JP3519572B2 - Yeast extract composition and yeast mutant for obtaining the same - Google Patents

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 peculiar to Candida yeast extract and an excellent balance of sweetness and umami, and a method for obtaining the yeast extract from a yeast mutant strain of the genus Candida.

[0002]

2. Description of the Related Art In recent years,
The use of natural seasonings has been reconsidered in line with general consumers' preference for natural foods, and yeast extracts have also been desired to have high quality. In general, yeasts of the genus Saccharomyces typified by baker's yeast and brewer's yeast are used as raw materials for yeast extracts. 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 suitable for seasoning Japanese dishes. On the other hand, a yeast extract derived from a yeast of the genus Candida (hereinafter referred to as a candida yeast extract) has almost no yeast odor peculiar to the yeast extract derived from a yeast of the genus Saccharomyces. Moreover, by using the abundant nucleic acid possessed by the yeast of the genus Candida, it can be used as a versatile seasoning suitable for seasoning Japanese dishes with a strong taste. (Japanese Patent Laid-Open No. 62-201595, Japanese Patent Publication No. 7-
93871 publication)

However, in the case of producing Candida yeast extract by an enzymatic decomposition method in order to particularly enhance the umami of nucleic acid, the extraction rate of free amino acids becomes low and the amino acid content other than glutamic acid content becomes relatively low. However, the flavor derived from amino acids had to be monotonous. Further, 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 adjusting the free alanine content of yeast extract in general. (Japanese Patent Publication No. 48-21507) However, there has been no yeast extract in which the specific odor is suppressed and the taste is improved by adjusting the amino acid balance of the Candida yeast extract.

[0004]

Means for Solving the Problems The present inventors have conducted extensive studies to solve the above problems, and as a result, alanine, glutamic acid, among free amino acids of Candida yeast extract,
The present invention has been completed by discovering that a seasoning with significantly improved flavor is obtained by increasing the composition ratio of histidine, with less odor peculiar to Candida yeast extract. That is, the present invention has a total free amino acid content of yeast extract of 3.0 or more and an alanine content of 10% of the total free amino acid content.
As described above, 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. 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 seasoning exhibits the taste of the amino acid.

The present invention will be described in detail below. The content of alanine, glutamic acid, and histidine of the yeast extract of the present invention is 10% or more, 25% or more, 10% or more, preferably 20% or more, respectively, with respect to the total amount of free amino acids of 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 umami of the nucleic acid and the flavor of the amino acid may be lost, and the peculiar odor may become strong.

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 amino acids 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 content of amino acids in the composition is 3
Even if it is about 5%, it is a seasoning that exhibits the taste of amino acids.

The method for producing the yeast extract of the present invention will be described below. First, there is a method in which alanine, glutamic acid, and histidine are added to the candida yeast extract obtained by a known method so that the amounts thereof are specified. Another method is to use a mutant strain obtained by mutating an edible yeast belonging to the genus Candida. That is, by using an edible yeast belonging to the genus Candida, which has aspartic acid hydroxamate resistance and a strain which requires 2 days or more for colony formation at 30 ° C. on an agar medium containing only glycerin as a carbon source, The derived yeast extract composition can be directly obtained. The method will be described in detail below.

First, an aspartic acid hydroxamate resistant strain is obtained by treating edible yeast belonging to the genus Candida with a mutagenesis agent such as nitrosoguanidine, or by irradiating it with ultraviolet rays, X-rays or the like. In this case, the aspartic acid hydroxamate resistant strain refers to a colony that grows in a completely synthetic medium containing aspartic acid hydroxamate and has a diameter that is at least twice that of a colony formed by a susceptible strain. Examples of edible yeasts belonging to the genus Candida include Candida tropicalis ( Candida tropicalis ), Candida lipolytica ( Candida lipolytica ), and Candida utilis (Candida utilis).
More preferably Candida Utyris IFO06
26.

Using the aspartic acid hydroxamate-resistant strain obtained above as a parent strain, the same mutagenesis treatment as described above was carried out again, and the glycerin alone was used as a carbon source on an agar medium.
Select strains that require more than 2 days for colony formation at ° C.
The strain thus obtained was added to 50 ml of nutrient medium at 30 ° C. for 18 hours.
After culturing for a time, the cells obtained are ground with a bead grinder,
Furthermore, endoprotease is added and the reaction is carried out at 50 ° C. for 12 hours. After that, the residue is removed by centrifugation, and the resulting supernatant is analyzed for amino acids. In this way, a mutant strain that can be used as a raw material yeast for obtaining a yeast extract composition containing a large amount of alanine, glutamic acid, and histidine can be obtained.
An example of the mutant strain thus obtained is the AHR4-24 strain. (Ministry of Engineering deposit number: FERM BP-5956)

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

The yeast cells thus obtained are centrifuged,
After washing, the suspension is diluted with water to obtain a suspension. And
The enzyme possessed by the yeast itself is inactivated by heating the suspension or drying the suspension. Physically damage the cell walls of inactivated cells. This treatment may be carried out by stirring the suspension or a suspension obtained by adding water to hot-air dried cells with a homogenizer or the like.

