JP4414837B2 - Method for producing self-digesting yeast extract - Google Patents

Description

  The present invention relates to a method for producing a self-digesting yeast extract capable of obtaining a yeast extract having a low cost, a high yield, a strong umami taste and a rich taste, and a good flavor.

Yeast extract is rich in free amino acids, peptides, saccharides, organic acids, and nucleic acid-based taste components, so it has a strong taste such as umami and richness. It has been widely used in the processed food industry, which has recently become more natural and health-oriented due to the fact that the quality of taste is similar to beef and other livestock meat extracts and that it is prepared from natural yeast and belongs to natural seasonings. Has been.
The yeast extract can be produced by acid digestion using hydrochloric acid to hydrolyze the entire cell, or by setting the conditions such as pH and temperature of the cell slurry within a specific range unsuitable for growth. Known are the self-digesting method for inducing, the enzyme decomposing method for degrading yeast cell components by adding foreign enzymes such as microorganisms and animals and plants, and various methods combining these methods.

 Among the above-described production methods, the self-digestion method is a method of degrading the intracellular components using the yeast cells' own enzymes. The yeast extract prepared by this method has a high content of free amino acids and peptides, and has a strong and heavy taste. And this method is widely used now because there are advantages such that various natural product components contained in yeast are not destroyed so much and the production cost is cheaper than the enzymatic decomposition method. However, normal live yeast cells, especially fresh cells obtained by culturing, are difficult to self-digest as they are, so pre-treatment of raw material yeast under specific conditions or addition of various self-digestion promoters It is necessary to induce autolysis. For example, a method of applying mechanical stimulation such as ultra-high hydrostatic pressure treatment, ultrasonic treatment or high-pressure homogenizer treatment (for example, refer to Patent Documents 1 to 3), salt, ethyl acetate, fatty acid ester, organic acid in yeast cell slurry , Organic solvents, chitin / chitosan and the like, and methods for inducing self-digestion by adding any one of them as self-digestion promoters (for example, see Patent Documents 4 to 9) have been published.

On the other hand, the enzymatic degradation method is a method of degrading bacterial cell components by adding various foreign enzymes. This method has an advantage that the extract yield from the raw material is high depending on the kind and concentration of the added enzyme, and the extract component can be artificially controlled. However, since yeast cells are covered with a mechanically strong cell wall consisting of an insoluble mainly β-1,3-glucan matrix structure and a cell membrane located immediately inside it, enzymes such as proteases are externally applied. Can not easily penetrate into the inside of the microbial cells. As a solution to this, it is necessary to cause the yeast cells to be denatured by heating at high temperature in advance to be easily subjected to enzymatic degradation, and then to sequentially act on cell wall degrading enzymes, proteases and the like (see Patent Document 10).
JP-A-2-255059 Japanese Patent Publication No. 50-25539 JP-A-9-56361 Japanese Patent Publication No.54-13396 Japanese Patent Publication No.54-14176 Japanese Patent Laid-Open No. 55-34096 JP 59-109152 A JP-A-57-68760 JP-A-2-42953 Japanese Patent Publication No. 50-29028

 In the case of the above-mentioned self-digestion method, it is inevitable that the manufacturing process becomes complicated by adding various physical and chemical treatment steps, and the manufacturing cost is unavoidable. Labeling is also required, and its use in wider food fields may be restricted.

And since the proteolytic enzymes contained in the yeast cells are mainly acidic proteases, the components of the cells are not completely decomposed by the autolysis-only production method. Has the disadvantage of not being so expensive.
In addition, in the case of the enzymatic decomposition method, almost all of the self-digesting enzymes contained in the cells are inactivated by heating, so that these enzymes cannot be effectively used. In order to increase the extract yield from the raw material, it is necessary to add a larger amount of exogenous enzyme, which increases the production cost. Furthermore, there is also a disadvantage that the color tone of the resulting yeast extract is easily browned by an extra heating step, and the value as a product is reduced.

