Methods of regulating the process of microbial saccharification of starch feedstocks

Abstract

This invention relates to the field of brewing technology, specifically to a method for regulating the process of microbial saccharification of starch raw materials. This method can construct a clear saccharification process control scheme and quickly detect changes in key indicators during saccharification, thereby regulating the saccharification process to bring each indicator closer to the standard saccharification process and achieve better saccharification results.

Description

Technical Field

[0001] This invention relates to the field of brewing technology, and more specifically to a method for regulating the process of microbial saccharification of starch raw materials. Background Technology

[0002] Saccharification is a fundamental stage of brewing and a crucial process in the production of baijiu (Chinese white liquor). Saccharification primarily relies on microorganisms in the yeast starter to convert the starchy components in the brewing raw materials into fermentable sugars, thus laying the foundation for alcoholic fermentation in the baijiu production process. The saccharification process can influence the effectiveness of alcoholic fermentation, thereby affecting the quality of the baijiu.

[0003] Research on the dual fermentation of baijiu (simultaneous saccharification and alcoholic fermentation) indicates that saccharification and alcoholic fermentation often occur simultaneously in solid-state pure grain baijiu brewing, and proper matching of saccharification and fermentation rates is crucial. An insufficient saccharification rate during baijiu brewing leads to inadequate yeast substrate concentration during alcoholic fermentation; conversely, an excessive saccharification rate results in an overaccumulation of fermentable sugars, which yeast cannot utilize during alcoholic fermentation, creating conditions for the growth of harmful bacteria and the generation of other substances, thus reducing the yield and quality of the baijiu. Therefore, rapid sensing and intelligent control of the saccharification process are of great significance for the high-quality brewing of baijiu.

[0004] Different types of baijiu (Chinese liquor) have different production processes, and the flavors of baijiu produced by the small-koji saccharification-large-koji fermentation process (where saccharification and alcoholic fermentation are carried out separately and independently) and the double fermentation process are significantly different. Furthermore, baijiu production processes are generally quite traditional, and the evaluation of the saccharification process has traditionally relied heavily on manual sensory methods, which require a high level of experience from the personnel. Therefore, if a small-koji saccharification method with lower personnel requirements can be developed, it will not only provide a richer baijiu flavor but also reduce labor and time costs.

[0005] Saccharification is essentially the growth and reproduction of microorganisms and their metabolism of fermentation substrate components (starch). Therefore, technically, the saccharification process is mainly perceived and regulated by detecting or monitoring environmental parameters (temperature) and metabolic products (sugars) of microbial growth and metabolism.

[0006] CN201911227420.2 discloses a fermentation and brewing system for baijiu (Chinese liquor), the technical solution of which involves a thermometer for detecting the fermentation temperature inside the fermentation pit. However, temperature only affects the reproduction and physiological activity of microorganisms, and sensing temperature is difficult to truly reflect the consumption of matrix components and the accumulation of metabolites during the saccharification process.

[0007] CN201580031037.3 discloses a method for online detection of the saccharification process using infrared spectroscopy, the technical solution of which involves real-time sensing of the types and relative contents of sugars in liquid fermentation broth using attenuated total reflectance infrared spectroscopy. However, the above solution is difficult to analyze the cumulative pattern of saccharification metabolic yield, thus making it difficult to construct a clear saccharification regulation scheme.

[0008] Therefore, there is an urgent need to develop a method that can construct a clear saccharification process control scheme. This method can quickly detect changes in important indicators during the saccharification process, thereby controlling the saccharification process to make each indicator approach the standard saccharification process and obtain better saccharification results. Summary of the Invention

[0009] The purpose of this invention is to overcome the above-mentioned problems in the prior art and provide a method for regulating the process of microbial saccharification of starch raw materials. This method can construct a clear saccharification process regulation scheme and can quickly detect changes in important indicators during the saccharification process, thereby regulating the saccharification process so that each indicator during the saccharification process is close to the standard saccharification process and a better saccharification effect is obtained.

[0010] To achieve the above objectives, the present invention provides a method for regulating the process of microbial saccharification of starch raw materials, the method comprising:

[0011] (1) Select a standard saccharification process. From the start of saccharification to the end of saccharification, at each time interval Δt, obtain the standard starch content, standard reducing sugar content, standard saccharification reaction time, standard temperature and standard humidity of the standard saccharification process, and use spectral technology to obtain the standard spectral information of the saccharified material.

[0012] The standard saccharification process is a saccharification process with an average hourly saccharification rate of 0.02-0.05% during the first 20 hours and an average hourly saccharification rate of 0.29-0.51% after 20 hours.

