US3929503A - Production of free-flowing particles of glucose, fructose or the mixture thereof - Google Patents

Free-flowing particles of glucose, fructose or mixtures thereof are produced by kneading an anhydrous powder of the sugar with a 40-90% by weight solution of said sugar to give a kneaded mixture having a moisture content of less than 7%, shaping the resultant mixture into the form of granules, pellets or the like and drying at a temperature below 70* C.

United States atent 1 1 Yamauchi 1 51 Dec. 30, 1975 PRODUCTION OF FREE-FLOWING PARTICLES OF GLUCOSE, FRUCTOSE OR THE MIXTURE THEREOF Inventor: Toshio Yamauchi, Kyoto, Japan Daiichi Seiyaku Co., Ltd., Kyoto, Japan Filed: May 31, 1974 Appl. No.: 475,198

Assignee:

Foreign Application Priority Data June 4, 1973 Japan 48-63250 US. Cl. 127/58; 127/30; 127/63 Int. Cl. C13K l/00; C13K 9/00 Field of Search 127/30, 58, 60, 63

References Cited UNITED STATES PATENTS 5/1970 Kusch 127/60 X 3,816,175 6/1974 Melaja 127/58 X Primary Examiner-Morris O. Wolk Assistant Examiner-Sidney Marantz Attorney, Agent, or Firm-James C. Haight 13 Claims, 1 Drawing Figure US. Patent Dec. 30, 1975 52 & $5 Q? kirsiq he REES SUGAR CONCENTRATION (75) PRODUCTION OF FREE-FLOWING PARTICLES OF GLUCOSE, FRUCTOSE OR THE MIXTURE THEREOF This invention relates to a method of production of anhydrous powders, pellets or granules of glucose, fructose or a mixture thereof. More particularly, it relates to a method whereby aqueous solutions containing glucose, fructose or mixtures thereof are converted into the form of dry powders, pellets, granules or the like without subjecting the-solution to a crystallization step.

Fructose or mixtures thereof with glucose are widely consumed in the form of a dry powder or solution. Although anhydrous crystalline fructose has been used even for dietary purposes, it is not essential that the fructose used for such purposes be pure, but rather a supply of fructose as cheap as possible in large quantities is more important when its nutritional value is taken into consideration. Fructose can also be produced from glucose by the action of the enzyme glucose isomerase. At equilibrium, the reaction mixture contains 43% fructose and 57% glucose but is very hygroscopic and difficult to crystallize. Therefore, the isomerized products are used as sweeteners for confectionaries and other food products in the form of a syrup. However, the syrup has certain disadvantages in that it is susceptible to deterioration due to coloration, microorganism growth or partial crystallization in winter on storage. It is, therefore, desirable to convert the syrup to a free-flowing solid which may find wide use in various fields, particularly in houshold consumption.

In my co-pending U.S. application Ser. No. 435,525 filed Jan. 22, 1974, a method of crystallization of anhydrous fructose has been disclosed. Crystallization of fructose according to the method described in said U.S. application or otherwise always accompanies formation of substantial amounts of green syrup, since the crystals are always present at equilibrium with the syrup regardless whether they are the first, second or third crops. The sugar concentration in the syrup decreases as the crop proceeds, for instance, to about 85%. About 20% of the starting fructose content remains in the syrup when 80% of the starting fructose has been recovered as crystals through the overall crops. Thus it becomes difficult and uneconomical to subject such syrup to further crystallization step. If the syrup can be converted to a free-flowing, dry solid suitable for dietary uses, the advantages of the above method will be greatly enhanced.

Attempts to dehydrate concentrated fructose solutions by means of spray or film-drying have been unsuccessful.

In Japanese patent publication No. 15647 of 1971 corresponding to U.S. Pat. No. 3,513,023, a method of producing crystalline fructose has been disclosed. According to this method, fructose solutions having at least a 95% concentration are further concentrated in vacuo to a water content from 2 to 5%, and then cooled to from 60 to 85C. A large quantity of fructose crystals is added to the solution and the mixture is stirred at a temperature of 60 to 85C until it becomes a soft mass. The mass is made solid, ground and dried at a temperature below 65C. This method has the difficulty of concentrating fructose to a concentration higher than 95%. At concentrations higher than 90%, a fructose solution becomes very viscous so that the evaporation rate decreases remarkably. Since a longer period of time or higher evaporation temperature is required to concentrate the solution to 90-95% or higher, a change of color due to partial caramelization will unavoidably take place. In addition to the fact that a crystallization step is required, the necessary apparatus and energy used for mixing or kneading a very viscous semi-solid mass make this technique uneconomical. Furthermore, the resulting particles produced by a strong mixing under cooling must be converted to a suitable form such as pellets or the like. The application of this technique has been confined to fructose only.

An object of the present invention is to provide an economical method of producing free-flowing, anhydrous particles of glucose, fructose or mixtures thereof in such forms as powders, pellets, granules and the like.

Another object is to provide a method whereby aqueous solutions of glucose, fructose or mixtures thereof are converted into dry, free-flowing particles such as powders, pellets granules and the like without subjecting the. solution to a crystallization step.

