Method for evaluating the quality of koji and method for producing koji

Abstract

To provide a malt quality evaluation method with which it is possible to evaluate a glucoamylase titer in a floor process.SOLUTION: A malt quality evaluation method is intended to evaluate malt quality in a floor process of a malt production process for producing a malt by dispersing a mold starter to steamed rice. An index at the end of the malt production process is evaluated on the basis of relationship information indicating a relationship between an increment in carbon dioxide concentration increased during execution of the floor process and an index indicating malt quality at the end of the malt production process, and an increment in carbon dioxide concentration measured during the execution of the floor process.SELECTED DRAWING: Figure 8

Description

[[Technical Field]]

[0001] The present invention relates to a koji quality evaluation method for evaluating the quality of koji in the bed step of a koji making process for producing koji by sprinkling seed koji on steamed rice, and to a method for producing koji. [[Background Art]]

[0002] Production of sake generally proceeds sequentially through the following steps: a koji making step of producing koji by sprinkling seed koji on steamed rice, a saccharification step of saccharifying steamed rice using the koji produced in the koji making step to produce a saccharified liquid, a fermentation step of fermenting the saccharified liquid by the fermentation action of yeast to produce moromi (unfiltered sake mash), and a solid-liquid separation step of pressing moromi, which is in a solid-liquid mixed state, to obtain sake (see, for example, Patent Document 1). The saccharification step and the fermentation step proceed simultaneously in a fermentation tank, which is called parallel multiple fermentation.

[0003] Incidentally, the koji making process is generally often carried out over two days. The process on the first day is called the "bed step", which is a step of growing mycelia by maintaining humidity at a high temperature of around 30°C in a closed environment. The process on the second day is called the "shelf step". By this time, the activity of the mycelia has already become active, and the temperature of the koji (product temperature) rises, so this step is to grow the proliferated mycelia by creating a low-humidity environment. [[Prior Art Literature]] [[Patent Literature]]

[0004] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2003-284542 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] As indicators representing the quality of produced koji, there are enzyme titers such as glucoamylase titer, α-amylase titer, and acid carboxypeptidase titer, as well as the amount of bacterial cells, and it is desired that at least one of these indicators can be evaluated during the bed step. For example, the glucoamylase contained in manufactured koji is an important enzyme that breaks down the starch in steamed rice and supplies sugars to the yeast. Since only glucoamylase can produce the sugar (glucose) necessary for alcoholic fermentation, the glucoamylase titer (U / g), which indicates the enzymatic activity of the glucoamylase contained in manufactured koji, is considered particularly important.

[0006] Traditionally, in order to produce high-quality koji, manufacturers have aimed to produce high-quality koji by using their five senses (sight, touch, texture, etc.) to judge the state of koji production and adjusting the production conditions of the process (for example, controlling temperature and humidity). However, in the initial stages of the koji-making process (the bed stage), there is little change in the steamed rice, making it difficult to judge the koji-making state using the five senses. As a result, it was not possible to consistently produce high-quality koji.

[0007] In particular, it is known that it is difficult to evaluate the glucoamylase activity of koji during the koji-making process because the glucoamylase activity cannot be determined by evaluating koji using the five senses. Incidentally, glucoamylase titer analysis is performed using reagents, but it takes half a day. Therefore, it is not possible to evaluate the glucoamylase titer after the koji is completed during the koji-making process. For this reason, in manufacturing facilities, the glucoamylase titer is measured after the koji-making process is finished.

[0008] This invention has been made in view of the above circumstances, and its purpose is to provide a method for evaluating the quality of koji that can evaluate an indicator representing the quality of koji completed during the koji-making process. Another objective is to provide a method for producing koji that enhances the indicators representing the quality of the koji. [Means for solving the problem]

[0009] The present invention relates to a method for evaluating the quality of koji in the koji-making process, specifically in the koji-making bed stage, where koji starter is sprinkled onto steamed rice. The characteristic configuration of this method is as follows: Based on relational information showing the relationship between the increase in carbon dioxide concentration during the koji-making process and an index representing the quality of the koji at the end of the koji-making process, and the increase in carbon dioxide concentration measured during the koji-making process, the index at the end of the koji-making process is evaluated. death, The aforementioned indicator is the glucoamylase titer or α-amylase titer of the koji. The aforementioned relationship information consists of early-stage relationship information from the start of the flooring process until a set elapsed time has elapsed, and later-stage relationship information from the set elapsed time until the end of the flooring process. The aforementioned related information for the earlier period is information that shows a high positive correlation between the increase in carbon dioxide concentration and the aforementioned indicator. The aforementioned late-stage relationship information is information showing a high negative correlation between the increase in carbon dioxide concentration and the aforementioned indicator. It's at a single point.