[0013] Among them, the standard temperature, standard humidity, standard saccharification reaction time, standard spectral information, standard starch content and standard reducing sugar content acquired at a certain moment are recorded as a standard data point;

[0014] (2) Based on all the standard data points, construct a functional model Yd = F for standard spectral information and standard starch content. d (M) is used to monitor the starch content in the process of rapidly obtaining the microbial saccharified starch raw material to be regulated.

[0015] Construct a functional model Yz = F based on standard spectral information and standard reducing sugar content. z (M) is used to monitor the reducing sugar content in the subsequent rapid acquisition of the microbial saccharification starch raw material to be regulated.

[0016] Where Yd represents the standard starch content, M represents the standard spectral information, and Yz represents the standard reducing sugar content;

[0017] (3) Based on all the standard data points, construct the functional model Yz=F1(j) of standard reducing sugar content and standard saccharification reaction time, and construct the monitoring model Yz=F2(Yd,T,E,j) between standard reducing sugar content and standard starch content, standard saccharification reaction time, standard humidity and standard temperature, and obtain the inverse function model T=F3(Yd,Yz,E,j) of standard temperature T and the inverse function model E=F4(Yd,T,Yz,j) of standard humidity E based on the monitoring model;

[0018] Where T is the standard temperature, E is the standard humidity, and j is the standard saccharification reaction time;

[0019] (4) During the process of microbial saccharification of starch raw materials to be regulated, at each time interval Δt1, the spectroscopic technique and the function model Yd=F are used. d (M), Yz = F z (M) Monitor the starch content and reducing sugar content in the saccharification material, and obtain the saccharification reaction time, temperature and humidity monitoring values;

[0020] By using the function model Yz=F1(j), the theoretical value of reducing sugar content corresponding to the monitored value of saccharification reaction time is obtained. The theoretical value of reducing sugar content, the monitored value of saccharification reaction time, and the monitored value of starch content are substituted into the inverse function model of standard temperature T and the inverse function model of standard humidity E to obtain the theoretical value of temperature and the theoretical value of humidity. The monitored value of temperature and the monitored value of humidity for the saccharification reaction time are then adjusted to the theoretical value of temperature and the theoretical value of humidity, respectively, thereby eliminating the difference between the monitored value of reducing sugar content and the theoretical value of reducing sugar content.

[0021] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0022] The technical solution of this invention, through analysis of the standard saccharification process, can establish a functional model between multiple saccharification indicators. According to the method of this invention, changes in important indicators during the saccharification process can be quickly detected. When important indicators become abnormal, the saccharification process to be controlled can be adjusted according to the functional model, bringing the indicators in the controlled saccharification process closer to the standard saccharification process, thereby achieving a better saccharification effect. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] This invention provides a method for regulating the process of microbial saccharification of starch raw materials, the method comprising:

[0025] (1) Select a standard saccharification process. From the start of saccharification to the end of saccharification, at each time interval Δt, obtain the standard starch content, standard reducing sugar content, standard saccharification reaction time, standard temperature and standard humidity of the standard saccharification process, and use spectral technology to obtain the standard spectral information of the saccharified material.

[0026] The standard saccharification process is a saccharification process with an average hourly saccharification rate of 0.02-0.05% during the first 20 hours and an average hourly saccharification rate of 0.29-0.51% after 20 hours.

[0027] Among them, the standard temperature, standard humidity, standard saccharification reaction time, standard spectral information, standard starch content and standard reducing sugar content acquired at a certain moment are recorded as a standard data point;

[0028] (2) Based on all the standard data points, construct a functional model Yd = F for standard spectral information and standard starch content. d (M) is used to monitor the starch content in the process of rapidly obtaining the microbial saccharified starch raw material to be regulated.

[0029] Construct a functional model Yz = F based on standard spectral information and standard reducing sugar content. z (M) is used to monitor the reducing sugar content in the subsequent rapid acquisition of the microbial saccharification starch raw material to be regulated.

[0030] Where Yd represents the standard starch content, M represents the standard spectral information, and Yz represents the standard reducing sugar content;

[0031] (3) Based on all the standard data points, construct the functional model Yz=F1(j) of standard reducing sugar content and standard saccharification reaction time, and construct the monitoring model Yz=F2(Yd,T,E,j) between standard reducing sugar content and standard starch content, standard saccharification reaction time, standard humidity and standard temperature, and obtain the inverse function model T=F3(Yd,Yz,E,j) of standard temperature T and the inverse function model E=F4(Yd,T,Yz,j) of standard humidity E based on the monitoring model;

[0032] Where T is the standard temperature, E is the standard humidity, and j is the standard saccharification reaction time;

[0033] (4) During the process of microbial saccharification of starch raw materials to be regulated, at each time interval Δt1, the spectroscopic technique and the function model Yd=F are used. d (M), Yz = F z (M) Monitor the starch content and reducing sugar content in the saccharification material, and obtain the saccharification reaction time, temperature and humidity monitoring values;

[0034] By using the function model Yz=F1(j), the theoretical value of reducing sugar content corresponding to the monitored value of saccharification reaction time is obtained. The theoretical value of reducing sugar content, the monitored value of saccharification reaction time, and the monitored value of starch content are substituted into the inverse function model of standard temperature T and the inverse function model of standard humidity E to obtain the theoretical value of temperature and the theoretical value of humidity. The monitored value of temperature and the monitored value of humidity for the saccharification reaction time are then adjusted to the theoretical value of temperature and the theoretical value of humidity, respectively, thereby eliminating the difference between the monitored value of reducing sugar content and the theoretical value of reducing sugar content.

