JPH10327802A - Yeast extract composition and yeast mutant for obtaining the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition that is useful as a taste enhancer having well balance between sweetness and deliciousness by increasing the composition ratios of alanine, glutamic acid and histidine among free amino acids in an extract from Candida yeast. SOLUTION: The whole content of the free amino acids in the yeast extract is >=3.0% and the contents of the following amino acids are increased: (i) the content of alanine to >=10%, (ii) glutamic acid to 25% and (iii) histidine to >=10% in the whole free amino acids. This yeast extract composition is directly obtained as a natural product by utilizing a strain of food yeast in Candida that is resistant to aspartic hydroxamate and needs 2 or more days for forming colonies in an agar culture medium containing glycerol as a carbon source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yeast extract composition having a low odor characteristic of a Candida yeast extract and an excellent balance between sweetness and umami, and a method for obtaining the yeast extract from a mutant strain of the genus Candida.

[0002]

2. Description of the Related Art In recent years,
The use of natural seasonings has been reconsidered with the general consumer orientation to natural foods, and high quality yeast extracts have come to be desired. Generally, yeast of the genus Saccharomyces represented by baker's yeast and brewer's yeast is used as a raw material for yeast extract. The yeast extract of the genus Saccharomyces has a unique yeast odor, which is suitable for the purpose of seasoning to enhance the meat flavor, but not for the flavor of Japanese cuisine. On the other hand, yeast extract derived from Candida yeast (hereinafter, referred to as Candida yeast extract) has almost no yeast odor peculiar to yeast extract derived from Saccharomyces yeast. In addition, by utilizing the abundant nucleic acid of yeast belonging to the genus Candida, it is possible to obtain a versatile seasoning suitable for seasoning Japanese-style dishes having a strong umami. (Japanese Unexamined Patent Application Publication No. 62-201595,
No. 93871)

[0003] However, when producing a Candida yeast extract by an enzymatic decomposition method, particularly in order to enhance the taste of nucleic acids, the extraction rate of free amino acids is reduced and the content of amino acids other than glutamic acid content is relatively reduced. However, the flavor derived from amino acids had to be monotonous. In addition, Candida yeast extract also has a peculiar odor, and it has been desired to suppress this peculiar odor. On the other hand, it has been reported that the astringency of yeast extract is suppressed by controlling the free alanine content of all yeast extracts. However, by adjusting the amino acid balance of the Candida yeast extract, there was no yeast extract in which the specific odor was suppressed and the taste quality was improved.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, among the free amino acids of the yeast extract of the genus Candida, alanine, glutamic acid,
The present inventors have found that increasing the composition ratio of histidine results in a seasoning with very little flavor, which has little odor peculiar to the Candida yeast extract, and has an extremely improved flavor. That is, in the present invention, the total free amino acid content in the yeast extract is 3.0 or more, and the alanine content in the total free amino acid content is 10%.
Thus, a yeast extract composition derived from a yeast of the genus Candida having a glutamic acid content of 25% or more and a histidine content of 10% or more and a method for producing the same are provided. The amino acid content in the composition of the present invention is 3.0% or more, and the larger the amount, the more preferable. However, according to the present invention, even if the content of the amino acid in the composition is about 3 to 5%, the flavoring agent exhibits the taste of the amino acid.

Hereinafter, the present invention will be described in detail. The content of alanine, glutamic acid, and histidine in the yeast extract of the present invention is 10% or more, 25% or more, 10% or more, and preferably 20% or more, respectively, based on the total amount of free amino acids in the yeast extract composition. , 40% or more and 10% or more. If the content of any of these amino acids is less than the above range, the balance between the taste of the nucleic acid and the flavor of the amino acid may be lost, and the specific odor may be increased.

Generally speaking, the composition ratio of each free amino acid in the total free amino acid content of Candida yeast extract is about 10% for alanine, about 15% for glutamic acid, and about 5% for histidine. The content of the amino acid in the composition of the present invention is 3.0% or more, and the larger the amount, the more preferable. However, in the case of the yeast extract of the present invention, the amino acid content in the composition is 3%.
Even if it is about 5%, it becomes a seasoning exhibiting the taste of amino acids.

Hereinafter, a method for producing the yeast extract of the present invention will be described. First, there is a method in which alanine, glutamic acid, and histidine are added to a Candida yeast extract obtained by a known method so as to have a prescribed amount. As another method, there is a method using a mutant strain obtained by mutating edible yeast belonging to the genus Candida. That is, the edible yeast belonging to the genus Candida is transformed into a natural strain by using a strain that has resistance to aspartate hydroxamate and requires two days or more to form a colony at 30 ° C. on an agar medium containing only glycerin as a carbon source. The yeast extract composition of interest can be obtained directly. The method is described in detail below.

