JPS5811839B2 - Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an isomerized sugar solution, and more particularly, to a method for producing an isomerized sugar solution by allowing a bacterial enzyme or an immobilized enzyme as glucose imerase to act on glucose. .

Conventionally, as a method for isomerizing glucose with glucose imerase to produce an isomerized sugar solution containing glucose and fructose, bacterial enzymes were added to the glucose solution to produce a solution containing 60-70%
A method for producing an isomerized sugar solution by carrying out an isomerization reaction of glucose in a batch manner at a temperature of about ℃, and then passing the obtained isomerized sugar solution through a layer of diatomaceous earth to separate bacterial enzymes. is being implemented.

However, in this method, the bacterial enzyme isolated from the isomerized sugar solution is contained in diatomaceous earth, so in order to reuse the bacterial enzyme in the glucose isomerization reaction, it is necessary to The diatomaceous earth filter slag must be added directly to the raw glucose solution.

Therefore, if the bacterial enzyme used in the isomerization reaction is repeatedly reused in the isomerization reaction process, the efficiency of filtration to separate the bacterial enzyme from the isomerized sugar solution will be significantly deteriorated, and in reality, The limit is that it can be used twice at most.

In addition, in the above method, when the bacterial enzyme is separated from the isomerized sugar solution using diatomaceous earth, leakage of glucose imerase eluted from the bacterial enzyme (leak phenomenon) is unavoidable, resulting in loss of the enzyme and An additional operation for separating the enzyme from the isomerized sugar solution is required.

Furthermore, the separation using the diatomist described above inevitably reduces the residual activity of the enzyme.

In addition, when the above-mentioned isomerization reaction is carried out using an immobilized enzyme, the sedimentation property of the immobilized enzyme is utilized to pass the resulting supernatant of the isomerized sugar solution through a diatomaceous earth layer and filter it. The supernatant liquid contains the immobilized enzyme in the form of fine particles with extremely poor settling properties, the bacterial enzyme leaked from the immobilized enzyme during the reaction process, and the enzyme eluted from the bacterial enzyme. These enzymes permeate through the diatomaceous earth layer and are lost.

As mentioned above, in the conventional method, it is not possible to effectively reuse the residual activity of the bacterial enzyme used in the isomerization reaction and the glucose isomerase eluted from it, so it is difficult to perform the isomerization reaction mainly from an economical point of view. It is necessary to lower the concentration of bacterial enzymes used, and as a result, when isomerizing glucose, the desired isomerization rate (generally 45%) is lowered.
50 to 80 hours and reaction time are required to achieve this.

Since the isomerization reaction of glucose is carried out over a long period of time as described above, the separation reaction of sugar occurs during this time, and as a result, the coloring of the resulting isomerized sugar solution becomes significant, resulting in the use of activated carbon and ion exchange resin. The drawback is that the burden of decolorization operation using is increased and the yield of isomerized sugar solution is reduced.

In view of the various drawbacks of the conventional methods described above, the present inventors have discovered that in order to shorten the isomerization reaction time by increasing the concentration of the enzyme used in the glucose isomerization reaction, bacterial enzymes are added from the isomerization reaction sugar solution. Alternatively, the immobilized enzyme and the glucose isomerase eluted from it (hereinafter referred to simply as enzyme) can be separated in a state in which their residual activities are substantially not lost and can be repeatedly used in isomerization reactions. As a result of research on such separation means, we found that an ultrafiltration membrane with a filtration limit molecular weight that can block the permeation of the above-mentioned enzymes can be used to remove the isomerized sugar solution produced by the isomerization reaction of glucose. When the solution is passed through the sugar solution, the enzymes in the sugar solution are virtually completely separated without leakage or loss of enzyme activity, and are effectively separated in a state that can be repeatedly reused for isomerization reactions. I learned that it is concentrated.

The present invention was completed based on the above-mentioned research results, and an object of the present invention is to provide a method that can advantageously isomerize glucose in a short time.

Other objects of the invention will become apparent from the description below.

The configuration of the present invention will be explained in detail below.

As the glucose-containing sugar solution used as the isomerization raw material in the present invention, generally suitable glucose-containing sugar solutions include hydrous glucose, anhydrous glucose, and a mixture of glucose and oligosaccharide such as Hytrol.

