JP6851595B2 - Yeast extract manufacturing method - Google Patents

Description

The present invention relates to a method for producing a yeast extract, and more particularly to a method for producing a yeast extract containing a high concentration of amino acids.

Yeast extract is an extract obtained by extracting useful components of yeast. It contains amino acids, nucleic acid-related substances, minerals, and vitamins as its main components, and is used in various fields such as pharmaceuticals, media, foods, and feeds. In particular, yeast extract is used in the food manufacturing process to improve and enhance the flavor, and demand is increasing due to the favorable image of a natural material, and the production volume is also increasing year by year.

Methods for producing yeast extract include an autolysis method, a hot water treatment method, and an enzyme treatment method. Yeast autolyzed products are those in which yeast cells are collected and autolyzed by the action of digestive enzymes contained in the yeast itself. As a result, the proteins constituting yeast are decomposed into umami-tasting amino acids and low-molecular-weight peptide chains.

When producing a yeast extract by such an autolysis method, it is desired to improve the content of useful components in the extract.

For example, autolysis can be promoted by adding toluene, ethyl acetate, an inorganic acid, or the like in the process of producing yeast extract. In addition, as a method for promoting autolysis, there are the following.

For example, Patent Document 1 states that when a yeast extract is produced by a self-digestion method, the first-stage enzymatic reaction is performed at the optimum reaction temperature of the proteolytic enzyme contained in the yeast, which activates the reaction more in a low temperature range. Then, the enzyme reaction of the second stage is carried out at a temperature higher than the optimum reaction temperature and above the temperature range that suppresses the growth of various germs, and further, the enzyme reaction of three or more steps having different enzyme reaction temperatures is carried out. The technology is disclosed.

Further, Patent Document 2 discloses a method for producing an amino acid-rich yeast in which yeast in a steady growth phase is liquid-cultured under the condition that the pH of a liquid medium is 7.5 or more and less than 11. Thereby, an amino acid-rich yeast containing a high concentration of amino acids can be obtained.

Japanese Unexamined Patent Publication No. 10-179084 Japanese Patent No. 5730579

As described above, when producing a yeast extract by an autolysis method, it is desired to improve the content of useful components in the extract.

However, the addition of chemicals to promote yeast autolysis spoils the image of natural materials. In addition, when yeast extract is used in foods, it is necessary to remove residual chemicals, and there are restrictions on the chemicals that can be used. In addition, the method of adjusting the temperature and pH requires time and cost for pretreatment and condition control.

Therefore, it is desired to develop a method for producing yeast extract in as short a time as possible, in a short process, and with easy control of conditions.

An object of the present invention is to provide a method for producing a yeast extract in a short time, in a short process, and in which conditions can be easily controlled. In particular, it is an object of the present invention to provide a method for producing a yeast extract containing a high concentration of useful components such as amino acids.

The method for producing a yeast extract of the present invention is after (a) a step of preparing a suspension containing yeast, (b) a step of applying an electric field treatment to the suspension, and (c) the above step (b). It has a step of self-digesting yeast in the above suspension.

In the step (b), the applied voltage is less than 1000 V / mm, and the temperature of the suspension during the voltage application period is 64 ° C. or lower.

In the step (b), the applied voltage is 3 V / mm or more and 150 V / mm or less.

In the step (b), the voltage application time is less than 25 seconds.

The voltage applied in the step (b) is an AC voltage.

The yeast is of the genus Saccharomyces or Candida.

By subjecting the yeast-containing suspension to an electric field treatment in this way, the content of amino acids in the yeast extract can be improved.

It is a schematic cross-sectional view which shows the electric field treatment process in the manufacturing process of yeast extract. It is a schematic cross-sectional view which shows the short-time heat treatment process in the manufacturing process of yeast extract. It is a figure which shows the graph of the total amino acid amount of test A to test D. It is a figure which shows the graph of the branched chain amino acid amount of test A to test D. It is a figure which shows the graph of the total amino acid amount of test E1 and test E2. It is a figure which shows the graph of the branched chain amino acid amount of test E1 and test E2. It is a figure which shows the waveform of the applied voltage pulse. It is a figure which shows the yeast extract production apparatus system (high electric field processing system). It is a figure which shows the yeast extract production apparatus system (low electric field processing system). It is a figure which summarized an example of the use condition of a device. (A) and (B) are graphs showing the relationship between the autolysis rate of yeast (dry yeast) and the retention time. (A) and (B) are graphs showing the relationship between the autolysis rate of yeast (raw yeast) and the retention time. (A) and (B) are graphs showing graphs of the total amount of free amino nitrogen in Test F2 and Test G2. (A) and (B) are diagrams showing graphs of the amounts of branched chain amino acids in Test F2 and Test G2. (A) and (B) are diagrams showing graphs of the amounts of glutamic acid in Test F2 and Test G2. (A) and (B) are graphs showing the amount of glutamine in Test F2 and Test G2.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Enriching the amino acid content of autolyzed yeast extract by electric field treatment)
FIG. 1 is a schematic cross-sectional view showing an electric field treatment step in the yeast extract manufacturing step. As shown in FIG. 1, a yeast suspension is flowed through a flow path R made of an electrically insulating material. As the yeast, for example, the genus Saccharomyces or the genus Candida can be used. As the suspension liquid, for example, water (pure water, ion-exchanged water) can be used. The concentration of yeast in the suspension is, for example, about several% to several tens of% (w / v).

A pair of electrodes EL1 and EL2 facing each other with a narrow interval (for example, about 0.1 to 5 mm) are arranged in the middle of the flow path R. An AC voltage having a frequency of, for example, about 5 kHz to 20 kHz is applied between the electrodes EL1 and EL2 at a distance of about 150 V per 1 mm between the electrodes EL1 and EL2. For example, the flow velocity of the suspension is controlled by a pump or the like, and the passage time of the suspension between the electrodes EL1 and EL2 is, for example, 0.1 second or less.

