FI72742B - FOERFARANDE FOER FRAMSTAELLNING AV SIRAP MED HOEJT FRUKTOSINNEHAOLL. - Google Patents

Description

72742

A method of making a syrup with an elevated fructose content

The invention relates to a process for the preparation of a syrup with an elevated fructose content from glucose syrup with an elevated glucose content by isomerization.

It is known to prepare fructose syrup from an elevated glucose syrup, e.g. 95% glucose, with a dry matter content of about 40%, by passing the purified glucose syrup through a column containing solid isomerized enzymes.

During the passage of the column, part of the glucose is converted into fructose and thus a fructose-containing syrup can be prepared, the composition of which on a dry matter basis is e.g. 42% fructose, 53% glucose and 5% higher saccharides and a dry matter content of about 40%.

This corresponds to an inversion rate of about 44%. Degree of inversion • refers to the amount of glucose that is converted to: fructose.

: The fructose syrup thus formed is normally purified by ion exchangers and / or carbon treatment and the purified syrup is evaporated to obtain a dry matter content of about 71%. The syrup thus prepared is marketed under the names Fructose Syrup, Isosupyr Syrup or HFCS (High Fructose Corn Syrup).

: It is theoretically possible to prepare a syrup from a glucose syrup such as the one mentioned above with a fructose content of 45% in the dry matter, but since isomerization is a reversible process, such large amounts of isomerase enzymes would be required that such a syrup is economically viable.

2,72742

In many areas, fructose syrup competes directly with sugar (sucrose) or an invert syrup made from it. The invert syrup comprises 50% fructose and 50% glucose. Because fructose has a higher sweetening ability than glucose, the sweetening ability of the above-described fructose syrup containing 42% fructose is slightly lower than that of sugar or invert syrup made therefrom.

Therefore, known methods have been developed for the production of fructose syrup having a fructose content of more than 50%, based on dry matter, e.g. fructose syrup containing 42% fructose, so that the sweetening capacity of this product is equal to or higher than that of sugar or invert syrup made therefrom.

These methods have in principle been based on fractional distillation, either chromatographically using special cation exchangers or with a special absorbent.

In each process, mainly 3 fractions are obtained, one fraction with a higher saccharide content, one fraction with an elevated glucose content and one fraction with an elevated fructose content. Both processes yield the desired products, e.g., fructose syrup containing 55% or more fructose. However, the method involves a high dilution of water for both methods, so that the energy requirement increases very strongly during the evaporation associated with the preparation of the finished syrup.

For example, in the production of 100 kg of fructose syrup with a fructose content of 42%, 75 kg of water must be evaporated. If fructose syrup containing 55% fructose has to be prepared using the above processes, 240 kg of water must be removed instead of 100 kg of syrup.

3,72742

It is an object of the invention to provide a method as described above which is economical and energy efficient and which can be used to prepare a syrup having a fructose content of 45% or more in the dry matter.

This object is achieved by the process according to the invention, which process is characterized in that the glucose syrup is mixed with a crystallization product containing decomposed fructose and glucose and glucose crystals to obtain a homogeneous solution, isomerized with isomerase enzymes, dried and inoculated with the isomerized product. glucose crystals, cooling the inoculated mixture to crystallize glucose, separating the prepared product into a crystallization product, at least a portion of which is recycled and mixed with glucose syrup, and into a syrup having an elevated fructose content.

The invention is based on the knowledge that the fructose content of isomerized glucose syrup can be substantially increased during the crystallization of glucose, and that both higher concentration and higher glucose content can be obtained in a simple manner ..

The method according to the invention can be used to prepare a syrup with a fructose content of up to 70%.

The term "glucose syrup with elevated glucose content" is to be understood here as meaning glucose syrups which contain at least 93% and preferably 95-98% glucose.

4,72742

Preferably, purified glucose syrup is used. Purification of the glucose syrup is conveniently performed by filtration, followed by ion exchange and possibly carbon treatment.

The glucose syrup is mixed, as mentioned, with the crystallization product prepared in the next step, and the mixture thus obtained is subjected to isomerization by means of isomerized enzymes, preferably solid isomerase enzymes, e.g., those sold under "Sweetzyme", "Taka-Sweet" and "Maxazyme GI-Immob". .

The isomerization with solid enzymes is carried out in a conventional manner by passing the mixture through a column containing solid enzymes.

After passing through the column, the composition of the isomerized product, calculated on the dry matter, is usually as follows: 42% fructose, 54% glucose and 4% higher saccharides, corresponding to a degree of inversion of 43.8% compared to 44.2%, required for the same fructose content. from a starting material having a glucose content of 95%.

The isomerized product is then expediently subjected to ion exchangers and possibly purification by carbon treatment. The purified syrup is then evaporated to a dry matter content of 75-80%.

