JPH0525478B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a sugar solution containing less oligosaccharide than hydrol or raffinate. Hydrol, which is produced as a by-product during the production of crystalline glycose, contains a large amount of oligosaccharides (hereinafter simply referred to as oligosaccharides in the present invention) such as maltose, maltotriose, isomaltose, nigerose, and panose, so it cannot contain the main component glucose. Although this hydrol contains a large amount of It has only been used as a sweetener or as a specialty sweetener (described in US Pat. No. 3,935,070). On the other hand, technology has recently developed to separate glucose and fructose in isomerized sugar, making it possible to increase the fructose content from the conventional 42% (based on solid content, hereinafter the same) to 80%. A product with a sugar content of 55% that is mixed at a certain ratio has become popularly manufactured, but during separation, reuse of the by-product glucose fraction (referred to as raffinate) has become a problem. It's here. In other words, raffinate also contains a large amount of oligosaccharides, and even if this raffinate is remixed with the starch saccharification solution and the isomerization is performed again, the oligosaccharide content in the isomerized sugar solution produced will increase. It was damaged and could not be reused. However, as a method to increase the glucose content and reduce the oligosaccharides in the starch saccharification solution, the method of starch saccharification is to use α-1,6 glucosidase such as pullulanase or isoamylase in combination with glucoamylase during starch saccharification. Various attempts were made. For example, JP 54-29570, JP 56-
23894, JP-A-57-170195, etc. However, even though these various methods actually have the effect of slightly increasing DE, the saccharification solution still contains a considerable amount of oligosaccharides, and as a result, hydrols or isomers that are by-produced during the production of crystalline glucose. The oligosaccharide is directly transferred from the high fructose sugar solution to the ruffinate by-produced during the production of the high fructose isomerized sugar solution, and in the end, despite these various attempts, the above problem remained unsolved. Therefore, the present inventors conducted intensive studies to re-mix hydrol or raffinate into the starch saccharification solution and used it in the production of isomerized sugar solution obtained after undergoing processes such as isomerization. Alternatively, α-glucosidase that has the ability to effectively decompose oligosaccharides in raffinate is added, and the mixture is heated at an appropriate temperature.
By allowing the diluted hydrol solution or raffinate to react for an appropriate period of time, the diluted hydrol solution or raffinate can be successfully made into a sugar solution containing less oligosaccharides, and the sugar solution containing less oligosaccharides obtained by the present invention can be used as it is or after being concentrated. The present invention was completed based on the knowledge that the starch can be remixed into the starch saccharified solution and then reused in the production of isomerized sugar solution after the isomerization step. Hydrol and raffinate have almost similar sugar compositions in terms of glucose and oligosaccharides, but hydrol has a higher solids content of about 50-70% (ruffinate has a content of 10-30%). α−
Since glucosidase is difficult to act as it is, it is necessary to dilute Hydrol appropriately. The relationship between the dilution ratio of hydrol and the oligosaccharide hydrolysis rate will be explained in Test Example 1. Test example 1 Hydrol stock solution (solid content 50%, oligosaccharide content in solid content 17.1%) was diluted with water to obtain solid content of 10% (), 20% () and 30% () year,
Each diluted hydrol solution, , was used as a substrate, and P. variotei α
- 4 units of glucosidase was added per ml of each substrate and reacted at 60°C, and the residual rate (%) of oligosaccharides in each diluted hydrol solution after each time period was examined. As a control, the oligosaccharide residual rate was also investigated for Hydrol stock solution. Table 1 shows the results.
Shown below.

