FI116532B - Prodn. of crystalline fructose - by cooling a seeded soln. at different rates with a slower intermediate rate - Google Patents

Abstract

(A) Crystalline fructose (I) is prepd. from a (I) soln. as follows: (a) the soln. is cooled through an initial temp. range (T1) at a rate R1; (b) the soln. is further cooled through an intermediate temp. range (T2) at a rate R2 that is slower than R1; then (c) the soln. is cooled through a final temp. range (T3) at a rate R3 that is faster than R2. (B) The (I) stream is produced by: (a) fractionating a (I)/dextrose (II) stream to afford a stream contg. above 90% (I) (dry solids basis); (b) treating the (I) stream with activated C; and (c) crystallising (I) as above. (C) crystalline (I) is prepd. as follows: (a) (I) is crystd. in a stream to afford a mixt. of crystalline (I) and a (I)-contg. mother liq.; (b) crystd. (I) is sepd.; (c) at least some of the mother liq. is mixed with a liq. comprising H20 to give a lower solids soln. of (I); (d) the diluted mother liq. is contacted with activated C; and (e) the dil. soln. is evaporated to afford a higher solids soln. of (I).

Description

116532

Process for the production of a liquid sweetener comprising fructose and dextrose - Förfarande för Produktion av fruktos och dextros innefattande sötnings-medel i vätskeform.

The present invention relates to edible sugars. A particular object of the invention is a process for the preparation of a sweetener consisting of fructose and dextrose.

Fructose is a monosaccharide which is highly valued as a nourishing sweetener. Most of the fructose sold in this country is derived from corn starch, with 10 fructose-rich corn syrups being the major form of the product [High Fructose Corn Syrup; (HFCS)]. These commercial syrups contain fructose in an amount of 42-90% by weight on a dry solid basis (pcs). (The term "kkpr" used herein, including the claims, refers to "dry solids by weight.") The remainder is mainly dextrose. HFCS typically used in soft drinks to replace sucrose typically comprises 55% fructose, 41% dextrose and 4% by weight. -% higher saccharides, each based on the weight of the dry solids, such a syrup usually having a solids content of about 77% by weight.

20 On an industrial scale, production of HFCS begins with enzymes of refined starch slurry. The main source of raw material in the United States is maize (starch obtained by the wet milling process. However, starches of similar purity from other sources are also useful.

25: ': In the first step of a typical process, the starch is liquefied by boiling at high temperature. The starch is then liquefied and dextrinized using a heat-stable alpha-amylase in a continuous two-step reaction. This:; the reaction product is a soluble dextrin hydrolyzate having a dextrose equivalent. 30 (DE) is 6-15 and can be used in the subsequent sugaring step.

After the liquefaction-dextrinization step, the pH of this hydrolyzate having a DE of 10-15

and adjusting the temperature to suit the saccharification step. During the saccharification step, the hydrolyzate is further hydrolyzed to dextrose by the enzymatic action of glucoamylase 2 116532. Although sugaring can be carried out as a batch reaction, continuous sugaring is still used in most modern plants. In a continuous saccharification reaction, glucoamylase is added to the hydrolyzate having a DE of 10 to 15 after adjusting the pH and temperature. The carbohydrate composition of a typical dextrose-rich sugar broth is: 94-96 wt% dextrose, 2-3 wt% maltose, 0.3-0.5 wt% maltotriose and 1-2 wt% higher saccharides (all percentages pc). The dry weight content of the product is typically 25-37%. This dextrose-rich hydrolyzate is then purified to provide a dextrose feed for the isomerization reaction.

10

Very high quality dextrose feeds must be prepared for isomerization since the final HFCS must contain only very little color and ash. Highly pure feed is also necessary for efficient use of the column containing the immobilized isomerase enzyme.

15

Columns containing the immobilized isomerase enzyme are used continuously over a period of several months. During this period, large volumes of dextrose feed pass through the column. For example, very small amounts of impurities present in the feed such as ash, metal ions and / or proteins

20 volumes may accumulate on the column, resulting in reduced enzyme production. dence. For these reasons, the dextrose feed is purified to a color of 0.1 (CRA

; v, t x 100) and has a conductivity of 5-10 micro ohms.

»•: Carbon-treated, filtered and deionized, high-dextrose broth * · '. Evaporate to a suitable solid concentration for isomerization. In addition, '; '. chemically treated by the addition of magnesium ions which not only activate immobilized isomerase but also inhibit residual isomerase:; potent inhibitory effect of calcium ions in competition with them.

> 30 The isomerization reaction in which some dextrose is converted to fructose is carried out as usual Ί! with a feed stream comprising 94-96 wt% dextrose and 4-6 wt% higher saccharides with a dry matter content of 40-50 wt%. The pH of this stream is 7.5-8.2 at 25 ° C and is exposed to the isomerase enzyme for 0.5-4 hours at 55-65 ° C.

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The conversion of glucose to fructose is a reversible reaction with an equilibrium constant of about 1.0 at 60 ° C. Thus, the equilibrium fructose content would be expected to be about 47-48% at the start of the feed containing 94-96% dextrose. However, the reaction rate of the isomerization reaction in the vicinity of the equilibrium is so low that it is reasonable to terminate the reaction 5 when fructose has been formed at about 42% in order to obtain useful delay times in the reactor.

The conversion rate of dextrose (glucose) to fructose in a given is column (column containing immobilized isomerase) is proportional to the enzymatic activity of the immobilized isomerase. This activity declines almost exponentially over time. When the column is new and the activity is high, the feed flow through the column is relatively high because a shorter lag time is required to reach a fructose level of 42%. As the column life increases, the flow through the column must be gradually reduced to reach longer delay times, which compensates for the reduced activity and maintains the conversion level unchanged.

In practice, multiple parallel columns are used to minimize production fluctuations in terms of capacity and conversion rate. In this arrangement, each of the major columns may be used substantially independently of one another. Fluctuations in the total flow of large columns must be kept within relatively narrow limits due to the requirements of evaporation and other finishing operations. In practice. While it is not possible to precisely control the flow at all times to obtain a current containing 42% fructose, such an average adjustment is nevertheless easy.

In such a process, one of the most critical action variables is the isocolon:. '; internal pH. This operating pH is usually the one leading to the highest activity; * * *; pH (typically about pH 8) and the pH leading to the highest stability. 30 (typically pH 7.07.5). The fact is complicated by the fact that the dextrose feed is not pH stable at temperatures around 60 ° C. Then! * some decomposition occurs, resulting in acidic byproducts which cause a drop in pH along the isocolumn during operation.

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In a typical manufacturing process, after isomerization, a second purification or polishing of a 42% HFCS product is used. During chemical treatment and isomerization, little additional color is transferred to the product when the feed is maintained at a higher pH and temperature for a period of time. The product also contains some 5 additional ash from chemicals added for isomerization. This dye and ash are removed by other carbon and ion exchange systems. The purified 42% HFCS is then evaporated to a solids content of typically 71% for transport.

The use of activated carbon for the purification of sugar syrups is generally known. U.S. Pat. No. 1,979,781 (van Sherpenberg) discloses a process for mixing crude sugar syrup (i.e., not mixed with glucose syrup and invert sugar syrup) having a Brix of 60 ° (60% dry solids) and the mixture is heated at 134 ° C for a short period. U.S. Pat. No. 2,763,580 (Zabor) describes extensively the treatment of sugar liquors (e.g., cane, beet or corn sugar) with a solids content of 10-60 wt.%, In particular 20-56% by weight with activated charcoal 125-200 ° F: n (about 52-93 ° C). It is described in this patent that the partial treatment may be carried out at a single concentration or under one type of condition, after which the treatment may be completed at a higher concentration (achieved by evaporation) or under other conditions.

116532 describes the introduction of a carbon-treated mixture of fructose and dextrose with a dry solids content of 10-70%, preferably 40%, and concentration of fructose-containing fractions. This patent specification 4,395,292 describes that fractions containing more than 90% fructose can be obtained and provides 5 examples (Example 7) in which the 40% dry matter feed was fractionated to produce a fraction containing fructose at 100 µl. -% (pc) with a dry solids content of 9%.

The HFCS obtained from the isomerization reaction typically contains 42 fructose, 52% unmodified dextrose and about 6% oligosaccharides. For the above reasons, this product represents the highest fructose content that can be practically achieved by isomerization. In order to reach more fructose-containing products, fructose must be selectively concentrated. Many conventional separation techniques are not suitable for this purpose because they are incapable of distinguishing clearly between two isomers of substantially the same size. However, fructose preferably forms a complex with various cations such as calcium. This distinction has been utilized in the development of commercial separation processes.

At present, there are basically two different commercial processes for large-scale purification of 20 fructose. In both processes: '; resins in the preferred cationic form are used in packed bed systems. In one process, an inorganic resin is used which leads to selective molecular absorption of fructose (see RJ. Jensen, "The Sarex Process for the High Fructose Corn Syrup", Abstracts of the Institute) Engineers, 85th National Meeting, Philadelphia, Pa., 1978).

