JPH11332511A - Production of yeast extract - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a yeast extract having a large content of 5'-nucleotide. SOLUTION: This method for producing a yeast extract comprises thermally treating yeast cells as a raw material under a temperature-time condition within a range obtained by binding temperatures x of 15-50 deg.C, times y of 2-72 hr, a point of 15 deg.C-72 hr and a point of 50 deg.C-24 hr to each other through lines, extracting the thermally treated cell components under a condition containing a nuclease and under a condition inhibiting an enzymatic activity for hydrolyzing 5'-nucleotides, and subsequently extracting the digestion product. In a preferable digestion method, an external enzyme (protease, nuclease, enzyme for hydrolyzing polysaccharides, enzyme for hydrolyzing lipids, etc.), is added to solubilize intracellular components. In a preferable mode, the yeast is subjected to a grinding treatment using a physical means (homogenizer, mill, etc.), before a process for digesting the cell components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[Background of the Invention]

[0001] The present invention relates to a method for producing a yeast extract, and more specifically, to a method for producing a yeast extract having a high 5′-nucleotide content.

[0002]

2. Description of the Related Art Yeast extract has an excellent taste produced by free amino acids, 5'-nucleotides, peptides, organic acids, saccharides, etc., and is widely used in the food industry for imparting complex tastes such as richness and depth. ing. In addition, with the recent tendency of consumers to be natural and healthy, the amount of use has been increasing and is attracting attention.

[0003] The method for producing yeast extract includes a self-digestion method of solubilizing cell components using a proteolytic enzyme inherent in yeast cells to obtain an extract, and an enzyme preparation obtained from microorganisms and plants. There are known an enzymatic decomposition method of solubilizing bacterial cell components by adding a compound, a hydrolysis method of solubilizing with an acid or an alkali, and various methods combining these.

[0004] 5'-nucleotide, which is a degradation product of nucleic acid, has excellent taste itself and also has a synergistic effect of umami with free amino acids, particularly glutamic acid. It is a very important factor in doing so. However, in the conventional method for producing yeast extract, the nucleic acid is not sufficiently extracted or is excessively decomposed, so that almost no 5'-nucleotide remains.

[0005] As an attempt to increase the amount of 5'-nucleotide production, a yeast cell or an extract thereof is inactivated by heat or alkali, and then a nuclease is externally added. A certain ribonucleic acid (RNA)
(JP-A-62-201595 and JP-A-2-79954), which is capable of autolyzing under alkaline conditions to prevent excessive degradation of 5'-nucleotides. A method of obtaining an extract by suppressing the amount (Japanese Patent Publication No. 3-24190) is known.

However, these methods have a low synergic effect because the yield of the extract is low and the cell components cannot be used sufficiently, a large amount of externally added enzyme is required, and the process is complicated, which is costly. There are drawbacks such as poor balance between '-nucleotides and free amino acids.

Until now, no attempt has been made to pay attention to pretreatment of yeast as a raw material in order to increase the amount of 5'-nucleotide production.

From the viewpoint of pretreatment of the yeast cells in the method for producing yeast extract, a method of treating the yeast cells with an acid or an alkali (Japanese Patent Publication No. 61-50592) and a method of treating the yeast cells with ethyl alcohol ( Tokuhei 02
These publications are directed to the initiation of self-digestion, the removal of contaminating bacteria, and the removal of off-flavors, and indicate the production or amount of 5'-nucleotide. Not something. Also,
In fact, in these methods, the amount of 5'-nucleotide production is not particularly increased.

[Summary of the Invention]

An object of the present invention is to provide a method for producing a yeast extract having a high 5'-nucleotide content by pretreating a yeast cell as a raw material for extract extraction. The purpose is.

[0010]

Means for Solving the Problems As a result of diligent studies on a pretreatment method for yeast cells, the present inventors have conducted a heating treatment under specific conditions, and then under a condition containing nuclease and 5'- By digesting and extracting the bacterial cell components under conditions in which the enzymatic activity of decomposing nucleotides is suppressed, it is found that the amount of 5'-nucleotide production after extraction is increased,
The present invention has been completed.

That is, according to the present invention, after subjecting a yeast cell as a raw material to a heating treatment under a temperature-time condition within a range surrounded by a straight line represented by the following formulas (i) to (iv), A method for producing a yeast extract, comprising digesting and extracting a cell component under conditions included therein and under conditions in which an enzyme activity for decomposing 5'-nucleotides is suppressed.