Next, the enzyme is added to this suspension. Any enzyme may be used as long as it can decompose yeast cell wall, bacterial protein, and high molecular weight nucleic acid. Examples thereof include endoprotease, exoprotease, nuclease, deaminase, cell wall lysing enzyme and the like. Enzymatic treatment is carried out for a certain time near the optimum temperature and pH of the enzyme,
For example, the reaction may be performed for about 1 to 15 hours. After completion of the enzymatic reaction, the residue is removed by centrifugation or the like to obtain a supernatant. Salt is added to the supernatant as needed, and then the desired yeast extract is obtained by concentrating to desired concentration. The yeast extract has a water content of 25% to 35% in the case of a pasty product,
The extract solid content is suitably 50% to 65%.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Examples.

[0014]

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

Subsequently, using the aspartic acid hydroxamate-resistant strain obtained here as the original strain, colony formation was carried out at 30 ° C. on the same complete synthetic medium as described above using glycerin alone as a carbon source by the same mutation operation as above. Strains that require more than 2 days were selected. Among the mutants thus selected, the yeast extract has a free amino acid content of 3.0% or more, and the total free amino acid content has an alanine content of 10%.
As described above, a mutant strain having a glutamic acid content of 25% or more and a histidine content of 10% or more was selected. Of these, the Candida utilis AHR4-24 strain, which had the highest alanine, glutamic acid, and histidine contents, was FERM B.
P-5956 has been deposited with the Institute of Microscopy. The Candida utilis AHR4-24 strain is the original strain Candida utilis (IF) except for the amino acid composition ratio.
It had the same mycological properties as O0626).

B. Preparation of yeast extract composition AHR4-24 strain was added to 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 disrupted with a high-pressure homogenizer (1000 bar). The obtained bacterial cells were subjected to enzyme treatment. First, 160 mg of neutral protease (Amano Pharmaceutical Protease N) was added to the disrupted cell suspension, and the mixture was reacted at 50 ° C. for 12 hours. Sequentially, nuclease (Amano Pharmaceutical Nuclease) 60mg in the disrupted cell suspension
Was added and the reaction was carried out at 65 ° C. for 4 hours. Then add 60 mg of deaminase (Amano Pharmaceutical Deazyme) and add 2
The reaction was carried out over time.

Centrifugation (1) of the disrupted cell suspension treated with enzyme
After performing 0000 rotation for 10 minutes), 1260 g of a supernatant was obtained.
24 g of sodium chloride was added to this supernatant, and the mixture was concentrated by an evaporator to obtain 160 g of pasty yeast extract. Extraction ratio of extract solids to dry weight of 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 weight ratio of each free amino acid to the total amount of free amino acids 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 the mutant strain AHR4-24, and the same method as in Example 1 using the original strain. Candida yeast extract (A) (Comparative Example 1) prepared in 1. was obtained. The components of the yeast extract (B) and the free amino acid weight ratio were the same as those 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 The weight ratio of each free amino acid in the total amount of free amino acids of the yeast extract (A) is as follows. It was the street. Alanine 6.0% Glutamic acid 25.0% Histidine 8.0% Total free amino acid content in yeast extract 5.5% Sample concentration 1% solution, sensory evaluation of yeast extracts (A) and (B) at sample temperature 50 ° C 2 panel 10 people
The point identification method was used. The results are shown in Table 1.

[0019]

[Table 1]

According to Table 1, the Candida yeast extract of the present invention has a sweetness and a low Candida yeast specific odor.
It was shown that not only (B) is superior with a significant difference of%, but also (B) is superior in taste balance.

[0021]

EFFECTS OF THE INVENTION The Candida yeast extract of the present invention has a strong sweetness and an excellent taste balance with little odor specific to Candida yeast.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C12R 1:72) C12R 1:72

Claims (6)

(57) [Claims] 1. A yeast extract having a total free amino acid content of 3.0% or more, an alanine content of 10% or more, a glutamic acid content of 25% or more, and a histidine content of 10% or more. A candy date
Lopicalis, Candida lipolytica or candy
Yeast extract composition derived from yeast belonging to Idautilis . 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. Agar medium having aspartic acid hydroxamate resistance and containing only glycerin as a carbon source 3
Candida requiring 2 days or more to form a colony at 0 ° C
Tropicalis, candida lipolytica or cat
Yeast belonging to Ndida utilis . 5. Candida utilis AHR4-
24 shares. 6. Agar medium having resistance to aspartic acid hydroxamate and having only glycerin as a carbon source 3
Candida requiring 2 days or more to form a colony at 0 ° C
Tropicalis, candida lipolytica or cat
A method for producing a yeast extract composition, comprising deactivating a yeast belonging to Ndida utilis by heat , subjecting the yeast to an enzyme treatment, centrifuging, and obtaining a supernatant thereof.