[Table] As is clear from Table 1, the higher the solid content in Hydrol, the higher the oligosaccharide residual rate. It was found that it is preferable to dilute the In the present invention, what is referred to as a diluted hydrol solution means a diluted hydrol solution with a solids content of 10 to 30%. The feature of the present invention is that alpha-glucosidase is allowed to act on a diluted hydrol solution or raffinate to convert the diluted hydrol solution or raffinate into a sugar solution with a low oligosaccharide content. For this purpose, the hydrol diluted solution or raffinate is acidic, has a high glucose content, and contains various oligosaccharides, so the optimal pH for α-glucosidase that can be used in the present invention is on the acidic side. α-glucosidase is preferred, which has broad substrate specificity for various oligosaccharides and acts well even at high glucose concentrations. There are many types of α-glucosidase (EC3.2.1.20), and α-glucosidase of microbial origin, for example, α-glucosidase produced by Pecilomyces variotei or Aspergillus niger, or α-glucosidase of plant origin, produced from sugar beet seeds, is used.
Examples include glucosidase. The preparation method and enzymatic chemical properties of these α-glucosidases will be described below. Preparation method of α-glucosidase from Pecilomyces variotei: P. variotei IFO 4855 strain was mixed with 1% glucose, 0.3% yeast extract, and malt extract.
After inoculating into a medium consisting of 0.3% and polypeptone 0.3% and pre-cultivating at 28°C for 2 days, potato starch 3%, NH ₄ NO ₃ 0.05%, KH ₂ PO ₄ 0.02%,
The pre-cultured cells were inoculated into this medium consisting of 0.05% MgSO ₄ 7H ₂ O and 2% CaCo ₃ , and cultured with shaking at 32°C for 40 hours to remove the cells and obtain a crude enzyme solution. 99
% ethanol was added, the resulting precipitate was collected, suspended in 0.01M phosphate buffer (PH6.4), the precipitate was removed, dialyzed, and DEAE-Sepharose CL
-6B (Pharmacia product), Bio-Gel P-150
(Bio-Rad product) and second DEAE-
Sepharose CL-6B was subjected to column chromatography to obtain a purified enzyme solution. This product was further subjected to a preparative disc electrophoresis treatment and a second gel filtration using Bio-Gel P-150 to obtain a single disc electrophoretic sample. Preparation method of Aspergillus niger α-glucosidase: Use the commercially available enzyme agent transglucosidase "Amano" (manufactured by Amano Pharmaceutical Co., Ltd.) as enzyme powder, dissolve this in 20mM phosphate buffer, dialyze, The supernatant obtained by centrifugation is used as a crude enzyme solution, and then the crude enzyme solution is mixed with DEAE-Sepharose and Toyopearl HW-55 (Toyo Soda Kogyo Co., Ltd. product).
It was processed by column chromatography and purified single by disk electrophoresis. Preparation method of sugar beet seed α-glucosidase: From sugar beet seed powder Agric.Biol.Chem.Volume 42, 241
~245 (1978) and a single purified α-glucosidase was obtained by polyacrylamide gel electrophoresis. In the present invention, various α-glucosidases from Pecilomyces variotei, Aspergillus niger, and sugar beet seeds obtained by the above-mentioned preparation method can be used as they are, including not only purified enzymes but also partially purified enzymes and crude enzymes. . Furthermore, these α-glucosidases can also be used in an immobilized state. In the case of immobilization, any conventional solidification method may be used, but in the present invention, specifically, it is prepared by the following method. Preparation method of immobilized α-glucosidase: 300 g (wet weight) of Sepharose 4B (product of Pharmacia) washed with purified water and 700 ml of 0.6N caustic soda solution containing 8% epichlorohydrin.
The suspension was suspended in water, reacted at 40°C for 2 hours, and washed with purified water to obtain activated sepharose. Next, 300 g of the activated cephalose was suspended in 700 ml of 0.5M hexamethylene diamine solution, reacted at 25°C for 16 hours, and washed sequentially with 1M saline and purified water to synthesize aminohexyl cephalose. 100g of the aminohexylcephalose was added to 250ml of 0.1M phosphate buffer containing 1% glutaraldehyde.
After reacting for 30 minutes with stirring at room temperature, wash with purified water and add 250 ml of 0.1 M phosphate buffer in which 5000 units of α-glucosidase from various sources have been dissolved.
suspended in. After reacting for 4 hours with stirring at room temperature, various α-glucosidase immobilized products were collected by filtration and washed successively with purified water and 1M phosphate buffer. The activity of the obtained immobilized product was 1 g for α-glucosidase of Pecilomyces variotei.
The activity yield was 14.6% at 7.3 units per wet gel. In the case of α-glucosidase from sugar beet seeds, the activity yield was 9.3 units per gram of wet gel, which was 18.5%. Next, the enzymatic chemical properties of various α-glucosidases will be compared and described. (1) Action: All α-glucosidases act on oligosaccharides, glycosides, or polysaccharides that have α-glucosidic bonds, and cleave them into glucose units from their non-reducing ends. (2) Substrate specificity: The water decomposition rate calculated from Vmax for various substrates of various α-glucosidases is
Table 2 shows the relative values set to 100.