Still other objects and advantages of the present invention will become apparent as the description proceeds. In a preferred embodiment of the present invention, crystals or powder of anhydrous glucose, fructose or mixtures thereof (hereinafter referred to as mother powder) are mixed and kneaded with a syrup or massecuite (hereinafter referred as syrup) containing 40 to 90%, preferably 60 to 90% of the same type of sugar as the mother powder so that the mixture forms wet particles having a moisture content of less than 7%, preferably from 1.5 to 4%. This step may be conveniently carried out by charging the mother powder in a kneader and adding the syrup gradually to the mother powder in amounts sufficient to make the moisture content less than 7%. Alternatively, the mother powder and the syrup may be mixed continuously by supplying them at a constant rate to a continuous mixer. This mixing may be carried out at room temperature or higher. Thus, hot syrup just withdrawn from a vacuum evaporator (about C) can be mixed without cooling. During this mixing step, the mixture forms wet, round fine particles which are still free-flowing. At this stage, the mixture may easily be shaped into a suitable size of granules or pellets using a conventional type of granulator or pelletizer. The wet granules or pellets are then dried. Alternatively, the wet particles may be dried without subjecting them to a granulating or pelletizing ste 'l he resulting particles, granules or pellets are dried at a temperature below 70C, preferably at about 60C, under reduced pressure, for example at 10mm Hg. Other drying methods such as air-blowing or fluid drying may also be applied. In this case, air is preferably dehumidified to an absolute humidity less than about 0.0lg of water per g. of air and heated from 50C to 70C.

The resulting products are free-flowing particles or pellets having an average particle size from 0.05 to 0.3mm. The granules preferably have a cylindrical form of 0.5 to 1.5mm in diameter and about 2mm in length.

Although the finished products are generally uniform in shape and size, it is sometimes desirable to sieve the product through a screen. As can be seen from the foregoing description, it is essential for the present invention that the mixture of the mother powder and the syrup has a moisture content less than 7%. At a moisture content higher than 7%, the mixture is a mud which turns into an aqueous solution of sugar on heating during the subsequent drying step. Thus, drying into solid particles becomes impossible. I

The relationship between the mixing ratio and the concentration of the syrup to give the requiredrange of the moisture content is shown in the accompanying drawing.

In the drawing the concentration of syrup is represented on the horizontal axis and the ratio of the weight of syrup to the weight of mother powder is represented in the vertical axis. Curve AB represents this ratio at varying concentrations of syrup to give a 7% moisture content, and curves A B and C D are those of 4% and 1.5% moisture contents respectively. The present invention is carried out within the range defined by points A, B, C and D, preferably the range defined points A, B, C, and D in the drawing.

Within this range, the weight of mother powder Wp, the weight of syrup Ws and the percentage of water content in the syrup Xs are in the relationship represented by the following equations: Ws Xs/Wp Ws 7, or preferably, 1.5 Ws Xs/Wp+Ws 4 out at a sugar concentration of syrup between 40% and 95%. At a concentration less than 40%, the mother powder must be used in a very large quantity. When the concentration exceeds the upper limit, the viscosity of the syrup increases too high to disperse the resulting mixture uniformly. Therefore, the sugar concentration is preferably from 40 to 90% by weight of glucose, fructose or a mixture thereof.

Consequently, the ratio of the quantities of the syrup to the mother powder, the sugar concentration of the syrup and the moisture content of the mixture of the mother powder with the syrup are less than 130% by weight, less than 95% by weight and less than 7% by weight, perferably to 65% by weight, 40 to 90% by weight and 1.5 to 4% by weight respectively.

Although the finished products produced'by the present invention have a sufficient strength against crushing, binders such as carboxymethylcellulose or sodium alginate, and/or lubricants such as sugar ester with higher alkanoic acid may be used.

It is one of the advantages of the present that the sugar need not always be the same in the syrup and the mother powder used. Thus, the syrup obtained invention .mercially available isomerized glucose solution with pure anhydrous fructose crystals.

The method of the present invention may preferably be practiced by returning a part of the finished product corresponding to the amount of mother powder used in the previous cycle to the subsequent cycle as the mother powder therefor. This recycling of mother powder can be conducted either in batch type or continuous operation. Thus, the finished product may be withdrawn from each cycle of the operation in an amount corresponding to the sugar content of the syrup. During the cycle of operation, sugar is not deteriorated because the drying is carried out at a temperature below C.

It is surprising the mixtures of fructose and glucose can satisfactorily be solidified in the form of free-flowing particles in accordance with the present invention, because the mixtures have heretofore been considered to be too hygroscopic to dry up into such forms.

' The following examples are offered for illustrative purposes only, and are not intended to limit the scope of the present invention, which is defined in the claims below. 7

EXAMPLE 1 charged in the kneader. 0.8 kg of an 83.8% aqueous solution of sugar consisting of 98.7% of fructose and 1.3% of glucose was added to the powder. After 10 to 15 minutes kneading, the resulting mixture became wet, free-flowing aggloinerates of crystals. The mixture retained 2.79% of water and the purity of fructose therein was 99.7%. The mixture was granulated by extruding through a screen at room temperature, and the granules were dried in a vacuum chamber at lOmm Hg and 65C for 4 hours. Free-flowing granules having a moisture content of 0.10% and an apparent density of 0.53 g/ml were obtained.