(I) x = 15, (ii) y = 50, (iii) y = 2, (iv) y = − (48/35) x + 648/7 [where x is a temperature (° C.); y is time (hour). ]

[Specific description of the invention]

BEST MODE FOR CARRYING OUT THE INVENTION The yeast used in the present invention is not particularly limited as long as it is edible, and for example, yeasts used in the ordinary food industry such as brewer's yeast, baker's yeast, alcoholic yeast and torula yeast are used. They can be used singly or in combination. The above specific yeast can be easily obtained from a manufacturer or the like that sells yeast. When brewer's yeast is used as a raw material, it is preferable to perform a normal debittering treatment as appropriate in order to remove bitterness derived from hops, so that a yeast extract with more flavor can be produced.

In the present invention, before the yeast cells are subjected to the digestion step, a heating treatment is performed as a pretreatment of the starting cells. Yeast cells in which endogenous enzymes are not inactivated (for example, live cells)
It is preferable to use those which have been stored at low temperatures such as freeze-drying, freezing, moistening, and suspension. The heating process is
Usually, yeast cells are squeezed (dry or wet yeast, etc.), paste (wet or freeze-thaw yeast, etc.), slurry or suspension (suspension, freeze-thaw yeast, etc.) by a filter press or the like.

In the heating process according to the present invention, the temperature within the range surrounded by the straight line represented by the formulas (i) to (iv) is used as described above.
The temperature-time condition is shown in FIG.
Can be represented as a hatched area. That is, the temperature-time conditions are as follows: temperature x is 15 to 50 ° C., and time y is 2 to 7
This is a condition within a range that linearly connects the points of 2 hours and 15 ° C.-72 hours and 50 ° C.-24 hours. In FIG. 1, the temperature-time condition is within a range connecting the following four points.

(I) 15 ° C. for 2 hours, (ii) 15 ° C. for 72 hours, (iii) 50 ° C. for 24 hours, (iv) 50 ° C. for 2 hours As shown in FIG. Depends on the processing temperature. In other words, the heating process needs only a short time if the temperature is high, and requires a long time if the temperature is low. If the treatment temperature is lower than 15 ° C., the effect (particularly the effect of increasing the amount of 5′-nucleotide produced) is weak, and the time required is too long, which is not practical for use in an actual production site. Further, it has been confirmed that even if the temperature exceeds 50 ° C., there is no effect of increasing the amount of 5′-nucleotide produced after extract extraction. Processing temperature is 1
The range is from 5 ° C to 50 ° C, but 25 to 40 ° C is more preferable. Heating process is usually performed in a suitable container (tank, etc.)
The yeast cells placed in the container are allowed to stand in a thermostat (an external force such as stirring (suspension) may be applied if necessary), but outside the thermostat at room temperature or room temperature. Can be left in the environment or preserved, and are included in the heating treatment.

On the other hand, the heating time is effective when the time is at least 2 hours. However, if the heat treatment time exceeds 72 hours, there is a risk of spoilage and an unpleasant odor is attached. There is. Also, as shown in FIG. 1, the higher the temperature, the shorter the maximum processing time allowed (corresponding to equation (iv)).
4 hours. Among the above-mentioned treatment times, particularly, a heating treatment for 4 to 16 hours (more preferably at a temperature of 25 to 40 ° C.) has a high effect of increasing the amount of 5′-nucleotide produced after extract extraction.

As described above, the heating process in the present invention can be represented by a specific formula or FIG. 1, and it is sufficient that the heating process is within the range. However, the preferred relationship between the processing temperature and the holding time (processing time) is preferred. Examples can be shown, for example, in the table below (these are examples and do not limit the invention).

[0019] Temperature of heating treatment Holding time More optimal holding time 25 ° C 2 to 58 hours 5 to 20 hours 35 ° C 2 to 45 hours 4 to 19 hours 45 ° C 2 to 31 hours 4 to 15 hours The treatment hardly deactivates various enzymes (protease, nucleolytic enzyme, polysaccharide degrading enzyme, lipolytic enzyme, etc.) in the yeast cells.

