JP2008237055A - Method for producing rice saccharified liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rice saccharified liquid for remarkably improving the saccharification efficiency of rice, by carrying out a pretreatment with an acid and a high-temperature and a high-pressure when the rice saccharified liquid is produced with a normal enzyme. <P>SOLUTION: The method for producing the rice saccharified liquid is carried out by introducing rice flour and water in 1:(1.5-2.5) mixing ratio (weight ratio) into a vessel, mixing and stirring both, then adding hydrochloric acid to the mixture liquid in the vessel, regulating the pH to 1.5-2.5, subsequently conducting a pretreatment of heating the mixture liquid, after the acid treatment in a pressurized vessel at a temperature within the range of 100-130°C for 15-25 min, and then carrying out saccharification with the enzyme. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a saccharified solution of rice, and more particularly, to a method for producing a saccharified solution of rice having high saccharification efficiency in a saccharified solution manufacturing step prior to ethanol production.

  In recent years, as part of measures to prevent global warming, there has been an increasing interest in ethanol, especially bio-derived ethanol, and the development of vehicles that use ethanol as fuel, as well as rising prices for raw corn and sugarcane. Is new to memory.

  Rice is a raw material for sake and is a familiar material for fermentation, but it is more expensive than corn and sugarcane, has a higher protein content than corn, and has a high gelatinization property when heated. As a result, its utilization as a raw material for industrial ethanol production was delayed.

  The ethanol production process includes a saccharification process in which a raw material containing a high molecular weight starch is mainly hydrolyzed into a sugar having a low molecular weight such as glucose, and a fermentation process in which ethanol is produced from glucose by yeast. As the saccharification step, an acid saccharification method in which hydrolysis is performed using an acid and an enzyme saccharification method in which hydrolysis is performed using an enzyme are known.

  In addition to producing alcohol as in the present invention, saccharification of rice is also performed to produce sweeteners such as starch syrup (the main ingredient is maltose in which two glucoses are combined). A technique is disclosed.

  Patent Document 1 discloses a technique for obtaining glucose in a high yield by promoting a saccharification reaction with a complex enzyme agent having a novel activity.

Moreover, in patent document 2, water is added to raw rice, a high temperature high pressure process is performed for 115 to 125 degreeC and 1 to 6 minutes, and starch is gelatinized, Then, amylase is added and homogenized, and the effect | action of an enzyme is heightened. And a technique for producing a sugar solution by saccharifying in a short time and then inactivating the enzyme immediately thereafter.
JP-A-6-62882 JP 2003-250485 A

  However, in the technique described in Patent Document 1, it is necessary to produce or purchase a special complex enzyme agent. In order to produce a complex enzyme agent, a nitrogen source and a carbon source are required, and further, temperature control and pH control must be performed for 2 to 4 days for the culture. Moreover, after culture | cultivation, centrifugation, disinfection, etc. must be performed and collection | recovery work must also be performed, and there exists a problem that an effort and expense start.

  In the technology of Patent Document 2, it is necessary to ensure fluidity with respect to α starch having strong gelatinization, and 2 to 4 times as much water as batch type and 8 to 12 times as much water as continuous type is added to the rice capacity. There must be.

  Then, the subject of this invention is the manufacturing method of the rice saccharified liquid which improves the saccharification efficiency of rice remarkably by performing the pretreatment of an acid and high temperature / high pressure when manufacturing rice saccharified liquid using a general enzyme Is to provide.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
After mixing and stirring rice flour and water in a container at a predetermined mixing ratio, hydrochloric acid is added to the mixture in the container to adjust the pH to 1.5 to 2.5, and then mixing after acid treatment A method for producing a rice saccharified solution, comprising pretreating the solution in a pressure vessel at a temperature of 100 to 130 ° C for 15 to 25 minutes, and then performing saccharification with an enzyme.

(Claim 2)
The method for producing a rice saccharified solution according to claim 1, wherein the heating temperature in the pretreatment is 110 to 125 ° C.

(Claim 3)
The method for producing a rice saccharified solution according to claim 1 or 2, wherein the heating time in the pretreatment is 18 to 22 minutes.

(Claim 4)
The method for producing a rice saccharified solution according to claim 1, 2, or 3, wherein the mixing ratio (weight ratio) of rice flour and water is 1: 1.5 to 2.5.

