JP3861277B2 - Production method of food material with high cysteine content - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a natural food material such as yeast extract and yeast cells containing glutathione in a solid content as high as 1% or more as a raw material, which is subjected to heat treatment and peptidase enzyme treatment, or γ -It relates to a method for obtaining a food material containing a high content of cysteine by subjecting it to two kinds of enzyme treatments, glutamyl peptide hydrolase and peptidase.
[0002]
[Prior art]
Cysteine is used for the purpose of improving the flavor of food. Proteolytic methods and semi-synthetic methods are known as methods for producing cysteine, but the methods currently used mainly are proteolytic methods and semi-synthetic methods.
[0003]
When cysteine is used for the above purpose, there is a strong demand for a natural food material containing a high content of cysteine, but few natural food materials containing a high content of cysteine have been known.
[0004]
[Problems to be solved by the invention]
Under the background of the prior art described in the preceding paragraph, the present invention aims to provide a natural food material containing a high content of cysteine.
[0005]
[Means for Solving the Problems]
As is well known, glutathione is a compound in which glutamic acid, cysteine and glycine are peptide-bonded in this order.
[0006]
As a result of intensive studies to achieve the object described in the preceding paragraph, the present inventor can decompose the peptide bond (γ-glutamyl peptide bond) between glutamic acid and cysteine in glutathione by heating or γ-glutamyl peptide hydrolase. It is found that natural food materials with high cysteine content can be easily obtained by exploiting the fact that the peptide bond between cysteine and glycine can be hydrolyzed by peptidase. The present invention has been completed based on the above.
[0007]
That is, the present invention provides a method for decomposing a bond between glutamic acid residues of glutathione and cysteine residues from a food material containing glutathione in a solid content of 1% by weight or more by heating in a water-containing state or γ-glutamyl. A novel process for producing a high-cysteine food material characterized by hydrolyzing with a peptide hydrolase and hydrolyzing the bond between a cysteine residue and a glycine residue with a peptidase, and such a method, It relates to a material characterized in that the raw material for natural food is yeast extract or yeast cells.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0009]
The natural food material, which is a raw material in the production method of the present invention, is a natural food material containing glutathione at a high content of 1% by weight or more in a ratio of solid content. Those having a glutathione content of 1% or less are not preferred because they are not industrially practical.
[0010]
As such a natural food material, for example, yeast cells and yeast extracts whose ratio to the solid content of glutathione is 1% by weight or more can be mentioned. Incidentally, yeast cells containing such glutathione at a high content can be obtained by devising a yeast culture method. The yeast extract can be prepared by extraction or self-digestion from such yeast cells, or by supplementing glutathione with a yeast extract whose glutathione content does not reach the predetermined amount.
[0011]
As mentioned above, glutathione is N- (N-γ-L-glutamyl-L-cysteinyl) glycine as well known, and L-glutamic acid, L-cysteine and glycine are dehydrated in this order. It is a combination. According to one aspect of the present invention, when an enzyme that hydrolyzes a γ-glutamyl group (γ-glutamyl peptide hydrolase) and a peptidase are allowed to act on the natural food material as described above, glutathione present therein is L-cysteine is produced by hydrolysis between L-glutamic acid and L-cysteine by γ-glutamyl peptide hydrolase and between L-cysteine and glycine by peptidase (Examination Example 1 below). .
[0012]
The conditions for causing the two types of enzymes to act (enzyme reaction conditions) are, for example, adding an enzyme to a natural food material, and maintaining the pH at 3 to 9 and 15 to 70 ° C. in a water-containing state. The two enzymes have overlapping expression conditions for their enzymatic action, so either of them may be preceded, or both may be acted on simultaneously. The abundance of water is determined from the viewpoint of operability, and can be, for example, 1 to 100 parts by weight per 1 part by weight (in terms of dry matter) of the natural food material. If the pH and temperature are outside the above ranges, the activities of γ-glutamyl peptide hydrolase and peptidase are weak, which is not preferable. When a natural food material is treated with an enzyme under the above conditions, a cysteine-rich natural food material in which a large amount of cysteine is produced and accumulated in 1 to 300 minutes is obtained.
[0013]
There are many types of γ-glutamyl peptide hydrolase. Particularly useful in the practice of the present invention are γ-glutamyltransferase, γ-glutamylcyclotransferase, glutaminase and the like.
[0014]
There are many types of peptidases, and not only exopeptidases such as aminopeptidases and carboxypeptidases but also endopeptidases that can break peptide bonds including terminal amino acid residues can be used.
[0015]
Needless to say, the pH can be adjusted with an acid such as hydrochloric acid or a base such as sodium hydroxide that is acceptable for food.
[0016]
There is a heating method as a method for decomposing the γ-glutamyl peptide bond. That is, when glutathione is heated at a pH of 1 to 7 and 50 to 120 ° C. in a water-containing state, the γ-glutamyl peptide bond is cleaved in 3 to 300 minutes, and PCA (pyrrolidone carboxylic acid) and cysteinyl glycine are generated. On the other hand, cysteine is produced by allowing peptidase to act on cysteinylglycine.
[0017]
According to the present invention (another embodiment), a peptidase is first allowed to act on the natural food material as described above. Thereby, glutathione present in the natural food material is hydrolyzed between L-cysteine and glycine to produce γ-glutamyl-L-cysteine. Next, when this is heated, γ-glutamyl-L-cysteine is decomposed to produce L-cysteine.
[0018]
The conditions for thermal decomposition and the conditions for causing peptidase to act are as described above.
[0019]
According to the present invention (a further embodiment thereof), in reverse order, the natural food material as described above is first heat-treated and then subjected to enzymatic treatment of peptidase.
[0020]
According to this method, the cysteinyl glycine produced by releasing the γ-glutamyl group by the first heat treatment is partially cyclized to cyclocysteinyl glycine, which is hydrolyzed by peptidase to produce cysteine. As a result, the final production rate of cysteine is reduced accordingly. From this point of view, it can be said that the other embodiments are preferred over this further embodiment.
[0021]
The cysteine-rich natural food material prepared in this way should be distributed in an appropriate form such as liquid, concentrated and pasted, dried and powdered, and other granules. Can do.
[0022]
In addition, the cysteine-rich natural food material obtained by the method of the present invention can be made into an excellent food flavor enhancing material by adding reducing sugar thereto, and further heats the food flavor enhancing material. Therefore, it can be an excellent food flavor enhancer (Japanese Patent Application No. 11-194209).
[0023]
The following is a supplementary explanation.
[0024]
Such a food flavor enhancing material can be produced by adding reducing sugar to a cysteine-rich natural food material obtained by the method of the present invention, as mentioned above.
[0025]
Examples of reducing sugars include glucose, fructose, xylose, maltose and the like. These reducing sugars are preferable because they are inexpensive and easily available and can be used as foods.
[0026]
The addition amount (use amount) of the reducing sugar is 1 to 10 mol per mol of the raw material glutathione or a ratio relative to glutathione contained in a natural material such as yeast cells or yeast extract containing the same. If the amount added is less than this range, the effect is weak, while if it is too large, the sweetness becomes strong and both are not preferred.
[0027]
The flavor-enhancing material that can be produced in this way is the same as described above in relation to the cysteine-rich natural food material, as it is in a liquid state, concentrated and in a paste state, or It can be put into circulation in an appropriate form such as dried and powdered and in the form of other granules. When this flavor enhancing material is used later in food processing, the cysteine and reducing sugar contained therein react with each other in the heating step in the processing to produce a flavor enhancing effect.
[0028]
Next, a method for producing such a food flavor enhancer will be described. This can be obtained, for example, by heat-treating the flavor enhancing material described above under appropriate conditions.
[0029]
In the heat treatment, for the purpose of obtaining a flavor enhancing effect, the cysteine concentration is 0.1% by weight or higher, preferably 0.6% by weight or higher if necessary, and then heated. The heating condition is set to a range in which a burning odor and a browning reaction do not occur within a range of 10 to 300 minutes at 50 to 180 ° C. Such heating conditions include, for example, conditions of heating at a low temperature such as 50 to 60 ° C. for 180 to 300 minutes for a long time and heating at a high temperature such as 90 to 100 ° C. (around the boiling point) for 30 to 120 minutes for a short time. Is included.
[0030]
The food flavor enhancer that can be prepared in this way is the same as the previous flavor enhancing material, in the liquid state, concentrated and pasted, or dried and powdered. The state can be put in circulation in an appropriate form.
[0031]
【Example】
Hereinafter, the present invention will be described in more detail with reference to inspection examples and examples.
[0032]
Inspection example 1
In a pH 7.0 aqueous solution of reduced glutathione with a concentration of 50 mmol, “Glutaminase Daiwa” (specific activity: 3.0 mM / min / mg) manufactured by Daiwa Kasei Co., Ltd. and “carboxypeptidase Y” (specific activity: 100 μM / min) manufactured by Sigma / Mg) was added to a concentration of 1 mg / ml, and the amount of cysteine produced (change over time) when the mixture was allowed to act at 37 ° C. for 3 hours was examined. The results are shown in FIG. In the figure, γ-GC represents reduced γ-glutamylcysteine, and Cys represents cysteine.
[0033]
As understood from FIG. 1, cysteine can be obtained from glutathione in high yield by glutaminase and carboxypeptidase.
[0034]
Inspection example 2
A 50 mmol aqueous solution of reduced glutathione having a pH of 5.0 was heated at 95 ° C. for 4 hours. As a result, 38 mmol of cysteinyl glycine was obtained. The solution was adjusted to pH 7.0 with sodium hydroxide, carboxypeptidase was added at a concentration of 1 mg / ml and allowed to act at 37 ° C. for 3 hours, and 12 mmol of cysteine was obtained.
[0035]
Example 1
Water was added to yeast extract powder containing 8% glutathione, and the pH was adjusted to 7 with sodium hydroxide to prepare an aqueous solution having a concentration of 10%. The same glutaminase and carboxypeptidase used in Test Example 1 were added to this solution to a concentration of 1 mg / ml, respectively, incubated at 37 ° C. for 120 minutes, and then freeze-dried. As a result, the cysteine content was about 1%. A yeast extract powder was obtained.
[0036]
In addition, the time course of cysteine during this incubation is shown in FIG.
[0037]
Incidentally, when this yeast extract powder was used for the production of a seasoning, a seasoning having a good roast meat flavor was obtained.
[0038]
【The invention's effect】
According to the present invention, a natural food material with a high content of cysteine such as a yeast extract with a high content of cysteine useful for improving the flavor of food can be easily obtained.
[Brief description of the drawings]
FIG. 1 shows a change with time in pH 7 of the amount of cysteine produced due to degradation of reduced glutathione by glutaminase and carboxypeptidase (Test Example 1).
FIG. 2 shows the change over time in pH 7 of the amount of produced cysteine (content in solids (%)) accompanying degradation of reduced glutathione contained in a yeast extract containing a high amount of glutathione by glutaminase and carboxypeptidase ( Example 1).

Claims (6)

From the food material containing 1% by weight or more of glutathione in the solid content, the bond between the glutamic acid residue and the cysteine residue of the glutathione is decomposed by heating in a water-containing state or hydrolyzed with γ-glutamyl peptide hydrolase. A novel process for producing a cysteine-rich food material, which comprises decomposing and hydrolyzing a bond between a cysteine residue and a glycine residue with a peptidase. After heating a food material containing 1% by weight or more of glutathione in a solid content at a pH of 1-7 and 50-120 ° C. in a water-containing state, a peptidase is allowed to act on this at pH 3-9 and 15-70 ° C. The novel manufacturing method of the food material with high cysteine content of Claim 1 characterized by these. 2. A γ-glutamyl peptide hydrolase and peptidase are allowed to act on a food material containing glutathione in a solid content of 1% by weight or more at a pH of 3 to 9 and 15 to 70 ° C. in a water-containing state. A novel method for producing the high-cysteine food material described. A peptidase is allowed to act on a food material containing 1% by weight or more of glutathione in a solid content at a pH of 3 to 9 and 15 to 70 ° C. in a water-containing state, and then this is pH 1 to 7 and 50 to 120 ° C. in a water-containing state. A novel process for producing a food material with a high content of cysteine according to claim 1, wherein the food material is heated by heating. The novel method for producing a cysteine-rich food material according to claim 1 or 3, wherein the γ-glutamyl peptide hydrolase is γ-glutamyltransferase, γ-glutamylcyclotransferase, or glutaminase. The novel method for producing a cysteine-rich food material according to any one of claims 1 to 5, wherein the raw food material is a yeast extract or a yeast cell.

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