  The present invention has been made in view of the various problems associated with the above-mentioned self-digestion method and enzymatic digestion method, and is effective for simple self-digestion without using pretreatment of yeast raw materials or self-digestion promoters. The present invention provides a method for producing a yeast extract that is capable of further degrading bacterial cell components than enzyme degrading methods, is low in cost and high in yield, and is rich in free amino acids and peptides. And

As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that a certain amount of H ⁺ per dry cell weight of the bacterial cell using an inorganic acid is used in the yeast cell slurry to effectively induce autolysis. It has been found that it is effective to add ions to cause self-digestion. In addition, the inventors found that it is effective to self-digest the yeast cell slurry by adjusting the pH to 1.2 or more and less than 3 using an inorganic acid, and completed the present invention.

That is, the first invention of the present invention, after the yeast cells slurry 40 to 60 ° C., in the yeast cells slurry, inorganic acids, and 10~60mol added as ^{H +} ions per cell dry matter 100kg A method for producing a self-digesting yeast extract characterized by self-digesting yeast.
Moreover, after adding 10-60 mol of inorganic acids as H ^<+> ion per 100 kg of microbial cell dry matter to yeast cell slurry, 2nd invention of this invention makes yeast microbial cell slurry 40-60 degreeC, yeast, Is a method for producing a self-digesting yeast extract.

  As described above, according to the production method of the present invention, the bacterial cell component can be further decomposed than before, and the yeast extract can be produced at low cost and high yield. The yeast extract obtained by the production method of the present invention has a high content of free amino acids and peptides, has a strong taste and richness, and can be widely used in the food industry, particularly in the field of natural health foods.

 The yeast cells used in the present invention are live yeasts, and examples thereof include edible yeasts such as Saccharomyces, Hansenula and Candida. For example, Saccharomyces cerevisiae brewing yeast, baker's yeast, cultured yeast of Candida utilis, which is often used in the manufacture of yeast extract, and sugars produced as a by-product during dissolution of pulp Examples include cultured yeast of torula that uses as a nutrient source. Moreover, not only live yeast newly cultured for yeast extract production, but also waste yeast discharged to brew such as beer and sake can be used as raw materials for the method for producing yeast extract of the present invention.

 Next, the manufacturing method of the yeast extract of 1st invention of this invention is demonstrated. First, an appropriate amount of distilled water is added to the raw material yeast cells to prepare a yeast cell slurry. The concentration of the cell slurry is preferably 10 to 30 g / dl, more preferably 10 to 18 g / dl. Within this range, it is preferable because autolysis can be further promoted.

Subsequently, 10-60 mol, preferably 15-45 mol, of H ⁺ ions are added per 100 kg of the microbial cell dry matter and self-digested to the microbial cell slurry using an inorganic acid. The reason for adding H ⁺ ions is that yeast consumes H ⁺ ions and activates autolysis. By adding 10 to 60 mol, the raw yeast cells can be more completely decomposed, and a yeast extract can be produced at a low cost and a high yield.

In the production method of the present invention, an inorganic acid is used to add H ⁺ ions to the bacterial cell slurry. The inorganic acid that can be used in the present invention is not particularly limited as long as it is an inorganic acid that has been approved for use as a food production agent. For example, hydrochloric acid, sulfuric acid, phosphoric acid, and the like are preferable, and hydrochloric acid is particularly preferable.
When an inorganic acid is used, it is completely dissociated after being added to the reaction solution, so that it is possible to accurately add the amount of H ⁺ ions as calculated. On the other hand, when an organic acid is used, the release of H ⁺ ions is caused by the component composition of the reaction solution and the pH state of the solution, particularly the pK value of the organic acid itself (for example, lactate pK _a = 3.76, citric acid pK _α1 = 3.01 and malic acid pK _α1 = 3.36), and so on, so it is difficult to calculate correctly. In addition, the negative ions dissociated from the added organic acid may be adversely affected in some way to the self-digestion reaction, which is not preferable.

The amount of H ⁺ ion added is in the range of 10 to 60 mol, and more preferably 15 to 45 mol, per 100 kg of the dry cell material. If the H ⁺ ion addition amount is within this range, the yeast extract can be produced in high yield. Furthermore, the optimum H ⁺ ion addition amount varies slightly depending on the type of raw yeast, the pretreatment state of the yeast, etc., but usually, the H ⁺ ion addition amount and the obtained extract yield with respect to the yeast raw material used in advance. Can be easily determined from experimental data. In the present invention, as shown in Test Example 1 to Test Example 3 below, for example, the optimal addition amount when using Saccharomyces cerevisiae baker's yeast and marine yeast as raw materials is about 15 to 45 mol per 100 kg of cell dry matter, In particular, it was within the range of about 15 to 30 mol.