[0035] The average hourly saccharification rate is the ratio of the difference between the reducing sugar content at the end and the initial reducing sugar content during a certain time period in the saccharification process to the duration (h) of that time period. The reducing sugar content is the ratio of the total mass of reducing sugar to the total mass of the saccharifying material. The calculation formula is as follows:

[0036]

[0037]

[0038] It is understandable that in step (1), the selected standard saccharification process is divided into two stages based on the change in reducing sugar. The first stage is from 0 to 20 hours, with an average hourly saccharification rate of 0.02-0.05%, and the second stage is after 20 hours, with an average hourly saccharification rate of 0.29-0.51%. The difference in the average hourly saccharification rate between the two stages is because the first stage is the initial stage of saccharification, where the temperature rises slowly and the microorganisms are in a sluggish phase, resulting in a relatively slow saccharification process. As microbial metabolism increases, the second stage begins, the temperature of the saccharified material rises, and the saccharification process accelerates. In other words, if the saccharification rate of the standard saccharification process is suitable, then the various indicators in this standard saccharification process can be considered suitable. Therefore, by using the values ​​of the indicators in this standard saccharification process to regulate the corresponding indicators in the process of microbial saccharification of starch raw materials to be regulated, a saccharification rate that is closer to that of the standard saccharification process can be obtained, thereby reducing trial and error in the existing saccharification process. Standard saccharification processes can be obtained by monitoring the saccharification of different batches from a particular manufacturer over a continuous period (at least six months), accumulating data, and then screening to obtain the standard saccharification process, or by conducting small-scale tests (such as shake-flask experiments).

[0039] Furthermore, those skilled in the art will understand that, generally, when the saccharification rate reaches 13%, the saccharification process can generally be considered complete. Here, the saccharification rate refers to the ratio of the total mass of reducing sugars generated in the saccharified material to the total mass of the saccharified material after saccharification, calculated using the following formula:

[0040]

[0041] The standard starch content in the standard saccharification process refers to the actual starch content in the saccharified material obtained through measurement during the standard saccharification process; the standard reducing sugar content has the same meaning. The standard saccharification reaction time is the actual saccharification reaction time carried out in the standard saccharification process. The standard temperature and standard humidity are the actual temperature and humidity of the material during the standard saccharification process, as measured. The standard temperature and standard humidity can be obtained by placing temperature and humidity sensors in a ring inside the saccharification tank where saccharification takes place. The starch raw materials and saccharifying agents used in the standard saccharification process are the same as those used in the process of microbial saccharification of starch raw materials to be controlled.

[0042] According to the present invention, in order to obtain a more suitable function model and thus better control the process of microbial saccharification of starch raw materials, preferably, the starch raw materials in the saccharification process are selected from at least one of sorghum, rice, glutinous rice, and corn. For example, in the saccharification tank of baijiu (Chinese liquor), sorghum, rice, glutinous rice, and corn are first cooked and gelatinized as starch raw materials, and then a saccharifying agent is added to enter the standard saccharification process.

[0043] According to the present invention, preferably, the saccharifying agent (microorganism) in the saccharification process is selected from at least one of Rhizopus (such as Rhizopus oryzae), Aspergillus (such as Aspergillus niger, Aspergillus oryzae, etc.) or Mucor, and Rhizopus, Aspergillus or Mucor can be inoculated onto raw materials such as wheat bran to prepare wheat bran koji for use.

[0044] According to the present invention, preferably, the magnitude of Δt is such that the number of standard data points is not less than 90 (e.g., it can be 100, 150, 200, 250, 300, or 400). It is understood that in the subsequent construction of the function model, a larger number of data points generally results in a more suitable function model, which can then be better used to regulate the process of microbial saccharification of starch raw materials. For example, when the total time used for the standard saccharification process is approximately 50 hours, standard data points can be taken every Δt = 0.25 hours, thereby increasing the number of standard data points and further ensuring the construction of a more suitable function model.

