FR2512059A1 - PROCESS FOR THE INDUSTRIAL PRODUCTION OF D-FRUCTOSE - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR THE INDUSTRIAL PRODUCTION OF D-FRUCTOSE USEFUL AS A SWEETENER FOR FOODS FROM D-GLUCOSE; D-GLUCOSE IS SPIRED INTO A MIXTURE OF D-GLUCOSE AND D-MANNOSE, D-GLUCOSE IS SEPARATED FROM THE MIXTURE, D-MANNOSE IS HYDROGENATED TO D-MANNITOL, D-MANNITOL OXIDIZED TO OBTAIN A SOLUTION OF D-FRUCTOSE AND THIS SOLUTION IS CRYSTALLIZED TO OBTAIN D-FRUCTOSE CRYSTALS.

Description

Your present invention relates to a process for industrial production

  of D-fructose D-fructose is useful

as a food sweetener.

  It is known that sugars, for example the D-series sugars, such as D-glucose, D-fructose and D-sucrose and others have been useful as sweeteners According to the patents of the United States of America n 2 753 279 and n 2 845 369, we oxidize

  the intermediate product, D-mannitol, to obtain D-fruc-

  tose However, this process has been abandoned because its cost is excessive and it is ill-suited to the industrial production of

the sweetener that is D-fructose.

  The production of synthetic sweeteners, such as D-series sugars, has been carried out on an industrial scale The process of the invention for producing D-series sugars

  allows as desired to produce sugars such as D-fruc-

  tose on an industrial scale, economically and conveniently.

  The present invention relates to a process for producing D-fructose from D-glucose The process comprises the stages of epimerization of Dglucose into a mixture of D-glucose and D-mannose, separation of Dglucose from the mixture, hydrogenation of D -manose in a fixed catalytic bed to obtain D-mannitol, oxidation of D-mannitol to obtain a D-fructose solution and crystallization of particles from the solution to obtain

D-fructose crystals.

  Other characteristics and advantages of the invention

  will be better understood on reading the description which follows

  and with reference to the appended single figure which is a functional diagram illustrating the process for the production of D-fructose from D-glucose according to the invention, D-fructose being a

  sweetener for most foods.

  The figure illustrates the stepwise process for producing D-fructose from D-glucose. According to this process, an aqueous solution of D-glucose is first epimerized into a mixture of D-glucose and D-mannose preferably. in a fixed catalytic bed This mixture is then passed through a fractional crystallizer where the D-glucose is separated from the mixture, that is to say from the D-mannose, and recycled in the epimerization zone to be again epimerized After separation of Dglucose, D-mannose

  is hydrogenated to provide a solution of D-mannitol.

  D-mannitol, in solution, is then treated with oxygen or air in the presence of oxidizing microbes, i.e. Gluconobacter suboxydans which is also called Acetobacter suboxydans. Mannitol after hydrogenation provides a solution of D -fructose that we treat, that is to say that we crystallize

in crystals.

  Unoxidized D-mannitol may pass with the solution

  of D-fructose in the crystallizer This non-oxidized D-mannitol is

  i.e. residual, is then recycled to the oxidation zone to

  be oxidized with that from the hydrogenation zone.

  The fixed bed catalyst in which the D-glucose is epimerized is preferably silicotungstic acid on silica gel. There are other catalysts that can be used in this epimerization process which include molybdic acid. on silica gel, phosphomolybdic acid on

  silica gel and similar derivatives of molybdenum and tungs-

  tene on a silica gel which is preferably washed with acid On

  uses this same fixed catalytic bed in the hydrogenation of D-man-

nose in D-mannitol.

  The epimerization process which produces D-mannose uses a 10 to 70% aqueous solution of D-glucose and better still a 50 to 70% aqueous solution 7 of D-glucose at 100-125 C and a p H of 3 to 5 with a reaction time of 30 to 120 minutes Also,

  instead of pure D-glucose, hydro-

  crude starch lysate to produce D-mannitol and finally Dfructose.

  In the hydrogenation of D-mannose with the cat-bed

  fixed lyque, the flow of hydrogen is related to the flow of liquid supply and the amount of catalyst used, because the current

  hydrogen gas entrains the droplets of feed liquid

  through the fixed catalytic beds to achieve a con-

  intimate tact with the particles of catalyst The flow rate of the

  Liquid mentation in the present hydrogenation is between about 0.3 and about 10.0 g / hg of catalyst and preferably from about 0.4 to about 8.0 g / hg of catalyst Consequently, the ratio of the flow rate of the hydrogen gas at the flow rate of the liquid feed under standard conditions is between approximately 500 and approximately 5,000 so that a satisfactory conversion is obtained.

  making D-mannose into D-mannitol.

  The aerobic fermentation bacteria consist of Gluconobacter suboxydans (subsp suboxydans) The quantity of suboxydans used is generally linked to the quantity of D-mannitol to be oxidized This quantity is between approximately 20 g and approximately g / 1 of the volume of reactor h.

  The conditions under which D-man-

  nose in D-mannitol in the fixed catalytic bed are a temperature between approximately 100 and approximately 150 C and a partial pressure

  of hydrogen between about 34.5 and about 138 bars manome-

triques.

  D-fructose can be used as a sweetener

  corante for food of all types D-fructose is an agent

  sweetener that is calorigenic and twice as sweet as saccha-

  pink So half the amount of D-fructose is enough to

sweeten food.

  Of course various modifications can be made by those skilled in the art to the devices or methods which have just been described solely by way of non-limiting example

  without departing from the scope of the invention.

12059

Claims (4)

  1 Process for producing D-fructose from D-glu-   cose which comprises the stages of: a) epimerization of D-glucose into a mixture of D-glucose and D-mannose; b) separation of said-D-glucose from the mixture with D-mannose; c) hydrogenating said D-mannose to produce D-mannitol;   d) oxidation of said D-mannitol to produce a solution of D-fruc-   tose; and e) crystallizing said D-fructose solution to produce D-fructose crystals.   2 Method according to claim 1, characterized in that said D-glucose is in the form of a 10% aqueous solution. 3 Method according to claim 1, characterized in that the epimerization of said D-glucose takes place in a catalytic bed   fixed silicotungstic acid on silica gel.   4 Method according to claim 1, characterized in that said D-mannose is hydrogenated in a fixed catalytic bed at   a temperature between about 100 and about 150 C.   Method according to claim 1, characterized in that said D-glucose is replaced by a hydrolyzate solution raw starch.   6 Method according to claim 1, characterized in that one carries out the oxidation of D-mannitol and D-fructose with a gas containing oxygen in the presence of Gluconobacter suboxydans.