A method for quality monitoring in high-temperature Daqu production process

Abstract

The present application relates to the field of high-temperature Daqu production, and particularly relates to a method for quality monitoring in the production of high-temperature Daqu, comprising the following steps: (1) obtaining the amino acid content data of high-temperature Daqu in different production links; (2) taking the amino acid content data obtained in step (1) as a control index, constructing a quality control chart by using the single-value-moving-range control chart principle in Shewhart control chart, and monitoring the quality of high-temperature Daqu in the production process by using the quality control chart; wherein the amino acid comprises one or more of L-aspartic acid, L-threonine, L-valine, L-methionine, L-tyrosine, L-isoleucine, L-leucine, L-phenylalanine and L-tryptophan; and the amino acid is a precursor of an important flavor component in high-temperature Daqu. The method can effectively monitor the quality of high-temperature Daqu in different production links, and further provides a reference for the quality monitoring method in Daqu production.

Description

Technical Field

[0001] This invention relates to the field of high-temperature Daqu production, and in particular to a method for quality monitoring during the high-temperature Daqu production process. Background Technology

[0002] High-temperature Daqu (a type of starter culture) primarily uses wheat as its raw material. It involves inoculating and fermenting microorganisms from the natural environment of the starter culture's production space. These microorganisms interact and multiply within the starter culture, undergoing natural temperature accumulation and air drying to form a multi-enzyme, multi-bacterial microecological product. High-temperature Daqu is a crucial saccharification and fermentation agent in the production of Baijiu (Chinese liquor), and its quality directly affects the quality of the base liquor.

[0003] High-temperature Daqu (a type of starter culture) is an important source of aroma and precursors in Baijiu (Chinese liquor). Its amino acid composition and content are among the key precursors of flavor components in Baijiu, primarily derived from protein enzyme degradation in wheat, microbial metabolites during fermentation, and microbial cell autolysis after fermentation. Under high-temperature fermentation conditions, amino acids and reducing sugars undergo Maillard reactions, forming a series of cross-reactions such as condensation, decarboxylation, deamination, and dehydrogenation, thereby generating various flavor components. Among these, pyrazines possess unique roasted and nutty aromas, phenols have caramel and similar aromas, furans and pyrans have a soy sauce-like flavor, and thiazoles and thiophenes have roasted aromas, contributing to a variety of aroma components and precursors in Baijiu.

[0004] During fermentation, amino acids, as precursors of important flavor components, can be considered one of the key indicators for evaluating the quality of high-temperature koji (a type of starter culture). Therefore, real-time monitoring of the amino acid content of these precursors in high-temperature koji at different production stages is crucial for producing high-quality koji. This invention aims to provide a method for quality monitoring during the production of high-temperature koji. Summary of the Invention

[0005] The purpose of this invention is to provide a method for quality monitoring during the production of high-temperature Daqu (a type of Chinese liquor).

[0006] Firstly, current methods for analyzing amino acids in precursors of important flavor components in high-temperature koji (a type of starter culture) mostly rely on automated amino acid analyzers. However, considering the high cost and time-consuming nature of these analyzers, this invention proposes a UPLC-HRMS-QAMS method to determine the amino acid content of precursors of important flavor components in high-temperature koji. This method is simple, rapid, stable, and reliable, and can comprehensively reflect the distribution of amino acid content in other important flavor component precursors of high-temperature koji even with the consumption of reference materials, thus helping to improve the quality control level of high-temperature koji.

[0007] Quality control charts are graphical representations that provide a clear and intuitive assessment of analytical quality while comprehensively and continuously reflecting fluctuations in test results. They are an effective method for routine testing quality control and a continuous evaluation system for laboratory analytical methods and procedures. To achieve quality control in the production process of high-temperature Daqu (a type of Chinese koji), this invention, based on the amino acid content data of important flavor component precursors in high-temperature Daqu determined by UPLC-HRMS-QAMS, establishes a quality control chart model for high-temperature Daqu quality using the principle of single-value moving range control charts in Shewhart control charts. This model is then applied to effectively monitor the quality of high-temperature Daqu at different production stages.