Said second commercial separation method is based on chromatographic fractionation using organic resins (see, e.g., K. Venkatasubramania, "Integration of * * t 0:": Enzyme Engineering, Large Scale Production and Purification of Biomolecules:], 30 6:37 -43, 1982). When an aqueous solution of dextrose and fructose (e.g. 42% HFCS) is

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'· * · * Is fractionated on a fractionating column, so the resin retains more fructose than' 'dextrose. The eluent used is deionized and deoxygenated water.

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The separation is typically carried out on a column packed with a bed of slightly crosslinked, finely divided polystyrene sulfonate cation exchange resin in which calcium is used as the preferred salt form. This enriched product containing about 90% fructose is called Very Enriched Fructose Corn Syrup (VEFCS). This VEFCS fraction can be blended with 42% HFCS feed to obtain products containing 42-90% fructose. The most typical of these products is 55% enriched fructose corn syrup, sometimes referred to as EFCS (Enriched Fructose Corn Syrup) or 55 EFCS. U.S. Pat. No. 4,395,292 (Katz et al.) Discloses an example (Example 1) of how a mixture containing fructose and dextrose can be fractionated into various fractions, and how fructose-enriched fractions can be combined at 55.8% (w / w). fructose-containing syrup. This same example also describes single fractions containing fructose in high concentrations (kpl) [e.g. 75.1% (w / w)], and combinations of fractions containing fruc-15 in lower concentrations have been described [e.g. the fraction containing 64.5 wt% fructose (pcs) is combined with the fraction containing 58.2 wt% fructose (pcs)).

An important consideration is the treatment of other raffinate streams in this fractionation process. Generally, the dextrose-rich raffinate stream is recycled to the dextrose feed of the 1-column system to further convert it to 42%; * ·: ', Sex for HFCS. A dextrose and fructose-containing raffinate stream containing more fructose than: feed may be recycled through a fractionator through a solid; to keep the content high and to reduce water consumption. A stream of raffinate rich in oligosaccharides 25 can be recycled to the sugaring system.

»

Because water is used as the eluent, it has a significant effect on the total evaporative loading of the system: ':. Extremely low solids concentrations increase the risk of microbial contamination in the system. Thus, the most important design parameter, which dictates the overall economy of the process, is to maximize solids yield while maintaining purity, while minimizing the dilution effect of eluent rinse. The efficiency of feed and water use must be maximized for optimum yield. Yield is important to reduce the cost of re-isomerization.

7 116532 Among the measures available to achieve these goals are recycling techniques, better alignment and proper redistribution of the resin phase in the packed column, and the addition of multiple entry and exit points to the column. These approaches can be used to improve purity and yield.

In a batch fractionation system, a slight apparent increase in the purity of the feed to the fractionating column, i.e. a higher fructose content, results in a much higher production increase due to the higher yields with 10 products of a certain purity. In practice, this is reflected in an increase in the ratio between the volume of sugar fed to the volume of resin per cycle, a decrease in the ratio of volume of water required to volume of resin per cycle, and a careful distribution of fluids into the columns.

Many methods for crystallizing fructose are known in the art. For example, crystalline fructose can be prepared by adding absolute alcohol to a syrup obtained by acid hydrolysis of inulin (Bates et al., Natl. Bur. Std. Circ. C440 399, 1942). The preparation of fructose from dextrose is described in US 2 354 664 and US 2 729 587 describes the preparation of fructose from sucrose 20 by enzymatic conversion.

Fructose in the alcohol forms orthorhombic, bisphenoidal prisms which halt at a temperature of about 103-105 ° C. Crystalline Hemihydrate and Dihydrate Forms -; Are also known, but it is preferable to avoid the formation of these species, since they are substantially more hygroscopic than the anhydrous form, and

1 I

: '; The points are close to room temperature. Because of these properties, it is very difficult to handle these crystalline forms of fructose.

The crystallized fructose (Solvent Crystalline Fructose; SCF) as a solvent is prepared by a process with an organic solvent such as denatured ethyl alcohol.

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Is mixed with a stream rich in fructose (95% w / w). The product is centrifuged to separate it from the mother liquor, the solvent is removed from the product and it is dried | a.

tilli I I

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US 4,199,374 describes a process for preparing crystallized fructose as a solvent. The fructose is crystallized from ethanol solution of VEFCS syrup. Fine fructose or glucose crystals are added to the solution as crystal embryos. The crystals are recovered by filtration, centrifugation or other suitable means. These crystals are then washed with alcohol and dried in vacuo. The moisture content of the alcohol and syrup must be carefully adjusted in this process to obtain fine free-flowing fructose crystals.

It is also possible to prepare a simply dried fructose sweetener 10 (DFS). In the DFS process, the fructose-rich stream obtained by fractionation is dried in a tumble dryer and then sorted by particle size in a separator comprising sieves and grinders. US 4,517,021 describes the preparation of granular semi-crystalline solid fructose comprising at least about 2% by weight of water. This patent 15 discloses that about 60% by weight of the product contains crystalline fructose and less than 35% by weight amorphous fructose. It uses a tumble drier with an inlet air temperature of 50-80 ° C. Some of this solid fructose product can be recycled to initiate crystallization.

One disadvantage of the DFS process is that the product cannot be called pure fructose. ' ·. because it is a total sugar product and does not comply with the Food Chemicals Codex * ·· *; requirements for "fructose". Also, because it is not completely crystalline; that is,. ,,: more hygroscopic and thus more difficult to handle under humid conditions ....: than crystalline fructose.

• ·: ·. ·. 25> # • a. ·: \ A water-based process may also be used to produce crystalline fructose. the water - based crystalline fructose process is typically started:. ·. with a fructose-rich feed stream which is cooled by fructose crystals, · · *. solution. Such a method has been described in numerous literature references.

In U.S. Patent No. 3,513,023, anhydrous fructose is obtained from an aqueous solution of fructose: (at least 95% of dry solids). The pH of the solution should be in the range '· 3.5-8.0. The fructose solution is concentrated in vacuo until a water content of: 2-5% is obtained. The solution is cooled to a temperature in the range 60-80 ° C, crystalline fructose is added as crystalline embryos and stirred vigorously while maintaining the temperature at 60-85 ° C. It is mentioned in this patent that the result is a crystalline mass which, after slow cooling, can be crushed or ground and subsequently required to produce a non-sticking, free-flowing fine crystalline powder. It is stated in this publication that this process avoids the formation of a product in the glass phase which is usually obtained by concentrating these types of fructose solutions in vacuo and allowing them to cool in the usual manner.

In US 3,883,365, fructose is crystallized from an aqueous solution of fructose and glucose containing 90% by weight dry solids and 90-99% by weight fructose (kpl). This solution is saturated (at 58-65 ° C). The fructose is crystallized from this solution by the addition of homogeneous fructose crystals. The formation of new crystals is minimized by keeping the distance between the crystal embryos small enough and maintaining the degree of supersaturation in the range of 1.1 to 1.2. The volume of the solution is increased either continuously or incrementally as the crystallization proceeds. The optimum pH of the fructose solution is shown to be 5.0. The crystals thus obtained have an average crystal size of 200-600 microns. Centrifugation is used to separate the crystals from the solution.

20,. U.S. Patent No. 3,928,062 discloses that anhydrous fructose crystals may be obtained by adding crystal embryos to a solution having a total sugar content of 83-95.5% (w / w), comprising 88-99% fructose. The crystallization can be accomplished simply by cooling the solution under atmospheric pressure or by evaporation-> ·; v. 25 miles of water under reduced pressure. Formation of hemihydrate and dehydrate * »; ·. is avoided by carrying out crystallization over a specific range of fructose concentration and temperature. This area is • within the supersaturation area below the point at which the hemihydrate. begins to separate by crystallization. It is mentioned in the publication that the mother liquor can be used for

• »» I

. ' ·. repeat to crystallize additional harvests in the same manner as for the first crop, ·, 30 without further treatment. Adding crystal embryos can be done using

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';;.' not a bulk form prepared previously by suspending the crystals in a fructose solution.

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In U.S. Pat. No. 4,199,373, crystalline fructose is produced by adding to fructose syrup (88-96% w / w) 2 to 15 fructose crystals acting as printing crystal embryos and allowing the syrup containing crystal embryos to stand at a temperature of about 50-90 ° F (about 10-32 ° C). , in conditions where the relative humidity is less than 70%. Crystallization is shown to take 2-72 hours. The crystalline product produced by this process is in large pellets.

US 4,164,429 describes a method and apparatus for producing crystallization embryos. Numerous centrifuge separations are used to select crystal embryos from a solution containing crystal embryos that are within a predetermined size range.

Cooling a saturated or supersaturated solution to crystallize the substance is, of course, well known in the art.

15

It is also known that the natural cooling of a saturated or supersaturated solution often results in a strong formation of crystal embryos, which contributes to the possible undesirable wide particle size distribution of the crystalline product. For example, in Encyclopedia of Chemical Technology, vol. 7, pp. 243-285 20 (Kirk-Othmer, ed., John Wiley 8i Sons, N. Y., 3rd Edition, 1979), is hereby incorporated by reference. that natural cooling leads to a peak of supersaturation during the early cooling period, which induces a strong formation of crystal embryos. In this article, ...: it is mentioned that a controlled cooling curve by following the constant supersaturation state ....: can be maintained, whereby the formation of crystal embryos can be adjusted to an acceptable ignition range of 25. Figure 5 illustrates the natural and controlled features disclosed in this work. ·: ·. cooling curves.