[0045] According to the present invention, preferably, Δt1 = 0.05-2.28% of the total time of the standard saccharification process. Wherein, the total time of the standard saccharification process is the total time required for the standard saccharification process to complete saccharification. It is understood that when Δt1 is within the above range, it is possible to measure and control at shorter time intervals while maintaining the simplicity of the control process, thereby achieving more accurate control.

[0046] According to the present invention, preferably, the spectroscopic technique is selected from visible hyperspectral and near-infrared hyperspectral. The camera used for the spectroscopic technique can be a linear array camera, the exposure time can be set to 50 ms, and the wavelength of the spectroscopic technique can be 430-960 nm. It is understood that the spectral resolution is 10... -2 The spectrum in the order of λ is called hyperspectral, and hyperspectral can provide richer information.

[0047] According to the present invention, in order to further ensure that a more accurate standard starch content value is obtained, so as to be used to construct a more suitable function model, preferably, the method for obtaining the standard starch content is selected from titration and starch detection kit method, and more preferably titration.

[0048] According to the present invention, in order to further ensure that a more accurate value of standard reducing sugar content is obtained, so as to be used to construct a more suitable function model, preferably, the method for obtaining the standard reducing sugar content is selected from direct titration, potassium permanganate titration, colorimetry and reducing sugar analyzer method, and more preferably direct titration.

[0049] Standard temperature and standard humidity can be obtained using temperature and humidity sensors, respectively. Furthermore, standard saccharification reaction time can be obtained using a digital timer.

[0050] It is understandable that a standard data point contains standard temperature, standard humidity, standard saccharification reaction time, standard spectral information, standard starch content, and standard reducing sugar content at a certain moment. Therefore, when constructing a function model using standard data points, the required data can be selected from the data contained in the standard data points for construction.

[0051] In step (2), a functional model Yd = F is constructed to represent the standard spectral information and the standard starch content. d The purpose of (M) is that: while the method of determining the standard starch content using chemical reagents is generally accurate, it is also slow. In order to achieve rapid sensing of the starch content in the process of microbial saccharification of starch raw materials to be controlled, the spectrum of the saccharified material during the saccharification process of standard starch can be measured, and the spectral data and the more accurate standard starch content determined by chemical reagents can be combined to construct a function model Yd=F d By linking it in the manner of (M), when subsequently regulating the microbial saccharified starch raw material to be regulated, it is only necessary to obtain the corresponding spectral data of the microbial saccharified starch raw material to be regulated through spectral technology, and then the function model Yd=F can be used to determine the appropriate spectral data. d (M) allows for rapid calculation of the corresponding starch content monitoring value. Furthermore, it is understandable that obtaining the corresponding spectral data from the microbially saccharified starch raw material to be regulated via spectroscopic technology is also relatively fast, thus further ensuring a rapid acquisition of the starch content monitoring value. A functional model Yz = F is constructed to represent the standard spectral information and standard reducing sugar content. z The purpose of (M) is similar.

[0052] According to the present invention, in order to further ensure that a more accurate function model is obtained, so as to better control the process of microbial saccharification of starch raw materials, preferably, in step (2), the methods for constructing the function model of standard spectral information and standard starch content and the method for constructing the function model of standard spectral information and standard reducing sugar content are each independently selected from chemometric methods, more preferably partial least squares method and partial least squares support vector machine method.

[0053] According to the present invention, in order to further ensure the acquisition of a more accurate function model, thereby better controlling the process of microbial saccharification of starch raw materials, preferably, the function model is Yd = F d (M), Yz = F z The coefficient of determination R of (M) 2 Not less than 90% (for example, it can be 90%, 91%, 92%, 93%, 94%).

[0054] According to the present invention, in order to further ensure that a more accurate function model is obtained, thereby better controlling the process of microbial saccharification of starch raw materials, preferably, the method for constructing the function model of standard reducing sugar content and standard saccharification reaction time and the monitoring model are each independently selected from machine learning methods, more preferably artificial neural network methods.

[0055] According to the present invention, in order to further ensure the acquisition of a more accurate function model, thereby better controlling the process of microbial saccharification of starch raw materials, preferably, the coefficient of determination R of the function model Yz=F1(j) is... 2 Not less than 90% (for example, it can be 90%, 91%, 92%, 93%, 94%).

[0056] It is understandable that any abnormality in the saccharification rate during the saccharification process, whether too high or too low, will be reflected in an abnormal reducing sugar content. Therefore, by quickly obtaining the monitoring value of the reducing sugar content during the microbial saccharification of starch raw material to be regulated, and comparing it with the theoretical value of the reducing sugar content, it is possible to determine whether there is an abnormality in the saccharification rate during the saccharification process.