First, edible yeast belonging to the genus Candida is treated with a mutation treating agent such as nitrosoguanidine,
By irradiating ultraviolet rays, X-rays, or the like, an aspartate hydroxamate-resistant strain is obtained. In this case, the aspartic acid hydroxamate-resistant strain refers to a colony that grows in a completely synthetic medium containing aspartic acid hydroxamate with a diameter of twice or more that of a colony formed by a sensitive strain. As edible yeast belonging to the genus Candida, Candida tropicalis (Candidatropi)
calis), Candida Ripolitica (Can)
and Candida utilis, and more preferably Candida utilis I.
FO0626.

The aspartate hydroxamate-resistant strain obtained above is used as a parent strain and subjected to the same mutation treatment again as described above to obtain a strain on an agar medium containing only glycerin as a carbon source.
Select strains that require more than 2 days for colony formation at 0 ° C.
The strain thus obtained was placed in a 50 ml nutrient medium at 30 ° C. for 18 hours.
After culturing for hours, the resulting cells are ground with a bead grinder,
Further, an endoprotease is added and reacted at 50 ° C. for 12 hours. Then, after removing the residue by centrifugation, the obtained supernatant is subjected to amino acid analysis. In this way, it is possible to obtain a mutant strain that can be used as a raw yeast for obtaining a yeast extract composition containing a large amount of alanine, glutamic acid, and histidine.
An example of the mutant strain thus obtained is AHR4-24 strain. (Deposit No .: FERM BP-5956)

Next, a method for producing a yeast extract composition using the yeast mutant will be described. First, the obtained mutant is cultured. Glucose, sucrose,
Acetic acid, ethanol, molasses, wood saccharified solution, dextrose corn syrup, sulfite pulp waste liquid, and the like can be used. As a nitrogen source, urea, ammonia, ammonium sulfate, ammonium chloride, nitrate and the like can be used. Phosphoric acid, potassium, and magnesium sources can be ordinary industrial raw materials.Additionally, inorganic salts such as zinc, copper, manganese, and iron ions are added, and vitamins, amino acids, and organic sources such as corn steep liquor are added. A nitrogen-containing substance may be added. The culturing temperature is 20 ° C to 38 ° C, particularly 30 ° C to 36 ° C.
And the pH is preferably 3.5 to 8.0, particularly preferably 4.0 to 6.0.

The yeast cells thus obtained are centrifuged,
After washing, the suspension is diluted with water to form a suspension. And
The enzyme of yeast itself is deactivated by heating the suspension or drying the suspension. Physically damage the cell wall of the inactivated cells. This treatment may be performed by stirring the above-mentioned suspension or a suspension obtained by adding water to hot-air-dried cells with a homogenizer or the like.

Next, an enzyme is added to the suspension. Any enzyme may be used as long as it can degrade yeast cell walls, bacterial proteins, and high molecular nucleic acids. For example, endoprotease, exoprotease, nuclease, deaminase, cell wall lytic enzyme and the like can be mentioned. The enzyme treatment is performed at the optimum temperature of the enzyme and the optimum pH for a certain period of time,
For example, the reaction may be performed for about 1 to 15 hours. After the enzyme reaction, the residue is removed by centrifugation or the like to obtain a supernatant. If necessary, salt is added to the supernatant and then concentrated to a desired concentration to obtain the desired yeast extract. The moisture content of the yeast extract is from 25% to 35% in the case of a pasty product,
The extract solid content is suitably from 50% to 65%.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

[0014]

Example 1 [Acquisition of Yeast Mutant and Preparation of Yeast Extract Composition] a. Acquisition of yeast mutant strain Candida utilis (IFO 06
26), and used a complete synthetic medium (glucose 1).
%, Ammonium sulfate 0.35%, potassium phosphate 0.
1%, magnesium sulfate 0.05%, sodium chloride 0.05%, calcium chloride 0.05%, trace metals, vitamins) at 30 ° C. for 18 hours. 10 ml of the obtained yeast suspension was aseptically placed in a petri dish, and directly irradiated with ultraviolet light at a distance of 20 cm from a 15 WUV lamp while stirring the liquid with a stirrer. An irradiated liquid having a survival rate of 0.1% or less as compared with the viable cell count of the same yeast suspension that was not irradiated with ultraviolet light was obtained. The irradiated liquid was diluted on a Petri dish to the extent that 100 to 500 colonies were obtained, and applied to an agar medium obtained by adding 1 mg / ml of aspartic acid hydroxamate to the same complete synthetic medium as described above. The agar medium was aseptically cultured at 30 ° C. for 2 days, and colonies having a diameter twice or more as large as those obtained from the non-irradiated strain on the same medium were obtained.