In this way, the yeast suspension treated with an electric field between the electrodes EL1 and EL2 is cooled and then heated in, for example, a constant temperature bath at 40 ° C. to 50 ° C. for several hours. This causes the yeast suspension to autolyze. Autolysis means that yeast cells are decomposed by the action of digestive enzymes contained in yeast itself. For example, the proteins that make up yeast are broken down into umami-tasting amino acids and low-molecular-weight peptide chains.

(Enriched amino acid content of autolyzed yeast extract by short-time heat treatment)
FIG. 2 is a schematic cross-sectional view showing a short-time heat treatment step in the yeast extract manufacturing step. As shown in FIG. 2, a yeast suspension is flowed through a flow path R made of an electrically insulating material. As the yeast, for example, the genus Saccharomyces or the genus Candida can be used. As the suspension liquid, for example, water can be used. The concentration of yeast in the suspension is, for example, about several% (w / v).

A heat exchanger is arranged in the middle of the flow path R. The heat exchanger allows the yeast suspension to be heated. The heating temperature is, for example, about 50 ° C. to 60 ° C. The flow rate of the suspension is controlled by a pump or the like, and the passage time of the heat exchanger is, for example, about several seconds, during which the yeast suspension is heated to the above 50 ° C. to 60 ° C. be able to.

In this way, the yeast suspension that has been heat-treated for a short time is cooled and then heated in, for example, a constant temperature bath at 40 ° C. to 50 ° C. for several hours. This causes the yeast suspension to autolyze.

(Example 1)
(Test A) Commercially available dry yeast (Saccharomyces cerevisiae) is suspended in ion-exchanged water so as to have a concentration of 5% (w / v), a yeast suspension is prepared, and the mixture is allowed to stand for 6 hours. , A suspension of yeast was obtained. Next, a high electric field (AC high electric field) of 20 kHz and 150 V / mm was applied to the yeast suspension for 0.03 s. The application time of this high electric field corresponds to the transit time between the electrodes of the suspension. Specifically, the suspension was passed between electrodes having an electrode spacing of 4 mm, a voltage of 600 V was applied between the electrodes, and the suspension was passed between the electrodes in 0.03 s. The application of an electric field raised the temperature of the suspension to 54 ° C. The suspension was cooled to 7 ° C. in a heat exchanger and then held at 45 ° C. for 6 hours for autolysis of yeast.

The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

(Test B) As control 1, commercially available dry yeast was suspended in water so as to have a concentration of 5% (w / v), left for 6 hours, and the obtained yeast suspension was used as in the case of the above test A. Similarly, yeast was autolyzed by holding at 45 ° C. for 6 hours. The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

(Test C) As control 2, commercially available dry yeast was suspended in water so as to have a concentration of 5% (w / v), left for 6 hours, and the obtained yeast suspension was subjected to no electric field. , Passed between the electrodes, and the suspension was held at 45 ° C. for 6 hours in the same manner as in Test A above to perform autolysis of yeast. The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

(Test D) In the electric field treatment of Test A, the temperature rise of the yeast suspension was confirmed, so a short-time heat treatment using a heat exchanger was performed. A suspension of 5% (w / v) yeast was allowed to stand for 6 hours, passed through a heat exchanger and heated to 54 ° C. for 8.3 s. The yeast was autolyzed by cooling this suspension to 7 ° C. in a heat exchanger and then holding it at 45 ° C. for 6 hours in the same manner as in Test A. The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

The free amino acid analysis results of Tests A to D are shown in Tables 1 to 4. Regarding the suspensions of Tests A to D, free amino acid analysis is also performed on the suspensions before autolysis, that is, the suspensions having a retention time of 0 hours.

Table 1 below shows the results of free amino acid analysis of the high electric field treatment (denoted as "electric field 150 V / mm" or "HEF150") in Test A. 0h indicates a case where the retention time is 0 hours (before autolysis), and 6h indicates a case where the retention time is 6 hours (after autolysis) (the same applies to the following tests B to D). Table 2 shows the results of free amino acid analysis of control 1 (indicated as “control” or “CON”) in Test B. Table 3 shows the results of free amino acid analysis of Control 2 (indicated as “passing through the system” or “HEF000”) in Test C. Table 4 shows the results of free amino acid analysis of the short-time heat treatment (denoted as “heat exchanger” or “PHE”) using the heat exchanger of Test D. In the table, "ND" indicates "below the detection limit". The relationship between the numbers (No.) and abbreviations in each table and the amino acid names (including some amino acids other than amino acids) is as follows.
1. 1. P-Ser: Phosphoserine
2. Tau: Taurine
3. 3. PEA: Phosphoethanolamine
4. Urea: Urea
5. Asp: Aspartic acid
6. Thr: Threonine
7. Ser: Serine
8. Asn: Asparagine
9. Glu: Glutamic acid
10. Gln: Glutamine
11. Sar: Sarcosine
12. AAA: Aminoadipic acid
13. Gly: Glycine
14. Ala: Alanine
15. Cit: Citrulline
16. a-ABA: α-Aminobutyric acid
17. Val: Valine
18. Cys: Cysteine
19. Met: Methionine
20. Cysta: Cystathionine
21. Ile: Isoleucine
22. Leu: Leucine
23. Tyr: Tyrosine
24. b-Ala: β-Alanine
25. Ph: Phenylalanine
26. b-ABA: β-Aminobutyric acid
27. GABA: γ-Amino Butyric Acid
28. MEA: Monoethanolamine
29. NH ₃ : Ammonia
30. Hylys-1: Hydroxylysine-1
31. Orn: Ornithine
32.1M-His: 1-Methylhistidine
33. His: Histidine
34. Lys: Lysine
35.3M-His: 3-Methylhistidine
36. Trp: Tryptophan
37. Ans: Anserine
38. Car: Carnosine
39. Arg: Arginine
40. Hyper: Hydroxyproline
41. Pro: Proline

また、上記試験Ａ〜試験Ｄの遊離アミノ酸分析から、総アミノ酸量のグラフを図３に示す。縦軸は、総アミノ酸量（ｍｇ／ｍＬ）を示す。また、上記試験Ａ〜試験Ｅの遊離アミノ酸分析から、分岐鎖アミノ酸量のグラフを図４に示す。

In addition, a graph of the total amino acid amount from the free amino acid analysis of Tests A to D is shown in FIG. The vertical axis shows the total amount of amino acids (mg / mL). In addition, a graph of the amount of branched chain amino acids from the free amino acid analysis of Tests A to E is shown in FIG.