【table】

[Table] (3) Optimal pH: α of Pecilomyces variotei and sugar beet seeds
-Glucosidase is around 4.5, and Aspergillus niger α-glucosidase is 4.0.
It is around ~4.5. (4) Stable pH: α-glucosidase of Pecilomyces variotei has a pH range of 4.5 to 9.0, and
α-glucosidase from niger has a pH range of 3.5 to 8.0, and α-glucosidase from sugar beet has a pH of 3.0.
Each is stable in the range of ~8.0. (5) Temperature stability: α-glucosidase from Pecilomyces variotei was treated at 55℃ for 15 minutes, α-glucosidase from Aspergillus niger was treated at 50℃ for 15 minutes, and α-glucosidase from sugar beet seeds was treated at 60℃ for 15 minutes. Each is stable even after treatment. (6) Molecular weight: Molecular weight of various α-glucosidases determined by SDS polyacrylamide disc electrophoresis. α-glucosidase of Pecilomyces variotei is 100,000, α-glucosidase of Aspergillus niger is
-Glucosidase is 58,000, α-glucosidase of sugar beet seeds is 91,000. (7) Activity measurement method: 0.5% maltose solution (PH4.0) as a substrate.
Prepare by dissolving in 0.2M acetate buffer. )0.8ml
Add 0.2 ml of enzyme solution and incubate α at 37℃.
- Glucosidase was reacted for 5 minutes to generate glucose, and glucose was measured by the glucose oxidase method (Glucose β-Test Wako: product of Wako Pure Chemical Industries, Ltd.). One unit (U) is the enzyme activity that breaks down 1 μmol of maltose to produce 2 μmol of glucose in 1 minute. Next, the conditions for decomposing oligosaccharides in the diluted hydrol solution or raffinate using these various α-glucosidases, such as the amount of enzyme added, the action temperature, and the action time, were investigated. Test example 2
This will be explained in 3. Test Example 2 In order to determine the amount of various α-glucosidases added, Hydrol diluted solution (solid content 20%, oligosaccharide content in solid content 17.1%) was used as a substrate, and 1 amount of each α-glucosidase was added per 1 ml of substrate. . The results are shown in Table-3.

【table】

[Table] As is clear from Table 3, when 2 units or more of each α-glucosidase is added, the hydrolysis of oligosaccharides in the diluted hydrol solution progresses. It was also found that 4 units or more of each α-glucosidase was required to further reduce the residual rate. Test Example 3 Hydrol diluted solution (solid content 20%, oligosaccharide content in solid content 17.1%) and ruffinate (solid content 20%, oligosaccharide content in solid content
Using 13.8%) as a substrate, 4 units of α-glucosidase from Pecilomyces variotei were added per 1 ml of substrate, and after allowing it to act at each temperature for each time, the oligosaccharide residual rate was examined for each substrate over time, and the effect temperature and effect were determined. I considered the time. Table 4 shows the results.
Shown below.