In the production method of the present invention, it is preferable to add H ⁺ ions while stirring the cell slurry. By adding H ⁺ ions while stirring, denaturation of intracellular enzymes due to excessively low pH can be prevented, and the entire yeast cell slurry can be self-digested more uniformly.

The action of this H ⁺ ion addition probably causes H ⁺ ions to enter the cell through the tunnel of the yeast cell wall, and to induce autolysis by disturbing the normal order of the yeast cells as a living organism. Therefore, it is considered that a predetermined amount of H ⁺ ion is an indispensable substance for activating the autolysis reaction.
If the predetermined amount of H ⁺ ions is not added and the yeast slurry is kept at the optimal digestion temperature for a long time, autolysis is hardly induced. For example, when distilled water was added to fresh baker's yeast to prepare a yeast slurry having a cell concentration of about 15 g / dl, the pH of the yeast slurry at this time was in a slightly acidic range of about 4.8 to 5.2. However, even if it is self-digested at 50 ° C for 24 hours, the nitrogen recovery rate from the yeast material (ratio of the total amount of nitrogen in the extract to the total amount of nitrogen in the raw yeast) is only about 14%. It was. Therefore, it was found that extraction is almost impossible without adding a predetermined amount of H ⁺ ions.

In the first production method of the present invention, unlike the usual acid treatment method, it is not always necessary to adjust the pH of the reaction solution after addition of H ⁺ ions. For example, as shown in Test Example 1 and Test Example 2 below, when H ⁺ ions in a range of 15 to 45 mol per 100 kg of dry matter of the microbial cell are added to the slurry of baker's yeast and marine yeast, respectively, the pH of the reaction solution is The pH dropped to 3.0 or less immediately after the addition of H ⁺ ions, but then gradually increased with heating, and the pH of the reaction solution after 5 hours was the pH of the solution immediately before the addition of H ⁺ ions for both baker's yeast and marine yeast. It rose within the range of about ± 0.5 and returned to the pH state before the addition of H ⁺ ions. This fact suggested that yeast must be inhaled with a certain amount of H ⁺ ions to induce autolysis. In addition, when the amount of H ⁺ ions within the above range was added, the nitrogen elution rate in each extract at the 5th reaction was still low, but if kept at the same temperature, the pH of the reaction solution at the 24th hour Although there was no significant difference from the pH at the 5th hour, the nitrogen elution rate increased greatly, and each increased to 50% or more. The umami and rich taste of the extract obtained at this time became stronger.

  When yeast is self-digested, it is preferable to warm the bacterial cell yeast slurry to 40-60 ° C. before or after the addition of the inorganic acid. By heating to 40-60 ° C., autolysis can be efficiently promoted. Furthermore, the temperature to be heated is preferably an optimum autolysis temperature within the above range. The optimal self-digestion temperature referred to here is slightly different depending on the type of raw yeast and the pretreatment state of the yeast, but usually the relationship between the reaction temperature of the self-digestion and the yield of the extract finally obtained is examined in advance, It is easily determined from experimental data. In the production method of the present invention, for example, the optimum autolysis temperature when using Saccharomyces cerevisiae baker's yeast or marine yeast as a raw material is about 50 to 55 ° C.

In addition, when heating before addition of an inorganic acid, it is especially preferable that the addition amount of H ^<+> ion is 15-30 mol per 100 kg of microbial cell dry matter. If it is 15-30 mol, a yeast extract can be manufactured with a very high yield.
In the case of heating after the addition of the inorganic acid, the temperature is raised to a predetermined temperature immediately after the addition, preferably within 2 hours, more preferably within 1 hour, particularly preferably within 30 minutes. The pH of the cell slurry immediately after the addition of a predetermined amount of H ⁺ ions is about 1.2 to 3.0, but if this is immediately heated, the pH rises and reaches around 5 relatively quickly. For this reason, there is little enzyme modification | denaturation regarding self-digestion, and the efficiency of self-digestion is high. On the other hand, if it is not immediately heated, as a result of maintaining a low pH for a long period of time, the enzyme relating to self-digestion is denatured and the efficiency of self-digestion tends to deteriorate.
Therefore, when actual production is performed in a factory or the like, it is preferable to add the inorganic acid after warming the cell yeast slurry in consideration of the fact that it takes a relatively long time for warming.

Next, the manufacturing method of the 2nd invention of this invention is demonstrated. First, a yeast cell slurry is prepared in the same manner as in the first invention. Then, an inorganic acid is added to adjust the pH to 1.2 or more and less than 3, and self-digest. By adjusting the pH to 1.2 or more and less than 3, yeast cells can be decomposed with higher efficiency.
Also in 2nd invention, it is preferable to heat a microbial cell yeast slurry to 40-60 degreeC before the addition of an inorganic acid or after addition similarly to the case of 1st invention. By heating to 40-60 ° C., autolysis can be efficiently promoted. Furthermore, the temperature to be heated is preferably an optimum autolysis temperature within the above range. In addition, when actual production is performed in a factory or the like, it is preferable to add the inorganic acid after warming the bacterial cell yeast slurry, considering that a relatively long time is required for heating.

According to the first production method or the second production method of the present invention, it is possible to prepare a high-yield yeast extract even when performing only autolysis without adding an exogenous enzyme. In this case, a high yield of yeast extract can be obtained by adding the above-mentioned predetermined amount of H ⁺ ions and holding the mixture for 5 to 24 hours at the same temperature while stirring as it is.

In the production method of the first invention or the second invention of the invention, after carrying out the above-mentioned self-digestion, one or more neutral or alkaline enzymes are further added and subjected to an enzymatic reaction to obtain yeast. It is preferable to further decompose the cells. By adding a foreign enzyme together with self-digestion, the extract yield from the raw yeast and the content of free amino acids and peptides in the extract can be further increased.
When an enzyme reaction is performed, autolysis is induced by adding and heating the above-described predetermined amount of H ⁺ ions in advance or adjusting to a predetermined pH and heating, and then the enzyme reaction is performed. By proceeding to some extent in advance, self-digestion breaks down the cells, making it easier for the proteins to be acted on by foreign enzymes, and just adding a small amount of foreign enzyme without heat-denaturing the cell slurry. Thus, yeast extract can be produced with high yield.
In this case, the self-digestion process may be within 2 to 6 hours, but after that, the pH of the cell slurry is readjusted to the optimum pH of the enzyme to be added, and one kind of predetermined neutral or alkaline enzyme, or It is preferable to add two or more types in combination and carry out the enzyme reaction for another 2 to 18 hours at the same temperature or the optimum reaction temperature of the enzyme. In this case, the enzymes contained in the cells continue to work, and the cells are further decomposed by the combined action of these enzymes and foreign enzymes. In addition, although the addition amount of a foreign enzyme is based also on the titer of an enzyme, it should just be in the 0.1 to 1.0% of range of a microbial cell dry matter.

Regardless of the origin of the animal, plant, or microorganism, the enzyme to be added can be used in the present invention as long as it is for food and has no off-flavor, and can further increase the yield of yeast extract. For example, protease P, protease A, protease S, protease N, equinezyme G, pancreatin F, papain W-40, peptidase R of Amano Enzyme Co., Ltd., actinase AS of Sanken Co., Ltd., Sankyo Co., Ltd. Examples include cochlase P, orientase 90A, orientase 10NL, orientase 22BF, and nuclease, and Alkalase 2.4L FG, flavorzyme, and neutraase 0.8L from Novozymes Japan.
If the enzyme is a protease containing a peptidase, it may be added by only one type, but if it is an endo-type enzyme, it is preferable to add two or more types of exo-type enzymes such as peptidases.
In the production method of the present invention, after self-digestion, or after further enzymatic degradation in a predetermined time, the yeast slurry is deactivated by heating to 95 ° C. for about 15 to 30 minutes, as in the normal extract production process, Furthermore, a yeast extract can be produced with high yield through centrifugation and concentration under reduced pressure. Moreover, according to the intended purpose, it can be processed into powder and paste.