:. ·. Various aspects of the present invention will now be considered.

One particular aspect of the invention relates to a process for the preparation of a liquid phase fruc-. For the production of a sweetener containing 'tosose and dextrose, wherein the process comprises crystallizing' * - fructose from an aqueous solution of fructose to form a mixture comprising crystalline fructose and mother liquor '; u 116532 - the crystalline fructose is separated from this mother liquor; and - mixing dextrose in the mother liquor to produce a liquid phase sweetener comprising dextrose and fructose.

5

In the preparation of crystalline sucrose from an aqueous solution, it is a common practice to recover successive batches of crystals to concentrate impurities in a mother liquor called molasses. This molasses is usually so impure that it is of value only as a supplement to animal feed or as a fermentation medium. US 3 928 10 062 discloses that the mother liquor from the crystallization of fructose can be used several times to crystallize additional crops of fructose crystals. The relatively poor yield of fructose crystals from a single batch of crystals using conventional crystallization techniques, as well as the difficulties associated with isomerisation and fractionation of corn syrup to obtain a feed with a high fructose crystallization device, . However, the integration of crystalline fructose production into the preparation of a liquid phase sweetener by adding dextrose to the mother liquor makes it possible to obtain two first-class sweeteners. This, in turn, maximizes the yield of the 20 fructose useful as a sweetener, thereby defending the difficulty of isomerization. However, this method leads to a reduction in the benefit obtained by fractionation in the sense that the whole fractionation is intended to remove dextrose: to prepare a feed for the crystallizer, thus adding dextrose to the mother liquor; partially impairs the enrichment obtained by fractionation.

25

In a particular embodiment of this aspect of the invention, the present invention relates to a process for producing a stream comprising dextrose and fructose from a dextrose-containing feed stream comprising: - part of the dextrose in the feed stream being isomerized to produce dextrose and fructose; dividing the first dextrose / fructose stream into a first feed stream and a second feed stream; 116532 - fractionating the first feed stream to produce a stream rich in fructose; crystallizing the fructose present in the fructose-rich stream to produce a mixture of crystalline 5 fructose and mother liquor; crystalline fructose is separated from the mother liquor; and - mixing at least a portion of the mother liquor with said second feed stream to produce a second dextrose / fructose stream wherein the ratio of fructose to dextrose in the second dextrose / fructose stream is greater than in the first dextrose / fructose stream. (As used herein, the term "dextrose / fructose stream", as used in the claims, refers to a stream consisting of dextrose and fructose.)

The mother liquor remaining after crystallization is a saturated solution of fructose. It is described in the art, for example in US 3,928,052, that the mother liquor can be used repeatedly to crystallize excess crystal yields. To produce these additional crystalline crops, the saturated mother liquor must be heated and concentrated in an appropriate manner to obtain a supersaturated fructose solution which allows crystallization, ·. from the mother liquor. It has been found that rather than allowing additional crops to crystallize, it would be more advantageous to try to prevent further crystallization so that the mother liquor can be used to produce a liquid phase sweetener. As mentioned above, the mother liquor is a saturated fructose solution. In order for the fructose crystals to precipitate from it, 25 during transport, transport and / or storage, such as fructose. the mother liquor must be prevented. This aspect of the invention is similar to the first aspect of the invention discussed above in that it avoids further crystallization. However, this feature does not necessarily require fractionation. 1. sacrifice of profits since inhibition of further crystallization does not necessarily require the addition of dextrose, but simple dilution of the mother liquor with water prevents crystallization so that the purity of the fructose in the mother liquor does not deteriorate from the dry matter.

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One aspect of the present invention relates to a process for producing a plurality of fructose-containing sweeteners, at least one of which comprises dextrose and fructose, wherein: the fraction containing more than about 90 wt% fructose (pcs); and a fraction of 10 to less fructose is mixed with a dextrose composition having a dextrose content (kpl) higher than said fraction containing less fructose to produce a liquid phase sweetener.

As used herein, "fructose-containing sweetener" refers to any fructose-containing sweetener, whether fructose in solution, dispersion, amorphous or crystalline.

The fractionation of isomerized dextrose syrup, i.e. a syrup containing both fructose and dextrose, to produce a fructose-containing sweetener is usually accomplished by recovering the dextrose raffinate and ffuctose fraction from the fractionation, however. taking two fractions, one containing fructose at a higher concentration (kpl) (ie: a fructose-containing fraction) and the other containing fructose at a lower concentration (kpl), whereby a fructose fraction can be obtained with a higher concentration than in only one fraction, but without increasing the overall resolution and associated problems of the isomerized feed [e.g., reduced fractionation capacity, higher evaporation load due to higher amount of elution water, * » \ And / or deleterious pressure drop due to higher flow rates eluointiveden, 30 are higher flow rates are necessary for the resolution (resolution) "!!. 'To improve) without difficulty.

The usefulness of the less fructose-containing fraction is more limited than that of the * more fructose-containing fraction (for example, the use of less fructose-containing fractions to produce crystalline fructose would be difficult), but the fructose present in corn syrup (e.g., 42% fructose-containing corn syrup-silicon) to produce more fructose-containing corn syrup (e.g., 55% fructose-containing corn syrup).

According to a particularly preferred embodiment of this aspect, the more fructose-containing fraction is used to prepare the feed of the crystallizer for crystallization of fructose 10. Accordingly, this aspect of the invention relates to a process for the production of a liquid phase sweetener comprising dextrose and fructose, comprising: fractionating a stream comprising dextrose and fructose into a dextrose-enriched raffinate, a fraction containing less fructose and a fraction containing more fructose; crystallizing the fructose from the aqueous solution obtained from the fructose-containing fraction; and 20 •. mixing the fraction containing less fructose with a dextrose composition having a dextrose content (kpl) higher than that containing less fructose; : in the fraction, a liquid phase sweetener comprising dextrose and fructose. : for production.

This embodiment is particularly advantageous because the concentration of fructose (kpl), which is generally required to crystallize fructose from an aqueous solution, is so high that dextrose and fructose from the isomerization process are present. »·; ''; fractionating the feeder stream may be impractical. In other words, such. The degree of resolution required to produce only one fraction, where the purity of "! / Fructose is high enough to use the fraction as the feed of the crystallizer, often reduces the fractionation capacity and / or increases other fractionation-related difficulties," that such a resolution is not practical.

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A possible disadvantage associated with recovering and using both fructose and less fructose fractions separately for the preparation of the crystalline sweetener and the liquid phase sweetener, respectively, is that the high fructose content of fruc-5 , is less than the amount present in only one fraction of fructose at the same common resolution. Thus, the total amount (fr) of fructose available as a liquid phase sweetener has decreased. This disadvantage is alleviated by the fact that the mother liquor is obtained more from the crystallization of the fructose portion present in the fructose-containing fraction. In other words, in a particularly preferred embodiment, the fructose-containing mother liquor, the less-fructose-containing fraction and the isomerized corn syrup are mixed to make a liquid phase sweetener (e.g., 55% fructose corn syrup).

Figure 4 shows typical cooling curves used in crystallization processes. Curve A is a natural cooling curve and curve B is a controlled curve to achieve a constant supersaturation state.

Using a cooling rate lower than the first cooling rate 20 and the last cooling rate during the middle cooling period makes. as well as minimizing the spontaneous formation of crystal embryos in solution. and minimizing the degradation of fructose induced by heat in solution, especially during the first cooling period. Reduction of crystal embryo formation leads to a crystalline product with a more nearly uniform particle size distribution, and reduction of thermal damage increases the yield of fructose crystals and mother liquor and reduces the concentration of impurity degradation products in the mother liquor, thereby improving its usefulness as a fructose sweetener.

. Although treatment of sugar syrups with activated carbon to purify these syrups is well known, it has been found that fructose syrups with high fructose content (kpl) should have a relatively low solids content in the presence of active carbon by-products (*). e.g., difructose), which byproducts may reduce the availability of fructose in the syrup, prevent crystallization of fructose 16 116532 from the syrup and / or affect the organoleptic properties of the syrup or sweetener made from it. (95+% w / w) syrup during the time the syrup is in contact with the activated carbon 5.

In particularly preferred embodiments, the aqueous solution (e.g., tap water, fresh water, sugar syrups such as 42% fructose corn syrups and the like) is mixed with the mother liquor obtained from the crystallization of fructose to reduce the solids content prior to treatment with activated charcoal. The resulting higher solids solution can be used in a variety of ways, e.g., as a feed to the crystallizer, as a sweetener, as a high-fructose corn syrup, or as a production stream, which in each case benefits from the above advantages. reducing the solids content of the mother liquor prior to the treatment with activated carbon, and then performing evaporation thereafter.

Figure 1 illustrates the various steps of the conventional method of producing 42% HFCS and 55% HFCS 20 (EFCS) from starch.

<·: '. Figure 2 shows an integrated starch-based process for the production of both crystalline ... ... fructose and EFCS.

* t; '. '. Figure 3 shows in more detail the method of Figure 2. Figure 3: The steps of drying, conditioning, and 99.5 +% anhydrous crystalline fructose shown are outside the scope of the invention.