The method for producing a yeast extract of the present invention comprises the steps of: using a yeast cell having been subjected to the above-mentioned heating treatment as a raw material, under the conditions containing at least a nuclease, and decomposing 5′-nucleotide. The method needs to be a method in which the cell components are digested (or decomposed) under conditions where the activity is suppressed. Here, “under the conditions containing nuclease” means
The presence of the nuclease is essential, and other digestive enzymes may be included as necessary, and the nuclease may be derived from the yeast cells used or may be added from the outside. Also means good. In addition, “under conditions under which the enzymatic activity for decomposing 5′-nucleotides is suppressed” refers to 5 conditions such as nucleotidase and phosphomonoesterase.
'-Means a condition or environment that suppresses the activity of an enzyme having the resolution of nucleotides.

One of the digestion methods of the cell components is a so-called autolysis method using enzymes in yeast cells. In the autolysis method, a yeast cell (the above-mentioned heated one in the present invention) as a raw material is subjected to a heat treatment so that a degrading enzyme (protease, nuclease, etc.) in the cell acts to solubilize the yeast. In order to suppress the degradation of 5'-nucleotide, the yeast cells are subjected to pH 6.
5-10 medium to alkaline, preferably 6.5-8.5
It is necessary to carry out the reaction under a moderate to weak alkaline condition. In the autolysis in the present invention, the yeast cells which have been subjected to a heating treatment as a pretreatment are usually adjusted to pH 6.5 to 10 with an alkali agent (such as sodium hydroxide) or a buffer in the form of an aqueous suspension. Thereafter, under conventionally known conditions, for example, 40 to 55
The heat treatment may be performed at 36 ° C. for about 36 to 48 hours. However, from the viewpoint of a sufficient and stable amount of 5'-nucleotide to be produced, a method of solubilizing intracellular components by adding an external enzyme agent further than the autolysis method alone, that is, a state in which the external enzyme agent is added Is more preferable. Here, the external enzyme agent is a foreign enzyme for digestion that can decompose at least the high molecular component of yeast cells,
Examples of such enzymes include various proteolytic enzymes (protease: for example, Protamex (Novo)), nucleases (nucleases (particularly, 5'-p nuclease)):
For example, nuclease “Amano” (Amano Pharmaceutical Co., Ltd.)), polysaccharide-degrading enzyme (eg, Zymolyase (Kirin Brewery)), lipolytic enzyme (eg, lipase A “Amano”)
(Amano Pharmaceutical Co., Ltd.) can be used singly or in combination (eg, a protease and a nuclease). As the nuclease, those having low phosphatase activity and nucleotidase activity (for example, protamex) which degrade 5'-nucleotide or those producing 5'-nucleotide (for example, 5'-nucleotidase)
Is desirable. In the combination of enzymes, a complex taste of various degradation products (free amino acids, 5'-nucleotides, organic acids, etc.) can be imparted by using various enzymes in combination. By using the enzyme and the nuclease in combination, the balance between the 5'-nucleotide and the free amino acid exhibiting a synergistic effect of taste is improved.

As the external enzymatic agent, in addition to the above digestive enzymes, deaminase (for example, 5'-AMP is replaced with 5'-AMP)
Other enzymes can also be used, such as -AMP deaminase which converts to IMP).

In the autolysis step in which an external enzyme agent is added, one or more external enzymes are usually added to an aqueous suspension of a yeast cell material (heat-treated according to the present invention),
As mentioned above, the pH is 6.5 to 10, preferably 6.5 to 10.
8.5 Enzyme reaction (autolysis + external enzyme reaction) is carried out under medium to alkaline conditions.

The timing of adding the external enzyme is not particularly limited, but is preferably at the beginning of autolysis.

The amount of the external enzyme to be added is not particularly limited as long as the enzyme effectively acts, and may vary depending on the type of the enzyme.
/ Ml.

Usually, the digestion reaction is stopped by adding 80
What is necessary is just to heat at -100 degreeC for about 5 to 15 minutes.

In the present invention, the digestion step may be performed only by the method of adding an external enzyme agent, in addition to the method of combining autolysis and the method of adding an external enzyme agent as described above. That is,
It is also possible to use a method of inactivating the intracellular enzymes of the heated yeast and then adding an external enzyme agent (one or more types of enzymes) to solubilize (digest) the intracellular components. . In this case, factors such as the type and amount of yeast to be added can be arbitrarily controlled, so that there is an advantage that process control for obtaining a desired yeast extract is easy.

The inactivation of intracellular enzymes can be carried out by heating the yeast cell solution after the heating treatment at 80 to 100 ° C. for about 5 to 15 minutes.