[0010] In other words, the inventor's diligent research revealed a correlation between the increase in carbon dioxide concentration during the koji-making process and an indicator representing the quality of the koji at the end of the koji-making process. For example, it was found that in the early stages of the fermentation process (for instance, until 6 hours have passed since the start of koji production), the greater the increase in carbon dioxide concentration, the higher the glucoamylase activity of the koji. In the later stages of the fermentation process, from the end of the early stages to the end of the fermentation process, the smaller the increase in carbon dioxide concentration, the higher the glucoamylase activity of the koji. Furthermore, during the koji-making process, the glucoamylase titer or α-amylase titer can be evaluated as an indicator of the quality of the koji. The glucoamylase contained in the produced koji is an important enzyme that breaks down the starch in steamed rice and supplies sugars to the yeast. Furthermore, relational information is set up to show the relationship between the amount of increase in carbon dioxide concentration during the mat process and an indicator representing the quality of the koji at the end of the koji production process, with early-stage relational information and late-stage relational information being set up. The relationship information for the first half of the process is the relationship information from the start of the bed process until the set elapsed time has elapsed. This information is set to indicate a relationship where a larger increase in carbon dioxide concentration corresponds to a higher indicator of the quality of the koji. The late-stage relationship information is relationship information from the time elapsed until the end of the fermentation process, and it is set as information that indicates a relationship where the greater the increase in carbon dioxide concentration, the lower the indicator representing the quality of the koji.

[0011] Therefore, for example, the increase in carbon dioxide concentration during the mat process and the glucoamylase titer of koji at the end of the koji-making process. or α-amylase titer If relational information showing the relationship is obtained and set in advance through experiments, etc., then the glucoamylase titer at the end of the koji-making process can be determined based on this relational information and the increase in carbon dioxide concentration measured during the koji-making process. or α-amylase titer This allows for real-time evaluation (prediction) of the floor construction process while it is being executed. Furthermore, during the bed processing stage, it is possible to evaluate the glucoamylase activity, which is one of the important enzyme activity levels.

[0012] In short, the characteristic configuration of the koji quality evaluation method of the present invention allows for the evaluation of an indicator representing the quality of the koji during the koji-making process.

[0013] A further characteristic configuration of the method for evaluating koji quality according to the present invention lies in that the increased amount of carbon dioxide concentration is an increased amount of carbon dioxide concentration from a reference state, wherein the carbon dioxide concentration at the start of the bed process or the carbon dioxide concentration when performing turning is taken as the reference state.

[0014] Since the increased amount of carbon dioxide concentration is determined as the increased amount of carbon dioxide concentration from the reference state where the carbon dioxide concentration at the start of the bed process is taken as the reference state, the increased amount of carbon dioxide concentration from the start of the bed process can be appropriately measured, and the index representing koji quality can be appropriately evaluated. Further, in the bed process, turning is performed on steamed rice on which seed koji has been sprinkled. At this time, the storage space for storing the steamed rice sprinkled with seed koji is opened, so that carbon dioxide present in the storage space diffuses to the outside. Therefore, since the increased amount of carbon dioxide concentration is determined as the increased amount of carbon dioxide concentration from the reference state where the carbon dioxide concentration when performing turning is taken as the reference state, even after turning is performed, the increased amount of carbon dioxide concentration can be appropriately measured, and the index representing koji quality can be appropriately evaluated.

[0015] A further characteristic configuration of the method for evaluating koji quality according to the present invention is ,before the early-stage related information is information indicating a relationship in which the higher the increased amount of carbon dioxide concentration, the higher the index, and the late-stage related information is information indicating a relationship in which the higher the increased amount of carbon dioxide concentration, the lower the index.

[0016] before The early-stage related information is related information from the start of the bed process until a set elapsed time has passed, and is set as information indicating a relationship in which the higher the increased amount of carbon dioxide concentration, the higher the index representing koji quality. The late-stage related information is related information from after the set elapsed time has passed until the bed process is completed, and is set as information indicating a relationship in which the higher the increased amount of carbon dioxide concentration, the lower the index representing koji quality.

[0017] In other words, through the inventor's diligent research, it was found that there is a high positive correlation between the increase in carbon dioxide concentration during the koji-making process and an indicator representing the quality of the koji at the end of the koji-making process. This correlation is high from the start of the koji-making process until a set time has elapsed, and high negative from the set time elapsed until the koji-making process is completed.

[0018] Therefore, indicators representing the quality of the koji can be appropriately evaluated both from the start of the koji-making process until the set elapsed time has elapsed, and from the end of the koji-making process after the set elapsed time has elapsed.

[0021] The characteristic configuration of the koji production method of the present invention lies in adjusting the production conditions in the koji production process to improve the index evaluated by the koji quality evaluation method.