[0008] On the one hand, the present invention provides a method for quality monitoring in the production process of high-temperature Daqu (a type of Chinese liquor), comprising the following steps:

[0009] (1) Obtain data on the amino acid content in high-temperature Daqu (a type of starter culture) at different production stages;

[0010] (2) The amino acid content data obtained in step (1) is used as a control indicator. A quality control chart is constructed using the principle of single-value moving range control chart in Shewhart control chart. The quality control chart is used to monitor the quality in the high-temperature Daqu production process.

[0011] The amino acids include one or more of L-aspartic acid, L-threonine, L-valine, L-methionine, L-tyrosine, L-isoleucine, L-leucine, L-phenylalanine, and L-tryptophan; the amino acids are precursors of important flavor components in high-temperature Daqu (a type of starter culture).

[0012] In some implementation schemes, the monitoring method is as follows: substituting the amino acid content data into the model of the quality control chart; if the result obtained does not exceed the range of the quality control chart, it is determined that the quality of the high-temperature Daqu meets the production requirements; if the result obtained exceeds the range of the quality control chart, it is determined that the quality of the high-temperature Daqu does not meet the production requirements; based on the amino acid content data in the high-temperature Daqu, the quality abnormality in the production process of the high-temperature Daqu is determined.

[0013] In some implementations, the construction of the quality control chart includes the following steps:

[0014] Based on the control index, calculate the center CL value, upper control UCL value, and lower control LCL value of the control index.

[0015] In some implementations, the CL value, UCL value, and LCL value are calculated according to the "3σ criterion" using the following formula:

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] LCL R =0

[0022] in, This represents the average content of the same amino acid in high-temperature Daqu (a type of Chinese liquor) produced at different production sites in different production plants. R is the average moving range, where: R = |X i+1 -X i |,X i This represents the content of the i-th amino acid in high-temperature Daqu (a type of Chinese liquor).

[0023] In some implementation schemes, the qualified and unqualified areas of the amino acid content in high-temperature koji at different key nodes are determined by the center CL value, upper control UCL value, and lower control LCL value of the control index; if the amino acid content is not within the range of the quality control chart, it is determined that the quality of the high-temperature koji is abnormal, and if the amino acid content is within the range of the quality control chart, it is determined that the quality of the high-temperature koji is normal.

[0024] In some embodiments, obtaining the amino acid content data includes determining the amino acid content in the high-temperature Daqu sample using UPLC-HRMS-QAMS.

[0025] In some implementations, the UPLC-HRMS-QAMS method includes the following steps:

[0026] 1) Pretreatment: The high-temperature Daqu sample is pretreated to obtain the test solution;

[0027] 2) Instrumental analysis: The test solution obtained in step 1) is analyzed by UPLC-HRMS technology to obtain the chromatographic information of amino acid substances in the test solution;

[0028] 3) The amino acid content of the important flavor component precursor in the test solution was calculated by QAMS method.

[0029] In some implementations, the QAMS method further includes the following steps:

[0030] Calculate the relative correction factor between the reference amino acid and the analyte amino acid;

[0031] The content of amino acids in the reference substance was calculated based on the relative correction factor.

[0032] Based on the relative correction factor and the content of the reference amino acid, the content of the amino acid to be tested in the test solution is calculated.

[0033] In some embodiments, the reference amino acid is L-lysine.

[0034] In some implementations, the preprocessing includes the following steps:

[0035] Sample sieving;

[0036] Extraction: Add extraction reagent to the sieved sample, mix well, and sonicate;

[0037] Centrifugation;

[0038] Filtration: The supernatant after centrifugation is filtered through a 0.22 μm aqueous PES syringe filter membrane to obtain the test solution.

[0039] In some implementations, the sieve aperture is 0.1-1 mm.

[0040] In some implementations, the centrifugation conditions are: 8000 rpm to 15000 rpm for 3-6 minutes.

[0041] In some embodiments, the addition ratio of the extraction reagent to the sample, in ml / g, is 200ml-500ml:1g; preferably, the addition ratio of the extraction reagent to the sample, in ml / g, is 250ml-400ml:1g; preferably, the addition ratio of the extraction reagent to the sample, in ml / g, is 280ml-350ml:1g; preferably, the addition ratio of the extraction reagent to the sample, in ml / g, is 280ml-320ml:1g; preferably, the addition ratio of the extraction reagent to the sample, in ml / g, is 300ml:1g.

[0042] In some implementations, the extraction reagent is ultrapure water.