As shown in Tables 1 to 4, 3 and 4, when the high electric field treatment of the test A (indicated as "electric field 150 V / mm" or "HEF150") is performed, the control 1 of the test B is performed. The total amount of free amino acids was increased as compared with the case of Control 2 (indicated as "passing through the system" or "HEF000") in Test C above (indicated as "control" or "CON"). For example, the total amount of free amino acids in the electric field 150 V / mm (HEF1506 h) was 1.2 times that of Control 2 (HEF0006h). In addition, this increasing tendency was also observed when the holding time was 0 hours. Further, when the high electric field treatment of Test A (indicated as "electric field 150 V / mm" or "HEF150") is applied, the total amount of branched chain amino acids Val (valine), Ile (isoleucine) and Leu (leucine). increased. This branched chain amino acid is an essential amino acid in humans, accounting for 35% of the essential amino acids in muscle proteins and 40% of the amino acids required by mammals. For example, the total amount of Val, Ile and Leu at an electric field of 150 V / mm (HEF1506 h) was 1.35 times that of Control 2 (HEF0006h).

In addition, an increase in the amount of all the analyzed amino acids including the branched chain amino acids (Val, Ile and Leu) could be confirmed. For example, as compared with Control 2 (HEF0006h), the amount of each amino acid in the electric field 150V / mm (HEF1506h) is all increased.

Further, from the comparison between Test A and Test D, the total amount of free amino acids was larger in the high electric field treatment of Test A than in the simple heat treatment as in Test D. In addition, this increasing tendency was also observed when the holding time was 0 hours. In addition, the total amount of branched chain amino acids Val, Ile and Leu was also large. For each amino acid, the amount of amino acids other than Glu (glutamic acid) and AAA (aminoadipic acid) increased.

In this way, the amino acid content of the autolyzed yeast extract can be increased by high electric field treatment or short-time heat treatment. In particular, in the above-mentioned high electric field treatment, a remarkable increase in free amino acids including useful free amino acids could be confirmed.

Such an increase in amino acid content may be due to electrical activation of yeast or the effect of leakage of some enzymes in yeast due to electroporation, but it is still possible. The cause has not been clarified yet.

However, it seems to be very effective to confirm that the amino acid content of the autolyzed yeast extract can be increased by the above-mentioned high electric field treatment.

According to such a high electric field treatment, it is possible to avoid the addition of chemicals or reduce the amount of chemicals added in order to promote autolysis, and it is possible to easily add amino acids that can be added to foods while maintaining the image of natural materials. Moreover, it can be produced in a short time and in a short process.

Here, in the above test A, the test was conducted under specific conditions (for example, 150 V / mm), but as shown in Examples 2 and 3 described later, the effect is also obtained at 100 V / mm and 50 V / mm. It turns out.

Therefore, the high electric field treatment referred to in the present specification means a treatment of 50 V / mm or more. However, the voltage per 1 mm of distance between the electrodes is preferably less than 1000 V. When the voltage is 1000 V or higher, electroporation is likely to occur in the yeast, and the yeast may die. Further, the maximum temperature during high electric field treatment is preferably 64 ° C. or lower. If the temperature exceeds 64 ° C, yeast may die.

Therefore, the voltage per 1 mm of spacing between the electrodes is preferably less than 1000 V / mm. Above all, as shown in this embodiment and Examples 2 and 3 described later, it was confirmed that the amino acid content of the autolyzed yeast extract was increased by the high electric field treatment in the range of 50 V / mm to 150 V / mm. is made of. Furthermore, an increase in branched-chain amino acids has been confirmed.

The processing time (voltage application time, voltage application period) of the high electric field treatment can be appropriately adjusted within the range of 0.1 seconds or less.

Further, in Example 1 above, the concentration of yeast in the suspension was set to 5% (w / v), but the concentration is not limited to this. For example, the yeast concentration can be adjusted between 1% and 30% (w / v). However, if the yeast concentration is too low, the treatment efficiency will decrease, and if the yeast concentration is too high, it will be difficult to control the flow velocity and the voltage application will vary. It is preferable to adjust between 30% (w / v).

(Example 2)
In Test A of Example 1, the same experiment was performed with the electric field set to 100 V / mm. Further, since the temperature rise of the yeast suspension in this case was 29 ° C., the same experiment was conducted in Test B of Example 1 with the heating temperature by the heat exchanger set to 29 ° C. The same experiment as in Test C of Example 1 was carried out using the yeast suspension used as a control.

Also in Example 2, when the electric field treatment of Test A was performed, the total amount of amino acids increased as compared with the case of heat treatment by the heat exchanger of Test B. In addition, the amounts of the branched chain amino acids valine, leucine, and isoleucine increased.

(Example 3)
In Test A of Example 1, a similar experiment was performed with an electric field of 50 V / mm. Further, since the temperature rise of the yeast suspension in this case was 18 ° C., the same experiment was conducted in Test B of Example 1 with the heating temperature by the heat exchanger set to 18 ° C. The same experiment as in Test C of Example 1 was carried out using the yeast suspension used as a control.

In Example 3 as well, when the electric field treatment of Test A was performed, the total amount of amino acids increased as compared with the case of heat treatment by the heat exchanger of Test B. In addition, the amounts of the branched chain amino acids valine, leucine, and isoleucine increased.

(Example 4)
In the above test A, a high electric field was applied, but a test was also conducted for electric field treatment with a low electric field. A 5% (w / v) yeast suspension was left for 6 hours, and the yeast suspension was subjected to low electric field treatment.

As test E1, a low electric field of 1 V / mm was applied to the yeast suspension for 25 s. The application time of this electric field corresponds to the transit time between the electrodes of the suspension. Specifically, the suspension was passed between electrodes having an electrode spacing of 75 mm, an electric field of 75 V was applied between the electrodes, and the suspension was passed between the electrodes in 25 s (see FIG. 1). The suspension was cooled to 7 ° C. in a heat exchanger and then held at 45 ° C. for 6 hours for autolysis of yeast.

As test E2, a low electric field of 3 V / mm was applied to the yeast suspension for 2.5 s. The application time of this electric field corresponds to the transit time between the electrodes of the suspension. Specifically, the suspension was passed between electrodes having an electrode spacing of 75 mm, an electric field of 225 V was applied between the electrodes, and the suspension was passed between the electrodes in 2.5 s (see FIG. 1). The suspension was cooled to 7 ° C. in a heat exchanger and then held at 45 ° C. for 6 hours for autolysis of yeast.

In the above tests E1 and E2, the yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

The results of free amino acid analysis in Tests E1 and E2 are shown in Table 5. Table 5 shows the results of free amino acid analysis of low electric field treatment. Test E1 is indicated as "1S joule" or "1SJH54". Test E2 is indicated as "15A joules" or "15AJH54". The relationship between the numbers (No.) and abbreviations in the table and the amino acid names (including some amino acids other than amino acids) is as described above.

また、上記試験Ｅ１、試験Ｅ２の遊離アミノ酸分析から、総アミノ酸量のグラフを図５に示す。縦軸は、総アミノ酸量（ｍｇ／ｍＬ）を示す。また、上記試験Ｅ１、試験Ｅ２の遊離アミノ酸分析から、分岐鎖アミノ酸量のグラフを図６に示す。

Further, a graph of the total amount of amino acids is shown in FIG. 5 from the free amino acid analysis of Tests E1 and E2. The vertical axis shows the total amount of amino acids (mg / mL). In addition, a graph of the amount of branched chain amino acids is shown in FIG. 6 from the free amino acid analysis of Tests E1 and E2.

As shown in Table 5, FIG. 5 and FIG. 6, when the low electric field treatment (indicated as “1S joule” or “1SJH54”) of the test E1 was performed, the total amount of free amino acids was controlled in Example 4. It was about the same as (not shown). Further, when the 3V / mm electric field treatment (15AJH546h) of the test E2 was performed, the total amount of free amino acids increased from the control (not shown) and the test E1 (1V / mm applied). The total amount of branched chain amino acids Val, Ile and Leu was also increased. The amount of each amino acid is also increasing.

As described above, the amino acid content of the autolyzed yeast extract can be increased in the treatment of 3 V / mm or more even in the low electric field treatment.

In the case of low electric field treatment, it is preferable to apply a voltage in the range of 3 V / mm or more and 10 V / mm. Further, the maximum temperature during processing is preferably 64 ° C. or lower. If the temperature exceeds 64 ° C, yeast may die. The processing time (voltage application time) can be appropriately adjusted in the range of less than 25 seconds, more preferably 10 seconds or less. As a method of suppressing the temperature rise of the suspension, there are methods such as 1) increasing the flow velocity of the suspension and 2) improving the conductivity of the suspension.

Further, in the case of low electric field treatment, the distance between the electrodes can be lengthened, so that a suspension having a relatively high concentration can be treated. For example, the yeast concentration can be adjusted between 1% and 50% (w / v).

(Embodiment 2)
In the first embodiment, an AC electric field of 150 V / mm or 3 V / mm is applied between the electrodes, but the applied electric field may be a pulse electric field.

FIG. 7 is a diagram showing waveforms of an applied AC electric field and a pulsed electric field. The voltage is set to be, for example, 300 V per 1 mm between the electrodes. The frequency can be adjusted, for example, in the range of 5 kHz to 60 kHz. For example, when the frequency of the AC electric field is 21 kHz, the voltage rise time and fall time (reversal time) can be set to 2 μs, and the voltage energization time (pulse width) can be set to 22 μs (see the upper diagram of FIG. 7). .. As shown in the lower figure of FIG. 7, a rest time may be provided in the energizing time. For example, the rest time can be adjusted in the range of 2 to 6400 μs. Table 6 shows an example of the combination of the voltage pulse frequency and the pulse width, and Table 7 shows an example of the pause time.

以上詳細に説明したように、実施の形態１の高電界処理において、通電時間に、休止時間を設けた高電圧パルス（例えば、５０Ｖ／ｍｍ〜１５０Ｖ／ｍｍ程度）を用いてもよい。なお、休止時間のない連続した高電圧パルス処理を交流高電界処理と言う場合がある。また、実施の形態１の低電界処理において、通電時間に、休止時間を設けた低電圧パルス（例えば、３Ｖ／ｍｍ〜１０Ｖ／ｍｍ程度）を用いてもよい。

As described in detail above, in the high electric field treatment of the first embodiment, a high voltage pulse (for example, about 50 V / mm to 150 V / mm) in which a pause time is provided for the energization time may be used. In addition, continuous high voltage pulse processing without a pause time may be referred to as AC high electric field processing. Further, in the low electric field treatment of the first embodiment, a low voltage pulse (for example, about 3V / mm to 10V / mm) in which a pause time is provided for the energizing time may be used.

The frequency can be adjusted, for example, in the range of 5 kHz to 60 kHz.

Further, as described above, the maximum temperature during electric field treatment is preferably 64 ° C. or lower, but as a method for suppressing the temperature rise of the suspension, 1) increase the flow velocity of the suspension, and 2) suspend. In addition to improving the conductivity of the turbid liquid, there are 3) a method of thinning out the pulses of the AC electric field (providing a pause time).

(Embodiment 3)
The apparatus used for the electric field processing described in the first and second embodiments is not limited, but for example, the apparatus described below can be used.

FIG. 8 is a diagram showing an apparatus system for producing yeast extract. In the system shown in FIG. 8, the hopper 10 into which the yeast suspension to be treated is charged, the electric field applying device 13 connected to the hopper 10 via the flow path, and the electric field applying device 13 via the flow path. It has a heat exchanger 15 connected to the device. A pump P is connected between the hopper 10 and the electric field application device 13.

The hopper 10 is a container to which the above flow paths are connected. In the hopper 10, a suspension liquid (for example, ion-exchanged water) and yeast may be mixed.