Subsequently, the aspartic acid hydroxamate-resistant strain obtained here was used as an original strain, and colonies were formed at 30 ° C. on the same complete synthetic medium as above using only glycerin as a carbon source by the same mutation procedure as described above. Strains requiring more than two days were selected. Among the mutant strains thus selected, the free amino acid content in the yeast extract is 3.0% or more, and the alanine content in the total free amino acid content is 10%.
As described above, mutants having a glutamic acid content of 25% or more and a histidine content of 10% or more were selected. Among them, Candida utilis AHR4-24 strain having the highest content of alanine, glutamic acid and histidine was FERM B
Deposited with PMI as P-5956. Candida utilis AHR4-24 strain is the original strain of Candida utilis (IF
O0626).

B. Preparation of Yeast Extract Composition AHR4-24 strain was transformed into a molasses medium (TS8%, phosphoric acid 0.25
%, Adjusted to pH 5.5 with ammonia) to obtain viable cells. After washing 800 g of viable cells with water, the cells were diluted with water and boiled. The boiled yeast suspension was crushed with a high-pressure homogenizer (1000 bar). The obtained cells were treated with an enzyme. First, 160 mg of neutral protease (Amano Pharmaceutical Protease N) was added to the cell lysate and reacted at 50 ° C. for 12 hours. Subsequently, 60 mg of nuclease (Amano Pharmaceutical Nuclease) was added to the cell lysate.
Was added and reacted at 65 ° C. for 4 hours. Thereafter, 60 mg of deaminase (Amano Pharmaceutical Deamizyme) was added and 2
A time reaction was performed.

The lysate of the cells treated with the enzyme is centrifuged (1.
0000 rotations for 10 minutes) to obtain 1260 g of a supernatant.
To the supernatant, 24 g of sodium chloride was added and concentrated by an evaporator to obtain 160 g of a pasty yeast extract. The extract solids extraction ratio based on the dry weight of the yeast used is 5
It was 0%. The components of the obtained yeast extract were as follows. Extract solid content 50% Salt 15% Total nitrogen 4.5% Nucleic acid (5′-IG) 1.7% pH 6.0 The free amino acid weight ratio to the total free amino acid amount was as follows. Alanine 12.5% Glutamic acid 31.0% Histidine 15.0% Total free amino acid content in yeast extract 5.5%

[0018]

Example 2 and Comparative Example 1 Candida yeast extract (B) (Example 2) prepared as in Example 1 using mutant AHR4-24, and the same method as Example 1 using the original strain To obtain the Candida yeast extract (A) (Comparative Example 1). The components of the yeast extract (B) and the free amino acid weight ratio were the same composition ratio as in Example 1. On the other hand, the yeast extract (A) had the following composition ratio. Extract solid content 50% Salt 15% Total nitrogen 4.5% Nucleic acid (5'-IG) 1.7% pH 6.0 Also, the weight ratio of each free amino acid to the total free amino acid of yeast extract (A) is as follows: It was as follows. Alanine 6.0% Glutamic acid 25.0% Histidine 8.0% Total free amino acid content in yeast extract 5.5% Sample concentration 1% solution, yeast extract (A), (B) with sample temperature of 50 ° C sensory evaluation Panel 10 people 2
Performed by the point identification method. Table 1 shows the results.

[0019]

[Table 1]

Table 1 shows that the Candida yeast extract of the present invention has a sweet taste and a low odor specific to Candida yeast.
%, It was shown that not only (B) was excellent but also the taste balance was excellent.

[0021]

Industrial Applicability The Candida yeast extract of the present invention has a strong sweetness and an excellent taste balance with little odor specific to Candida yeast.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C12R 1:72)

Claims (6)

[Claims] The yeast extract has a total free amino acid content of not less than 3.0%, an alanine content of not less than 10%, a glutamic acid content of not less than 25% and a histidine content of not less than 10%. A yeast extract composition derived from a Candida yeast. 2. A food containing the yeast extract composition according to claim 1. 3. A feed containing the yeast extract composition according to claim 1. 4. An agar medium resistant to aspartic acid hydroxamate and containing only glycerin as a carbon source.
A yeast belonging to the genus Candida which requires two days or more to form a colony at 0 ° C. 5. Candida utilis AHR4-
24 strains. 6. An agar medium which is resistant to aspartic acid hydroxamate and uses only glycerin as a carbon source.
After inactivating the edible yeast belonging to the genus Candida which requires two days or more to form a colony at 0 ° C. by heat, the yeast is subjected to an enzyme treatment, centrifuged, and the supernatant is obtained. A method for producing a yeast extract composition, comprising: