JPS5953040B2 - Manufacturing method of sugar solution - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for acid saccharification of cellulose.

A huge amount of 40 billion tons of cellulose, ie, cellulose, is produced as a by-product every year, but cellulose has poor degradability and is mostly disposed of unused.

Acid saccharification methods and enzymatic saccharification methods have been attempted as methods to utilize this huge amount of unused cellulose as an effective resource, but these methods have not yet been implemented industrially.

The acid saccharification method of cellulose is performed using 0.2 to 1.0% dilute acid.
A dilute acid saccharification method in which saccharification is performed at a temperature of 00 to 240°C and a method in which saccharification is performed with concentrated sulfuric acid of 50% or more are known, but either method involves radical hydrolysis and results in cellulose decomposition products. The saccharification rate is 4 due to excessive decomposition of glucose.
It is as low as 5 to 55%, and the overly decomposed products of glucose contained in the saccharified solution are harmful to microorganisms, so they cannot be used as a carbon source for fermentation.

As a result of intensive research to improve the conventional drawbacks of the acid saccharification method, the present inventors acetylated cellulose with acetic acid, which can be assimilated by microorganisms, and destroyed the microcrystalline structure of cellulose. We have developed a method for producing a sugar solution suitable as a fermentation raw material using cellulose as a raw material in high yield without overly decomposing sugar by hydrolyzing mineral acid and acetic acid as catalysts.

The method of the invention consists of destroying the microcrystalline structure of cellulose and then hydrolyzing it using mineral acids and acetic acid as catalysts.

Cellulose or cellulose-containing substances used in the present invention include general papers such as old newspapers and magazines, this material,
wood chips, sawdust), rice husks, soybean waste, straw,
Any material containing cellulose, such as agricultural waste such as bagasse, linters, cotton, and pulp, can be used without being restricted by its origin.

As a method for destroying the microcrystalline structure of the cellulose of the present invention, acetylation with acetic acid, which can be assimilated by microorganisms, is preferable, but conventionally known ball mill destruction methods, high-temperature steam methods, etc. may also be used.

The cellulose acetylation method for destroying the microcrystalline structure of cellulose involves adding 5 to 1 part of an acetylation mixture to 1 part of cellulose.
It is carried out according to the usual liquid phase acetylation method in which 0 part is added and acetylated.

The acetylation mixture used for acetylation of cellulose consists of an acetylation main agent,
It consists of a catalyst and a diluent, and the main acetylation agent is acetic anhydride,
Acetyl chloride, ketene, etc. are used in an amount of 1 to 6 parts per 1 part of cellulose.

The catalyst is sulfuric acid, perchloric acid, zinc chloride, zinc acetate, potassium acetate, etc., and is 0.01% per part of cellulose.
~0.15 part is used.

Although the diluent is not necessarily required, it is desirable to add it so that the concentration of cellulose in the acetylation reaction solution is 10 to 40%.

Acetylation is carried out using an acetylation mixture of 5 to 10 parts per part of cellulose, for example, acetic anhydride:acetic acid:sulfuric acid (1:1:0).
, 1) or acetic anhydride: methylene chloride: sulfuric acid (1: 1,
5: 0.003) etc., and the reaction is carried out at a temperature of 40 to 130°C, and the reaction time varies depending on the reaction temperature.
At 5℃, ``is'' 4 days, at 60℃, ``is'' 1 day, and at 100℃, ``is 1''.
~2 hours, 20-30 minutes at 120°C.

Acetylation of cellulose is to destroy the microcrystalline structure of cellulose, and since it is acetylated from the non-crystalline structure of cellulose, if the acetylation is insufficient, the microcrystalline structure remains, leading to saccharification. It is desirable to introduce 2.0 mol or more of acetyl group per 1.0 mol of glucose, since this will reduce the ratio.

Furthermore, acetolysis can be carried out by raising the temperature during acetylation, but since this requires the use of a large amount of the acetylation base agent, it is undesirable to carry out acetolysis more than necessary.

Although the microcrystalline structure of the acetylated cellulose thus obtained has been destroyed, it is insoluble in water as it is.

There is no need to pay particular attention to other methods that destroy the microcrystalline structure of cellulose, such as the ball mill method and the high-pressure steam method; conventional methods may be used.

In the hydrolysis method of cellulose whose microcrystalline structure has been destroyed, the treated cellulose or its contents are hydrolyzed with 3 to 15% mineral acid and acetic acid.

As the mineral acid, sulfuric acid is preferable, and hydrochloric acid, nitric acid, etc. are also used alone or in combination.

Hydrolysis is significantly accelerated by allowing 10 to 20% or more of these mineral acids and acetic acid to coexist in the decomposition solution.

To hydrolyze with only mineral acid, add 5 to 10 parts of mineral acid to 1 part of cellulose whose crystal structure has been destroyed, and add 100 to 1 part of mineral acid.
Must be heated at 50° C. for 10-24 hours.

On the other hand, when acetic acid coexists, 10
~30 minutes is enough.

As a result, cellulose is hydrolyzed to more than 60% glucose and a small amount of cellooligosaccharide.

In addition, when the acetylation method is used, a small amount of acetylglucose and acetylcellooligosaccharide are produced in addition to glucose.

In the case of the acetylation method, sufficient mineral acid for hydrolysis and acetic acid, which is a decomposition accelerator, are present in the acetylated product after acetylation, so the acetylated product can be used as it is or by adding an appropriate amount of water. When hydrolyzed at 110-140°C for 10-30 minutes, glucose is almost completely hydrolyzed, and glucose,
Produces acetylglucose, cellooligosaccharide (acetylated).

In the acetylation method, the decomposition solution (sugar solution) contains acetylglucose acetate in addition to glucose, but these are not only microorganisms of the genus Previbacterium used for fermentation of amino acids such as glutamic acid and lysine, but also microorganisms of the genus Satucharomyces. The saccharified liquid obtained by the acetylation method is suitable as a raw material for fermentation because it is assimilated and utilized by microorganisms belonging to yeast, cellulase-producing bacteria of the genus Seribibrio, and oil-producing bacteria of the genus Aureobacidum.

In the saccharified solution produced by the acetylation method, free acetic acid has a ratio of 0.5 to 2.0 relative to glucose, but it is easy to separate acetic acid from the sugar solution, and the acetic acid in the sugar solution can be converted to ethyl acetate. - If the azeotrope is distilled after extraction with a benzene mixed solvent etc., acetic acid can be recovered with a yield of 99.0% or more, and this recovered acetic acid is reused as the main acetylation agent and recycled.
Therefore, sugar solution can be produced at low cost.

As mentioned above, the cellulose saccharification method of the present invention destroys the microcrystalline structure of cellulose and then hydrolyzes it using mineral acids and lower fatty acids as catalysts, so it does not require extreme hydrolysis conditions as in conventional methods. Therefore, the yield of saccharification is 80
It is an excellent cellulose saccharification method that has a high percentage of over 100% and produces almost no by-products of over-decomposition of the produced sugars. It is used as it is as a sugar solution for fermentation such as amino acid fermentation and yeast cell production.

The present invention provides an industrial means for utilizing cellulose, which is a vast unused resource, as an effective resource.

This will be explained in detail in the examples above.

Example 1 10 ml of an acetic acid mixture having a composition of acetic anhydride:acetic acid:sulfuric acid=1:1:0.1 was added to 2.0 g of Whatman Cellulose Powder CC-41, and an acetylation reaction was carried out at 60°C for 3 hours.

An equal amount of water was added to this and the mixture was thermally decomposed at 120°C for 30 minutes.

Acetic acid in this saccharified solution was extracted with ether, and insoluble residues were removed to obtain a sugar solution.

Theoretically, sugar can be obtained by multiplying the weight of raw material cellulose by 1.11, but if the decomposition rate is expressed as the ratio of the obtained water-soluble sugar to this theoretical value, the decomposition rate of the above sugar solution is 98. ．．
5%, of which 80.1% glucose, 8.4% acetylglucose, 9.7% cellobiose and other acetylcellobiose.

Example 2 Whatman Cellulose Powder CC412, Og Add 10 ml of the same acetylated mixture as in Example 1, and heat at 45°C for 24 hours.
Time acetylation was performed.

After the reaction, 3 times the amount of water was added and centrifuged to separate the insoluble fraction.

When this was thoroughly washed with water and dried under reduced pressure, 2.9 g of acetate was obtained.

2.0%, 4.5%, 9.0% of this acetide 10 times the amount
, 1.8% sulfuric acid was added and hydrolyzed at 120°C for 30 minutes, the decomposition rates were 13.3%, 31.1%, and 98%, respectively.
．． 0% and 92.5%.

In addition, when hydrolyzing with the above 4.5% sulfuric acid, acetic acid is
%, 30%, and 50% coexisting and hydrolyzed at 120°C for 30 minutes, the decomposition rates were 73.8%, 99.1%, and 1
It was 00%.

Example 3 To 2.0 g of rice hulls, add 10 ml of the same acetylated mixture as in Example 1.
1 was added and acetylation reaction was carried out at 45°C for 24 hours, and an equal amount of water was added thereto and hydrolysis was carried out at 120°C for 30 minutes.

The amount of reducing sugar and total sugar (in terms of glucose) in the saccharification solution from which insoluble residues were removed was measured using the Somogyi-Nelson method and the phenol-sulfuric acid method, and the decomposition rate was determined from the ratio of raw rice hull to sugar, which was 43% as reducing sugar. , 66.4 as total sugar
%Met.

Example 4 50 ml of the same acetylation mixture as in Example 1 was added to Whatman Cellulose Powder CC-41Log and acetylated at 60°C for 3 hours.

An equal amount of water was added to this and hydrolyzed at 120°C for 30 minutes, and the decomposition liquid was washed with ammonia.

A glutamic acid production medium having the composition shown in Table 1 was prepared using this cellulose saccharified liquid as the main carbon source.

This medium was dispensed in 30 ml portions into 500 ml shaking flasks, sterilized at 115°C for 10 minutes, and after cooling, Brevibacterium flavum ATCC 14067, which had been slant-cultured on a bouillon agar slant medium at 30°C for 24 hours, was added. One platinum loopful was inoculated and the flask was cultured with shaking at 30°C for 48 hours (shaking width: 7.0 cm, 115 osil, /min).
.

The amount of glutamic acid in the culture solution was measured and was 1.5g.
/di.

Furthermore, the amounts of glucose, acetylglucose, and acetic acid remaining in the culture solution were determined to be 0.1 g/dl or less, respectively.

Claims (1)

[Scope of Claims] 1. A method for producing a sugar solution using cellulose as a raw material, which comprises destroying the microcrystalline structure of cellulose and then hydrolyzing it using mineral acid and acetic acid as catalysts. 2. The method for producing a sugar solution according to claim 1, wherein the microcrystalline structure of cellulose is destroyed by using an acetylating agent.