In the electric field application device 13, the electrodes EL1 and EL2 are arranged so as to face each other via the flow path R. The electrodes EL1 and EL2 are insulated by an insulator IL. A power supply unit U is connected between the electrodes EL1 and EL2, and a predetermined electric field can be applied between the electrodes EL1 and EL2. Further, an AC electric field having a predetermined frequency can be applied between the electrodes EL1 and EL2. The frequency can be adjusted, for example, in the range of 5 kHz to 20 kHz. The distance between the electrodes EL1 and EL2 is, for example, about 0.1 to 8 mm, and a voltage of 3 V to 1000 V per 1 mm of distance can be applied between the electrodes EL1 and EL2.

Therefore, the yeast suspension flowing in from the inflow port IN passes between the electrodes EL1 and EL2, and in the meantime, is subjected to electric field treatment and discharged from the outflow port OUT. The electric field-treated yeast suspension is heated by the application of an electric field and cooled by the heat exchanger 15.

The configuration of the heat exchanger 15 is not limited, but for example, cooling water is flowed around the outer circumference of the coiled flow path to adjust the temperature of the suspension in the flow path.

The suspension cooled through the heat exchanger 15 is, for example, injected into a pack, sealed, injected into a constant temperature bath 17, and held in the constant temperature bath 17 at a predetermined temperature for a predetermined time. To. The constant temperature bath 17 serves as an autolyzing part of yeast.

Specifically, a suspension of yeast at room temperature, in which commercially available dry yeast is suspended in water so as to be 5% (w / v), is put into the hopper 10 and, for example, via a pump P, for example. The liquid is sent at 100 L / h. An electric field of 150 V / mm is applied for 0.03 seconds when the yeast suspension passes between the electrodes EL1 and EL2 of the electric field application device 13. This raises the temperature of the yeast suspension to 54 ° C. After this, the yeast suspension is cooled to 7 ° C. by a heat exchanger, and 100 ml each is dispensed into a plastic pack and sealed. Each plastic pack is heated at 45 ° C. for 0 to 6 hours in a constant temperature bath 17.

As described above, by producing the yeast extract from the yeast suspension using the system as shown in FIG. 8, the yeast extract can be efficiently produced. That is, in the production of yeast extract, the process can be shortened in a short time. Further, in the production of yeast extract, it becomes easy to control conditions such as applied electric field and temperature.

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment and can be variously modified without departing from the gist thereof. Needless to say.

For example, in Example 1 and the like, the yeast suspension was left for 6 hours, and then tests A to E1 and E2 were performed. This suppressed the variation of the suspension and made the comparison of each test more accurate. It's meant to be done, not essential. For example, electric field treatment may be performed immediately after preparing the yeast suspension. It has been confirmed that the amount of amino acids also increases by the electric field treatment immediately after preparing the yeast suspension.

Further, in Example 1 and the like, yeast was autolyzed by holding the yeast suspension after the electric field treatment at 45 ° C. for 6 hours, but the holding temperature and holding time are limited to this. is not it. The holding temperature can be appropriately adjusted at 64 ° C. or lower. Further, as the retention time increases, the amount of amino acids tends to increase, but it has been confirmed that the amount of amino acids increases even when the retention time is 0 hours. In addition, the amount of amino acids increases as the retention time increases from 0 hours to 6 hours.

Further, in Example 1 and the like, for example, ion-exchanged water was used as the liquid for suspending yeast, but other solvents may be used. Further, in order to adjust the conductivity of the suspension, salts (for example, NaCl), sugars and the like may be added to the suspension.

(Embodiment 4)
The apparatus used for the electric field processing described in the first and second embodiments is not limited, but for example, the apparatus described below can be used.

FIG. 9 is a diagram showing an apparatus system for producing yeast extract. In the system shown in FIG. 8, a hopper 10 into which a yeast suspension to be treated is charged, an electric field applying device (electric field applying section) 23 connected to the hopper 10 via a flow path, and an electric field applying device 23. And a heat exchanger 15 connected via a flow path. A pump P is connected between the hopper 10 and the electric field application device 23.

The hopper 10 is a container to which the above flow paths are connected. In the hopper 10, a suspension liquid (for example, ion-exchanged water) and yeast may be mixed.

In the electric field application device 23, ring electrodes (ring-shaped electrodes) REL1, REL2, and REL3 are arranged via tubes R1 and R2. The tubes R1 and R2 are made of an insulating material. A power supply unit U is connected between the ring electrodes REL1 and REL2 and between the ring electrodes REL2 and REL3, and a predetermined electric field can be applied between the ring electrodes REL1 and REL2 and between the ring electrodes REL2 and REL3. Further, an AC electric field having a predetermined frequency can be applied between the ring electrodes REL1 and REL2 and between the ring electrodes REL2 and REL3. The frequency can be adjusted, for example, in the range of 5 kHz to 100 kHz. The distance between the ring electrodes REL1 and REL2 and between the ring electrodes REL2 and REL3 (distance between electrodes ED) is, for example, about 75 mm, and the distance between the ring electrodes REL1 and REL2 and between the ring electrodes REL2 and REL3 is 1 mm. A voltage of 1V to 1000V can be applied. The inner diameters of the tubes R1, R2 and the ring electrodes REL1, REL2, and REL3 are, for example, about 17.5 mm.

Therefore, the yeast suspension flowing in from the inflow port IN passes between the ring electrodes REL1 and REL3, and in the meantime, is subjected to electric field treatment and discharged from the outflow port OUT. The electric field-treated yeast suspension is heated by the application of an electric field and cooled by the heat exchanger 15.

The configuration of the heat exchanger 15 is not limited, but for example, cooling water is flowed around the outer circumference of the coiled flow path to adjust the temperature of the suspension in the flow path.

The suspension cooled through the heat exchanger 15 is, for example, injected into a pack, sealed, injected into a constant temperature bath 17, and held in the constant temperature bath 17 at a predetermined temperature for a predetermined time. To. The constant temperature bath 17 serves as an autolyzing part of yeast.

