JP5241213B2 - Production method of ethanol from brown rice - Google Patents

Description

The present invention relates to a method for obtaining high-concentration ethanol by using brown rice as a raw material and fermenting it by liquefaction.

“Bioethanol” refers to ethanol obtained by fermenting plant resources (biomass resources) such as sugarcane and corn and then distilling them.

Bioethanol raw materials are roughly divided into starchy raw materials and sugar raw materials. The starchy raw material is a cereal containing starch, for example, cereals such as corn, wheat and rice, and potatoes such as sweet potato and potato. Typical sugar raw materials are sugarcane and sugar beet.

Most of these starchy raw materials and sugar raw materials can be used as food or feed. On the other hand, there are great expectations for ethanol production technology using non-edible cellulosic biomass (such as crop foliage, forest residue, grass and fast-growing trees), but the hurdles to industrial production are high.

The bioethanol production process basically includes the same steps as distilled spirits including shochu. That is, pulverization / saccharification of raw materials (not required for sugar raw materials), fermentation / distillation.

The most energy-intensive process in these processes is the distillation process, and how to increase the ethanol concentration in the fermentation stage is one of the technical problems.

In addition, ethanol production using rice, which is one of starchy raw materials, is generally performed in sake brewing or rice shochu production. However, it is necessary to remove the wax portion of brown rice by whitening in the raw material processing step. Attempts have been made to ferment brown rice as it is. However, as described in JP-A No. 54-117096, brown rice is hard to use as it is, and the utilization rate of raw materials is reduced. , Pulverization, scratching, and the like were preferred (Patent Document 1).

JP 54-117096 “The Front Line of Illustrated Bioethanol” Yasuhiro Daisei / Mitsui & Co., Ltd.

When ethanol fermentation is performed using brown rice as a raw material, brown rice is very hard compared to white rice and is difficult to process. In addition, the rice grains are difficult to dissolve in the moromi during fermentation, and the fermentation is difficult to proceed. In order to solve these problems, in general, pretreatment is carried out such as shaving a part of the brown rice surface, causing germination, or treatment with each enzyme such as cellulase, protease, and amylase. However, even if these methods are used, problems such as cost and time required for pretreatment and a decrease in raw material utilization rate remain. Patent Document 1 describes that it is preferable to grind brown rice. However, it is actually difficult to grind brown rice to a high raw material utilization rate, and no examples have been reported so far. .

As a result of intensive studies, the present inventors have found that the above problems can be solved by emulsifying and liquefying brown rice without any pretreatment such as shaving the surface of brown rice and optimizing the liquefaction treatment. It was. That is, the method for producing ethanol using brown rice as a raw material according to the present invention is as follows.
Obtaining a soaking brown rice and brown rice is immersed in water,
Step (II) of adding water to the soaked brown rice and grinding to obtain a brown rice emulsion,
Adding a heat-resistant liquefied enzyme to the brown rice emulsion and performing a liquefaction reaction at 100 ° C. for 10 minutes to obtain liquefied brown rice (III);
Step (IV) for obtaining mash by adding brown rice bran to the liquefied brown rice,
A step (V) of fermenting the moromi to obtain ethanol;
Including
In the step (II), (a) the first stage of grinding so that the grain size of the brown rice after grinding becomes 1 to 2 mm, and (b) further grinding the brown rice obtained in the first stage. Including a second step of reducing the particle size after grinding to 5 μm or less,
In the step (II), the ratio of water to the final brown rice weight is 140 to 170%.

  Conventionally, in ethanol production using brown rice as a raw material, there have been problems such as slow fermentation or insufficient progress, and low raw material utilization rate. A concentration of ethanol could be obtained. In addition, the pretreatment process that has been necessary in the past can be omitted, and work efficiency and cost reduction have been realized.

(1) Foreign matter removal

Any brown rice may be used as long as it contains starch. As edible brown rice, there are standards such as first grade, second grade, and third grade, but in the present invention, non-edible ones such as non-standard ones, blue rice, and immature grains can be used. In addition, the use of such raw materials is advantageous in terms of social and economic aspects.

There are cases where stones and the like are mixed in the brown rice that has been brought in, but these mixed foreign substances may be removed by a general method. For example, it is desirable to use a general stone remover.

(2) Immersion

  Brown rice may be immersed by a generally used method. In other words, water may be added from the previous day and immersed overnight. The temperature of the immersion water is preferably low temperature and more preferably 10 ° C. or less in order to prevent propagation of various bacteria. In addition, since brown rice has a slower water absorption rate than white rice, it is desirable that the immersion time be longer than that of white rice.

(3) Emulsification

  In order to liquefy brown rice, it is necessary to grind and make an emulsion. For the grinding, a commonly used grinding machine can be widely used. For example, Supermass colloider manufactured by Masuko Sangyo Co., Ltd. K. It can be performed using a My colloider or the like. Grinding is performed while adding water to the soaked brown rice.