»· '; Fig. 4 is a graph showing temperature versus time for batch operation; . 30 and in the case of the natural cooling curve (curve A),. * that in the case of a constant cooling curve (curve B) corresponding to • permanent supersaturation.

! i t 17 116532

An important feature of the present invention is the synergy achieved when anhydrous crystalline fructose (ACF) is produced in combination with EFCS. The yield of fructose crystals from the fructose fill mass is typically in the order of 40-55%, for example 45%. Longer crystallization times can improve the yield, but only at the expense of the 5 substances passed through the process. Thus, a significant advantage is achieved by integrating the crystallization of fructose into a process which not only provides the fructose feed for the ACF crystallization process, but can also easily use non-crystallized fructose from the ACF process.

In some prior art processes for producing crystalline fructose, the non-crystalline moiety is recycled through the crystallization process. The difficulty of this alternative is that unwanted by-products such as difructose, 5- (hydroxymethyl) -2-furfural (HMF) and higher saccharides tend to form in the recycling stream because crystallization is essentially selective for fructose. As a result, the recycling stream is eventually so contaminated with by-products that it is. should be removed from the system, leading to the loss of essential fructose levels.

In the present invention, this problem of byproduct formation is solved by incorporating the residual solution phase (mother liquor) remaining after crystallization of fructose into the process of producing a high amount of fructose-containing, liquid phase sweetener or sweeteners. In this way, the inactive by-products are not concentrated to the part of the • integrated process that produces ACF, but are continuously removed from the system. This integration eliminates the need for: j fructose-containing effluents, thereby maintaining fructose economically most valuable products.

•

Referring now to Figure 1, it can be seen that 55% HFCS (EFCS) production requires a separation step (fractionation step) in the process stream.

; "*; Generally, fractionation is required to make syrups containing j. 30 fructose more than about 48%. A syrup preferred for crystallization of fructose contains more than 95% (w / w) fructose. Although fructose may be crystallized from solutions containing less fructose, it will still result in lower yields and the process would not be as economically desirable.

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Fractionation techniques are known in the art in which a stream containing 95+% fructose is obtained from a feed containing about 42% (w / w) fructose (typical yield of dextrose isomerization). Thus, the ACCS feed stream can be obtained from the EFCS process with little or no change. Most preferably, the fractionation system is a chromatography system of the simulated moving bed type, which is well known in the art.

Referring now to Figure 2, the details of the integrated process will be described. As shown in the "preliminary conversion / purification" block, starch 10 is first converted to dextrose using the conventional enzyme-based method described above.

Isomerisation The isomerization step uses an enzyme to convert dextrose to fructose. The enzyme is attached to the support and remains in place on the column (isobol) until it is replaced after its activity has ceased. An advantage of the present invention is that it enables the efficient use of large amounts of isomerase in isocolumns. Producer investing in additional isomerization-20 capacity due to seasonal fluctuations in demand for EFCS syrup (55% fructose). to meet peak demand, he must pay for this greater isomerization capacity throughout the year, even when his EFCS production is relatively low. Instead, by implementing the integrated method described below, selec-; the producer can efficiently exploit the greater isomerization capacity '· *; 25 by channeling more fructose-rich fructose: * \ ': flows to EFCS production when demand for this product is high and using the greater part of this flow to ACF production when demand for EFCS is lower.

j In this way, investments in higher isomerization capacity can be efficiently exploited throughout the year.

30h · ·

• * I

Fractionation 'Fractionation is carried out in a batch system, i.e. a series of resin-containing vessels, which act as a feed stream to separate fructose 19 116532 from dextrose present in the syrup used. The feed stream and the eluting water stream are fed to a batch system, and one or more fructose-rich product streams, dextrose-rich raffinate streams and / or one or more oligosaccharide-rich raffinate streams are removed. As shown in Figure 3, the dextrose-rich stream is recycled to isomerization to convert dextrose to fructose, while the high-fructose stream (s) is fed to the ACF portion of the process or mixed to produce EFCS.

Fractionation capacity is measured by the feed flow rate, the percent fructose content of the product stream, and the recovery of fructose present in the stream. For a given fructose content (kpl), the higher the fractionation capacity, the lower the fructose conversion needed for isomerization. Therefore, in order to reduce the costs associated with isomerase, fractionation is preferably run continuously at maximum capacity.

15

In order to achieve practical yields of the crystallizer in the ACF process, the fractionation product must be more than about 90 wt% fructose, preferably more than about 95 wt% fructose. Because this is more than the 90 wt% (kpl) fructose that is normally isolated in the EFCS process, special fractionation conditions must be used in conventional fractionation systems, which may result in reduced fractionation capacity. These include: 1) slowing the syrup feed rate without changing the ratio of eluting water to improve resolution, and / or 2) increasing the ratio of eluting water to improve resolution. The disadvantage of these operating conditions is that either the throughput of the product is reduced and / or the amount of water subsequently removed is increased, which at least involves higher energy consumption. However, there is a cheap alternative.

'' ': It is clear to those skilled in the art that when dextrose and fructose comprise water; The solution is passed through a suitable chromatography column, whereby at least partial separation of the two species is achieved. In order to effect fractionation, the removal of the column must be suitably subdivided to isolate the desired fractions.

These separated parts are commonly referred to as "fractions". A "narrow fraction" contains less volumetric elements than a "wide fraction". Thus, when talking about purity 20 116532, the separation can be optimized for a particular species by taking a suitably narrow fraction. The trade-off for separating a narrow fraction from the deletion is that the narrow fraction adversely affects the total amount recovered for the selected species.

It has been found that 95+% by weight (pcs.) Of fructose stream, preferably used in the part of the process described as producing crystalline fructose, can be obtained by taking a suitable narrow fraction from the product stream of a fractionation system of the conventional process used to produce EFCS. . One such particularly advantageous fractionation system is described in U.S. Patent Application Serial No. 861,026, filed by the same applicant as John F. Rasche 5.8.86 and entitled "Simulated Moving Bed Chromatographic Separation Apparatus". The contents of this publication are specifically appended hereto, as if part of this disclosure.

A preferred way of using the aforementioned chromatographic separation apparatus, when operating as a fractionation residue system in the present invention, is to increase the eluent to feed ratio from about 1.7 to about 2.0. The syrup feed preferably comprises about 60% by weight of dry matter and is maintained at a temperature of about 140 ° F (about 60 ° C).

The raffinate stream from the fractionation system can be subdivided in the same manner as the effluent stream. In this way, the relatively high oligosaccharide stream 20 can be isolated to be recycled to the sugaring system, sent to a separate, specific sugaring system, or removed from the system.

,,: In the event that the oligosaccharides are not removed or recycled to the sugaring system, the only way out of the oligosaccharides is the effluent stream, because of the nature of the. 25 oligomeric oligosaccharides are not affected by isomerization of 25 columns. So in the raffinate stream: '. the oligosaccharides present, which are recycled back to the isomerization system, simply pass through the system unchanged and return with the feed to the fractionation system.

Oligosaccharides are undesirable in the effluent stream because at least part of this stream is used as a feed in the part of the process where the fructose is crystallized and the fructose is crystallized preferably from a solution containing as little *: * other species. Likewise, oligosaccharides are undesirable in the liquid phase sweetener produced by the process of the invention, since only a limited amount of 21 116532 such oligosaccharides can be removed from the system with the liquid phase product.

A further advantage is achieved by recycling the high oligosaccharide-rich stream from the fractionation system to the sugaring system. The dry solids content of such a stream is typically relatively low, with a dry solids content generally being about 10 wt%, i.e. the stream contains about 90 wt% water. The starch slurry from the liquefaction / dextrinization portion of the process is typically diluted prior to saccharification. At least a portion of the water required to dilute the starch slurry can be replaced by water in the ol-10 gosaccharide stream, thereby saving water and reducing the total evaporation capacity required by the system.

Blend 15 In a conventional EFCS process, the fructose-rich fraction obtained from fractionation is mixed with the product of isomerization [typically 42-48 wt% fructose] to achieve the desired fructose content in the final product [55 wt% w / w EFCS]. In the process of the present invention, the mother liquor obtained from the centrifugation step of the crystallization process contains about 88-92 wt% fructose, preferably 90-92 wt% fructose, with a dry content of about 83 wt%. , is also available for mixing. In this way, the process is further made more flexible because various streams can be mixed before being fed to EFCS polishing steps, whereby the mixture is typically ion-exchanged, treated with carbon and then evaporated to give a solids content of 77% by weight, as part of normal EFCS production. Some: ·, possible mixing points are shown in dashed lines in Figure 3. Of course, the final choice of mixing streams depends on the material balance of the entire system.

Since the ACF process does not add any ke-chemicals to the fructose-rich stream, except for very small amounts of hydrochloric acid or calcined soda for pH adjustment, the ACF process does not generate significant amounts of new: trace components. Colored compounds, HMFr and difructose may be formed during the crystallization and evaporation of the feed of the device. However, these compounds can also be removed by final carbon treatment and ion exchange treatment in the EFCS process.