The amount of the external enzyme to be added is desirably increased by a method combined with autolysis due to the inactivation of enzymes in the yeast cells.
The concentration is on the order of mg to 20 mg / ml. The reaction conditions in the subsequent digestion step (including the termination of the digestion reaction) may be basically the same as those in the case of autolysis, but the pH may be within the range in which the enzyme to be added acts, and is not necessarily 6.5 to 6.5. 8.
It need not be in the range of 5 (or 10).

In the present invention, a conventional acid or alkali hydrolysis method can be combined with the above-described enzyme digestion step, if necessary.

In the present invention, after the heating step and prior to the digestion step, the yeast cells are crushed by physical means, in particular, using a physical means such as a homogenizer or a mill (for example, a ball mill). Treatment, and then use a method of solubilizing intracellular components by performing autolysis or autolysis by adding an external enzyme.
The amount of 5'-nucleotide production after extract extraction is further remarkably increased. The treatment by a physical means may be performed under the condition that the yeast cells are physically crushed. Preferred conditions for the treatment by the homogenizer are described below.

Homogenizer: T, manufactured by RANNIE
Ype 10.51 VH Treatment conditions: 200 to 1000 kgf / cm ² (1 pass) The yeast cell component solubilized by the digestion step (preferably after crushing treatment by physical means) is then subjected to the extraction step. Then, the target yeast extract, that is, a yeast extract having a high 5′-nucleotide content can be obtained by separating the insoluble cell components. Such an extraction step can be performed by any suitable method,
Specifically, a centrifugal separation method (for example, 1000 to 3000 rpm)
m for 3 to 10 minutes), a filter press, a coagulation sedimentation method and the like.

The supernatant fraction obtained in the extraction step can be used as it is, or can be diluted or concentrated to obtain a yeast extract, but it can be processed into a powder, paste, semi-fluid or the like depending on the purpose of use.

As described above, according to the method of the present invention,
By digesting and extracting the yeast cell components under conditions in which the enzymatic activity of decomposing 5'-nucleotides is suppressed, the raw yeast cells previously heated under a specific temperature-time condition are digested and extracted.
-A yeast extract having a high nucleotide content can be obtained.

[0035]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 and Comparative Example 1 Yeast by-produced in the beer brewing process (usually referred to as brewer's yeast) has a solid concentration of 10% (w
/ V) The slurry was kept at 35 ° C. for 12 hours and then cooled with ice. As a comparison, 4 without heat treatment
The one stored at ℃ was also prepared.

Each was placed in a glass beaker and kept in a boiling water bath at 80 ° C. or higher for 10 minutes to inactivate all enzymes in the yeast. After cooling, the nuclease nuclease Amano (Amano Pharmaceutical Co., Ltd.) was added to 50 g of dry solids.
mg. After holding at 45 ° C. for 6 hours, the enzyme was inactivated by holding at 80 ° C. or higher for 10 minutes in a boiling water bath. Then the solids are separated by centrifugation,
An extract was obtained.

Of the 5'-nucleotides, the 5 '
-The quantification of GMP was determined by high performance liquid chromatography under the following conditions.

Column: MCI GEL CDR-10, 4.6 m
mX 250 mm (manufactured by Mitsubishi Chemical Corporation) Eluent: 1 M ammonium acetate buffer (pH 3.5) Pump: Tosoh CCPD Flow rate: 1 ml / min Detector: Tosoh UV8010 Measurement wavelength: 254 nm Calculator: Tosoh SC-8010 5 ' -The nucleotide amount was represented by the number of mg contained per 1 g of the solid content of the extract component (table below). Generated 5'-GMP amount (mg / g) Comparative Example 1 1.03 Example 1 1.75

[Example 2 and Comparative Example 2] As in the case of Example 1 and Comparative Example 1, brewer's yeast subjected to a temperature treatment of 35 ° C. for 12 hours and yeast not subjected to the temperature treatment were prepared.

Each sample was processed at a processing pressure of 1000 k.
gf / cm ² high pressure homogenizer (RANNIE)
(Type 10.51 VH). These treatment liquids were adjusted to pH 7.5 with sodium hydroxide and adjusted to 30 ° C.
Hold at ４７47 ° C. for 8 hours. 80 ° C to stop the enzyme reaction
After holding for 10 minutes as described above, solid-liquid separation was performed with a centrifugal separator to obtain an extract component.