Grinding is performed in two stages, and finely pulverized in the first stage, and finer particles can be obtained in the second stage, so that the liquefaction after emulsification and the subsequent fermentation can be performed. Go smoothly. In the first stage grinding, the particle diameter is desirably 5 mm or less, and more desirably 1 to 2 mm. The particle size in the second stage is desirably 100 μm or less, more preferably 50 μm or less, and further preferably 5 μm or less. In addition, although it is desirable to finally make hydration 120-200% by the brown rice weight ratio, it is more preferable to obtain an emulsion as 140-170%, More preferably, 145-155%.

(4) Liquefaction

  The liquefaction method is not particularly limited. For example, the liquefaction method can be performed by heating the emulsion obtained in the previous step to a temperature of about 100 ° C. and allowing a thermostable liquefying enzyme to act on the emulsion. The kind of heat-resistant liquefying enzyme in this case is not particularly limited, and for example, kristase (manufactured by Daiwa Kasei Co., Ltd.) can be used. The brown rice emulsion can be supplied according to a conventional method for producing liquefied white rice. That is, at the time of grinding, a heat-resistant liquefied enzyme solution and warm water (about 60 to 70 ° C.) having a predetermined concentration are simultaneously supplied to the grinding device at a constant flow rate, and a wet pulverized emulsion containing the enzyme solution (about 45 ° C) may be continuously supplied. The emulsion thus supplied is instantaneously heated (90 to 110 ° C.) by heat exchange or steam injection and injected into the reaction tank. After performing the liquefaction reaction for 5 to 30 minutes, the liquefied liquid in the tank may be cooled, or the reaction temperature may be maintained in the line and then injected into the tank. At this time, the temperature of the liquefaction liquid may be 50 to 60 ° C., and the saccharification reaction may be performed for 3 to 4 hours by adding brown rice bran described later. However, the saccharification here is not intended to completely saccharify the liquefied liquid, but mainly to blend brown rice bran with the liquefied liquid, but part of the liquefied liquid is saccharified. For convenience, it is called a saccharified solution. The saccharified solution is cooled and then transferred to the fermentation tank (FIG. 1).

The koji ratio (ratio of koji with respect to the weight of the brown rice in the whole charge) is preferably 5 to 25%, more preferably 10 to 20%. Various enzyme activities, especially glucoamylase activity, can be adjusted by adding commercially available brewing enzyme agents, and it is possible to supplement the whole activity with enzyme agents without using any koji. It is.

In addition, by heating the emulsified liquid to around 100 ° C. and allowing it to act on a heat-resistant liquefied enzyme, the starch of brown rice is gelatinized and the liquefaction of the gelatinized starch is continuously performed, resulting in high viscosity The difficulty in handling gelatinized brown rice can be avoided.

(5) Brown rice cake

  As the rice bran, normal white rice bran can be used, but it is desirable to use brown rice bran to reduce raw material and production costs. Koji making using brown rice may be performed in accordance with a general method for making white rice koji. For example, rice bran may be used in the steaming process, or a continuous steamer may be used. In any case, considering that brown rice is harder than white rice, it is desirable to set the steaming time longer than that for white rice. That is, it is desirable that the steaming time of white rice is approximately 40 to 50 minutes, while that of brown rice is 55 to 70 minutes.

  After the temperature of the steamed brown rice is cooled to 30 to 40 ° C., the koji mold is sprayed. After spraying the seed gonococcus, “turning back” is performed after 17 to 24 hours while maintaining the product temperature at 28 to 33 ° C. Cut-back is an operation performed for the purpose of dispersing rice grains by sticking together to form a nodule for drying after spraying the seed gonococcus.

  After turning back, brown rice bran is obtained by further culturing for 25 to 30 hours while maintaining the product temperature at 33 to 38 ° C. The obtained brown rice bran may be used immediately, may be used after storage (3 to 9 days), or may be dried and used after long-term storage.

(6) Fermentation

  At first, the “original stand” (preparation of a liquor mother) is performed, but yeast is added to the above raw materials so as to be 500,000 to 2,000,000 cells / ml, and the product temperature is set to 22 to 27 ° C. Fermented on the day. The yeast is not particularly limited as long as it has alcohol fermentability, but it is desirable to use Saccharomyces cerevisiae, and it is more preferable to use sake yeast having excellent alcohol fermentability. Moreover, although there is no restriction | limiting in particular in the kind of sake yeast, The productivity of ethanol can be improved by using an alcohol tolerance mutant.

  Subsequently, it is possible to carry out a three-stage preparation of initial addition, middle addition, and distillation, which is generally performed in sake brewing, or it may be omitted in one or two stages. In the case of three-stage charging, the percentage of the liquor is preferably 5 to 20%, and in the case of one-stage or two-stage charging, it is preferably 10 to 30%. The product temperature at the first addition is preferably 18 to 22 ° C. From the second to third days after the distillation, the product temperature is increased by 1 ° C per day and finally maintained at 23 to 27 ° C for fermentation. It should be continued. Although the final product temperature can be further increased, in this case, the volatilization of ethanol increases, so that the ethanol recovery rate can be improved by taking measures such as sealing the fermentation tank and recovering the steam.