As the glucose isomerase used for isomerizing the glucose-containing sugar solution, a bacterial enzyme or an immobilized enzyme is used.

Among these, immobilized enzymes have a long active life, but are currently expensive, so they should be selected appropriately when using them.

A conventional batch method can be applied to allow the above-mentioned enzyme to act on the glucose-containing sugar solution.

The isomerization reaction of glucose by glucose isomerase generally shows a tendency for the rate to increase linearly in the early stage of the reaction and then gradually decrease, and is completed when the isomerization rate of glucose reaches around 50% (theoretical value). It is something.

As is well known, the rate of this isomerization reaction is influenced by the enzyme concentration and reaction temperature used in the reaction.

In the present invention, the above isomerization reaction conditions include the concentration of glucose solution (approximately 50%), pH
(6,5-7.0) and temperature (approximately 55-75℃), but as for the enzyme concentration, the enzyme used in the reaction can be repeatedly recycled to the isomerization reaction step as described later. For example, 70
It is possible to use it at a considerably higher concentration than in the conventional method of ~400 units (hereinafter the units are generally referred to as Takasaki units), which makes it possible to significantly shorten the reaction time.

In the present invention, the ultrafiltration membrane used to separate the enzyme from the isomerization sugar solution can block the permeation of the bacterial enzyme or immobilized enzyme used in the isomerization reaction and the glucose isomerase eluted from it. It is applicable as long as it has a filtration limit molecular weight.

Next, the above ultrafiltration membrane will be outlined.

Membrane materials for ultrafiltration membranes include cellulose acetate,
Any ordinary ultrafiltration membrane material such as polyamide, polyvinyl chloride, polyacrylonitrile, etc. can be used.

Furthermore, the type of membrane differs depending on the membrane forming method such as flat membrane method, tubular method, spiral method, hollow fiber method, etc., but any of these film forming methods can be applied in the present invention, and I don't care.

Each of these types of membranes formed into a suitable unit is called a module.

There are two methods for operating the ultrafiltration method: one method involves pumping the solution to be treated into the module and filtering it, and the other method involves applying suction pressure to the membrane and filtering it under reduced pressure. Both are applicable.

Generally, in the ultrafiltration method, since the material to be filtered is colloidal, as the filtration progresses, the colloidal substances form a membrane with concentration polarization on the membrane surface, and this membrane acts as the rate-limiting step. As a result, filtration efficiency may decrease.

As a method for peeling off the concentration polarized layer, a method is usually employed in which a filtered solution is passed through the membrane surface at high speed and maintained in a turbulent flow state.

Therefore, in the present invention, when passing an enzyme-containing high-fructose sugar solution that exhibits a colloidal state through an ultrafiltration membrane, it is efficient to circulate the sugar solution at high speed over the membrane surface and allow it to permeate. .

However, even with the extrafiltration method as described above,
Since the filtration effect is not always perfect, it is more preferable to employ an ultrafiltration module and a filtration system that can employ a so-called backwash method, in which pressure can be applied from the opposite direction to the direction in which the membrane is pressurized.

That is, according to this backwashing method, the concentration polarized layer is efficiently peeled off, and the filtration efficiency is further improved.

The most preferable membrane that can be applied to ultrafiltration using a backwash method is one that has membranes with the same performance on the outer and inner surfaces of the membrane, and that does not peel off from the support under normal pressure or reverse pressure. It is a hollow fiber membrane with strength.

Therefore, it is most preferable to use a hollow fiber membrane as the ultrafiltration membrane used in the present invention.

However, it should be understood that various types of membranes can be used in the present invention, as described above.

According to the present invention, when the above-mentioned enzyme is separated from the isomerized sugar solution using an ultrafiltration membrane, the ultrafiltration membrane is placed in communication with the reaction tank, and the isomerized sugar solution from the reaction tank is The enzyme in the sugar solution is separated through the membrane by passing through the filtration membrane, and the isomerized sugar solution that has passed through the membrane is recovered outside the system.

During this separation, no permeation of the eluted glucose isomerase is observed, and the residual activity of the separated enzyme is not substantially impaired.