[0022] In other words, by adjusting the manufacturing conditions in the koji-making process to improve the indicators evaluated using the koji-quality evaluation method, the indicators at the end of the koji-making process can be appropriately increased.

[0023] Incidentally, adjusting the manufacturing conditions in the koji-making process includes, for example, in the floor process, temperature and humidity control, the frequency and timing of maintenance, ventilation, and lighting, while in the shelf process, temperature and humidity control, the frequency and timing of maintenance, the thickness of the koji being produced in the koji-making machine for the shelf process, lighting, and the timing of ending the koji-making process. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram of a koji-making machine for the flooring process. [Figure 2] This is a diagram showing the koji-making conditions for a sample. [Figure 3] This is a diagram showing the temperature and humidity program for koji production. [Figure 4] This graph shows the change over time in the increase in carbon dioxide concentration after the start of koji production. [Figure 5]This table shows the increase in carbon dioxide concentration at various time points after the start of koji production. [Figure 6] This table shows the glucoamylase activity at the end of the koji-making process. [Figure 7] This graph shows the change in moisture content over time after the start of koji production. [Figure 8] This graph shows the relationship between the increase in carbon dioxide concentration four hours after the start of koji production and the glucoamylase titer at the end of the koji production process. [Figure 9] This graph shows the relationship between the increase in carbon dioxide concentration 20 hours after the start of koji production and the glucoamylase titer at the end of the koji production process. [Figure 10] This table shows the correlation coefficient between the increase in carbon dioxide concentration at multiple time points after the start of koji production and the glucoamylase titer at the end of the koji production process. [Figure 11] This table shows the correlation coefficients between the moisture content at multiple time points after the start of koji production and the glucoamylase titer at the end of the koji production process. [Figure 12] This table shows the koji-making conditions and glucoamylase activity at the end of the koji-making process for other samples. [Figure 13] This graph shows the relationship between the increase in carbon dioxide concentration four hours after the start of koji production for other samples and the glucoamylase titer at the end of the koji production process. [Figure 14] This graph shows the relationship between the increase in carbon dioxide concentration 20 hours after the start of koji production for other samples and the glucoamylase titer at the end of the koji production process. [Figure 15] This table shows the increase in carbon dioxide concentration at multiple time points after the start of koji production for other samples. [Modes for carrying out the invention]

[0025] [Embodiment] Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the glucoamylase titer of the koji is used as an example to represent the quality (koji-making state) of the koji at the end of the koji-making process.

[0026] (Overview of the koji-making process) The koji-making process involves sprinkling koji starter onto steamed rice to produce koji, and consists of a bed stage, which is performed after the start of the koji-making process, and a shelf stage, in which the koji produced in the bed stage is further cultured. In the following description, steamed rice to which seed koji has been sprinkled, or koji produced in the koji-making process, may be abbreviated as koji-making processed product Y.

[0027] In this embodiment, we illustrate a case where the koji-making process consists of a bed process that lasts for 20 hours from the start of koji-making, and a shelf process that lasts for 48 hours thereafter. However, the time spent in the bed process and the shelf process can be varied.

[0028] In the bed process, a koji-making machine P for the bed process (see Figure 1) equipped with a storage space for storing steamed rice sprinkled with koji starter will be used. In the shelf process, although not shown in the illustration, a koji-making machine for the shelf process will be used, equipped with a storage space for supporting the koji produced in the shelf process in a shelf configuration with multiple levels. The storage spaces for the koji-making machines P for the floor process and the koji-making machines for the shelf process are controlled by a control device, which regulates the temperature and humidity from the start to the end of the koji-making process to a preset temperature and humidity (koji-making temperature and humidity program), as shown in Figure 3.

[0029] As shown in Figure 1, the koji-making machine P for the flooring process comprises a cylindrical main body 1 with an open top and a wooden lid 2 that opens and closes the top of the main body 1, and the aforementioned storage space is formed as a space enclosed by the main body 1 and the wooden lid 2. A metal plate mounting section 3 is provided in the upper and lower middle section inside the main body 1. A slatted mat 4 is placed on this mounting section 3, and the koji-making processed material Y, covered with a cloth, is placed on top of the slatted mat 4. Furthermore, a carbon dioxide sensor 5 is provided between the mounting section 3 and the slatted tray 4 to detect the concentration of carbon dioxide generated by the koji-making process of the koji-processed product Y.

[0030] (Specific examples of the koji-making process) Figure 2 shows the koji-making conditions for samples A to E. Samples A to E used yellow koji A as the starter koji and sake-brewing rice (400g) as the steamed rice. The rice polishing ratio is as shown in the figure. For samples A-B and D-E, the rice was stored in a way that minimized airflow to the rice by covering the koji-processed material Y with three cloths. For sample C, the koji-processed material Y was covered with one cloth, allowing for more airflow to the rice.