[0043] In some embodiments, the ultra-high performance liquid chromatography (UPLC-HRMS-QAMS) conditions are as follows: the column is a Thermo Hypersil Gold C18 (150 mm × 2.1 mm, 1.9 μm); the column temperature is 35-45 °C; the injection volume is 1-3 μL; the flow rate is 0.1-0.3 mL / min; and 0.1% formic acid aqueous solution (A) and methanol (B) are used as the mobile phase.

[0044] In some implementations, the high-resolution mass spectrometry conditions in the UPLC-HRMS-QAMS are as follows: heated electrospray ionization source; sheath gas flow rate and auxiliary gas flow rate are 30-50 alb and 5-15 alb, respectively; spray voltage: 3.2 kV; ion source temperature and capillary temperature are 350 °C and 320 °C, respectively; the scanning conditions of the high-resolution mass spectrometer are: full-scan positive ion scanning acquisition mode; scanning range and resolution are 50.0–250.0 Da and 70000, respectively; automatic gain control for the number of ions entering the orbital trap: 1e6; maximum injection time: 30 ms.

[0045] In summary, this application has the following beneficial technical effects:

[0046] (1) This invention collects high-temperature koji samples from different production stages and uses UPLC-HRMS-QAMS to determine the amino acid content of nine important flavor component precursors in high-temperature koji. At the same time, based on Minitab15 software, a quality control chart for monitoring the quality of high-temperature koji is constructed using the principle of single-value moving range control chart in Shewhart control chart. This method enables effective monitoring of the quality of high-temperature koji at different production stages, thereby providing a reference for koji production and providing data support and technical guarantee for achieving high-quality and high-yield production in enterprises.

[0047] (2) This invention uses L-lysine as a reference to quantify the amino acids of nine important flavor component precursors in high-temperature koji using UPLC-HRMS-QAMS, which solves the problem of lack of reference standards in the quantification of multiple components and quality control of multiple indicators in high-temperature koji.

[0048] (3) The present invention establishes a quality control chart based on Minitab 15 software to monitor the quality stability of high temperature Daqu between different production stages, thereby ensuring the quality of high temperature Daqu.

[0049] (4) The UPLC-HRMS-QAMS method provided by this invention for determining the amino acid content of various important flavor component precursors in high-temperature Daqu has the advantages of being rapid, simple, highly sensitive, highly precise, and stable. Attached Figure Description

[0050] Figure 1 shows the amino acid TIC diagrams of the precursors of the important flavor components to be tested under different volumes of methanol-water (v / v) extraction solution; Figure 1(A) shows the amino acid TIC diagram of the precursors of the important flavor components to be tested under 10 mL of extraction solution; Figure 1(B) shows the amino acid TIC diagram of the precursors of the important flavor components to be tested under 15 mL of extraction solution; Figure 1(C) shows the amino acid TIC diagram of the precursors of the important flavor components to be tested under 20 mL of extraction solution; Figure 1(D) shows the amino acid TIC diagram of the precursors of the important flavor components to be tested under 30 mL of extraction solution.

[0051] Figure 2 shows the chromatograms of amino acids from the precursors of important flavor components under different volume ratios of methanol-water (v / v) extraction solutions. Specifically, Figure 2(A) shows the chromatogram of L-valine under different volume ratios of methanol-water (v / v) extraction solutions; Figure 2(B) shows the chromatogram of L-methionine under different volume ratios of methanol-water (v / v) extraction solutions; and Figure 2(C) shows the chromatogram of L-tyrosine under different volume ratios of methanol-water (v / v) extraction solutions. Sample pretreatment analysis was performed by adding 30 mL of extraction solutions with methanol-water volume ratios (v / v) of 40 / 60, 30 / 70, 20 / 80, 10 / 90, 5 / 95, and 0 / 100, respectively.

[0052] Figure 3 shows the mean and range control charts of amino acid precursors of important flavor components in the "one-time fermentation" high-temperature Daqu sample; Figure 3(A) shows the mean control chart of amino acid precursors of important flavor components in the "one-time fermentation" high-temperature Daqu sample; Figure 3(B) shows the range control chart of amino acid precursors of important flavor components in the "one-time fermentation" high-temperature Daqu sample.