22 116532

Because most steps in the entire fructose process can be accomplished with high dry pressure streams, microbial growth is avoided and should not be a major concern. Therefore, the acetaldehyde level should not increase significantly and may be reduced, if necessary, during the final ion exchange step and the final evaporation step.

Input of Fructose to Crystallization pH Adjustment It has been found that the pH of the aqueous fructose solution from which the fructose crystals are to be obtained is preferably in the range of about 3.7 to 4.3, although contrary estimates have also been made in the art (see, e.g., U.S. Pat. 883,365). Appropriate adjustment of the pH of the fructose feed to the crystallizer is necessary to minimize the formation of difructose anhydrides. The presence of difructose anhydrides in the crystallizer has been found to result in lower yields in the crystallizer and to affect the size distribution of the fructose crystals that are formed adversely. It is assumed that the anhydride formation rate is at its lowest in the pH range of 3.7-4.3. The rate of formation of anhydrides is higher both below and above this range. It is further assumed that colored compounds are formed more readily at higher pH values.

Example In this example, the effect of pH on the solubility of fructose and the formation of impurities in a syrup containing about 95% by weight was investigated as described below. fructose on a dry basis. The syrups studied were similar to those used as feed for the fructose crystallization part of the process below.

Crystalline fructose was added to a VEFCS sample (90 wt% fructose, kpl) to obtain a syrup comprising about 95 wt% to 30 wt% (kw) fructose. The syrup was then treated with 'granular activated carbon in the manner described in the accompanying paragraph on carbon treatment of the application (hereinafter). Thus, this syrup was treated in the same way: · In the same way as the feed of the crystallizer.

23 1 1 6532

A sample was taken from the syrup described above, adjusted to a pH of 3, 94 and evaporated at 73 ° C to a high solids content. Two liters of this high solids syrup was placed in a sealed, mixed bottle, immersed in a bath maintained at a constant temperature of about 55 ° C. This sample-5 product (pH-4 sample) was continuously stirred in this constant temperature bath while another sample was pretreated (for about 5 hours).

A second sample of this 95 wt% fructose syrup was taken, adjusted to a pH of 5.48, and evaporated at 77 ° C to a high solids content. Evaporation was slower than the pH 4 sample. Two liters of this sample (pH 5.5 sample) was placed in a sealed mixed flask which was immersed in a bath containing pH 4 sample maintained at a constant temperature.

After the bath temperature was set at 55.5 ° C, 50 g of fructose crystal embryos were added to each sample. Stirring was continued for 60 hours at constant temperature. This is approximately the syrup delay time in the crystallizer of the ACF process described below.

The resulting filling masses were sampled, centrifuged and analyzed for mother liquor and 20 feed syrups. The results of the analyzes are summarized in the following table.

Table I

Input_ Balanced 25 pH 4 pH 5.5 pH 4 pH 5.5 t ·

Fructose (wt%, pc) 95.81 95.86 95/33 95.24 •. ·. Fructose hydrolysis 96.08 96.10 95/33 95.72 _ ···. after (wt%, pc) 30 Mono anhydrides (wt%, pc) 0.27 0.24 e. i. * 0.48

Solid, (wt%) 89.79 89.13 88/90 88.86 HMF (ppm, pc) 5.71 4.03 25.9 6.58: Acetaldehyde 104 48 58 66 ':: (ppb, total) ) 24 116532

Furfural (ppm, pc) e. I. * E. I. * 0.29 0.44 Color (RBUs) 14.0 39.6 50.7 163.1

Solubility - - 7.64 7.60 (g fructose / g water) 5 Supersaturation - - 1.0 1.0 * e.m .: Unable to detect.

Mono anhydrides are calculated from the difference between the fructose results obtained before and after hydrolysis of the sample. The solubility of fructose is calculated from the fructose content (before hydrolysis) and the solids content of the sample. Some fructose crystallized out of the sample solutions to achieve equilibrium.

The color enhancement in the pH 5.5 sample was significantly more than in the pH 4 sample. Higher color results in poorer yields in the crystallization process because more centrifuge cake 15 needs to be washed.

It is also likely that the cleaning requirements of the mother liquor will increase.

Both samples exhibited similar increases in mono-anhydrides during 20 feed preparation (0.27 wt.% At pH 4 compared to 0.24 wt.% At pH 5.5); however, the results of liquid chromatography studies (not shown: *. above) indicated that more diffructose anhydrides may have formed at pH 5.5.

25 In summary, the pH 4 samples showed less color formation. the total acetaldehyde content decreased, and its solubility did not significantly differ from that of the pH 5.5 sample. Thus, the pH 4 feed syrup of the ACF process is more favorable than the pH 5.5 feed in terms of product yield and mother liquor; ''; quality due to its low color content. Lower pH apparently minimizes. \ 30 color and formation of difructose, and has a negligible effect on solubility.

As shown in Figure 3, the pH is suitably adjusted after fractionation '' and before carbon treatment. At this point in the process, the viscosity of the fructose solution is relatively low, and so it is relatively easy to mix the acid or base thoroughly to adjust the pH. Numerous acids and bases which can be used for this purpose are known in the art. Particularly preferred are hydrochloric acid (HCl) for lowering the pH and anhydrous sodium carbonate (Na 2 CO 3, calcined soda) for raising the pH.

5

Hiilikäsittelv

Preferably, the feed stream to the crystallization process containing 95% w / w fructose (w / w) is treated with carbon prior to concentration by evaporation. One of the purposes of carbon treatment 10 is to remove impurities that can prevent crystallization. Another object is to remove impurities such as colored compounds, HMF, furfural and acetaldehyde which adversely affect the quality of the mother liquor and thus make it difficult to use it as a component of the liquid phase sweetener. The carbon treatment is preferably carried out with granular carbon at a dosage of from about 1 to about 3 solids, or with powdered carbon which is typically dosed less than granular carbon. The temperature of the syrup is preferably about 160 ° F (about 71 ° C), and the syrup has a solids content typically of 15-30% by weight, preferably about 20-25% by weight. 1

The carbon treatment is most preferably carried out immediately after fractionation and. before evaporation. It has been found that low solids carbon treatment: ·. the fructose loss leading to difructose is less than 0.5%. If the carbon treatment is carried out after evaporation, a fructose loss of more than 2.5% can be expected. The temperature of the syrup should be about 160 ° F (about 71 ° C) (instead of 25 140 ° F; about 60 ° C) to prevent microbial growth in the carbon adsorbent and the syrup should:. viscosity, whereby diffusion to the carbon particles is better.

. ·. An example. '. In this example, an amount of difructose of at least 95% by weight was measured. (Kpl) in fructose-containing aqueous solutions with varying dry solids content. In the first two experiments, the aqueous solutions were mixed in a bottle with 2.7 wt% granular carbon (dry granular carbon based on the dry weight of the aqueous solution), and the bottles were stirred at 1160 ° F (about 71 ° C) for 24 hours. Samples were taken at 0, 6, 14 and 26 1 6532 after 24 hours to measure the amount of difructose present. The results are shown below:

Table 11 5 Diffructose (wt%; pcs) at 25 wt% 50 wt% dry weight

Time, (hl 0 0.25 0.47 6 0.32 0.85 10 14 0.38 1.62 24 0.78 1.94

From the above results, it is seen that difructose was formed much faster (up to 4 times faster) in a 50 wt% solids solution than in a 15 wt% solids solution.

In the following four experiments, it was desired to mimic the operation of a commercial-scale carbon treatment tower as a plug flow, thus attempting to measure the formation of difructose in a dynamic flow system as compared to a static system formed by mixed vials.

; Two 12-inch (about 30.5 cm) consecutive glass columns were used in the experiments; that the syrup feed was delayed for about 20 hours. These columns and the stainless steel short tube used to preheat the feed were immersed in water baths with temperature control.

To simulate the reverse flow of carbon in the unchanged state, the columns were first run to stabilize the carbon and partially deplete its activity, after which the second column was loaded with new granular activated carbon. 30, that about two inches (about 5.1 cm) of new carbon was placed at the outlet of this column.

Four different modes (using standardized new granular carbon in each mode) were investigated with this apparatus: 27 116532 70 wt% solids at 140 ° F (about 60 ° C) 70 wt% solids at 160 ° F ( about 71 ° C) 50 wt% dry matter at 160 ° F 25 wt% dry matter at 160 ° F.

5

Each of these states was run with continuous feed and without circulation for 36 hours, and the amounts of difructose in the column effluent at 0, 6, 14, 24 and 36 hours are shown below:

10 Table III

Difructose (w / w pc)

Temperature 140 ° F (60 ° Ο_160 ° F (71 ° G)

Dry solids 70 wt% 25 wt% 50 wt% 70 wt% 15 substance

Time fh) 0 0.32 0.32 0.35 0.32 6 0.83 - - 1.6 14 0.26 0.92 0.95 20 24 0.39 0.61 1.35 1.83 36 0.24 0.64 1.72 2.24

The formation of difructose at 140 ° F (about 60 ° C) and a solids content of 70 wt% does not seem to be a problem, but the lower temperature mer-v. However, they limit the risk of microbial growth and the higher viscosity of the syrup. In both experiments: 1. higher mass solids (50 and 70 wt.% Solids) and 160 ° F (about 71 ° C) experiments showed levels of difructose with . Significant growth continued all the time, even though heat and coal were active. the same for all samples taken. While not intended to be limited to any theory, a possible explanation may be that the molding of difructose is catalyzed and / or co-catalyzed by a substance removed by the aqueous solution of carbon and thus: that the conversion of fructose to difructose is accelerated while carbon is used. A syrup exiting the carbon column * 'may use a carbon retaining filter to remove any fine carbon particles present in the stream. Effective filtration is important because any insoluble material that enters the crystallizer is centrifuged into crystalline fructose and thus directly affects product quality.