The amount of 5'-GMP produced in the extract was analyzed in the same manner as in Example 1, and the results are shown below. Generated 5'-GMP amount (mg / g) Comparative Example 2 0.05 Example 2 3.31

Example 3 and Comparative Example 3 Yeast subjected to temperature treatment in the same manner as in Example 2 and non-treated yeast were homogenized, the pH was adjusted to 7, and the proteolytic enzyme Protamex MG (Novo Industry) was used. 0.25)
mg / ml and kept at 30 ° C to 47 ° C for 8 hours. The enzyme reaction was stopped and centrifuged as in Example 2 to obtain an extract.

The amount of 5'-GMP produced in the extract was analyzed in the same manner as in Example 1, and the results are shown below.

Example 4 and Comparative Example 4 Cultivated torula yeast (Candida utilis) was used as a material and treated with and without a temperature treatment at 35 ° C. for 12 hours in the same manner as in Example 1.

Crushing was carried out using a high-pressure homogenizer in the same manner as in Example 2, and the mixture was treated at 30 ° C. to 45 ° C. at pH 7.5.
For 8 hours, and then inactivated at 80 ° C. for 10 minutes, followed by centrifugation to obtain an extract.

The results of analyzing the amount of 5'-GMP contained in the extract in the same manner as in the method described in Example 1 are shown below.

Example 5 After pretreatment was performed using brewer's yeast by changing the heating temperature and the treatment time, a yeast extract was prepared in the same manner as in Example 3 to produce 5 ′.
-The amount of GMP was analyzed by the method described in Example 1. The results are summarized in the table below. It should be noted that when the pretreatment was performed at 55 ° C., an unpleasant odor was generated even if the treatment was performed for a short time, and thus it was determined that the pretreatment was not suitable for the method of the present invention.

[0048] 18 ° C 24 ° C 30 ° C 35 ° C 40 ° C 45 ° C 0 hours 1.58 1.58 1.58 1.58 1.58 1.58 4 hours---3.28 4.97 2.69 8 hours---6.69 8.42 2.67 12 hours----17.3 7.05 1.76 16 hours 4.33 6.51 13.3 15.4 2.05 nd 40 hours 7.82 12.8 12.9 8.60 nd 72 hours (off-flavor) (off-flavor) (off-flavor) (off-flavor) (off-flavor) (-: not measured nd: not detected)

[0049]

According to the present invention, in particular, the starting yeast cells heated under specific temperature conditions are digested under conditions in which the enzymatic activity for decomposing 5'-nucleotides is suppressed. By extraction, a yeast extract having a high 5'-nucleotide content can be provided.

As a digestion method, by adding an external enzyme agent to solubilize intracellular components, a yeast extract having a high 5'-nucleotide content can be stably supplied.

Further, prior to the digestion step of the cell components,
By disrupting the yeast by physical means, the effect of solubilizing the cell components is further enhanced.

Using the yeast cells which have been pretreated by heating under the above specific conditions as raw materials for the digestion step;
It is surprising to those skilled in the art that the combination of performing the digestion step under conditions in which the enzymatic activity to degrade 5'-nucleotides is suppressed and the 5'-nucleotide content after extract extraction can be significantly increased. It is understood that there was no.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between temperature and time in a heating process.

Claims (5)

[Claims] 1. A method comprising heating a yeast cell as a raw material under a temperature-time condition within a range surrounded by a straight line represented by the following formulas (i) to (iv), A method for producing a yeast extract, comprising digesting and extracting bacterial cell components under conditions under which enzyme activity for decomposing 5'-nucleotides is suppressed. (i) x = 15, (ii) y = 50, (iii) y = 2, (iv) y = − (48/35) x + 648/7 [where x is temperature (° C.) and y is time (Time). ] 2. The method for producing a yeast extract according to claim 1, wherein the method of digesting the bacterial cell component is a method of inactivating the intracellular enzyme and then adding an external enzyme agent to solubilize the intracellular component. . 3. The method of digesting cell components comprises the steps of:
The method for producing a yeast extract according to claim 1, which is a method of autolyzing under a medium to alkaline condition of 6.5 to 10. 4. The method for producing a yeast extract according to claim 3, wherein autolysis is performed by adding an external enzyme agent. 5. The method according to claim 1, wherein the yeast is crushed by physical means prior to the step of digesting the cell components.
5. The method for producing a yeast extract according to any one of 4.