[0053] Figure 4 shows the mean and range control charts of amino acid precursors of important flavor components in the "double-turned koji" high-temperature koji sample; Figure 4(A) shows the mean control chart of amino acid precursors of important flavor components in the "double-turned koji" high-temperature koji sample, and Figure 4(B) shows the range control chart of amino acid precursors of important flavor components in the "double-turned koji" high-temperature koji sample.

[0054] Figure 5 shows the mean and range control charts of amino acid precursors of important flavor components in the "disassembled" high-temperature Daqu sample; Figure 5(A) shows the mean control chart of amino acid precursors of important flavor components in the "disassembled" high-temperature Daqu sample; Figure 5(B) shows the range control chart of amino acid precursors of important flavor components in the "disassembled" high-temperature Daqu sample. Detailed Implementation

[0055] The following specific embodiments further illustrate the technical solution of the present invention. These specific embodiments do not represent a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention.

[0056] The reagents and equipment used in the embodiments of this invention are as follows:

[0057] Methanol was purchased from Merck, Germany; formic acid from Fisher Scientific, USA; and a mixed standard of nine amino acids (2.5 mmol / L) including L-aspartic acid, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-threonine, L-tyrosine, and L-valine, all purchased from Merck; L-tryptophan (99.04%) standard was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; and L-leucine (98.1%) and L-theanine (98.2%) standards were purchased from Beijing Solarbio Science & Technology Co., Ltd.

[0058] The ultra-high performance liquid chromatography-tandem high-resolution mass spectrometer used was purchased from Thermo Fisher Scientific; the QT-1 vortex mixer was purchased from Shanghai Qite Analytical Instrument Co., Ltd.; the HC-3518 high-speed centrifuge was purchased from Anhui Zhongke Zhongjia Scientific Instrument Co., Ltd.; the AR2140 ppm analytical balance was purchased from Mettler Toledo Instruments (Shanghai) Co., Ltd.; and the Aikopu ultrapure water system was purchased from Millipore, USA.

[0059] Example 1: A method for determining the amino acid content of precursors of multiple important flavor components in high-temperature Daqu (a type of starter culture).

[0060] (1) Preparation of the test solution:

[0061] Sample sieving: The sample of Daqu to be tested is dried, pulverized, and then passed through a 0.5mm mesh sieve;

[0062] Accurately weigh 0.1g of the sieved sample into a 50mL centrifuge tube, add 30mL of ultrapure water; mix well: shake to mix for 2min, and sonicate for 15min;

[0063] Centrifugation: Centrifuge at 10000 rpm for 5 min; Filtration:

[0064] Take the supernatant and filter it through a 0.22μm aqueous PES syringe filter membrane to obtain the test solution, which is ready for instrumental analysis;

[0065] (2) Preparation of reference solutions: Using ultrapure water as reagent, amino acid mixed reference stock solution with a concentration of 100 μmol / L was used to prepare a series of standard working solutions of 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 μmol / L.

[0066] (3) Computer-based analysis:

[0067] The test solution prepared in step (1) and the standard working series solutions prepared in step (2) were respectively analyzed using ultra-high performance liquid chromatography-tandem high-resolution mass spectrometry (UHPLC-MS / MS). The peak areas corresponding to each amino acid component in the test solution and the peak areas corresponding to each amino acid in mixed reference solutions of different mass concentrations were obtained. The relevant parameters of the UHPLC-MS / MS used are as follows:

[0068] The ultra-high performance liquid chromatography (UHPLC) column was a Thermo Hypersil Gold C18 (150 mm × 2.1 mm, 1.9 μm); the column temperature was 40 °C, the injection volume was 2 μL, and the flow rate was 0.2 mL / min; 0.1% formic acid aqueous solution (A) and methanol (B) were used as the mobile phase, and the gradient elution conditions were as follows:

[0069] Table 1 Gradient elution program

[0070]

[0071] The ion source conditions for the high-resolution mass spectrometer were as follows: heated electrospray ionization source; sheath gas flow rate and auxiliary gas flow rate were 40 arb and 10 arb, respectively; spray voltage was 3.2 kV; ion source temperature and capillary temperature were 350℃ and 320℃, respectively. The scanning conditions for the high-resolution mass spectrometer were as follows: full-scan positive ion scanning acquisition mode; scanning range and resolution were 50.0–250.0 Da and 70,000 Da, respectively; automatic gain control was used to control the number of ions entering the orbital trap: 1 e^(-1 / 2)^2. 6 Maximum injection time: 30ms.