Specifically, a suspension of yeast at room temperature, in which commercially available dry yeast is suspended in water so as to be 5% (w / v), is put into the hopper 10 and, for example, via a pump P, for example. The liquid is sent at 100 L / h. An electric field of 3 V / mm is applied for 2.5 seconds when the yeast suspension passes between the ring electrodes REL1 and REL3 of the electric field application device 23. As a result, the temperature of the yeast suspension rises to about 54 ° C. After this, the yeast suspension is cooled to 7 ° C. by a heat exchanger, and 100 ml each is dispensed into a plastic pack and sealed. Each plastic pack is heated at 45 ° C. for 0 to 6 hours in a constant temperature bath 17.

As described above, by producing the yeast extract from the yeast suspension using the system as shown in FIG. 9, the yeast extract can be efficiently produced. That is, in the production of yeast extract, the process can be shortened in a short time. Further, in the production of yeast extract, it becomes easy to control conditions such as applied electric field and temperature. In the electric field application device 23, three ring electrodes are used, but the number of ring electrodes may be two, or three or more (for example, five).

FIG. 10 is a diagram summarizing an example of the usage conditions of the apparatus described in the third embodiment and the present embodiment. For example, the apparatus of the third embodiment (FIG. 8) is suitable for the high electric field treatment (test A) described in the first embodiment, and the apparatus of the fourth embodiment (FIG. 9) is described in the first embodiment. Suitable for low and high electric field treatment (test E2).

Although overlapping with the description of Test A and Test E2 described above, the apparatus of the third embodiment (FIG. 8, high electric field processing apparatus) and the apparatus of the fourth embodiment (FIG. 9, low electric field processing), referring to FIG. An example of the usage conditions of the device) will be described.

As shown in FIG. 10, the electrode material of the high electric field processing device and the low electric field processing device is, for example, Ti. Pt may be used in addition to Ti. Further, an electrode obtained by coating Ti with Pt may be used.

Regarding the size of the flow path (electric field processing unit) provided with the electrodes, the cross section of the high electric field processing device is approximately 6 mm × 2 mm, and the length (RD) is 32 mm. Further, in the low and high electric field processing apparatus, the cross section is a circle with a diameter of 17.5 mm, and the length (ED × 2) is 75 mm × 2.

The high electric field processing device can apply a high electric field (here, 150 V / mm) by setting the distance between the electrodes to be small (here, 4 mm) and setting the voltage between the electrodes to 600 V. The electric field for high electric field processing can be adjusted between 50 V / mm and 500 V / mm by adjusting the distance between the electrodes and the voltage between the electrodes.

The low electric field processing device has a relatively large distance between electrodes (75 mm here), and a low electric field (3 V / mm here) can be applied by setting the voltage between the electrodes to 225 V. The electric field for low electric field processing can be adjusted between 3V / mm and 50V / mm by adjusting the distance between the electrodes and the voltage between the electrodes.

An AC electric field is applied to both the high electric field processing device and the low electric field processing device. That is, the positive and negative voltages between the electrodes are switched at predetermined intervals. The frequency is, for example, 20 kHz. The frequency is preferably 5 kHz to 100 kHz. Below 5 kHz, deterioration of the electrode due to electrolysis is likely to occur, and the frequency of electrode maintenance increases. In particular, the high electric field processing device and the low electric field processing device are in-line processing, and cleaning or replacement of electrodes involves decomposition of the device (electric field applying device), resulting in a decrease in processing efficiency. Further, if the frequency exceeds 100 kHz, the power loss becomes large, which leads to a high production cost.

The electric field application time (treatment time) is the time during which the treatment material (yeast suspension) flows between the electrodes. In a high electric field treatment device, for example, a region (length RD, here) in which the electrodes face each other. Then, about 32 mm), and the processing material passes through this in about 0.03 seconds by pressing the pump. Further, in the low electric field processing apparatus, for example, the distance between the electrodes (2 × ED, here, about 2 × 75 = 150 mm) is between the electrodes, and the processing material is, for example, about 2.5 seconds by pressing the pump during this distance. Pass by.

This electric field application time (processing time) can be adjusted by adjusting the size of the flow path (electric field processing unit) provided with the electrodes and the pump pressure. For example, in a high electric field processing apparatus, the electric field application time (processing time, passage time of the electric field application unit) can be adjusted in the range of 0.001 seconds or more and 1 second or less. Further, in the low electric field processing apparatus, the electric field application time (processing time, passage time of the electric field application unit) can be adjusted in the range of 1 second or more and 30 seconds or less.

As described above, in the high electric field processing apparatus, the cross section of the flow path (electric field processing unit) provided with the electrodes is small, and it is suitable for processing a material having a low viscosity. As a standard of viscosity, for example, it is suitable for processing a juice having a viscosity lower than that of tomato juice (viscosity of about 50 mPa · s). In the case of yeast suspensions, the high electric field treatment apparatus is suitable for treating, for example, 13% (w / v) or less. In the low electric field processing apparatus, the cross section of the flow path (electric field processing unit) provided with the electrodes is large, and it is possible to process a material having a high viscosity. As a reference for the viscosity, for example, a high-viscosity substance such as red bean paste (viscosity of 1000000 mPa · s or more) can be processed. For example, a yeast suspension of 13% (w / v) or more is preferably treated with a low electric field treatment device.

The yeast suspension used in Test A and Test E2 is about 5%, and can be treated by either a high electric field treatment device or a low electric field treatment device. In addition, the treatment efficiency can be improved by increasing the concentration of the yeast suspension. As described above, when the viscosity becomes high, it is preferable to use a low electric field processing device.

As described above, yeast extract can be efficiently produced by subjecting yeast to a suspension electric field treatment using the above-mentioned high electric field treatment device or low electric field treatment device. That is, in the production of yeast extract, the process can be shortened in a short time. Further, in the production of yeast extract, it becomes easy to control the applied electric field conditions and the like.

(Embodiment 5)
In the present embodiment, the influence of the retention time of the autolysis rate of yeast will be described.

(Example 5)
The effects of the retention time of yeast autolysis rate were examined by conducting the following tests F1, test F2, test G1, and test G2.