Because non-crystallized fructose is mixed to form a liquid phase sweetener, carbon treatment also improves the quality of this product. Because EFCS is usually treated with carbon near the end of the process (i.e. after mixing), the mother liquor from the centrifuge is already twice purified by carbon treatment as it reaches the final product.

10 Crystallization Inlet Beaker

The driving force for crystallization is supersaturation, which is achieved by cooling the syrup rich in fructose to a point below the saturation temperature of the syrup. The saturation curve of fructose (concentration versus saturation temperature) is very steep. In order to obtain theoretical yields in the crystallization apparatus in the range of 40-55%, for example in the range of 40-48%, the fructose-containing syrup must be cooled to a temperature in the range of about 45-55 ° F (about 7.2-12.8 ° C), e.g. ° F (about 8.3 ° C).

During the evaporation step (s), water is removed from the feed syrup to concentrate it to the point where the fructose crystallizes from the solution upon cooling. The evaporators are preferably designed and operate to concentrate the solution with minimal damage to the syrup. One preferred method of evaporation; its implementation involves a two-step process. The feed syrup is concentrated in a 25-pass evaporator-based evaporator with a plurality of effects and mechanical re-compression. A stream containing 95+% w / w fructose from the carbon treatment step containing about:; 20-25% by weight of dry substance, is introduced into the evaporator at a temperature of about 190 ° F (about 88 ° C), with a pH of about 3.7-4.3. From this step a syrup is obtained, i. 30 having a solids content of about 55-65% by weight. 1

In the second evaporation step, the stream from the first step is fed to a plate '', rising film based evaporator with only one effect, operated at a vacuum of about 23-24 Hg (584-610 mm Hg). This second step of 29116532 yields a syrup having a temperature of about 165-175 ° F (about 73.9-79.4 ° C) and a solids content of about 88-90% by weight. More preferably, the evaporator is used in a vacuum of about 26 Hg (about 660 mm Hg), with a product temperature in the range of about 140-150 ° F (about 60-65.6 ° C), with a loss of fructose in this manner.

The most important criterion in the design and operation of the crystallizer feed evaporator is the concentration of the solution so that the syrup is minimized by heat. The most problematic heat damage to the feed of the crystallizer is the conversion of fructose 10 into difructose, which reduces the yield of the crystallizer. The formation of difructose is promoted by the high temperature, high concentration and long residence time in the evaporator. Since the concentration is essentially solid, the structure and operating conditions of the evaporator should be chosen so that the temperature of the syrup in the evaporator is minimized and the lag time in the evaporator is minimized.

15

Suitable evaporators, such as the tubular descending film based evaporator and the sheet type rising film based evaporator are well known in the art.

20 Kitvtvs'. The crystallization of fructose can be carried out in either batch or continuous crystallizers. Both batch crystallization and continuous crystallization have: advantages and disadvantages. Batch crystallization is more flexible in that it produces \ 25 different crystal size distributions, and can respond to process failures more easily and quickly. However, in batch crystallization, the productivity of the crystallizer (the time it takes to fill, drain, and add crystal embryos) is. less; generating constant crystal size distributions from one charge to another is * · '; harder; it requires larger storage tanks to keep the feed and fill mass to as short a charge period as possible; and requires separate cooling systems for each crystallizer. There are just the opposite advantages and disadvantages of continuous crystallization ^ “.

30 116532

The crystallization can be carried out either as a single pass or as multiple passes. However, one passage is preferably used. It is estimated that only 88% of the yield is achieved per charge and the crystallization time would be 87% longer for the second pass crystallization. In addition, the mother liquor obtained from crystallization of the second passage is most viscous because it contains higher amounts of higher saccharides and the density of the slurry (kilograms of crystals / kg of fill mass) is lower in the case of the filler mass of the second passage. Both of these factors tend to reduce the productivity of the centrifuge. The usefulness of the mother liquor as a blend component in the liquid phase sweetener is largely dependent on the purity of the mother liquor. Although the exact amounts of by-products 10 that can be tolerated or effectively removed from the mother liquor depend on a number of factors, efforts should nevertheless be made to minimize the formation of by-products in the crystallization portion of the process. Since crystallization is essentially selective for fructose, by-products tend to concentrate in the mother liquor at each successive crystallization pass. Thus, this problem is exacerbated by many pass-through crystallizations, and the level of by-products in the mother liquor often sets an upper limit on the number of crystallizable passes that can actually be used in this integrated process.

It has been found that the content of both color, ash, HMF, furfural, and acetaldehyde tends to increase in the mother liquor over a period of multiple pass crystallization; as. Of these byproducts, the concentration of dye increases most rapidly and is therefore a factor that determines the number of effective crystallization passes.

• · Suitable measures for keeping the mother liquor pure include 25 conditions under evaporation, carbon treatment and crystallization such as pH; careful adjustment of value, temperature and delay time. Preferred conditions are discussed in the various paragraphs of this description, which address the various steps of the process.

The syrup fed to the crystallizer is preferably cooled to about 140 ° F (about 60 ° C to 30 ° C) before being introduced into the crystallizer. In order to obtain a theoretical yield of crystalline fructose '- -' of 40-48%, the syrup should contain at least 95 l | '·' Wt% (w / w) fructose and should have a solids content of 88.5 to 89.7 wt% (typically 89 wt% w / w).

3i 1 1 6532

Add crystal embryos to the batch and mix thoroughly. The temperature at which the crystal embryos are added (about 135 ° F; about 57.2 ° C) is based on the estimated percentage of dry matter and fructose present in the batch to be crystallized. After thoroughly mixing the crystal embryos with the syrup, the sample taken from the batch should be analyzed to determine the actual saturation temperature. The cooling system of the crystallizer should be adjusted to obtain a charge in the supersaturation range of 1.00-1.05 (based on the fructose content). If the filling mass is already below this range but nucleation has not yet occurred, cooling should be continued.

10

Nucleation is an event in which crystals are formed from liquids, supernatant solutions (gels) or saturated vapors (clouds). The crystal originates from a small amount of foreign matter that acts as the core of the crystal. Impurities usually act as such kernels. The crystals first form in small areas of the parent phase and then spread there by coalescing. In the process of the present invention, nucleation is undesirable because it results in the formation of small crystals. In addition, crystal size distribution can no longer be controlled if significant nucleation occurs. For this reason, it is preferable to use crystal embryos.

The progress of crystallization can be indirectly controlled by the rate of cooling of the filling mass. by setting the cooling water setpoint according to a predetermined cooling curve such that the degree of supersaturation is 1.0-1.35, e.g. 1.0-1.3.

• ^

More preferably, supersaturation is actually measured to directly control the crystallization pathway. Over-saturation can only be assessed by maternal ·. % dry matter content, when the original percentage dry matter content and percentage fructose content are known. Ylikyllästystie-. '. These decisions can be used to decide whether or not to continue cooling the stake. ": According to a predetermined cooling curve or changing the cooling curve so as to keep the degree of supersaturation desired.

One preferred way of carrying out the crystallization comprises adding crystal embryos to 95% by weight (pcs) of fructose syrup containing about 88-90% by weight of dry substance having a pH of about 3.7-4.3 and a temperature of about 130 -138 ° F (about 54.4-58.9 32116532 ° C), using about 7-10 wt% crystal embryos having an average particle size of about 150-250 µm. The syrup containing crystal embryos is then cooled in a controlled manner to crystallize the fructose in solution.

Cooling can be accomplished as follows: cooling the syrup from about 138 ° F (about 58.9 ° C) to about 115 ° F (about 46.1 ° C) at a rate of 0.5 ° F / h (about 0, 28 ° C / h); cooling the syrup from about 115 ° F (about 46.1 ° C) to about 86 ° F (about 30 ° C) at about 1.0 to 1.5 ° F / h (about 0.560.83 ° C / h) ). It is recommended that the supersaturation level be maintained below about 1.17 when the syrup 10 temperature is greater than about 115 ° F (about 46.1 ° C), and is maintained at less than about 1.25 if the syrup temperature is below about 115 ° F (about 46.1 ° C). Preferably, the maximum temperature difference between the coolant and the fill mass is about 10 ° F (about 5.6 ° C). Too much temperature difference can lead to nucleation.

However, preferably, the cooling is controlled at different speeds for at least three time periods. For example, during the first period, when the syrup temperature is about 138-125 ° F (about 58.9-51.7 ° C), cooling is performed at about 1.0-1.5 ° F / h (about 0.56- 0.83 ° C / h) and supersaturation is kept below about 1.20. During the critical period in which.