[0031] In this embodiment, as preparation before koji production, 400g of sake-brewing rice was steamed and then allowed to cool while being kneaded, and 0.67g of koji starter was brought into contact with the steamed rice. The steamed rice was quickly kneaded so that the temperature of the product would not fall below 30°C, wrapped in Gore-Tex® and a cloth, and placed in a constant temperature and humidity chamber. Next, using a constant temperature and humidity chamber (not shown) that mimicked a koji-making machine P for the floor process, the storage space for the koji-making material Y was controlled according to the koji-making temperature and humidity program, as shown in Figure 3, and the koji-making process was carried out. As will be described in detail later, in the floor process of the koji-making process, maintenance (loosening the rice) was performed 4.5 to 6 hours after the start of koji-making, and after maintenance was completed, the rice was returned to its original state and placed back into the constant temperature and humidity chamber. After that, maintenance was performed at appropriate times while adjusting the temperature and humidity. The rice was left unattended during times other than maintenance.

[0032] For samples B and E, the first maintenance was performed 270 minutes after the start of the koji-making process (bed process), while for samples A, C, and D, the first maintenance was performed 360 minutes after the start of the process (see Figure 3). Subsequently, samples A through E underwent the second to fifth maintenance steps at four points in time where the elapsed time after the start of the koji-making process was the same (see Figure 3).

[0033] In this embodiment, a constant temperature and humidity chamber (IGM300) manufactured by Yamato Scientific Co., Ltd. was used as the constant temperature and humidity chamber, an NDIR type gas sensor manufactured by NISSHA FIS Co., Ltd. was used as the CO2 sensor for measuring the CO2 concentration inside the constant temperature and humidity chamber, and a temperature and humidity sensor (TR72rf) manufactured by T&D Corporation was used as the sensor for measuring the temperature and humidity inside the constant temperature and humidity chamber. However, the invention is not limited to these instruments. 。

[0034] (Results of the koji-making process) Figure 4 shows the change in carbon dioxide concentration detected by the carbon dioxide sensor 5 after the start of the koji-making process (bed process) for samples A to E, i.e., the change in the increase in carbon dioxide concentration over time. The increase in carbon dioxide concentration is shown with the carbon dioxide concentration at the start of koji-making (0h) set to 0. In the following description, the increase in carbon dioxide concentration may be referred to as the increase in CO2 concentration, and the same applies to the attached drawings.

[0035] Incidentally, for samples B and E, the carbon dioxide concentration drops sharply 270 minutes after the start of the koji-making process (bed process), while for samples A, C, and D, the carbon dioxide concentration drops sharply 360 minutes after the start of the koji-making process (bed process). This rapid decrease in carbon dioxide concentration is due to the diffusion of carbon dioxide from the storage space to the outside when the wooden lid 2 is opened and maintenance is performed.

[0036] Figure 5 shows the increase in carbon dioxide concentration per unit weight (kg) of rice at 2 hours, 4 hours, 12 hours, 16 hours, and 20 hours after the start of the koji-making process (bed process). In calculating the increase in carbon dioxide concentration, for the period from 2h to 4h, the carbon dioxide concentration at the start of the koji-making process (bed process) was set to 0. For the period from 8h to 20h, maintenance is performed after 6h, so the carbon dioxide concentration 6h after the start of the koji-making process (bed process) was set to 0. In other words, when maintenance is performed, the increase in carbon dioxide concentration is calculated by using the carbon dioxide concentration at the time of maintenance as the baseline state, and determining the increase in carbon dioxide concentration from that baseline state.

[0037] Figure 6 shows the results of measuring the enzyme activity of glucoamylase (GA) in samples A to E at the end of the koji-making process, 48 ​​hours after the start of koji production. Furthermore, the enzyme titer (U / g), which indicates the enzymatic activity of glucoamylase (GA), was measured using an enzyme titer measurement kit manufactured by Kikkoman Corporation.

[0038] Figure 7 shows the results of measuring the change in moisture content of koji-processed product Y after the start of the koji-making process for samples A to E. The moisture content remains approximately the same during the bed process and gradually decreases during the shelf process. In this embodiment, the moisture content was calculated by placing approximately 2g of rice on an aluminum tray, measuring its weight, baking it at 135°C for 1 hour, measuring its weight again, and dividing the weight change before and after baking by the weight of the rice before baking.