EXAMPLE 2 parts by weight of dried granules obtained in I Example 1 was mixed with 38 parts by weight of anhydrous glucose. The mixture was pulverized to fine particles of 50 mesh (Tyler). 4.0 kg of the resulting powder (moisture content 0.25%) was kneaded as in Example 1 with 1.55 kg of the same syrup as used in Example 1. The resulting mixture having' a moisture content of 3.0% was pelletized to small pellets using a laboratory type rotary disc-pelletizer at room temperature. The 7 resulting freefflowingwet pellets were dried as in Example l. Free-flowing pellets having moisture content of 0.17 and an apparent density of 0.59 g/ml were obtained.

EXAMPLE 3 In this example, the mother powder and the syrup were continuously mixed using a double screw type continuous mixer. The same type of sugar powder as used in Example 2 (particle size less than 50am, moisture content 0.19%) and a 12.2% solution of isomerized glucose (fructose 70%, glucose 30%) were supplied at a ratio 4:0.76 parts by weight. The mixture passed through the mixer for about 15 minutes. The resulting mixture containing 2.14% of water was granulated and the granules were dried as in Example 1. Free-flowing granules having a moisture content of 0.05% and an apparent density of 0.49 g/ml were obtained.

EXAMPLE 4 Example 1 was repeated with the exception that 4 kg of dry sugar powder consisting of 98.5% of fructose and 1.5% of glucose (moisture content 0.15%) and 0.92g of an 88.7% solution of enzymatically isomerized glucose (fructose 46.5%, glucose 53.5%) were used. The kneaded mixture containing 4.1 1% of water was granulated and dried in vacuo. Free-flowing granules having a moisture content of 0.15% and an apparent density of 0.54 g/ml were obtained.

EXAMPLE 5 Example 1 was repeated with the exception that 4 kg of a mixed sugar powder of fructose and glucose (7:3, moisture content 0.21%) and 0.4 kg of the same syrup as used in the Example 4 were mixed. The resulting mixture containing 2.13% of water was pelletized by the same manner as Example 2 and then dried. Freeflowing pellets having a moisture content of 0.21% and an apparent density of 0.54 were obtained.

EXAMPLE 6 Example 1 was repeated with the exception that 4 kg of a mixture of fructose and glucose (7:3, moisture content 0.21) and 1.20 kg of an 87.6% solution of the same sugar were mixed. The resulting mixture containing 3.03% of water was granulated and dried. Free flowing granules having a moisture content of 0.08% and an apparent density of 0.54 g/ml were obtained.

Various other examples and modifications of the foregoing examples can be devised by the person skilled in the art after reading the foregoing disclosure and the appended claims without departing from the spirit and scope of the invention. All such further examples and modifications thereof are included within the scope of said claims.

What is claimed is:

1. A method for preparing anhydrous, free-flowing solid particles of a sugar selected from the group consisting of glucose, fructose and admixtures thereof, which comprises:

a. kneading an anhydrous powder of said sugar with a 4090% by weight solution of said sugar in an amount of 5-65% by weight of said powder within the area shown between points A, B, C and D of the attached Drawing without subjecting said solution to a crystallization step to form a kneaded mixture having a moisture content of less than 7% by weight;

b. shaping said kneaded mixture into particles; and

c. drying the shaped particles at a temperature lower than C. to form anhydrous particles.

2. A method according to claim 1, wherein said particles are in the form of granules.

3. A method according to claim 1, wherein said particles are in the form of pellets.

4. A method according to claim 1, wherein said sugar is fructose.

5. A method according to claim 1, wherein said sugar is invert sugar.

6. A method according to claim 1 wherein said sugar solution is a massecuite wherein 3050% of the total sugar is present in the form of crystals.

7. A method according to claim 1 wherein said sugar solution is green syrup having a sugar concentration of -90%.

8. A method according to claim 1, wherein said moisture content is from 1.5 to 4%.

9. A method according to claim 8, wherein said anhydrous sugar powder has a particle size from 0.005 to 0.3mm.

10. A method according to claim 1, wherein said anhydrous sugar powder has a particle size from 0.005 to 0.3mm.

11. A method according to claim 10, wherein said anhydrous sugar powder is made from the finished product of a previous cycle.

12. A method according to claim 1, wherein said sugar is isomerized glucose.

13. A method according to claim 12 wherein said sugar solution has a sugar concentration of 70-90%.

UNITED STATES PATENT AND TRADEMARK OFFICE CETIFICATE OF CORRECTIGN PATENT NO. 3 ,929,503

DATED December 30 1975 INVENTOR(S) 1 TOSHIO YAMAUCHI It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

1E THE HEADING Line 5, Assighee: "Daiichi Seiyaku Co., LTD., Kyoto, Japan" should be -Dai-Ichi Kogyo Seiyaku Co., Ltd., Kyoto, Japan-- Signed and Sealed this thirteenth D ay Of April 1 9 76 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmixsirmvr uj'lau'ms and T radcmarks