What is necessary is just to complete | finish fermentation by confirming that fermentation fully progressed and the raise of ethanol concentration stopped. The fermentation period may be 20 to 28 days after the distillation.

  The mash obtained finally can be squeezed as necessary, and an ethanol solution can be obtained by solid-liquid separation. Moreover, ethanol can also be recovered by distillation of the mash as it is without pressing.

Example

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated in detail, this invention is not limited to these.

Brown rice soaking Brown rice is so-called non-standard (non-standard) and contains a large amount of immature grains such as blue rice and small grains. This is because it is socially and economically advantageous to use an edible raw material instead of edible rice as a raw material for bioethanol. This unpolished rice was passed through a stone remover GA30RB (2) (manufactured by Satake Co., Ltd.) to remove unnecessary things such as stones, seeds, berries, garbage, rice husks.

  After finishing this treatment, 15,000 kg of brown rice was immersed the day before liquefaction. Brown rice was put in a tank, and well water cooled to 10 ° C. was poured therein and immersed overnight while maintaining the product temperature.

Emulsification, liquefaction and saccharification reaction After draining water from the tank, well water was injected again so that the ratio of water to be drawn (ratio of water weight to brown rice weight) was 150%. Two types of grinders were connected to the tank in series, and grinding was performed in two stages. The first stage uses a super mass collider MKZA-12 series MK2A12-20J type (manufactured by Masuko Sangyo Co., Ltd.), using a grinding stone on both the fixed side and the rotating side, setting the clearance to 1.25 mm, and first polishing roughly Crushed. Subsequently, T. K. Particles after milling using a Mycoloider S type (manufactured by Primics Co., Ltd.) using a metal blade on both the fixed and rotating sides, and adjusting the clearance by looking at the state of the emulsion at the second stage outlet. An emulsion was obtained with a diameter of 5 μm or less.

The obtained emulsion was heated to 100 ° C. with a steam blowing type continuous heating device in the presence of a heat-resistant liquefying enzyme agent (Chrytase: manufactured by Daiwa Kasei Co., Ltd.), and immediately held for 10 minutes to 50 ° C. It cooled to -60 degreeC and 42,000 kg of liquefied brown rice was obtained. Thereafter, 3,000 kg of brown rice bran produced according to Example 3 was added, and a saccharification reaction was performed for 3 to 4 hours to obtain a brown rice saccharified solution.
Brown rice koji making

  3,000 kg of soaked brown rice obtained in the same manner as in Example 1 was steamed for 60 minutes with a continuous steaming machine (manufactured by Nagata Brewing Machinery Co., Ltd.) to obtain steamed brown rice.

After cooling this to 30 to 40 ° C., seed gonococcus was sprayed. After spraying the seed gonococcus, the product temperature was maintained at 30 ° C., and turning was performed after 20 to 22 hours. After turning over, the product temperature was maintained at 34 to 36 ° C. and further cultured for 25 to 30 hours to obtain brown rice bran.

The brown rice bran was used after being stored for 3 to 9 days as needed.
fermentation

  First of all, we made a stand (manufacture of a sake mother). 9,000 kg of the brown rice saccharified solution obtained in Example 2 was kept at 25 ° C. and charged into a fermentation tank, and further, No. 901 yeast was added so as to be 1,000,000 cells / ml. The product temperature was lowered by 2 ° C. per day and cultured for 2 days to complete the liquor mother. The final product temperature was 20 ° C.

Next, 10,000 kg of the brown rice saccharified solution obtained in Example 2 was added while maintaining the product temperature at 20 ° C. Two days later, 10,000 kg of brown rice saccharified solution was added for mediation. The next day, 5,200 kg of brown rice saccharified solution was added for distillation. During this time, the product temperature was maintained at 20 ° C. After 3 days, the product temperature was increased by 1 ° C. per day and kept at 25 ° C. until the end of fermentation.
The ethanol concentration after the end of fermentation was about 15%.

  The method of the present invention is very useful as a production method of bioethanol using non-edible plant raw materials because ethanol can be produced using non-standard (non-standard) brown rice as a raw material. Moreover, since the ethanol concentration obtained is as high as about 15% to 20%, it is industrially very advantageous in terms of cost in the subsequent distillation process for bioethanol production.

The manufacturing process of liquefied and saccharified brown rice is shown.

Claims (1)

Step (I) of obtaining brown rice by immersing brown rice in water;
Step (II) of adding water to the soaked brown rice and grinding to obtain a brown rice emulsion,
Adding a heat-resistant liquefied enzyme to the brown rice emulsion and performing a liquefaction reaction at 100 ° C. for 10 minutes to obtain liquefied brown rice (III);
Step (IV) for obtaining mash by adding brown rice bran to the liquefied brown rice,
A step (V) of fermenting the moromi to obtain ethanol;
Including
In the step (II), (a) the first stage of grinding so that the grain size of the brown rice after grinding becomes 1 to 2 mm, and (b) further grinding the brown rice obtained in the first stage. Including a second step of reducing the particle size after grinding to 5 μm or less,
A method for producing ethanol using brown rice as a raw material, wherein the ratio of water to the final brown rice weight in the step (II) is 140 to 170% .