[0039] (Regarding the relationship between the increase in carbon dioxide concentration and enzyme activity) Figure 8 is a graph showing the relationship between the glucoamylase titer (GA) of samples A to E at the end of koji production, 48 hours after the start of koji production, and the increase in carbon dioxide concentration for samples A to E 4 hours after the start of koji production, with the increase in carbon dioxide concentration at the start of koji production set to 0. Furthermore, a similar graph can be obtained at any point in time from the start of koji production until 6 hours have passed, including 2 hours after the start of koji production when maintenance is performed.

[0040] As can be seen from this graph, there is a high positive correlation between the glucoamylase titer (GA) of samples A to E at the end of koji production and the increase in carbon dioxide concentration of samples A to E 4 hours after the start of koji production. An approximate formula for this correlation (for example, the dashed line shown in the example) can be derived. Similarly, the above approximate formula for this initial stage can be derived at various points in time, such as 2 hours after the start of koji production, from the start of koji production until maintenance is performed (until the period during which the high positive correlation is maintained). These early-stage approximation formulas correspond to early-stage relationship information that shows the relationship between the increase in carbon dioxide concentration during the mat process and the glucoamylase activity of koji at the end of the koji production process.

[0041] Figure 9 is a graph showing the relationship between the glucoamylase titer (GA) of samples A to E at the end of koji production, 48 hours after the start of koji production, and the increase in carbon dioxide concentration for samples A to E at 20 hours after the start of koji production, with the increase in carbon dioxide concentration at 6 hours after the start of koji production being set to 0. Furthermore, similar graphs can be obtained at any time after the initial 6 hours of koji production, such as 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, and 18 hours after the start of koji production.

[0042] As can be seen from this graph, there is a strong negative correlation between the glucoamylase titer (GA) of samples A to E at the end of koji production and the increase in carbon dioxide concentration of samples A to E 20 hours after the start of koji production. An approximation formula for the later stages (e.g., the dashed line shown in the example) can be derived for this correlation. Similarly, the above approximation formula for the later stages can be derived at appropriate points in time after maintenance has been performed (during the period in which the strong negative correlation is maintained), such as 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, and 18 hours after the start of koji production. These later-stage approximation formulas correspond to later-stage relational information that shows the relationship between the increase in carbon dioxide concentration during the mat process and the glucoamylase titer of koji at the end of the koji production process. Furthermore, the correlation between glucoamylase titer (GA) and the increase in carbon dioxide concentration shows a high positive correlation in the early stages of the bed process and a high negative correlation in the later stages. The boundary (set elapsed time) between these early and later stages of the bed process can be exemplified by the timing of the last maintenance (called turning) performed among the maintenance carried out during the period of approximately 6 to 12 hours from the start of the koji-making process.

[0043] In other words, in this embodiment, as shown in Figure 10, the correlation coefficient showing the relationship between the increase in carbon dioxide concentration during the bed process and the glucoamylase titer of koji at the end of the koji production process shows a high positive correlation from the start of the bed process until the set elapsed time (6 hours) has elapsed, and a high negative correlation from the set elapsed time (6 hours) until the bed process is completed.

[0044] As described above, the relationship information showing the relationship between the increase in carbon dioxide concentration during the bed process and the glucoamylase titer of koji at the end of the koji production process consists of early-stage relationship information from the start of the bed process until the set elapsed time (6 hours) has elapsed, and late-stage relationship information from the set elapsed time (6 hours) until the end of the bed process. Furthermore, the information for the early stage shows a relationship where a greater increase in carbon dioxide concentration corresponds to a higher glucoamylase titer, while the information for the later stage shows a relationship where a greater increase in carbon dioxide concentration corresponds to a lower glucoamylase titer.

[0045] Furthermore, as shown in Figure 11, it was found that there is no high correlation between the decrease in moisture content during the shelf process and the glucoamylase activity of the koji at the end of the koji-making process.

[0046] (Evaluation method for the koji-making process) The aforementioned relational information, namely the early-stage relational information and the late-stage relational information, is a relational expression that shows the relationship between the change in the increase in carbon dioxide concentration at the evaluation point of the koji-making process after the start of the bed process and the change in the glucoamylase titer of the koji after the koji-making process is completed. Therefore, by measuring the increase in carbon dioxide concentration at the evaluation point, the glucoamylase titer at the time the koji-making process is completed can be estimated based on the relational information. In other words, the glucoamylase titer at the end of the koji-making process can be evaluated based on the increase in carbon dioxide concentration at the evaluation point during the mat process and the related information described above.