In addition, when separating the above enzyme, if the temperature of the isomerized sugar solution from the reaction tank is higher than the working temperature of the ultrafiltration membrane, the reaction tank and the ultrafiltration membrane should not be directly connected, and the heat exchanger and circulation tank should be used. The isomerized sugar solution from the reaction tank is transferred in an amount corresponding to the amount of the isomerized sugar solution taken out of the system after passing through the ultrafiltration membrane. It is also possible to adjust the temperature of the isomerized sugar solution passed through the ultrafiltration membrane to the appropriate working temperature of the membrane by operating it to be transferred to a circulation tank.

Next, according to the present invention, when the enzyme separated as described above is repeatedly reused in the isomerization reaction step,
The enzyme separated through the ultrafiltration membrane (which has been concentrated by passing through the membrane) is returned to the reaction tank and used in the isomerization reaction of the freshly charged raw material glucose-containing sugar solution.

At this time, the activity of the enzyme that has been cyclically returned to the reaction tank has decreased somewhat due to the influence of oxygen during the reaction process, so new enzyme is replenished and the isomerization reaction continues. It is possible to do so.

In addition, in the present invention, when the separated enzyme is repeatedly recycled and reused in the isomerization reaction step, when the isomerized sugar solution is extracted from the reaction tank and passed through the ultrafiltration membrane, the A portion is left in the reaction tank, and a new raw material glucose-containing sugar solution is added and mixed with the isomerized sugar solution containing the concentrated enzyme in the reaction tank. It is also possible to repeatedly carry out the isomerization reaction using an enzyme.

In this case, a new enzyme may be replenished as necessary.

This operation is extremely advantageous in practice, since the reaction time required to achieve the desired isomerization rate can be significantly shortened depending on the amount of the isomerized sugar solution left in the reaction tank.

In this case, the amount of isomerized sugar solution to be left in the reaction tank can be changed arbitrarily, but according to the experimental results of the present inventors, the amount is set to about 1/2 volume, When reacting by adding approximately the same amount of raw material glucose-containing sugar solution to this, the time required to isomerize the total amount of sugar solution in the isomerization reaction tank can be reduced to about 1/2 compared to the conventional method. This makes it possible to significantly improve the productivity of the isomerized sugar solution.

The above-mentioned operation was explained mainly for the case where a bacterial enzyme was used as the enzyme, but even when an immobilized enzyme is used as the enzyme, there are no steps other than extracting the supernatant obtained by the sedimentation method in the reaction tank. It can be carried out by a similar operation, and the productivity of the isomerized sugar solution is also significantly improved to the same extent.

Further, the present invention can be applied to a reaction operation using a column method using an immobilized enzyme, and can also be applied to a reaction operation using a combination of a column method and a conventional reaction tank.

As described above, according to the present invention, the enzyme used in the isomerization reaction can be very efficiently separated from the isomerization sugar solution and recycled and reused in the isomerization reaction process. By increasing the concentration appropriately, the isomerization reaction time can be significantly shortened compared to conventional methods, and the system can be operated in a semi-continuous manner by simply adding simple equipment to the conventional batch method. It becomes possible.

In particular, as mentioned above, when separating the enzyme from the isomerized sugar solution using an ultrafiltration membrane, if a method is adopted in which a part of the isomerized sugar solution remains in the reaction tank, the isomerization reaction Since the time is further shortened, the production amount per unit time is significantly improved.

In addition, as mentioned above, with the shortening of the reaction time, there is less decomposition of sugar in the isomerization reaction process, and therefore, the degree of coloring of the isomerized sugar solution based on it is also 1/4 to 11 times that of the conventional method.
5, and there is no enzyme leakage during the enzyme separation process, and the fatty layer polymer dextrin derived from the raw sugar solution is also separated in the ultrafiltration step, so the isomerized sugar solution obtained from the filtration step is No colloidal substances or the above-mentioned substances are contained therein, and therefore, the decoloring operation using activated carbon is performed extremely efficiently, and the cost of decolorizing is significantly reduced.