[0057] It is understandable that even when using a standard saccharification process as a benchmark, the monitored value of reducing sugar content and the theoretical value of reducing sugar content will still differ to some extent when the process of controlling the microbial saccharified starch raw material to be controlled is adjusted. Adjusting the monitored value and the theoretical value of reducing sugar content to be exactly the same would make the control process quite complex. According to the present invention, in order to reduce the complexity of the control process while making the process of the microbial saccharified starch raw material to be controlled closer to the standard saccharification process, preferably, the process of the microbial saccharified starch raw material to be controlled is controlled when the difference between the monitored value and the theoretical value of reducing sugar content is greater than 10% of the theoretical value of reducing sugar content.

[0058] According to the present invention, preferably, the method further includes obtaining the theoretical value of reducing sugar content corresponding to a certain saccharification reaction time monitoring value through the function model Yz=F1(j), obtaining the theoretical value of temperature and the theoretical value of humidity, and recording the difference between the theoretical value of reducing sugar content and the monitoring value of reducing sugar content. After adjusting the temperature monitoring value and humidity monitoring value of the saccharification reaction time to the theoretical value of temperature and the theoretical value of humidity respectively, after a time interval of Δt1, (4) is repeated, and the difference between the theoretical value of reducing sugar content and the monitoring value of reducing sugar content is obtained again. The difference before and after is compared, which can be used to determine whether the difference between the monitoring value of reducing sugar content and the theoretical value of reducing sugar content is gradually being eliminated. Furthermore, (4) can be repeated multiple times to gradually eliminate the difference between the monitoring value of reducing sugar content and the theoretical value of reducing sugar content.

[0059] In this invention, the "temperature" refers to the internal temperature of the saccharified starch raw material, which can be obtained by taking measurements at internal points and calculating the average value. As mentioned above, this can be achieved by placing temperature sensors in a ring inside the saccharification tank, taking measurements at points in the ring, and calculating the average value. Temperature can be controlled by increasing or decreasing the stirring rate, or by increasing or decreasing the ambient temperature.

[0060] In this invention, "humidity" refers to the internal humidity of the saccharified starch raw material, which can be obtained by taking measurements at internal points and calculating the average value. As mentioned above, this can be achieved by placing humidity sensors in a ring inside the saccharification tank, taking measurements at points in the ring, and calculating the average value. Humidity can be regulated by using water-retaining materials for capillary water supply or by increasing or decreasing the humidity of the surrounding environment.

[0061] The present invention will be described in detail below through embodiments.

[0062] Example 1

[0063] A method for illustrating the process of regulating microbial saccharification of starch raw materials provided by the present invention

[0064] (1) The saccharification process of the factory was monitored for six consecutive months. Data was accumulated and screened to obtain a standard saccharification process. The standard saccharification process is as follows: 1000 kg of starch raw materials (including 600 kg of sorghum, 150 kg of glutinous rice and 250 kg of rice) were soaked in water, mixed evenly and steamed. The saccharifying agent Rhizopus oryzae (purchased from Guizhou Ligao Light Industry Technology Development Co., Ltd.) was weighed and sprinkled into the steamed starch raw materials cooled to 28°C. The amount of saccharifying agent used was about 0.5% by weight of the added starch raw materials. After the materials were mixed evenly, they were transferred to the saccharification tank and entered the standard saccharification process. In the standard saccharification process, the average hourly saccharification rate was 0.045% from 0 to 20 hours and 0.47% after 20 hours. A sampling area was set up in the baijiu saccharification tank. Temperature sensors and humidity sensors were placed in a ring around the sampling area.

[0065] From the start of saccharification t0 = 0h to the end of saccharification t e =45h, at intervals Δt = 0.25h: the standard temperature and humidity of the saccharifying material at each time point are obtained using temperature and humidity sensors; the standard saccharification reaction time at this time is obtained using a digital timer; 100g of saccharifying material is taken for visible and near-infrared hyperspectral information acquisition to obtain standard spectral information; 100g of saccharifying material is taken for titration to obtain the standard starch content in the saccharifying material; 100g of saccharifying material is taken for direct titration to obtain the standard reducing sugar content in the saccharifying material. The wavelength range of the obtained standard spectral information is 430.00nm-960.24nm.

[0066] The determination of standard starch content and standard reducing sugar content at a given moment was repeated three times to minimize error. The determination of standard temperature and standard humidity was performed by taking measurements at circular points and calculating the average value to reduce error. A standard data point was recorded at a given moment, comprising the standard temperature, standard humidity, standard saccharification reaction time, standard spectral information, standard starch content, and standard reducing sugar content, from the start of saccharification t0 = 0 h to the end of saccharification t0 = 0 h. e =45h, a total of 184 standard data points were acquired.

[0067] Among the 184 data points obtained, the standard starch content ranged from 9.52 to 26.34 g / (100g saccharified material), and the standard reducing sugar content ranged from 8.31 to 16.97 g / (100g saccharified material).