[0047] For example, a target value for glucoamylase titer at the end of the koji-making process (after 48 hours) is set in advance through experiments or other means. This target value for glucoamylase titer can be determined according to the activity that the koji mold should have at the end of the koji-making process (after 48 hours). The increase in carbon dioxide concentration measured at the point when the set elapsed time (6 hours) from the start of the bed process has elapsed (for example, after 4 hours) is compared with the approximate formula for the earlier stage of the related information at 4 hours after the start of the bed process. Specifically, the set target value for glucoamylase titer is applied to the approximate formula for the earlier stage to derive the target increase in carbon dioxide concentration (target value). If the measured increase in carbon dioxide concentration is lower than the increase in carbon dioxide concentration (target value) derived from the approximate formula for the earlier stage, it can be evaluated (predicted) that the glucoamylase titer at 4 hours after the start of the bed process is low, and that the glucoamylase titer at the end of the koji-making process will also be low. On the other hand, if the measured increase in carbon dioxide concentration is greater than or equal to the increase in carbon dioxide concentration (target value) derived from the approximation formula used earlier, it can be evaluated (predicted) that the glucoamylase titer at 4 hours after the start of the bed process will be sufficiently high, and that the glucoamylase titer at the end of the koji-making process will also be sufficiently high. Similarly, the increase in carbon dioxide concentration measured after a set elapsed time (6 hours) from the start of the bed process (for example, after 20 hours) is compared with the late-stage approximation formula for late-stage related information at 20 hours from the start of the bed process. Specifically, the target increase in carbon dioxide concentration (target value) is derived by applying the set target value of glucoamylase titer to the late-stage approximation formula. If the measured increase in carbon dioxide concentration is higher than the increase in carbon dioxide concentration (target value) derived from the late-stage approximation formula, it can be evaluated (predicted) that the glucoamylase titer is low due to the presence of a large amount of carbon dioxide at 20 hours from the start of the bed process, and that the glucoamylase titer at the end of the koji-making process will also be low. On the other hand, if the measured increase in carbon dioxide concentration is less than or equal to the increase in carbon dioxide concentration (target value) derived from the later approximation formula, it can be evaluated (predicted) that the glucoamylase titer at 20 hours after the start of the bed process will not be low, and that the glucoamylase titer at the end of the koji-making process will be sufficiently high. Furthermore, the quality of the koji production during the bed stage has a greater impact on the koji production state (glucoamylase titer) at the end of the koji production process compared to the quality of the koji production during the shelf stage. Therefore, it is extremely useful to be able to evaluate (predict) the koji production state (glucoamylase titer) at the end of the koji production process at an early stage (bed stage) from the start of the koji production process, and to adjust the manufacturing conditions of the koji production process (especially the bed stage).

[0048] (Adjustment of manufacturing conditions in the koji-making process) As described above, the glucoamylase titer at the end of the koji-making process can be evaluated based on the increase in carbon dioxide concentration at the time of evaluation of the bed process and the relationship information described above. Therefore, based on the evaluated glucoamylase titer, the manufacturing conditions in the koji-making process can be adjusted to increase the glucoamylase titer at the end of the koji-making process.

[0049] Incidentally, adjusting the manufacturing conditions in the koji-making process includes, in the floor-making process, temperature and humidity control, the frequency and timing of maintenance, ventilation, and lighting. For example, as described above, if the increase in carbon dioxide concentration measured at the point when the set elapsed time (6 hours) from the start of the bed process has elapsed (for example, when 4 hours have elapsed) is lower than the increase in carbon dioxide concentration (target value) derived from the approximation formula for the earlier stage, adjustments can be made to increase the temperature in the storage space to raise the temperature of the koji-making product Y, thereby improving the activity of koji mold in the earlier stage of the bed process. If the measured increase in carbon dioxide concentration is equal to or greater than the increase in carbon dioxide concentration (target value) derived from the approximation formula for the earlier stage, the temperature and humidity can be maintained at their current levels, and the state in which the activity of koji mold is improved in the earlier stage of the bed process can be maintained. Furthermore, as mentioned above, if the increase in carbon dioxide concentration measured after a set elapsed time (6 hours) from the start of the bed-laying process (for example, after 20 hours) is higher than the increase in carbon dioxide concentration (target value) derived from the approximation formula for the later stages, adjustments can be made to reduce the carbon dioxide concentration in the storage space by opening the storage space for ventilation, thereby suppressing the decrease in the activity of Aspergillus oryzae in the later stages of the bed-laying process. If the measured increase in carbon dioxide concentration is less than or equal to the increase in carbon dioxide concentration (target value) derived from the approximation formula for the later stages, the current state can be maintained, and the activity of Aspergillus oryzae can be kept stable in the later stages of the bed-laying process. Furthermore, in the shelf-making process, factors such as temperature and humidity control, the frequency and timing of maintenance, the thickness of the koji-making material Y when stored in the koji-making machine for the shelf-making process, lighting, and the timing of ending the koji-making process are all important. Incidentally, this method can be applied not only to the koji-making process, but also to adjusting the manufacturing conditions in the processes before and after it.