[0072] The compound information and high-resolution mass spectrometry parameters of each amino acid standard are shown in Table 2:

[0073] Table 2. Information on the amino acid standard compounds and their high-resolution mass spectrometry parameters.

[0074]

[0075] (4) Calculate the relative correction factor:

[0076] Based on the peak areas of each amino acid obtained by injecting and analyzing the mixed reference solutions of different mass concentrations prepared in step (2), and using L-lysine as a reference, the relative correction factor of L-lysine for the amino acid to be tested was calculated according to formula (1). The f-values ​​of L-aspartic acid, L-threonine, L-valine, L-methionine, L-tyrosine, L-isoleucine, L-leucine, L-phenylalanine, and L-tryptophan were then calculated. k / m value:

[0077]

[0078] In the formula C m C k The content (μmol / L) of L-lysine (reference) and the amino acid component to be tested, A m A k The peak areas are for L-lysine and the amino acid component to be tested. It should be noted that in the embodiments of this invention, the content of amino acids is equivalent to the concentration of amino acids; that is, the concentration and content of amino acids are only different in description, but are essentially the same.

[0079] (5) Calculate the content C of L-lysine in the test solution. m :

[0080] A series of L-lysine standard working solutions with concentrations of 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, and 20.0 μmol / L were prepared. Then, the solutions were analyzed using an ultra-high performance liquid chromatography-tandem high-resolution mass spectrometer (UHPLC-MS / MS) with the corresponding parameters as described in step (3). A standard curve was obtained showing the relationship between the L-lysine content and peak area in the standard solutions. The L-lysine content C in the test solution was calculated based on the peak area of ​​L-lysine in the test solution. m .

[0081] (6) Calculate the content of other amino acids in the test solution:

[0082] The relative correction factor f calculated above k / m And the content of L-lysine in the test solution C m The content of other amino acid components to be tested in the test sample solution is calculated by combining formula (2);

[0083]

[0084] In the formula C x C represents the content (μmol / L) of other analyte amino acid components in the test solution. m To determine the content (μmol / L) of L-lysine in the test solution, A m A x This represents the peak area of ​​L-lysine and other amino acids in the sample to be tested.

[0085] Table 3 shows the amino acid content data of various important flavor component precursors in high-temperature koji obtained by the above method:

[0086] Table 3. Amino acid content (μmol / L) of nine important flavor component precursors in high-temperature Daqu (a type of starter culture) at different production stages.

[0087]

[0088]

[0089] Example of effect 1

[0090] (1) Linear range, limit of detection, and limit of quantitation of each amino acid detection method

[0091] The mixed standard working series solutions of each amino acid were determined according to the conditions described in step (3), and quantification was performed using the internal standard method. A standard curve was plotted with the content of each amino acid as the abscissa (X) and the chromatographic peak area of ​​the quantitative ion as the ordinate (Y), thus obtaining the relevant linear regression equation. The limit of detection (LOD) of each amino acid was calculated with a signal-to-noise ratio (S / N) of 3, and the limit of quantitation (LOQ) was calculated with a signal-to-noise ratio (S / N) of 10. For details, please refer to Table 4.

[0092] Table 4. Linear equations, limits of detection, and limits of quantitation for each amino acid standard working series solutions.

[0093]

[0094] (2) Recovery and precision of each amino acid determination method

[0095] Three amino acid standard solutions with different concentrations were added to the high-temperature Daqu sample according to the quantitation limits of each amino acid to prepare spiked samples. Pretreatment was performed according to step (6) above, and analysis was conducted using ultra-high performance liquid chromatography-tandem high-resolution mass spectrometry. Each spiked level was performed in triplicate, and each parallel determination was repeated six times. The average recovery rate was calculated to verify the accuracy, precision, and stability of the assay method. The analytical results are shown in Table 5. For the three different spiked levels, the average recovery rate ranged from 77.71% to 109.56%, and the relative standard deviation (RSD) ranged from 0.24% to 4.20%. It can be seen that this assay method has good recovery rate, precision, and stability for amino acids of various important flavor component precursors in high-temperature Daqu. Furthermore, the pretreatment method results in low loss of amino acids of important flavor component precursors in the sample.