(Test F1)
Commercially available dry yeast (Saccharomyces cerevisiae) is suspended in ion-exchanged water to a concentration of 5% (w / v), the yeast suspension is prepared, and the yeast suspension is left for 6 hours. A turbid liquid was obtained. Next, a high electric field (AC high electric field) of 20 kHz and 500 V / mm was applied to the yeast suspension for 0.03 s. The application time of this high electric field corresponds to the transit time between the electrodes of the suspension. Specifically, the suspension was passed between electrodes having an electrode spacing of 4 mm, a voltage of 600 V was applied between the electrodes, and the suspension was passed between the electrodes in 0.03 s. The application of an electric field raised the temperature of the suspension to 54 ° C. The suspension was cooled to 7 ° C. in a heat exchanger and then held at 45 ° C. for 0 to 24 hours for autolysis of yeast. That is, the holding time was set to 0 to 24 hours. Since the weight of cells decreases over time due to autolysis, yeast cells contained in a certain amount of suspension are collected by centrifugation, and their dry weight (insoluble fraction) is determined to reduce the weight. The autolysis rate [(weight of dried cells at 0 hours-weight of dried cells after treatment / weight of dried cells at 0 hours) x 100%] was determined from the ratio of. The weight of dried cells at 0 hours can be said to be the insoluble fraction at the start, and the weight of dried cells after treatment can be said to be the insoluble fraction at the time of measurement.

The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. Then, free amino acid analysis in yeast solution was performed.

As a control, commercially available dry yeast was suspended in water so as to have a concentration of 5% (w / v), left for 6 hours, and the obtained yeast suspension was cooled at 45 ° C. without applying an electric field. The yeast was autolyzed by holding it for 0 to 24 hours. The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. After that, the autolysis rate was calculated.

In addition, as a comparative test, commercially available dry yeast is suspended in water so as to be 5% (w / v), and ethyl acetate is added to 3.3 ml / L as a chemical for promoting autolysis of yeast. After the addition as described above, the yeast suspension was allowed to stand for 6 hours at 45 ° C. for 0 to 24 hours without applying an electric field to autolyze the yeast. The yeast suspension (yeast solution) after autolysis was heated to 80 ° C. to inactivate the yeast. After that, the autolysis rate was calculated.

FIG. 11 (A) is a graph showing the relationship between the autolysis rate of yeast and the retention time. Graph (a) shows the case of high electric field treatment of dry yeast, graph (b) shows the case of adding ethyl acetate, and graph (c) shows the case of control. The horizontal axis is the retention time (hr), and the vertical axis is the autolysis rate (%).

As shown in FIG. 11 (A), in the high electric field treatment of dry yeast, the autolysis rate was higher than that in the case of adding ethyl acetate at any holding time. In particular, in graph (a), the autolysis rate increased rapidly, and a high autolysis rate of 25% or more was obtained even with a retention time of about 6 hours.

(Test F2)
Further, the same test as in the test F1 was conducted with the holding time set to 0 to 72 hours, which is a longer period than the 0 to 24 hours in the test F1. FIG. 11B is a graph showing the relationship between the autolysis rate of yeast and the retention time. Graph (a) shows the case of high electric field treatment of dry yeast, graph (b) shows the case of adding ethyl acetate, and graph (c) shows the case of control. The horizontal axis is the retention time (hr), and the vertical axis is the autolysis rate (%).

As shown in FIG. 11B, in the high electric field treatment of dry yeast, the holding time was about 24 hours and the autolysis rate was about 50%. The reached value of the autolysis rate of general yeast is considered to be about 50%.

(Test G1)
The yeast was changed from dry yeast (dried yeast) to raw yeast (squeezed yeast), and the same test as in test F1 was performed.

FIG. 12 (A) is a graph showing the relationship between the autolysis rate of yeast and the retention time. Graph (a) shows the case of high electric field treatment of raw yeast, graph (b) shows the case of adding ethyl acetate, and graph (c) shows the case of control.

As shown in FIG. 12 (A), in the high electric field treatment of raw yeast, the autolysis rate was higher than that in the case of adding ethyl acetate at any retention time. In particular, in graph (a), the autolysis rate increased rapidly, and a sufficient autolysis rate was obtained even with a retention time of about 6 hours.

(Test G2)
Further, the same test as in the test G1 was conducted with the holding time set to 0 to 72 hours, which is a longer period than the 0 to 24 hours in the test G1. FIG. 12B is a graph showing the relationship between the autolysis rate of yeast and the retention time. Graph (a) shows the case of high electric field treatment of raw yeast, graph (b) shows the case of adding ethyl acetate, and graph (c) shows the case of control. The horizontal axis is the retention time (hr), and the vertical axis is the autolysis rate (%).

As shown in FIG. 12B, in the high electric field treatment of raw yeast, the holding time was about 24 hours and the autolysis rate was about 50%.

(About the free amino acid analysis results of test F2 and test G2)
The results of free amino acid analysis in Test F2 and Test G2 will be described below with reference to FIGS. 13 to 16.

FIG. 13 is a diagram showing a graph of the total amount of free amino nitrogen in the test F2 and the test G2, and FIG. 14 is a diagram showing a graph of the amount of branched chain amino acids in the test F2 and the test G2. Further, FIG. 15 is a diagram showing a graph of the amount of glutamic acid in the test F2 and the test G2, and FIG. 16 is a diagram showing a graph of the amount of glutamine in the test F2 and the test G2. In any of the figures, (A) shows the case of test F2 (dry yeast), and (B) shows the case of test G2 (raw yeast). Further, in each figure, the graph (a) shows the case of high electric field treatment, the graph (b) shows the case of adding ethyl acetate, and the graph (c) shows the case of control.

In FIG. 13, the horizontal axis is the retention time (hr), and the vertical axis is the total amount of free amino nitrogen (mg / mL). As shown in FIG. 13, in both the dry yeast of FIG. 13 (A) and the raw yeast of FIG. 13 (B), the total amount of free amino nitrogen is rapid in the case of the high electric field treatment of the graph (a). I was able to confirm a significant rise. In particular, it was possible to confirm an increase in the total amount of free amino nitrogen in a short retention time as compared with the case where ethyl acetate was added in the graph (b).