[0050] (Regarding other specific examples of the koji-making process) Figure 12 shows the koji-making conditions for other samples A' to F'. Samples A' to F' used yellow koji B as the starter koji and sake-brewing rice or general rice (500 kg or 550 kg) as the steamed rice. The rice polishing ratio is as shown in the figure. Then, the storage space for the koji-processed material Y was controlled in the same way as in the specific example described above, according to the koji-making temperature and humidity program shown in Figure 3, and the koji-making process was carried out.

[0051] Regarding maintenance, as shown in the diagram, maintenance was performed at appropriate times for samples B' to D', while maintenance was omitted for the other samples. The rice koji-making environment was standardized. Specifically, for sample B', maintenance was performed approximately 300 minutes after the start of the koji-making process (bed process), for sample C', maintenance was performed approximately 240 minutes after the start of the koji-making process (bed process), and for sample D', maintenance was performed approximately 240 minutes and 300 minutes after the start of the koji-making process (bed process). Figure 12 shows the changes in moisture content from the start of the koji-making process (at the start (0h), 22 hours after the start (22h), and at the end of the koji-making process after 48 hours (48h)), as well as the glucoamylase titer (GA) at the end of the koji-making process after 48 hours from the start of koji-making.

[0052] Figure 15 shows the increase in carbon dioxide concentration per unit weight (kg) of rice at 2 hours, 4 hours, 12 hours, 16 hours, and 20 hours after the start of the koji-making process (bed process). In calculating the increase in carbon dioxide concentration, for the period from 2h to 4h, the carbon dioxide concentration at the start of the koji-making process (bed process) was set to 0. For the period from 8h to 20h, since maintenance is performed up to about 6h, the carbon dioxide concentration 6h after the start of the koji-making process (bed process) was set to 0.

[0053] Figure 13 is a graph showing the relationship between the glucoamylase titer (GA) of samples A' to F' at the end of koji production, 48 hours after the start of koji production, and the increase in carbon dioxide concentration for samples A' to F' at 4 hours after the start of koji production, with the increase in carbon dioxide concentration at the start of koji production being set to 0. Furthermore, a similar graph can be obtained at any point in time from the start of koji production until 6 hours have passed, including 2 hours after the start of koji production when maintenance is performed.

[0054] As can be seen from this graph, there is a high positive correlation between the glucoamylase titer (GA) of samples A' to F' at the end of koji production and the increase in carbon dioxide concentration of samples A' to F' 4 hours after the start of koji production. An approximate formula for this correlation (for example, the dashed line shown in the example) can be derived. Similarly, the above approximate formula for this initial stage can be derived at various points in time, such as 2 hours after the start of koji production, from the start of koji production until maintenance is performed (until the period during which the high positive correlation is maintained). These early-stage approximation formulas correspond to early-stage relational information showing the relationship between the increase in carbon dioxide concentration during the mat process and the glucoamylase titer of koji at the end of the koji production process. However, since samples A'~F' and A~E use different starter koji, the slope of these early-stage approximation formulas differs from that of samples A~E.

[0055] Figure 14 is a graph showing the relationship between the glucoamylase titer (GA) of samples A' to F' at the end of koji production, 48 hours after the start of koji production, and the increase in carbon dioxide concentration for samples A' to F' at 20 hours after the start of koji production, with the increase in carbon dioxide concentration at 6 hours after the start of koji production being set to 0. Furthermore, similar graphs can be obtained at any time after the initial 6 hours of koji production, such as 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, and 18 hours after the start of koji production.

[0056] As can be seen from this graph, there is a strong negative correlation between the glucoamylase titer (GA) of samples A' to F' at the end of koji production and the increase in carbon dioxide concentration of samples A' to F' 20 hours after the start of koji production. An approximation formula for the later stages (e.g., the dashed line shown in the example) can be derived for this correlation. Similarly, the above approximation formula for the later stages can be derived at appropriate points in time after maintenance has been performed (during the period in which the strong negative correlation is maintained), such as 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, and 18 hours after the start of koji production. These later-stage approximation formulas correspond to later-stage relational information showing the relationship between the increase in carbon dioxide concentration during the mat process and the glucoamylase titer of koji at the end of the koji production process. However, since samples A'~F' and A~E use different starter koji, the slope of these later-stage approximation formulas differs from that of samples A~E. Furthermore, the correlation between glucoamylase titer (GA) and the increase in carbon dioxide concentration shows a high positive correlation in the early stages of the bed process and a high negative correlation in the later stages. The boundary (set elapsed time) between these early and later stages of the bed process can be exemplified by the timing of the last maintenance (called turning) performed among the maintenance carried out during the period of approximately 6 to 12 hours from the start of the koji-making process.