The evaporated product is then inoculated with an inoculum containing glucose crystals, and preferably the recrystallized crystallization product is used. The inoculated product is then cooled to e.g. 35 ° C and then further cooled to e.g. 15 ° C.

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During the crystallization, which usually requires 60-100 hours, the mixture of syrup and crystals is stirred. Crystallization can be assessed, for example, by taking samples, filtering the crystals and measuring the fructose content of the mother liquor.

When the desired value of fructose is reached, e.g. 55% fructose from the dry matter, the crystals are separated, e.g. by filtration on a filter press or centrifugation, to obtain the desired fructose-containing syrup. The dry matter content of this syrup is usually 70-75% and the sugar composition of the dry matter is as follows: 55% fructose, 38% glucose and 7% higher saccharides. This only applies in cases where the separated crystal mass is not returned to circulation. By recirculating the crystalline mass back to the mixing stage for isaneration, a fructose-containing syrup with the following dry matter composition is gradually obtained: fructose 55%, glucose 40% and higher saccharides 5%.

Some of the separated crystals, e.g. about 10%, can be used as an inoculum material as mentioned when inoculating the above-mentioned evaporated isomerized product.

The rate of crystallization of syrups with a fructose content of up to 50-55% in the liquid phase (from dry matter) is a linear function of time. The crystal content causes an increase in the apparent viscosity in the crystal mass, resulting in a decrease in the crystallization rate.

By separating some of the glucose crystals prepared and restoring the flowable fructose-like phase to crystallization, it is possible to continue crystallization without reducing the crystallization rate and thus achieve a reduction in crystallization time and / or a dry product with an increased fructose content, e.g. 70% fructose.

72742

The invention will now be described in more detail with reference to the following example, which illustrates a preferred method according to the invention.

Example 1000 kg of purified glucose syrup with 95% glucose content having the following composition: fructose 0%, glucose 95%, higher saccharides 5% were mixed with 667 kg of crystalline mass with the following dry matter composition: 21% fructose, 77% glucose, of which 14% was in solution and the rest as crystals (glucose monohydrate crystals) and 1.8% higher saccharides. The combination of glucose monohydrate crystals dissolved and a mixture with a dry matter content of 40% and the following composition was obtained: 8% fructose, 88% glucose and 4% higher saccharides. The mixture was isomerized and evaporated to give a product with a dry matter content of 75% and a dry matter composition of 41.9% fructose, 54.3% glucose and 3.8% higher saccharides. To the evaporated mixture containing 1667.0 kg of dry matter was then added a crystalline mass containing 83.4 kg of dry matter and having the following dry matter composition: 21.0% fructose, 77.1% glucose, of which 62% was crystals and 1.9% higher saccharides to give a mixture with a dry matter content of 1750 kg and the following composition: 41% fructose, 55.3% glucose, of which 3% were crystals and 3.7% higher saccharides.

The mixture was then cooled, and when crystallization ceased, the amount of glucose as crystals was 26.8%, with the remaining amount of glucose being in a continuously dissolved state.

Separation was then performed to form a crystalline mass having a dry matter content of 750.4 kg and a dry matter content of the mother liquor of 1000 kg. The dry matter composition of the mother liquor was as follows: 56% fructose, 39% glucose and 5.0% higher saccharides.

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The crystal mass was divided into two portions, one of which was 83.4 kg of dry matter, as mentioned above, recycled as an inoculum, and the other of 667 kg of dry matter was recycled and mixed with a syrup with a glucose content of 95%.

Claims (8)

72742 A process for the preparation of a syrup with a higher fructose content of at least 45% from a high glucose glucose syrup by isomerization, characterized in that the glucose syrup is mixed with a crystallization product containing dissolved fructose and glucose to form an isomeric that the isomerized product is evaporated and seeded with an inoculum containing glucose crystals, that the inoculated mixture is cooled to crystallize glucose, that the resulting product is separated into a syrup with increased fructose content and a crystallization product, preferably at least partially recycled and mixed with glucose syrup. Process according to Claim 1, characterized in that part of the crystallization product is recycled and used as inoculum. Process according to Claim 1, characterized in that glucose syrup having a glucose content of 93 to 98% is used. Process according to Claim 1, characterized in that the isomerized product is purified before evaporation and inoculation. Process according to Claim 1, characterized in that the isomerized product is evaporated to a dry matter content of 75 to 80%. Process according to Claim 1, characterized in that the inoculated mixture is cooled to a temperature of 15 to 30 ° C. 9,72742 Process according to Claims 1 and 2, characterized in that about 10% of the crystallization product is used as inoculum. Process according to Claim 1 or 2, characterized in that during the crystallization, the crystals are filtered either continuously or intermittently and the filtrate is recycled to continuous crystallization.