[0096] Table 5 Recovery and precision of the methods for determining each analyte

[0097]

[0098] Example 2

[0099] To further evaluate the feasibility and applicability of the UPLC-HRMS-QAMS method provided by this invention for determining the amino acid content of important flavor component precursors in high-temperature Daqu samples, the UPLC-HRMS-QAMS method and the internal standard method in Example 1 were used to analyze the amino acid content of corresponding important flavor component precursors in high-temperature Daqu samples. The standard method difference (SMD) between the internal standard method and the UPLC-HRMS-QAMS method was compared and analyzed using formula (3) to evaluate the feasibility and applicability of the UPLC-HRMS-QAMS method for determining the amino acid content of important flavor component precursors in samples.

[0100]

[0101] In the formula C IS With C QAMS The values ​​represent the content of amino acids, precursors of important flavor components, in high-temperature Daqu samples determined by internal standard method and UPLC-HRMS-QAMS method, respectively.

[0102] Specifically as follows:

[0103] I. Comparison of internal standard method and UPLC-HRMS-QAMS method for determining the amino acid content of important flavor component precursors in "one-time fermentation" high-temperature koji samples

[0104] This embodiment follows the method of Example 1 to determine the amino acid content of important flavor component precursors in "one-time fermentation" high-temperature koji samples. The amino acid content of nine important flavor component precursors in the "one-time fermentation" high-temperature koji samples was analyzed using both the internal standard method and UPLC-HRMS-QAMS, and the SMD values ​​between the two methods were calculated, as shown in Table 6. The SMD values ​​of the amino acid content of each important flavor component precursor were less than 0.96%, 7.07%, 2.77%, 7.19%, 3.09%, 8.49%, 1.13%, 1.48%, and 5.28%, respectively, indicating that the UPLC-HRMS-QAMS method can be used to determine the amino acid content of each important flavor component precursor in "one-time fermentation" high-temperature koji samples.

[0105] Table 6. SMD values ​​(%) of amino acid content of important flavor component precursors in high-temperature Daqu samples from "one-time fermentation".

[0106]

[0107] II. Comparison of internal standard method and UPLC-HRMS-QAMS method for determining the amino acid content of important flavor component precursors in high-temperature koji samples after "secondary fermentation".

[0108] This embodiment follows the method of Example 1 to determine the amino acid content of important flavor component precursors in "double-turned" high-temperature Daqu samples. The amino acid content of nine important flavor component precursors in the "double-turned" high-temperature Daqu samples was analyzed using both the internal standard method and UPLC-HRMS-QAMS, and the SMD values ​​between the two methods were calculated. The results are shown in Table 7. The SMD values ​​of the amino acid content of each important flavor component precursor were less than 0.65%, 8.13%, 2.66%, 8.26%, 3.68%, 2.85%, 7.66%, 2.92%, and 8.97%, respectively, indicating that the UPLC-HRMS-QAMS method can be used to determine the amino acid content of each important flavor component precursor in "double-turned" high-temperature Daqu samples.

[0109] Table 7. SMD values ​​(%) of amino acid content of important flavor component precursors in high-temperature Daqu samples from "secondary fermentation".

[0110]

[0111] III. Comparison of internal standard method and UPLC-HRMS-QAMS method for determining the amino acid content of important flavor component precursors in "disassembled" high-temperature koji samples

[0112] This embodiment describes the determination of amino acid content in precursors of nine important flavor components in "disassembled" high-temperature Daqu samples, following Examples 1 and 2. The amino acid content of these precursors was analyzed using both internal standard method and UPLC-HRMS-QAMS, and the SMD values ​​between the two methods were calculated. The results are shown in Table 8. The SMD values ​​of the amino acid content of each important flavor component precursor were less than 7.39%, 6.05%, 2.31%, 9.22%, 2.73%, 6.30%, 2.95%, 5.19%, and 7.92%, respectively, indicating that the UPLC-HRMS-QAMS method can be used to determine the amino acid content of each important flavor component precursor in "disassembled" high-temperature Daqu samples.

[0113] Table 8. SMD values ​​(%) of amino acid content of important flavor component precursors in "disassembled" high-temperature Daqu samples.

[0114]

[0115] Comparative Example 1 explores the impact of different pretreatment methods on test results.