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing rice saccharified liquid using a general enzyme, the manufacturing method of the rice saccharified liquid which improves the saccharification efficiency of rice markedly by performing pretreatment of acid and high temperature and pressure is provided. can do.

  Hereinafter, preferred embodiments of the present invention will be described.

(Pretreatment process)
Normally, when rice starch is converted to glucose using an enzyme, the efficiency of glucose recovery is poor. This is because starch in rice exists as β starch having low mobility. In this invention, it changes from beta starch to alpha starch by performing heat processing as pre-processing which performs enzyme treatment, and it becomes easy to decompose | disassemble the starch in rice by improving the motility. On the other hand, α-starch rice is highly viscous, and when it becomes pasty, the enzyme is less likely to act. Therefore, by adding an acid and carrying out at low pH, it is prevented from becoming pasty (gelatinization) and the fluidity of the pregelatinized starch is enhanced.

  When the acid treatment or the heat treatment of the present invention is performed, the enzyme treatment is performed while maintaining the starch at 60 ° C. or higher so that the starch is not β-ized, thereby increasing the glucose recovery efficiency and improving the rice saccharification efficiency. .

  The first step in the method for producing a rice saccharified solution of the present invention is a step of introducing and mixing and stirring rice flour and water in a container at a predetermined mixing ratio.

  The mixing ratio (weight ratio) of rice flour and water is preferably 1: 1.5 to 2.5, more preferably 1: 1.2 to 2.2. When the mixing ratio (weight ratio) exceeds 1: 2.5, the enzyme reaction effect decreases, which is not preferable. When it is less than 1: 1.5, the concentration of the resulting sugar solution decreases, which is not preferable.

  Examples of the container used in this step include a cylindrical container (about 10 L) having acid resistance and heat resistance.

  The next step is a step of performing an acid treatment for adjusting the pH to a range of 1.5 to 2.5 by adding hydrochloric acid to the mixed solution in the container.

  The reason for using hydrochloric acid for the acid treatment is that it is preferable for alcohol fermentation (ethanol production) after the saccharification step. For example, when sulfuric acid is used, sulfur is contained in the obtained saccharified solution, and this sulfur is not preferable because it inhibits alcohol fermentation.

  In the present invention, the pH is adjusted to a range of 1.5 to 2.5, but if the pH is less than 1.5, it is not preferable because the production process needs to be resistant to strong acid, and the pH is 2 If it exceeds .5, the effect of preventing gelatinization of pregelatinized rice is small, which is not preferable.

  In the present invention, a preferred pH is in the range of 1.6 to 2.4, and a more preferred pH range is in the range of 1.8 to 2.2.

  The next step is a step of heating the mixed solution after acid treatment in a pressure vessel at a temperature of 100 to 130 ° C. for 15 to 25 minutes.

  When the heating temperature is less than 100 ° C., it is not preferable since the pregelatinization of starch does not proceed sufficiently, and when the heating temperature exceeds 130 ° C., it is not preferable because the manufacturing process must be pressure resistant. The heating temperature is preferably 110 to 125 ° C, more preferably 120 to 122 ° C.

  Also, if the heating time is less than 15 minutes, starch is not sufficiently converted to gelatin, and if it exceeds 25 minutes, there is no further effect, and energy in the production process is wasted. It is not preferable. The heating time is preferably 18 to 22 minutes.

  By heating, it becomes a high temperature and high pressure environment, and the motility can be enhanced by changing the starch in rice from β starch to α starch. Moreover, since pH is adjusted to the range of 1.5-2.5, it can prevent that gelatinized rice gelatinizes strongly.

  An autoclave is preferably used as the pressure vessel for performing the high-temperature and high-pressure treatment.

  In this invention, after completion | finish of reaction, it is preferable to use for an enzyme saccharification process in the state which hold | maintained the temperature at about 60 degreeC so that the starch in rice flour may not be beta-ized again.

  In the present invention, the mixing / stirring step, the acid treatment step, and the heat treatment step are referred to as pretreatment, and by performing this step as a pretreatment for a normal saccharification step, the saccharification efficiency of starch into glucose is greatly improved. Can be made.

(Saccharification process)
As described above, the pH of the pretreated rice flour solution is neutralized to the optimum pH of the enzyme used for the primary enzyme reaction. For neutralization, an aqueous NaOH solution or the like is preferably used. At this time, it is preferable to keep the temperature from 50 to 60 ° C. or lower.