The temperature of the 20 syrups is about 125-110 ° F (about 51.7-43.3 ° C), the cooling rate is: preferably about 0.5-1.0 ° F / h (about 0.28-0.56 ° C) / h), and supersaturation is kept "less than about 1.17. Finally, during the rapid cooling period, when the syrup temperature is about 110-86 ° F (about 43.3-30 ° C), the cooling rate is preferably about *; · 1.5-2.5 ° F / h (about 0.83-1.4 ° C / h), and supersaturation is considered to be less than • '·'; 25 about 1.25.

> »·

It has been found that in a preferred cooling operation, over-saturation is continuous; the next unit is connected to the automatic cooling water temperature control. Erääs-

ί J I

In a particularly advantageous cooling operation, the data processing device continuously receives; '. t 30 information about the mass of the mass, the temperature of the cooling water and the supersaturation * I »' '. *. The processor then uses this information to cool the temperature of the cooling water and The data processing device is] programmed to first cool the filling mass from the temperature at which the crystals were added (Ta) to a predetermined critical temperature (T) at a rate of 2.5 33 to 116532 ° F / h (about 1.4 ° C / h). (The critical temperature is predetermined by calculating the percentage of fructose and dry matter present in the feed of the crystallizer, the temperature at which the supersaturation reaches 1.17.) The program is then cooled from a fill mass of T to about 115 ° F (about 46.1). ° C) at 5 1 ° F / h (about 0.56 ° C / h) and 115 ° C F temperature to final temperature (typically 86 ° F to about 30 ° C) at a rate of 1.5 ° F / hr (about 0.83 ° C / hr). However, the program also includes bypasses to prevent excessive kerneling. First, the program will in any case ensure that the difference between the filling mass temperature and the cooling water temperature at any time during cooling does not exceed a predetermined value (typically about 14 ° F; about 7.8 ° C). Second, the program will in any case ensure that the supersaturation does not exceed a predetermined value at any time during cooling (typically 1.28). The specific temperatures and velocities described above can be varied to optimize the curve in view of certain conditions during crystallization without the need for cumbersome experiments. The most important factors affecting the temperature are the total solids content (wt%) and the total surface area of the crystal embryos. For example, the increase in dry matter content shifts the critical time period to the region that previously occurred on the cooling curve and vice versa. Decreasing the total area of crystal embryos, for example, by reducing the total number of crystal embryos added, expands the critical period, and vice versa.

20; Crystallization kinetics

Over saturation; ··; In crystallization kinetics, the rate of growth depends on the concentration-induced mobilization. 25, which is the concentration present in the mother liquor with respect to this heat; state, in equilibrium with the concentration present.

'Over saturation is a measure of this concentration-driven driving force.

There are many ways to define over saturation. When crystallizing fructose. ]. It has been found that water-based supersaturation is the most reliable definition for monitoring the progress of a charge. Therefore, supersaturation is defined as the ratio of grams of fructose to grams of water in the supersaturated syrup divided by the ratio that achieves equilibrium: 34 116532 (fructose / water)

Supersaturation = -------------------------- (Fructose / Water) Balance 5 Ideally, the cooling rate of the batch should be set to adjust the supernatant level of the mother liquor. In the crystallization of fructose, it has been found that supersaturation in the range of 1.0 to 1.30 results in an acceptable yield of crystals in the desired size range. Below this range, supersaturation levels lead to longer cooling times on the charge, while supersaturation levels above 1.35 result in strong nucleation.

Ydintvminen

The choice of target value for supersaturation requires compromise. Fructose does not appear to have a detectable metastable zone, i.e., no nucleation. The growth of existing crystals is always in competition with the formation (nucleation) of new crystals. As the supersaturation level is raised, the growth rate of the crystals increases, but so does the nucleation rate. The goal is to find a level of supersaturation that will achieve the desired crystal size economically over a stock period.

; The above nucleation is of the "shower" or "shock" type. As mentioned above, crystallization of fructose always involves nucleation. Shock nucleation can occur upon initiation of a charge when crystal embryos are added to it. It is assumed that this is due to the low temperature when crystal embryos are added. If nucleation-; preferably, the filler mass should preferably be heated to remove the cores. Cooling may begin after the nuclei have dissolved.

. ; '· The preferred method to avoid shock nucleation is to keep the supersaturation level below 1.30 after the addition of crystal embryos. Strong nucleation increases butter. viscous viscosity of the filling mass, which makes centrifugation very difficult, '·' and significantly increases the emptying time. Fine crystals separated from the fill mass are • much harder to dry and tend to aggregate more easily. Vigorous nucleation results in a product with an average crystal size of 35 undesirably small.

35 1 1 6532

It has been found that for a batch of 95 gallon syrup in a 100 gallon crystallizer, a cooling period of about 30 to 80 hours and usually a cooling period of about 35 to 40 hours is required to crystallize fructose. During this period, the syrup is preferably cooled at many different, preferably three, different speeds. This requirement for different cooling rates is due to the non-linearity of the crystallization of fructose. These different rates correspond to the different growth cycles that occur during cooling.

The first cooling covers a temperature range of about 120 ° F (about 10 48.9 ° C); the desired cooling rate is about 1-4 ° F / h (about 0.56-2.2 ° C / h); a typical rate is 2 ° F / h (about 1.1 ° C / h), whereby this period lasts from four to six hours, preferably about eight hours. During this period, growth occurs almost exclusively on the surface of crystal embryos and the density of the slurry increases slowly. Most of the heat load of the cooling water is due to the removal of free heat.

15 Core nucleation can. happen in this area; however, this only occurs if the temperature when crystal embryos are added is too low or if the supersaturation is greater than 1.3.

During the "critical period", the growth rate increases by a factor of 2 to 4. The density of slurry 20 increases rapidly and new crystals are formed and grow to the desired size range. Both crystal growth and nucleation, which are competing events, accelerate. The boundaries of this area are not clearly defined. For best estimates, it is located between · · 120 ° F (48.8 ° C) and 110 ° F (43.3 ° C). There is a need for action in this area; ··· caution, as nucleation events are easy to control and still prevail: '*; 25 len. It has been found that by maintaining moderate supersaturation (1.0-1.20), core nucleation can be maintained within acceptable limits. A lower cooling rate is an advantageous way to control the degree of supersaturation. In this range, the cooling rate is about 0.5- •: 3.0 ° F / h (about 0.28-1.7 ° C / h), typically a cooling rate of 0.5-1.5 · · · ♦: "' : ° F / h (about 0.28-0.83 ° C / h) At this rate, a critical period of time is estimated at about 30 ~ 10-40 hours, preferably about 18-22 hours. - * · ». · · ·, The stages do not lead to nucleation In this case, additional cooling may lead to the formation of • fructose hemihydrate This species occurs as needle-like crystals forming a very high viscosity (> 800,000 cps; about 800 Ns / Centrifugation of the slurry is practically impossible and can even overload the actuator of the crystallizer. Hemihydrate can be detected by routine inspection of crystals, which should be performed throughout the cooling phase. After the critical stage, the density of the slurry is sufficiently high maintaining a faster cooling rate without nucleation. Within this range of rapid cooling, the temperature of the cooling water can be rapidly reduced. Cooling rates of the filling mass in the range of 1-7 ° F / h (about 0.56-3.9 ° C / h), preferably in the range of 1-40 ° F / h (0.56-2.2 ° C / h), are preferred. . Cooling from 110 ° F (43.3 ° C) to about 100-75 ° F (37.8-23.9 ° C) takes about 3-12 hours, typically 8-12 hours. Faster cooling is possible without nucleation, but growth does not occur so rapidly and at the end of the charge, supersaturation may be greater. Residual supersaturation can be triggered by placing the infill in the mixer or mixing tank for a period of time.

Although cooling can be accomplished more rapidly during the rapid cooling period than in the earlier stages of the batch, there is a limit to how large a temperature difference can be allowed between the cooling water and the filling mass. This limit is not exactly known, but cooling rates should not lead to temperature differences between the mass of filling and the cooling water greater than about 15 ° F (about 8.3 ° C). Greater temperature differences can cause nucleation and fouling of the cooling surface.

Formation of Crystalline Germs The addition temperature of the crystal germs can be obtained from the saturation temperature of the mother liquor of the full crystallizer. To obtain this information, the liquid chromatogram of the syrup is run and its refractive index is determined. The fructose content is then calculated as a percentage of the fructose present in the feed syrup and as a percentage of the dry matter. The crystal embryos should be added in a supersaturation range greater than > 0.96, for example, in the range of 1.0 to 1.10.

:: ·. In the most preferred case, crystalline fructose having an average crystal size of about 100-400 microns is used as crystal embryos. A dose of 1-20% (w / w) is recommended. The dose of the crystal embryos depends on the particle size desired in the final product. The crystal embryos should be added to the full crystallizer, and the crystal embryos 37 116532 should be distributed as evenly as possible into the crystallizer. As mentioned above, U.S. Patent No. 4,164,429 describes a method and apparatus for producing crystalline embryos useful in crystallization.

The addition of crystal embryos is preferably accomplished by first mixing the crystal embryos with the fructose feed syrup to obtain a liquid slurry which is added to the crystallizer. In this way, the surface of the crystals acting as crystal embryos is stabilized. The mixing of crystal embryo crystals in the syrup also minimizes bubble formation in the crystallizer as crystal embryos are added. Bubbles are potential focal points.