[0068] (2) Based on the 184 standard data points obtained in (1), standard spectral information and standard starch content were taken from the 184 data points. Partial least squares method was used to construct a functional model Yd=F for standard spectral information and standard starch content. d (M), with a coefficient of determination of 0.95, is used to monitor the starch content in the process of rapidly obtaining the microbial saccharified starch raw material to be regulated.

[0069] Based on the 184 standard data points obtained in (1), standard spectral information and standard reducing sugar content from the 184 standard data points are taken, and a function model Yz = F for standard spectral information and standard reducing sugar content is constructed using the partial least squares support vector machine method. z (M), with a coefficient of determination of 0.93, is used to monitor the reducing sugar content in the process of rapidly obtaining the microbial saccharified starch raw material to be regulated.

[0070] Where Yd represents the standard starch content, M represents the standard spectral information, and Yz represents the standard reducing sugar content.

[0071] Based on the 184 data points obtained in (1), the standard reducing sugar content and standard saccharification reaction time were selected from the 184 data points. A functional model Yz = -7 × 10⁻⁷ was constructed using an artificial neural network method for the standard reducing sugar content and standard saccharification reaction time. -6 j 3 +6×10 -4 j 2 -0.008j+0.012, its coefficient of determination R 2 The value is 0.94. (Where j is time in hours)

[0072] Based on the 184 data points obtained in (1), an artificial neural network method was used to construct a monitoring model between standard reducing sugar content and standard starch content, standard saccharification reaction time, standard humidity and standard temperature. Based on this monitoring model, the inverse function model of standard temperature T was obtained as T = -8.08Yd + 5.97E - 0.16Yz - 9.42j + 0.0011, and the inverse function model of standard humidity E was obtained as E = 1.17Yd + 7.69T + 0.03Yz + 6.56j - 0.0016.

[0073] Where T is the standard temperature, E is the standard humidity, and j is the standard saccharification reaction time;

[0074] (4) In the process of microbial saccharification of starch raw materials to be regulated, the saccharification process to be regulated is carried out in a baijiu saccharification tank. The process of microbial saccharification of starch raw materials to be regulated is as follows: 1000 kg of starch raw materials (containing 600 kg of sorghum, 150 kg of glutinous rice, and 250 kg of rice) are soaked in water, mixed evenly, and steamed. The saccharifying agent, *Rhizopus oryzae* (purchased from Guizhou Ligao Light Industry Technology Development Co., Ltd.), is weighed and sprinkled into the steamed starch raw materials cooled to 28°C. The amount of saccharifying agent used is approximately 0.5% by weight of the added starch raw materials. After the materials are mixed evenly, they are transferred to the saccharification tank and enter the standard saccharification process.

[0075] A sampling area is provided in the baijiu saccharification tank (for acquiring spectral information, temperature monitoring values, and humidity monitoring values). Within the sampling area, temperature sensors and humidity sensors are placed in a ring. A temperature control device and a humidity control device are installed to regulate the temperature and humidity by setting the ambient temperature and humidity, respectively.

[0076] For the process of microbial saccharification of starch raw material to be regulated, every 15 minutes, spectroscopic techniques and the function model Yd=F were used. d (M) and the function model Yz=F z (M) Obtain the theoretical value of reducing sugar content corresponding to the monitored saccharification reaction time. Substitute the theoretical value of reducing sugar content, the monitored saccharification reaction time, and the monitored starch content into the inverse function models of standard temperature T and standard humidity E to obtain the theoretical values ​​of temperature and humidity. Adjust the monitored temperature and humidity values ​​for the saccharification reaction time to the theoretical values ​​of temperature and humidity, respectively, thereby eliminating the difference between the monitored value of reducing sugar content and the theoretical value of reducing sugar content. The following explanation uses the adjustment of the monitored saccharification reaction time starting from 30 hours as an example:

[0077] When the saccharification reaction time monitoring value is 30h, the spectroscopic technique and the function model Yd=F are used. d (M), Yz = F z(M), the starch content and reducing sugar content in the saccharification material were quickly obtained as 30.75 g / (100g saccharification material) and 9.7 g / (100g saccharification material), respectively. The temperature and humidity monitoring values ​​were obtained as 32.09℃ and 90.11%, respectively, using temperature and humidity sensors in the saccharification tank.

[0078] Through the function model Yz=-7×10 -6 j 3 +6×10 -4 j 2 -0.008j+0.012, obtain the theoretical value of reducing sugar content corresponding to the saccharification reaction time monitoring value of 30h, which is 12.3g / (100g saccharified material). At this time, the difference between the theoretical value of reducing sugar content and the monitoring value of reducing sugar content is 2.6g / (100g saccharified material) (100%*(12.3-9.7) / 12.3=21%, which is greater than 10% and needs to be adjusted).