(Example)
Hereinafter, the present invention will be described more specifically using test examples and examples, but the present invention is not limited to these examples.
(Test Example 1)
150 g of commercial baker's yeast flakes (Oriental Yeast Industry Co., Ltd. product, moisture 68.7%) and 200 ml of distilled water were added to eight 500 ml beakers, and 350 g of each cell slurry having a dry cell concentration of about 13.4% was prepared. . When these beakers are placed in a constant temperature water bath at 50 ° C. and the temperature of the cell slurry rises to 50 ° C., a predetermined amount of H ⁺ ions are added to each beaker while stirring (a predetermined amount of 2N hydrochloric acid solution is used in this test). The amount of H ⁺ ions was calculated) was added to each bacterial cell slurry all at once. Thereafter, the mixture was self-digested at the same temperature for 24 hours with stirring. In addition, in order to investigate the nitrogen recovery rate during the reaction, 100 g of the liquid was taken out from each reaction solution at the time of 5th and 24th hours, deactivated by heating, and centrifuged to prepare 86 g of extract to recover nitrogen. Rate (TN recovery rate (%); ratio of total amount of nitrogen in extract to total amount of nitrogen in raw yeast), decomposition rate (ratio of free amino nitrogen to total amount of solubilized nitrogen in sample (%)) and extract The total amount of free amino acids eluted (total amount of free amino acids in the extract measured by a fully automatic amino acid analyzer). Furthermore, in order to investigate the pH change of each reaction solution after adding H ⁺ ions, the pH value for each reaction time was also measured.
The results are shown in Tables 1 and 2.

From the above results, when baker's yeast is used as the raw material yeast, when 15 to 45 mol of H ⁺ ions are added per 100 kg of dry cell matter, the nitrogen elution rate from the raw material is 50% or more, and 15 to 30 mol is added. It was found that particularly excellent results were obtained.

(Test Example 2)
Eight types of marine yeast extracts were prepared under exactly the same conditions as in Test Example 1, except that marine yeast “Sankyo East M” (manufactured by Sankyo Foods Co., Ltd., moisture 67.1%) was used as the raw bread yeast. Tables 3 and 4 show the changes over time in the pH of each yeast slurry after addition of nitrogen recovery and H ⁺ ions.

From the above results, in the case of marine yeast, when 10 to 60 mol of H ⁺ ions are added per 100 kg of dry cell matter, the nitrogen elution rate from the raw material is 40% or more, and when 20 to 45 mol is added, 50%. As described above, it was found that when 30 mol was further added, 60% or more was obtained.

(Test Example 3)
As in Test Example 2, eight types of marine yeast slurry were prepared. Before heating these bacterial cell slurries, the same amount of H ⁺ ions as in Test Example 2 was added with stirring. Thereafter, each bacterial cell slurry was heated to 50 ° C. in 15 minutes, and further self-digested at the same temperature for 24 hours. Thereafter, in the same manner as in Test Example 2, the yeast extract was prepared by heat inactivation and centrifugation. Tables 5 and 6 show the changes over time in the pH of each bacterial cell slurry after nitrogen recovery and addition of H ⁺ ions.

From the above Test Example 1, Test Example 2 and Test Example 3, in the case of baker's yeast and marine yeast, the amount of H ⁺ ions (dissociated from the inorganic acid) was added within a range of 15 to 45 mol per 100 kg of dry cell matter. It was found that the nitrogen recovery rate in this case was particularly high, and that the pH of the reaction liquid immediately after the addition of H ⁺ ions within these ranges was greatly reduced to 1.2 or more and less than 3.0.

Moreover, in Test Example 1 and Test Example 2, it was found that the production efficiency of the yeast extract was high particularly when the H ⁺ ion addition amount was 15 to 30 mol per 100 kg of the dry cell material.
In Test Example 3, no significant difference was observed in the production efficiency of yeast extract compared to Test Example 2. In Test Example 3, it was found that the nitrogen elution rate from the raw material was 50% or more when 20 to 45 mol was added per 100 kg of the dried bacterial cell.