  Next, a liquefied enzyme is added and mixed roughly, and then a primary enzyme reaction (starch liquefaction) is performed while heating and stirring.

  Examples of the enzyme used for liquefaction of starch include α-amylase and β-amylase. Here, α-amylase is preferably used.

  Next, after cooling in an aseptic state, the pH is adjusted to the optimum pH for the secondary enzyme reaction (starch saccharification), and the secondary enzyme reaction is performed while adding the enzyme and stirring. Examples of the saccharifying enzyme used for saccharification of starch include gluczyme, protease, lipase and the like.

  The enzyme reaction is performed for a predetermined time, the enzyme is deactivated as necessary, and the saccharification step is completed.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited by this Example.

Example 1
(Pretreatment: acid treatment / heat treatment)
After 1000 g of rice flour and 2000 g of water (rice: water = 1: 2) were put in a container and stirred, the pH of the rice-containing flour solution was adjusted to 2.0 with HCl (6 mol / L), and the autoclave was 121 ° C., 20 Heated for minutes.

  After completion of the reaction, it was subjected to the enzymatic saccharification step while maintaining the temperature at around 60 ° C. so that the starch in the rice flour was not β-ized again.

(Saccharification process)
After the pretreatment, if the total volume was reduced, ion exchange water was replenished.

  The pH of the pretreated rice flour solution was adjusted to 5.8 with an aqueous NaOH solution (10 mol / L).

  At this time, the temperature was kept at 50 to 60 ° C. or less, and a large lump was loosened and stirred with a previously sterilized spoon, and 0.05 wt% of liquefying enzyme (amylase RG-IIG) was added to the raw rice flour.

  Set a stirring blade and lid (both sterilized), place on a heater, fix the stirrer and stirring rod, set a thermocouple, turn on the data logger, and stir at 200 rpm while measuring the temperature. However, it heated to 95-100 degreeC and hold | maintained for 60 minutes.

  Remove the stirring blade and lid, cool to 60-65 ° C under aseptic conditions, adjust the pH to 4.5 with HCl, add Gluczyme AF-6 (Amano), Protease N “Amano”, Lipase “Wako” 0.07 wt% was added with respect to each raw rice flour.

  Place the reaction vessel on the heater again, close the lid and firmly fix the stirrer and stirrer blade, set the thermocouple, hold at 58 ° C and 200 rpm, hold for 20 hours, and complete the saccharification process And the glucose concentration of the saccharified solution was measured.

  The glucose concentration is measured by high performance liquid chromatography (HPLC LC-8010, manufactured by Tosoh Corporation), and the recovery rate is expressed as (glucose concentration in saccharified solution) / (total sugar amount in rice starch).

(Comparative Example 1)
In Example 1, the same enzymatic saccharification step as in Example 1 was performed without performing pretreatment.

(Comparative Example 2)
Under the conditions of Example 1, without performing pH adjustment with hydrochloric acid, only the heat treatment was performed to carry out the enzymatic saccharification step.

(Comparative Example 3)
Under the conditions of Example 1, a pretreatment was performed with a heating time of 5 minutes, and an enzymatic saccharification step was performed.

(Comparative Example 4)
Under the conditions of Example 1, a pretreatment was performed at a heating temperature of 95 ° C., and an enzymatic saccharification step was performed.

  The results of the above experiment are shown in Table 1.

  From Table 1, it can be seen that Example 1 has a higher sugar recovery amount and higher recovery rate than Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4.

Claims (4)

  After mixing and stirring rice flour and water in a container at a predetermined mixing ratio, hydrochloric acid is added to the liquid mixture in the container to adjust the pH to 1.5 to 2.5, and then mixing after acid treatment A method for producing a rice saccharified solution, comprising pretreating the solution in a pressure vessel at a temperature of 100 to 130 ° C for 15 to 25 minutes, and then performing saccharification with an enzyme.   The method for producing a rice saccharified solution according to claim 1, wherein the heating temperature in the pretreatment is 110 to 125 ° C.   The method for producing a rice saccharified solution according to claim 1 or 2, wherein the heating time in the pretreatment is 18 to 22 minutes.   The method for producing a rice saccharified solution according to claim 1, 2, or 3, wherein the mixing ratio (weight ratio) of rice flour and water is 1: 1.5 to 2.5.