[Table] As is clear from Table 4, the higher the action temperature is, the lower the oligosaccharide residual rate is. However, at temperatures above 60°C, enzyme deactivation is observed, so the preferred action temperature is 50-60°C. It is ℃. If the action time is more than 1 hour, the residual rate of oligosaccharides will decrease, but if a long period of time passes, oligosaccharides will start to be regenerated by retrosynthesis from the glucose produced, so the residual rate of oligosaccharides will decrease. rate increases and therefore it is preferable to stay within 24 hours. As shown in Test Examples 1 to 3, alpha-glucosidase derived from Pecilomyces variotei, Aspergillus niger, or sugar beet seeds is added to a diluted hydrol solution or raffinate at an appropriate temperature for an appropriate time.
That is, by reacting at 50 to 60°C for 1 to 24 hours, the oligosaccharides in the diluted hydrol solution or raffinate are decomposed into glucose, thus creating a sugar solution with less oligosaccharides than the diluted hydrol solution or raffinate. was able to manufacture. The sugar solution containing few oligosaccharides obtained by the method of the present invention can be widely used as it is or by being remixed into the starch saccharification solution after concentration for producing an isomerized high-fructose sugar solution. The present invention will be explained in more detail below with reference to Examples. Example 1 Solid content concentration 15%, sugar composition (solid content is 100% and the ratio of each sugar component is shown in %) fructose
When 3000 units of α-glucosidase from Pecilomyces variotei was added to 1000 ml of ruffinate containing 10.4% fructose, 72.7% glucose, and 16.9% oligosaccharides and the mixture was reacted at 60°C for 4 hours, 10.3% fructose, 82.9% glucose, and 6.8% oligosaccharides were added. A sugar solution was obtained. This product was concentrated under reduced pressure using a known method to achieve a solid content concentration of 45%, and when an isomerization reaction step was performed using glucose isomerase, fructose was 42.5%.
%, glucose 50.6%, and oligosaccharides 6.9%. This product could be used as a normal high-fructose sugar solution. Example 2 Solid content concentration 20%, PH4.3, sugar composition is glucose
Add 4 units of Aspergillus niger α-glucosidase per ml to 1000 ml of a diluted glucose hydrol solution containing 81.3% and 18.7% oligosaccharides, and heat at 60°C.
After 4 hours of reaction, a sugar solution containing 92.6% glucose and 7.4% oligosaccharide was obtained. Concentrate this to a solid concentration of 35%, add 10% to the same concentration of liquefied cornstarch (decomposition rate 15%), and add 4 units of glucoamylase (Gluczyme AF-6: manufactured by Amano Pharmaceutical) per 1g of solid content. In addition, when the mixture was saccharified at 60°C for 40 hours, a sugar solution with a sugar composition of 94.5% glucose and 5.5% oligosaccharide was obtained. This product could be used for producing isomerized sugar using glucose isomerase. Moreover, this product could of course be effectively used in the production of purified glucose and crystalline glucose. Example 3 Solid content concentration 15%, sugar composition fructose 10.4%,
300 ml of raffinate containing 72.7% glucose and 16.9% oligosaccharide, with sugar beet seed α-glucosidase immobilized on aminohexyl sepharose, was packed in a column (0.3 units/g wet gel, column volume 100 ml) at 60°C, 500 ml/ When the solution was passed with Hr and allowed to circulate for 4 hours, a sugar solution containing 10.4% fructose, 83.0% glucose, and 6.6% oligosaccharides was obtained.
Concentrate this material under reduced pressure using a known method to obtain a solid content concentration.
When the isomerization reaction step was carried out using glucose isomerase, fructose was 42.5%,
An isomerized sugar solution with a sugar composition of 50.8% glucose and 6.7% oligosaccharide was obtained. This product could be used as a normal high-fructose sugar solution. In addition, this aminohexylcepharose on which sugar beet seed α-glucosidase was immobilized retained 100% of its initial activity even after the reaction was repeated five times under the above conditions.

Claims (1)

[Scope of Claims] 1. Ruffinate obtained after separating a high fructose fraction by treating a diluted solution of hydrol obtained after crystallizing glucose from a starch saccharified solution or an isomerized sugar solution with an ion exchange resin to separate α- A method for producing a sugar solution with a low oligosaccharide content, which comprises converting the diluted hydrol solution or raffinate into a sugar solution with a low oligosaccharide content by allowing glucosidase to act at 50 to 60°C for 1 to 24 hours. 2. The method for producing a sugar solution with low oligosaccharides according to claim 1, wherein the α-glucosidase is α-glucosidase produced by a strain belonging to Pecilomyces variotei or Aspergillus niger or α-glucosidase derived from sugar beet seeds. . 3. The method for producing a sugar solution containing few oligosaccharides according to claim 1, wherein the α-glucosidase is immobilized α-glucosidase.