(Comparative Test Example 1)
In this comparative test example, the test was performed for the case where an organic acid was used instead of the inorganic acid. However, since it is difficult to accurately calculate the amount of H ⁺ ions dissociated from the organic acid, the organic acid should be adjusted so as to have the same pH as 2.8 immediately after the addition of 15 mol of H ⁺ ions in Test Example 1. Added. Specifically, 350 g of baker's yeast slurry each having a dry cell concentration of about 13.4% was prepared and heated to 50 ° C., and then each of the organic acids lactic acid, citric acid, malic acid and acetic acid was added. Was adjusted to 2.8. Thereafter, it was self-digested at 50 ° C. for 24 hours. The obtained extract was prepared to the same 450 g with distilled water and subjected to analysis of nitrogen recovery rate and decomposition rate. The results are shown in Table 7.

  From the above results, it was found that when using an organic acid, a high nitrogen recovery rate as in the case of the inorganic acid cannot be obtained even when the pH is adjusted to about 3.0 or less, which is the same as that of the inorganic acid. .

200 g of distilled water was added to 150 g of commercially available baker's yeast to prepare 350 g of a cell slurry having a dry cell concentration of about 13.4%. After heating the cell slurry to 50 ° C, add 4.7 ml of 2N hydrochloric acid (addition amount of H ⁺ ions per 100 kg of cell dry matter is about 20 mol) and hold at that temperature for 3 hours. And self-digested. Next, after adjusting the pH of the solution to 7.0, 0.35 g of enzyme protease A (manufactured by Amano Enzyme Co., Ltd.) was added, and the mixture was further enzymatically degraded at 50 ° C. for 15 hours to prepare a yeast extract.

  A yeast extract was prepared in the same manner as in Example 1 except that the pH was adjusted to 5.5 after autolysis and 0.35 g of cochlase P (manufactured by Sankyo Co., Ltd.) was used as the enzyme.

  A yeast extract was prepared in the same manner as in Example 1 except that pH was adjusted to 8.0 after autolysis and 0.35 g of protease P3 (manufactured by Amano Enzyme) was used as the enzyme.

(Comparative Example 1)
In this comparative example, yeast extract was prepared by performing only enzymatic degradation without autolysis. First, 200 g of distilled water was added to 150 g of commercially available baker's yeast to prepare 350 g of a cell slurry having a dry cell concentration of about 13.4%. Next, since it was difficult for enzymatic degradation in live yeast, the protein was denatured by heating at 95 ° C. for 15 minutes. Then, the pH of the solution was adjusted to 7.0, 0.35 g of enzyme protease A was added, and the mixture was reacted at 50 ° C. for 18 hours to prepare a yeast extract.

(Comparative Example 2)
A yeast extract was prepared in the same manner as in Comparative Example 1 except that the pH of the solution was adjusted to 5.5, and 0.35 g of cochlase P was used as the enzyme.

(Comparative Example 3)
A yeast extract was prepared in the same manner as in Comparative Example 1 except that the pH of the solution was adjusted to 8.0 and 0.35 g of protease P3 was used as the enzyme.
Table 8 shows nitrogen recovery rates and decomposition rates of the yeast extracts of Examples 1 to 3 and Comparative Examples 1 to 3.

Moreover, the comparison of the free amino acid component composition in the final extract obtained in Example 3 and Comparative Example 3 is shown in FIG.
From the above results, it was found that the combined use of autolysis and enzymatic degradation resulted in higher nitrogen recovery than the usual enzymatic degradation, and the free amino acid content in the extract was greatly increased.

500 ml of distilled water was added to 250 g of commercial marine yeast “Sankyo East M” (manufactured by Sankyo Foods Co., Ltd., moisture 67.1%) to prepare 750 g of a cell slurry having a dry cell concentration of about 11.0%. After heating the temperature of these cell slurries to 50 ° C., 12.3 ml of 2N hydrochloric acid (the amount of H ⁺ ions added is about 30 mol per 100 kg of dry cells), and 5 ° C. at 5 ° C. Self-digested for hours. Subsequently, the pH was not adjusted, and the mixture was further self-digested at the same temperature for 19 hours, then deactivated by heating at 95 ° C. for 15 minutes, and centrifuged. 150 g of distilled water was added to the residue after the supernatant was taken out and washed, followed by a second centrifugation. The first and second supernatants were combined and concentrated under reduced pressure to prepare a Bx.40% concentrated extract.