Furthermore, when purifying the isomerized sugar solution using an ion exchange resin, as mentioned above, since it does not contain colloidal substances, fats, or polymer dextrins, the load on the resin is greatly reduced, making the purification operation more effective. It will be held in

Further, by separating enzymes using an ultrafiltration membrane according to the present invention, there is no need for the filtration step using diatomaceous earth in the conventional method, which has the advantage of significantly improving workability.

Furthermore, according to the present invention, as mentioned above, it is possible to increase the concentration of the enzyme used in the isomerization reaction, so unlike the conventional method in which the enzyme is used at a low concentration, Co There is also the advantage that it is no longer necessary to add heavy metal ions such as ions, and food hygiene problems caused by these heavy metal ions are also eliminated.

Therefore, it is believed that the present invention greatly contributes to the production of isomerized sugar solution.

The present invention will be specifically explained below by way of examples.

Example A glucose solution prepared by dissolving anhydrous glucose 3000F in 3000 ml of water was placed in a reaction tank, and MgSO
Add and dissolve 4.77H2O6, and while stirring gently at a temperature of 60°C, add 300g of glucose isomerase in the form of bacterial enzyme (manufactured by Godo Shusei Taru, unit: 100g).
0G, 1. U,/g) was added, well dispersed, and the isomerization reaction was carried out.

During this time, the pH of the reaction solution was adjusted to 6.0 using a 1N NaOH solution.
It was adjusted to 5-7.0.

The progress of the reaction was measured by optical rotation, and when the isomerization rate reached 45% (8 hours and 20 minutes after the start of the reaction), the liquid in the reaction tank was communicated with the tank via a pump. The isomerized sugar solution that has passed through the ultrafiltration membrane system is collected, and the return liquid from the system, i.e.
The isomerized sugar solution containing the enzyme separated and concentrated from the isomerized sugar solution was returned to the reaction tank.

The ultrafiltration membrane system has a filtration limit molecular weight of 20,000.
A hollow fiber membrane (effective membrane area: 0.2 m2) was used, and the pressure was 0.4 kg/cm2. Average permeation rate 30C
Permeation was carried out at a rate of C/min, and the permeation operation was stopped when the permeated liquid reached 2500 ml.

Next, 3000 glucose solution prepared in the same manner as above
g is added to the reaction tank and the isomerization reaction is carried out under the same conditions as described above, while the progress of the isomerization is measured by sampling the sugar solution in the reaction tank and measuring its specific rotation. When the isomerization rate reached 45% (6 hours after the start of the reaction), the liquid in the reaction tank was passed through an ultrafiltration membrane system in the same manner as above, and the isomerized high-fructose sugar that passed through the system was 3000f of liquid was obtained.

The above operation was repeated 10 times, and the reaction time, isomerization rate, sugar concentration, and coloration of the isomerized sugar solution obtained by ultrafiltration were measured in each isomerization reaction step. The results are summarized in the table below. and show.

However, when the above operation was repeated, the isomerization reaction was carried out by replenishing 2.5 liters of bacterial enzyme each time after the 7th operation.

Claims (1)

[Scope of Claims] 1. When producing an isomerized sugar solution containing glucose and fructose by causing glucose imerase to act on a glucose-containing sugar solution to isomerize glucose, bacterial enzymes are added to the glucose-containing sugar solution. Or by using immobilized enzyme,
An isomerized sugar solution characterized in that the obtained isomerized sugar solution is passed through an ultrafiltration membrane to separate the above-mentioned bacterial enzyme or immobilized enzyme and glucose imerase eluted therefrom from the isomerized sugar solution. Method of manufacturing liquid. 2. Isomerize glucose by allowing glucose imerase to act on the glucose-containing sugar solution (by adding bacterial enzymes or immobilized enzymes to the glucose-containing sugar solution when producing an isomerized sugar solution containing glucose and fructose) Let it work,
Then, the obtained isomerized sugar solution is passed through an ultrafiltration membrane to separate the above-mentioned bacterial enzyme or immobilized enzyme and glucose imerase eluted from it from the isomerized sugar solution, and the concentrated bacterial cells obtained are obtained. An isomerized sugar solution containing an enzyme or immobilized enzyme and glucose imerase eluted therefrom is repeatedly circulated to the isomerization reaction step of the glucose-containing sugar solution and reused. manufacturing method.