The purpose of uniformly adding crystal embryos is particularly to provide the same surface area for the growth of fructose crystals. Since the surface-to-volume ratio of crystalline crystals generally decreases with increasing particle size, if the size of crystals that are crystalline crystals is increased, a greater weight of crystalline crystals is needed to obtain the desired surface area.

Alternatively, a residue of about 5 to 30%, preferably about 10 to 20%, may be left in the crystallizer, which acts as a crystal embryo. This operation requires much less work than the use of dry crystal embryos, but it results in a larger crystal size distribution, since fine particles remain which would otherwise be removed during the centrifugation and drying steps. This process yields * larger crystals that may need to be subsequently milled to meet crystal size requirements in the final product.

: 25

In a preferred operation, hot syrup is added over the residue. The hot syrup raises the temperature of the filling mass residue to the estimated saturation temperature:: (about 133 ° F; about 56.1 ° C) while cooling the feed syrup to the addition temperature of the crystal embryo • '": Some crystal mass is likely to be lost during this X 30 operation. should preferably be at least in the range of 2 to 10% by weight (pcs.) The critical part of this operation is the final temperature reached by the feed syrup and filler residue resulting in a degree of supersaturation in the range of 1.00 to 1.10. loss is minimized and nucleation is minimized.

38 1 1 6532

Example

Crystallization of fructose was carried out in a modification of the pilot size of a conventional crystallizer using a feed syrup comprising 95.82% (w / w) fructose with a dry solids content of 89.60%. The crystallizer used had a mixer attached to the center axis. Cooling was effected by internal cooling fins attached to the center shaft. The crystallizer was almost full with 102 gallons (about 386 L) of syrup. Cooling occurred about 40 hours after addition of crystal embryos; however, supersaturation was still significant (1.17) after this period. The contribution was monitored by monitoring the change in supersaturation.

Crystalline embryos were prepared by grinding the crystalline product through a 2A Fitzmill sieve. The ground material was sieved through a 55 mesh sieve and a 100 mesh sieve. The average size of crystal embryos was 161 microns. The dry crystal embryos were added directly to the syrup in the crystallization apparatus. Table IV shows the cooling program actually used during crystallization. During the first 18 hours of driving, supersaturation peaked at 1.26. It then dropped to about 1.17 where it remained for the remainder of the cooling cycle.

20 Table IV

Time Period (Hours Start - Stop - Cooling Element Temperature • Temperature Speed;! Increase) ° F (° C) ° F (° C) ° F / h (° C / h) 25 --------- -------------------------------------------------- -------------------------------------; ':: 2.0-10.8 133.5 (56.4) 122.5 (50.3) 1.25 (0.69) 10.8-20.8 122.5 (50.3) 111.7 (44.3) 0.98 (0.54): 20.8-30.8 111.7 (44.3) 100.6 (38.1) 1.11 (0.62) 30.8- 40.8 100.6 (38.1) 86.0 (30) 1.46 (0.81): X 30. "*. The average size of the product crystals was 268 microns. The yield of crystals was 46% calculated on the fructose content of the syrup.

39 1 1 6532

Difference

A preferred method of separating fructose crystals from the mother liquor is centrifugation in a basket centrifuge. It has been found that about 4 gallons (about 15 liters) of filling mass in a 14 "x 5 16" (about 35.6 cm x 40.6 cm) centrifuge can be separated in about 10 to 15 minutes. This time period comprises one to three, typically two washes with warm water (120-200 ° F; about 48.9 to 93.3 ° C): Higher wash water temperatures can result in more fructose dissolution and reduced yield. The recommended amount of wash water is 1-5% of the filling mass. Deionized wash water 10 may be used. It is preferred that the pH of the wash water be in the range of about pH 3-5.

Preferred operating conditions for a basket spinner used to remove crystalline fructose from the mother liquor are: a force of about 1400 x g; a cake thickness of about 2 to 3 inches (about 5.1 to 7.6 cm); a moisture content of about 0.7-1.5% water in the cake; and a purity greater than about 99.5%, preferably greater than about 99.8. Moisture and purity of the cake are considered important factors in obtaining a non-caking and stable product.

The product cake is preferably washed in a centrifuge before being removed from it. The washing is preferably with water at a temperature in the range of about 150 ° C to 180 ° C (65.5 ° C to 82.2 ° C). water in an amount of about 1-1.5% by weight, based on the weight of the filling mass placed on the centrifuge. When using this method, product loss during the washing step was typically found to be about 5-10%. The washed fructose-containing wash water can be recycled: '*: to a coal treatment step for removal of impurities and subsequent re-concentration.

* ►

Mixing • t

In the centrifuge, the mother liquor separated from the crystalline product can be returned to 30 parts of the process EFCS-i, ·,.

f * I

In addition to mixing dextrose with the mother liquor remaining after separation of the crystalline fructose, the mother liquor can simply be diluted with water to produce a VEFCS syrup.

40 1 1 6532

After separation of the mother liquor from the crystalline fructose, the mother liquor can be mixed with dextrose or dextrose-containing solutions to finally produce a liquid phase sweetener comprising dextrose and fructose in 55% HFCS syrup (EFCS). As shown in Fig. 3, numerous dextrose-containing streams 5 may be mixed with the mother liquor prior to being subjected to final finishing steps. The choice of a particular stream or streams will depend on the balance factors so that the desired level of fructose in the final liquid phase sweetener product is sought. Most often, in this integrated method, this level is 55 wt% (kpl) fructose. If enough fructose is available in the mother liquor, it is even possible to use a dextrose product stream [which typically contains 94-96% (w / w) dextrose] from the sugaring, which is mixed with the inlet stream for EFCS finishing.

Alternatively, the mother liquor, typically containing 90-92% (w / w) fructose, may simply be diluted with water to provide a liquid phase sweetener. Dilution is recommended if the fructose present in the mother liquor is to be kept in the liquid, since it is likely that additional fructose will crystallize in the mother liquor if the solution is not diluted below its saturation point, considering all temperatures likely to be encountered by the product. In addition to water, other suitable diluents include aqueous saccharide solutions such as dextrose syrups, HFCS, EFCS, VEFCS and production streams for such syrups. In the mother liquor separated from other means to prevent crystallization of fructose, mention may be made of measures to prevent or reduce the evaporation of water from the solution and the addition of anti-crystallizing additives.

Another application of the separated mother liquor or portion thereof is the manufacture of a non-crystalline or semi-crystalline fructose sweetener. One way to accomplish this is: to disperse the mother liquor onto an inert particulate solid, followed by drying the resulting dispersion to obtain a sweetener comprising fructose in amorphous or semi-crystalline form.

···, A preferred particulate solid for this purpose is crystalline fructose.

• I

41 116532

The separated mother liquor of the present invention can be used as an aqueous fructose syrup in this process, and crystalline fructose can be used to initiate crystallization. Thus, there is provided a process for producing a liquid phase sweetener comprising fructose.

5

The foregoing description is directed to specific embodiments of the present invention in accordance with the requirements of U.S. Patents, to illustrate and explain the invention. However, it will be apparent to those skilled in the art that many modifications and modifications may be made to the apparatus, compositions, and methods disclosed, without departing from the spirit and objects of the invention. The following claims are to be construed as embracing all such modifications and modifications.

15 'I «· • *» ·

Claims (7)

A process for the production of fructose and dextrose comprising liquid sweeteners, characterized in that in this process fructose is crystallized from a fructose containing aqueous solution, the crystalline fructose is separated from this solution, after which dextrose is added to the solution. Process according to claim 1, characterized in that the fructose and dextrose-containing aqueous solution stream is divided into a first and second streams, said first streams fractionated to generate more than 90% by weight fructose containing streams, fructose crystallized from said fructose containing stream and at least a portion of the stream containing fructose from which fructose is separated is combined with said second stream. 3. A process according to claim 2, characterized in that the dextrose-containing aqueous solution is treated to isomerize the dextrose proportion present therein, wherein said fructose and dextrose-containing aqueous solution are obtained. 4. A process according to any one of claims 1-3, characterized in that the crystallization of the fructose is realized at a pH in the range 3.7 to 4.3. Method according to any of claims 1-4, characterized in that before,; The crystallization of fructose from a fructose-containing aqueous solution undergoes a solution of carbon treatment and then a solution of evaporation. Process according to any one of claims 1-5, characterized in that the fructose and dextrose-containing aqueous solution is fractionated to obtain a dextrose-enriched solution, a fructose-containing solution and a second fructose-containing solution. fructose content is greater than the first fructose containing that of the solution, and that fructose; : crystallized from said second solution or solution obtained therefrom, and that the obtained solution, from which fructose was separated, is added to the first solution and ':' 'the dextrose containing aqueous solution, the dextrose content of which is greater, calculated on the dry matter weight: , than the first solution. 116532 Process according to claim 6, characterized in that the fructose and dextrose-containing solution is divided into a first and second stream, said first stream undergoes fractionation and crystallization of fructose, and said second stream is added to said first solution and said solution, from which fructose is separated, as said dextrose containing aqueous solution. »» I * »1 ^» · 'I »• S 1 · • t • 1» »I» ·