-08 1998-07-08 Process for preparing crystallized fructose

Publications (2)

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EP0971040A1 EP0971040A1 (en) 2000-01-12
EP0971040B1 true EP0971040B1 (en) 2003-09-10

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EP (1) EP0971040B1 (en)
JP (1) JP2002520030A (en)
AT (1) ATE249524T1 (en)
DE (1) DE69818023T2 (en)
DK (1) DK0971040T3 (en)
ES (1) ES2206826T3 (en)
IL (1) IL140640A (en)
WO (1) WO2000003040A1 (en)
ZA (1) ZA200100133B (en)

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Publication number Priority date Publication date Assignee Title
EP2292803B1 (en) 2009-07-07 2013-02-13 DuPont Nutrition Biosciences ApS Separation process
US9162999B2 (en) 2011-09-28 2015-10-20 Wisconsin Alumni Research Foundation Catalytic conversion of cellulose to fuels and chemicals using boronic acids

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2588449A (en) * 1950-03-03 1952-03-11 Us Agriculture Levulose dihydrate
US3513023A (en) * 1966-04-29 1970-05-19 Boehringer Mannheim Gmbh Process for the production of crystalline fructose
US3607392A (en) * 1967-12-21 1971-09-21 Boehringer Mannheim Gmbh Process and apparatus for the recovery of crystalline fructose from methanolic solution
US3883365A (en) * 1972-01-04 1975-05-13 Suomen Sokeri Oy PH adjustment in fructose crystallization for increased yield
US4199373A (en) * 1979-04-13 1980-04-22 Chimicasa Gmbh Process for the manufacture of crystalline fructose
GB8506482D0 (en) * 1985-03-13 1985-04-17 Tate & Lyle Plc Sugar process
US5047088A (en) * 1989-06-30 1991-09-10 A. E. Staley Manufacturing Company Method for crystallization of fructose

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DE69818023D1 (en) 2003-10-16
IL140640A0 (en) 2002-02-10
US6607603B1 (en) 2003-08-19
ES2206826T3 (en) 2004-05-16
ZA200100133B (en) 2001-07-23
DE69818023T2 (en) 2004-07-08
WO2000003040A1 (en) 2000-01-20
EP0971040A1 (en) 2000-01-12
DK0971040T3 (en) 2003-12-08
IL140640A (en) 2005-11-20
JP2002520030A (en) 2002-07-09
ATE249524T1 (en) 2003-09-15

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