[0079] The theoretical value of reducing sugar content, the monitored saccharification reaction time of 30h (corresponding to j in the inverse function model), and the monitored starch content (corresponding to y in the inverse function model) are used. d Substituting these values ​​into the inverse function model of standard temperature T and standard humidity E, we obtain a theoretical temperature value of 33.21℃ and a theoretical humidity value of 94.86%.

[0080] The temperature and humidity of the saccharification tank were adjusted using temperature and humidity control devices, so that the temperature and humidity monitoring values ​​reached 32.09℃ and 94.46%, respectively.

[0081] (5) After a 15-minute interval, the spectral technique and the function model Yz=F were used. z The starch content and reducing sugar content in the saccharified material obtained by (M) were 26.83 g / (100g saccharified material) and 10.9 g / (100g saccharified material), respectively. The temperature and humidity monitoring values ​​obtained by the temperature and humidity sensors in the saccharification tank were 33.25℃ and 91.41%, respectively.

[0082] Through the function model Yz=-7×10 -6 j 3 +6×10 -4 j 2 -0.008j+0.012, obtain the theoretical value of reducing sugar content corresponding to the saccharification reaction time monitoring value of 30.25h, which is 12.5g / (100g saccharified material). At this time, the difference between the theoretical value of reducing sugar content and the monitoring value of reducing sugar content is 1.6g / (100g saccharified material) (100%*(12.5-10.9) / 12.5=12.8%, the difference has decreased, but it is still greater than 10%, and further adjustment is needed).

[0083] The theoretical value of reducing sugar content, the monitored saccharification reaction time of 30.25 h (corresponding to j in the inverse function model), and the monitored starch content (corresponding to Δy in the inverse function model) are used. d Substituting these values ​​into the inverse function models of standard temperature T and standard humidity E, we obtain a theoretical temperature value of 33.39℃ and a difference of 90.02% between the theoretical and monitored humidity values.

[0084] The temperature and humidity of the saccharification tank were adjusted using temperature and humidity control devices, so that the temperature and humidity monitoring values ​​reached 33.39℃ and 90.02%, respectively.

[0085] (6) After an interval of 15 minutes, the theoretical value of reducing sugar content was measured as 12.8 g / (100 g saccharified material) according to the method in (5). The difference between the value of reducing sugar content and the monitored value was 1.4 g / (100 g saccharified material) (100% * 1.4 / 12.8 = 10.94%, the difference has decreased, but it is still greater than 10%, and further adjustment is needed). (5) needs to be repeated for further adjustment.

[0086] (7) After an interval of 15 minutes, the theoretical value of reducing sugar content was measured as 13g / (100g saccharified material) according to the method in (5). The difference between the theoretical value of reducing sugar content and the monitored value of reducing sugar content was 1.2g / (100g saccharified material) (100%*1.2 / 13=9.23%, the difference has decreased and is less than 10%, no further adjustment is needed). At this time, the difference between the monitored value of reducing sugar content and the theoretical value of reducing sugar content is less than 10% of the theoretical value of reducing sugar content, no further adjustment is needed.

[0087] The process of microbial saccharification of starch raw materials was controlled according to the above method. When the saccharification rate reached 13%, the saccharification process of the microbial saccharification of starch raw materials to be controlled ended. The average hourly saccharification rate was calculated to be 0.04% from 0 to 20 hours and 0.40% after 20 hours.

[0088] The difference between the monitored value and the theoretical value of reducing sugar content was eliminated, making the process of microbial saccharification of starch raw materials to be controlled closer to the standard saccharification process.

[0089] Comparative Example 1

[0090] The process of using microbial saccharification starch raw material similar to that in Example 1 was carried out without any control. The saccharification process was considered complete when the saccharification rate reached 13%. The average hourly saccharification rate was measured to be 0.015% from 0 to 20 hours, and 0.19% after 20 hours.

[0091] The results of Example 1 show that the technical solution provided by this invention can achieve a function model with a good coefficient of determination, thus enabling better control of the process of microbial saccharification of starch raw materials. Furthermore, Examples 1 and Comparative Example 1 demonstrate that the method of this invention can reasonably control the saccharification process, bringing the various indicators closer to the standard saccharification process and achieving better saccharification results.