500 ml of distilled water was added to 250 g of commercial marine yeast “Sankyo East M” (manufactured by Sankyo Foods Co., Ltd., moisture 67.1%) to prepare 750 g of a cell slurry having a dry cell concentration of about 11.0%. After heating the temperature of these cell slurries to 50 ° C, add 12.3 ml of 2N hydrochloric acid (the amount of H ⁺ ions added is approximately 30 mol per 100 kg of dry cells) at 50 ° C. Self-digested for 5 hours. Next, the pH of the solution was adjusted to 8.0, and 0.3 g of an enzyme equinezyme (Amano Enzyme Co., Ltd.) was added. Thereafter, the mixture was further reacted at 50 ° C. for 19 hours, then deactivated by heating to 95 ° C. for 15 minutes, and centrifuged. 150 g of distilled water was added to the residue after the supernatant was taken out and washed, followed by a second centrifugation. The first and second supernatants were combined and concentrated under reduced pressure to prepare a Bx.40% concentrated yeast extract.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of protease A and 0.1 g of auxiliary enzyme peptidase R (manufactured by Amano Enzyme Co., Ltd.) were used as the enzymes.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of protease P3 and 0.1 g of auxiliary enzyme peptidase R were used as enzymes.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of protease N (manufactured by Amano Enzyme Co., Ltd.) and 0.1 g of auxiliary enzyme peptidase R were used as enzymes.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of orientase 90N (manufactured by HIBI) and 0.1 g of auxiliary enzyme peptidase R were used as the enzymes.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of nucleicin (manufactured by HIBI Co., Ltd.) and 0.1 g of auxiliary enzyme peptidase R were used as the enzymes.

  A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.3 g of actinase (manufactured by Kaken Pharmaceutical Co., Ltd.) and 0.1 g of the auxiliary enzyme peptidase R were used as the enzymes.

A concentrated yeast extract was prepared in the same manner as in Example 5 except that 0.9 g of Alcalase 2.4 L FG (manufactured by Novozymes Japan) and 0.1 g of auxiliary enzyme peptidase R were used as the enzymes.
Table 9 shows the measured nitrogen recovery rates of the yeast extracts of Examples 4 to 12 prepared as described above.

From the results of each example, the addition of a predetermined amount of H ⁺ ions of the present invention can effectively induce autolysis, and the addition of a small amount of commercially available enzyme can further increase the yield of the extract, It was confirmed that a high-quality yeast extract could be prepared at low cost and high yield.

It is a figure which shows the comparison of the free amino acid component composition in the final extract obtained in Example 3 and Comparative Example 3.

Claims (6)

After the yeast cells slurry 40 to 60 ° C., in the yeast cells slurry, inorganic acids, and 10~60mol added as ^{H +} ions per cell dry matter 100 kg, is characterized in that the yeast is autolyzed A method for producing a self-digesting yeast extract. Self-digestion characterized in that after adding 10 to 60 mol of inorganic acid as H ⁺ ions per 100 kg of cell dry matter to yeast cell slurry, the yeast cell slurry is brought to 40 to 60 ° C. to self-digest the yeast. A method for producing digestive yeast extract. The method for producing an autolytic yeast extract according to claim 1 or 2, wherein the initial pH of the yeast cell slurry after addition of the inorganic acid is 1.2 or more and less than 3. The temperature of the yeast cells slurry, a temperature in the range of 40 to 60 ° C., according to any one of claims 1 to 3 is intended to autolysis in the autolysis optimum temperature of the yeast cells Of producing self-digesting yeast extract. After the autolysis, further a neutral or alkaline enzyme by adding one or more kinds by enzymatic reaction, it claims 1-4, characterized in that allowed to further degrade the yeast cells A method for producing the autolysed yeast extract according to item 1. 6. The method for producing an autolytic yeast extract according to claim 5 , wherein the enzyme is added after the pH of the cell slurry is readjusted to the optimum pH of the enzyme to be added.

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