In FIG. 14, the horizontal axis is the retention time (hr), and the vertical axis is the amount of branched chain amino acids (free amino acid amount (mg / mL)). As shown in FIG. 14, in both the dry yeast of FIG. 14 (A) and the raw yeast of FIG. 14 (B), the amount of branched chain amino acids (free amino acids) in the case of the high electric field treatment of the graph (a). A rapid increase in quantity) was confirmed. In particular, an increase in the amount of branched-chain amino acids (amount of free amino acids) in a short retention time could be confirmed as compared with the case where ethyl acetate was added in the graph (b).

In FIG. 15, the horizontal axis is the retention time (hr), and the vertical axis is the amount of glutamic acid (amount of free amino acids (mg / mL)). Glutamic acid is a type of amino acid that has an umami taste. As shown in FIG. 15, in both the dry yeast of FIG. 15 (A) and the raw yeast of FIG. 15 (B), the amount of glutamic acid (the amount of free amino acids) in the case of the high electric field treatment of the graph (a). Was confirmed to rise rapidly. In particular, an increase in the amount of glutamic acid (amount of free amino acids) in a short retention time could be confirmed as compared with the case where ethyl acetate was added in the graph (b).

In FIG. 16, the horizontal axis is the retention time (hr), and the vertical axis is the amount of glutamine (amount of free amino acids (mg / mL)). As shown in FIG. 16, in both the dry yeast of FIG. 16 (A) and the raw yeast of FIG. 16 (B), the amount of glutamine (the amount of free amino acids) in the case of the high electric field treatment of the graph (a). Was confirmed to rise rapidly. In particular, an increase in the amount of glutamine (amount of free amino acids) in a short retention time could be confirmed as compared with the case where ethyl acetate was added in the graph (b).

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment and can be variously modified without departing from the gist thereof. Needless to say.

For example, in Example 1 and the like, the yeast suspension was left for 6 hours, and then tests A to E1 and E2 were performed. This suppressed the variation of the suspension and made the comparison of each test more accurate. It's meant to be done, not essential. For example, electric field treatment may be performed immediately after preparing the yeast suspension. It has been confirmed that the amount of amino acids also increases by the electric field treatment immediately after preparing the yeast suspension.

Further, in Example 1 and the like, yeast was autolyzed by holding the yeast suspension after the electric field treatment at 45 ° C. for 6 hours, but the holding temperature and holding time are limited to this. is not it. The holding temperature can be appropriately adjusted at 64 ° C. or lower. Further, as the retention time increases, the amount of amino acids tends to increase, but it has been confirmed that the amount of amino acids increases even when the retention time is 0 hours. In addition, the amount of amino acids increases as the retention time increases from 0 hours to 6 hours.

Further, in Example 1 and the like, for example, ion-exchanged water was used as the liquid for suspending yeast, but other solvents may be used. Further, salts (for example, NaCl), sugars and the like may be added to the suspension in order to adjust the conductivity of the suspension.

10 Hopper 13 Electric field application device 15 Heat exchanger 17 Constant temperature bath 23 Electric field application device EL1 Electrode EL2 Electrode IL Insulator IN Insulator OUT Outlet P Pump R Flow path R1 Tube R2 Tube REL1 Ring electrode REL2 Ring electrode REL3 Ring electrode U Power supply unit

Claims (10)

(A) Step of preparing a suspension containing yeast,
(B) A step of applying an electric field treatment to the suspension,
(C) A step of autolyzing yeast in the suspension after the step (b).
Have,
The step (b) is a step of applying a voltage to the electrode while continuously flowing the suspension through an electric field application portion which is a flow path having an electrode.
In the step (b),
The temperature of the suspension during the voltage application period is 64 ° C. or lower.
The applied voltage is 50 V / mm or more and 500 V / mm or less.
A method for producing yeast extract, wherein the applied voltage is an AC voltage having a frequency of 5 kHz or more and 100 kHz or less, and the number of pulses exceeds 100. In the method for producing yeast extract according to claim 1,
In the step (b),
A method for producing a yeast extract, wherein the application time of the AC voltage to the suspension is 0.001 second or more and 1 second or less. In the method for producing yeast extract according to claim 1,
In the step (b),
The electrode has a first electrode and a second electrode arranged so as to face each other.
A method for producing a yeast extract, wherein the suspension flows between the first electrode and the second electrode. In the method for producing yeast extract according to claim 1,
A method for producing a yeast extract, wherein the yeast belongs to the genus Saccharomyces or the genus Candida. In the method for producing yeast extract according to claim 1,
A method for producing a yeast extract, wherein the yeast is dry yeast or raw yeast. (A) Step of preparing a suspension containing yeast,
(B) A step of applying an electric field treatment to the suspension,
(C) A step of autolyzing yeast in the suspension after the step (b).
Have,
The step (b) is a step of applying a voltage to the electrode while continuously flowing the suspension through an electric field application portion which is a flow path having an electrode.
In the step (b),
The temperature of the suspension during the voltage application period is 64 ° C. or lower.
The applied voltage is 3 V / mm or more and 50 V / mm or less.
A method for producing yeast extract, wherein the applied voltage is an AC voltage having a frequency of 5 kHz or more and 100 kHz or less. In the method for producing yeast extract according to claim 6,
In the step (b),
A method for producing a yeast extract, wherein the application time of an AC voltage to the suspension is 1 second or more and 30 seconds or less. In the method for producing yeast extract according to claim 7,
In the step (b),
The electrode has a ring-shaped first electrode and a second electrode, and has a ring-shaped first electrode and a second electrode.
A method for producing a yeast extract, wherein the suspension flows through the first electrode, a tube between the first electrode and the second electrode, and the second electrode. In the method for producing yeast extract according to claim 6,
A method for producing a yeast extract, wherein the yeast belongs to the genus Saccharomyces or the genus Candida. In the method for producing yeast extract according to claim 6,
A method for producing a yeast extract, wherein the yeast is dry yeast or raw yeast.

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