[0092] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method of modulating a process for microbial saccharification of a starch feedstock, characterized in that, The method comprises: (1) selecting a standard saccharification process, at every interval of At time from the start of saccharification to the end of saccharification, obtaining standard starch content, standard reducing sugar content, standard saccharification reaction time, standard temperature and standard humidity of the standard saccharification process, and obtaining standard spectral information of the saccharification material by using spectral technology; Wherein, the standard saccharification process is a saccharification process with an average saccharification rate of 0.02-0.05% per hour for 0-20 hours and an average saccharification rate of 0.29-0.51% per hour after 20 hours; The size of At is such that the number of standard data points is not less than 90; Wherein, the standard temperature, standard humidity, standard saccharification reaction time, standard spectral information, standard starch content and standard reducing sugar content obtained at a certain time are recorded as a standard data point; (2) According to all the standard data points, a function model Yd=F of standard spectrum information and standard starch content is constructed d (M) for subsequent rapid acquisition of the starch content monitoring value in the process of the microorganism saccharifying starch raw material to be controlled; A function model Yz=F of standard spectrum information and standard reducing sugar content is constructed z (M) for subsequent rapid acquisition of the reducing sugar content monitoring value in the process of the microorganism saccharifying starch raw material to be controlled; Wherein, Yd is the standard starch content, M is the standard spectral information, and Yz is the standard reducing sugar content; (3) According to all the standard data points, a function model Yz = F1(j) of the standard reducing sugar content and the standard saccharification reaction time is constructed, and a monitoring model Yz = F2(Yd, T, E, j) between the standard reducing sugar content and the standard starch content, the standard saccharification reaction time, the standard humidity and the standard temperature is constructed, and the inverse function model T = F3(Yd, Yz, E, j) of the standard temperature T and the inverse function model E = F4(Yd, T, Yz, j) of the standard humidity E are obtained according to the monitoring model; Wherein, T is the standard temperature, E is the standard humidity, and j is the standard saccharification reaction time; (4) in the process of the microorganism saccharifying starch raw material to be controlled, every interval Δt1 time, using the spectrum technology and function model Yd=F d (M), Yz=F z (M) to monitor the starch content monitoring value and the reducing sugar content monitoring value in the saccharifying material, and to obtain the saccharification reaction time monitoring value, the temperature monitoring value and the humidity monitoring value; By the function model Yz = F1(j), the theoretical value of the reducing sugar content corresponding to the saccharification reaction time monitoring value is obtained, the theoretical value of the reducing sugar content, the saccharification reaction time monitoring value and the starch content monitoring value are substituted into the inverse function model of the standard temperature T and the inverse function model of the standard humidity E to obtain the theoretical value of the temperature and the theoretical value of the humidity, and the temperature monitoring value and the humidity monitoring value of the saccharification reaction time are adjusted to the theoretical value of the temperature and the theoretical value of the humidity respectively, so as to reduce the difference between the monitoring value of the reducing sugar content and the theoretical value of the reducing sugar content; When the difference between the monitoring value of the reducing sugar content and the theoretical value of the reducing sugar content is greater than 10% of the theoretical value of the reducing sugar content, the process of the microbial saccharification starch raw material to be controlled is controlled; Δt1 = 0.05-2.28% of the total duration of the standard saccharification process.

2. The method of claim 1, wherein, The starch raw material of the saccharification process is selected from at least one of sorghum, rice, glutinous rice and corn; And / or, the saccharifying agent in the saccharification process is selected from at least one of rhizopus, aspergillus or mucor.

3. The method of claim 1 or 2, wherein, The spectral technology is selected from visible hyperspectrum and near-infrared hyperspectrum.

4. The method of claim 1, wherein, In step (1), the method for obtaining the standard starch content is selected from titration method and starch detection kit method.

5. The method of claim 1 or 4, wherein, In step (1), the method for obtaining the standard starch content is titration method.

6. The method of claim 1, wherein, In step (1), the method for obtaining the standard reducing sugar content is selected from direct titration method, potassium permanganate titration method, colorimetric method and reducing sugar detector method.

7. The method of claim 1 or 6, wherein, In step (1), the method for obtaining the standard reducing sugar content is direct titration method.

8. The method of claim 1, wherein, In step (2), the method for constructing the function model of the standard spectral information and the standard starch content and the method for constructing the function model of the standard spectral information and the standard reducing sugar content are independently selected from chemometrics methods.

9. The method of claim 1, wherein, In step (2), the method for constructing the function model of the standard spectral information and the standard starch content and the method for constructing the function model of the standard spectral information and the standard reducing sugar content are partial least squares method and partial least squares support vector machine method.

10. The method of claim 1, wherein, Function model Yd = F d (M), Yz = F z Determination coefficient R of (M) 2 Not less than 90%.

11. The method of claim 1, wherein, In step (3), the method for constructing the function model of the standard reducing sugar content and the standard saccharification reaction time and the method for constructing the monitoring model are independently selected from machine learning methods.

12. The method of claim 1, wherein, In step (3), the method for constructing the function model of the standard reducing sugar content and the standard saccharification reaction time and the method for constructing the monitoring model are artificial neural network method.

13. The method of claim 1, wherein, The determination coefficient R of the function model Yz = F1(j) 2 Not less than 90%.

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