[0116] The difference between this comparative example and the pretreatment method used in Example 1 is that this comparative example includes solvent extraction and selection of the sample before the high-speed centrifugation step of the high-temperature Daqu sample. All other conditions and steps are the same as in Example 1. The specific settings of this comparative experiment are as follows:

[0117] A: Different volumes of methanol-water (40:60, v / v) were added to high-temperature Daqu samples to extract the amino acid content of precursors of important flavor components. Then, the samples were subjected to high-speed centrifugation and membrane filtration, and the obtained samples were tested by instrument.

[0118] B: Add the same volume of methanol-water (v / v) to high-temperature Daqu samples in different proportions to extract the amino acid content of important flavor component precursors, then perform high-speed centrifugation and membrane filtration, and then perform instrumental analysis on the obtained samples;

[0119] C: The high-temperature Daqu sample was first subjected to solvent extraction, followed by centrifugation and membrane filtration. The resulting sample was then tested. The experimental steps for this group were the same as in Example 1.

[0120] In the comparative experiments set up above, A differs from Example 1 in that the volume of the extraction solvent for the sample is selected before centrifuging the high-temperature Daqu sample; otherwise, they are the same as in Example 1. B differs from Example 1 in that the ratio of the extraction solvent for the sample is selected before centrifuging the high-temperature Daqu sample; otherwise, they are the same as in Example 1. C is exactly the same as Example 1.

[0121] The high-temperature Daqu samples obtained by the above three pretreatment methods were subjected to instrumental analysis. The same liquid chromatography and mass spectrometry conditions as in Example 1 were used to obtain the chromatograms (or TIC chromatograms) of the components to be tested in each group of samples.

[0122] It should be noted that the above pretreatment method is the best pretreatment method for the analysis of all analytes under these conditions, after experimental exploration.

[0123] Taking the amino acid TIC chart of the precursors of important flavor components to be tested as an example, as shown in Figure 1, in order to ensure that the amino acid content of the 10 precursors of important flavor components in the high-temperature Daqu sample meets the content range of the standard working series solution, it is necessary to determine the volume of the extraction solution. When the volume of the extraction solution is 30 mL, the amino acid content of the precursors of important flavor components in the tested sample can meet the content range of the standard working series solution.

[0124] Taking L-valine, L-methionine, and L-tyrosine as examples, as shown in Figure 2, as the methanol-water ratio gradually decreases to 0 / 100 (i.e., only ultrapure water is needed as the extraction solution), the chromatographic peak response values ​​of L-valine, L-methionine, and L-tyrosine are the highest. Simultaneously, the peak widths of L-methionine and L-tyrosine are narrower, and their peak shapes are significantly better. Therefore, the above results indicate that when the methanol-water extraction solution ratio is 0 / 100, the extraction effect of amino acids from important flavor component precursors in high-temperature Daqu (a type of Chinese liquor) is better.

[0125] Example 2: A method for quality monitoring during the production of high-temperature Daqu (a type of Chinese liquor).

[0126] (1) 54 samples were selected from 3 locations (near the door, in the middle, and near the window) in 6 production workshops of 3 high-temperature Daqu production workshops, including "first turning of Daqu", "second turning of Daqu" and "dismantling of Daqu".

[0127] (2) The amino acid content of nine important flavor component precursors in high-temperature Daqu collected in different production stages was determined according to the method of Example 1. The amino acids of the important flavor component precursors include: L-aspartic acid, L-threonine, L-valine, L-methionine, L-tyrosine, L-isoleucine, L-leucine, L-phenylalanine, and L-tryptophan. The amino acid content of the nine important flavor component precursors in 54 high-temperature Daqu samples was calculated and is shown in Table 3.

[0128] (3) The amino acid content of the nine important flavor component precursors in high-temperature koji obtained in step (2) is used as the control index. The central CL value, upper control UCL value, and lower control LCL value of the control index are calculated as follows:

[0129] First, based on the control indicators, a quality control chart for high-temperature Daqu (a type of Chinese liquor) quality monitoring is established using Minitab 15 software and the principle of single-value moving range control chart in Shewhart control charts. The center line (CL) represents the average value of the sample quality characteristics. The upper control limit (UCL) and lower control limit (LCL) are calculated according to the "3σ criterion" using formulas (4) to (6). The moving range (R) quality control chart is calculated using formulas (7) to (9).