[0057] In other words, for samples A' to F', the correlation coefficient showing the relationship between the increase in carbon dioxide concentration during the bed process and the glucoamylase titer of koji at the end of the koji-making process shows a high positive correlation from the start of the bed process until the set elapsed time (6 hours) has elapsed, and a high negative correlation from the set elapsed time (6 hours) until the koji-making process is completed. Figure 13 shows the relationship information (correlation and approximation formula) at 4 hours after the start of koji production, and Figure 14 shows the relationship information (correlation and approximation formula) at 20 hours after the start of koji production. However, using the increase in carbon dioxide concentration at 2 hours, 12 hours, and 16 hours after the start of the koji production process (bed process) shown in Figure 15, the relationship information (correlation and approximation formula) at each point in time can be determined.

[0058] [Another embodiment] (1) In the above embodiment, yellow koji A and yellow koji B were given as examples of starter koji, but the same can be carried out using other starter koji.

[0059] (2) In the above embodiment, as example of relational information, relational information showing the relationship between the amount of increase in carbon dioxide concentration during the bed process and the glucoamylase titer of koji at the end of the koji-making process was given. However, the relational information may also be derived using the amount of increase in carbon dioxide concentration that is converted into an amount of increase in carbon dioxide corresponding to that increase in carbon dioxide concentration. In this case, the glucoamylase titer at the end of the koji-making process can be evaluated based on the amount of increase in carbon dioxide concentration that is measured during the bed process and converted into an amount of increase in carbon dioxide corresponding to that increase in carbon dioxide concentration, and the relational information.

[0060] (3) In the above embodiment, an example was given in which relational information for the first period and relational information for the second period are set as relational information, but it is also possible to implement the system in which only one of the relational information for the first period and relational information for the second period is set.

[0061] (4) When carrying out the present invention, the manufacturing conditions in the koji-making process may be adjusted manually based on the evaluated glucoamylase titer, but may also be carried out in an automated manner, such as by using a control device to automatically adjust the temperature and humidity.

[0062] (5) In the above embodiment, the example was given of storing one type of sample in the storage space of the koji-making machine P for the floor process, but it is also possible to carry out the implementation in which multiple types of samples are stored in the storage space of the koji-making machine P for the floor process. In this case, multiple types of koji-processed materials Y are placed in different containers such as trays or boxes, and the carbon dioxide from each of the multiple types of koji-processed materials Y is measured. Specifically, this can be done by inserting a carbon dioxide sensor into each of the containers holding the multiple types of koji-processed materials Y, or by installing a shared carbon dioxide sensor in a location separate from the multiple containers, and using a blower to draw air from each container and blow it onto the carbon dioxide sensor.

[0063] (6) In the above embodiment, the glucoamylase titer of koji was given as an example of an indicator of the quality of koji at the end of the koji-making process, but other indicators such as enzyme titers such as α-amylase titer and acid carboxypeptidase titer, or the amount of microbial cells can also be used.

[0064] Furthermore, the configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. In addition, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention.

Claims

1. A method for evaluating the quality of koji in the koji-making process, which involves sprinkling koji starter onto steamed rice to produce koji, wherein the quality of the koji is evaluated during the koji-making bed stage, Based on relational information showing the relationship between the amount of increase in carbon dioxide concentration during the flooring process and an index representing the quality of the koji at the end of the koji-making process, and the amount of increase in carbon dioxide concentration measured during the flooring process, the index at the end of the koji-making process is evaluated. The aforementioned indicator is the glucoamylase titer or α-amylase titer of the koji. The aforementioned relationship information consists of early-stage relationship information from the start of the flooring process until a set elapsed time has elapsed, and later-stage relationship information from the set elapsed time until the end of the flooring process. The aforementioned related information for the earlier period is information showing a high positive correlation between the increase in carbon dioxide concentration and the aforementioned indicator. The aforementioned late-stage related information is a method for evaluating the quality of koji, in which the increase in carbon dioxide concentration and the aforementioned indicator show a high negative correlation.

2. The method for evaluating the quality of koji according to claim 1, wherein the amount of increase in carbon dioxide concentration is the amount of increase in carbon dioxide concentration from the reference state, with the carbon dioxide concentration at the start of the bed process or the carbon dioxide concentration when maintenance is performed being used as the reference state.

3. The aforementioned relationship information is information that shows a relationship in which the greater the increase in carbon dioxide concentration, the higher the index. The method for evaluating the quality of koji according to claim 1, wherein the aforementioned late-stage relationship information is information that shows a relationship in which the greater the increase in carbon dioxide concentration, the lower the index.

4. A method for producing koji, in which the manufacturing conditions in the koji-making process are adjusted to improve the index, based on the index evaluated by the koji quality evaluation method described in any one of claims 1 to 3.

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