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] In the formula: The average amino acid content of the same important flavor component precursor in high-temperature Daqu (a type of starter culture) produced at different production sites in different production plants; R is the average moving range, where: R = |Xi+1 -X i |,X i This represents the amino acid content of the precursor of the i-th important flavor component in high-temperature Daqu (a type of Chinese liquor).

[0137] The quality control chart for high-temperature Daqu quality monitoring was calculated using Minitab 15 software, as shown in Figures 3 to 5. The quality control chart is a graph that measures, records, and controls the quality characteristic values. The vertical axis of the graph represents the quality characteristic values, with a center CL value, an upper control UCL value, and a lower control LCL value. The horizontal axis represents the sample number of high-temperature Daqu at different production sites in different production plants.

[0138] (4) Monitoring: The qualified and unqualified areas of the amino acid content in high-temperature Daqu at different key nodes are determined by the center CL value, upper control UCL value, and lower control LCL value of the control index. If the measured amino acid content is not within the range of the calculated quality control chart, it is determined that the quality of high-temperature Daqu has become abnormal. If the measured amino acid content is within the range of the calculated quality control chart, it is determined that the quality of high-temperature Daqu is normal. In this way, the quality of high-temperature Daqu is monitored in the production process through the quality control chart calculated in step (3).

[0139] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for quality monitoring during the production of high-temperature Daqu (a type of Chinese liquor), characterized in that, Includes the following steps: (1) Obtain data on the amino acid content in high-temperature Daqu (a type of starter culture) at different production stages; (2) The amino acid content data obtained in step (1) is used as a control indicator. A quality control chart is constructed using the principle of single-value moving range control chart in Shewhart control chart. The quality control chart is used to monitor the quality in the high-temperature Daqu production process. The amino acids include L-aspartic acid, L-threonine, L-valine, L-methionine, L-tyrosine, L-isoleucine, L-leucine, L-phenylalanine, and L-tryptophan; these amino acids are precursors of important flavor components in high-temperature Daqu (a type of starter culture). The acquisition of the amino acid content data includes: determining the amino acid content in the high-temperature Daqu sample using UPLC-HRMS-QAMS; the UPLC-HRMS-QAMS method includes the following steps: 1) Pretreatment: The high-temperature Daqu sample is pretreated to obtain the test solution; 2) Instrumental analysis: The test solution obtained in step 1) is analyzed by UPLC-HRMS technology to obtain the chromatographic information of amino acid substances in the test solution; 3) Calculate the content of the amino acids in the test solution using the QAMS method; The QAMS method also includes the following steps: Calculate the relative correction factor between the reference amino acid and the analyte amino acid; The content of amino acids in the reference substance was calculated based on the relative correction factor. Based on the relative correction factor and the content of the reference amino acid, the content of the amino acid to be tested in the test solution is calculated; The ultra-high performance liquid chromatography (UPLC-HRMS-QAMS) conditions were as follows: The column was a Thermo Hypersil Gold C18, 150 mm × 2.1 mm, 1.9 μm; the column temperature was 35-45℃; the injection volume was 1-3 μL; and the flow rate was 0.1-0.3 mL / min. 0.1% formic acid aqueous solution (A) and methanol (B) were used as the mobile phase, and the gradient elution program for the mobile phase is shown in the table below. ； The high-resolution mass spectrometry conditions in the UPLC-HRMS-QAMS are as follows: heated electrospray ionization source; sheath gas flow rate and auxiliary gas flow rate: 30-50 alb and 5-15 alb, respectively; spray voltage: 3.2 kV; ion source temperature and capillary temperature: 350℃ and 320℃, respectively; the scanning conditions of the high-resolution mass spectrometer are: full-scan positive ion scanning acquisition mode; scanning range and resolution: 50.0–250.0 Da and 70000 Da, respectively; automatic gain control for the number of ions entering the orbital trap: 1 e 6 Maximum injection time: 30ms.

2. The method as described in claim 1, characterized in that, The construction of the quality control chart includes the following steps: Based on the control index, calculate the center CL value, upper control UCL value, and lower control LCL value of the control index.

3. The method as described in claim 2, characterized in that, The CL value, UCL value, and LCL value are calculated according to the "3σ criterion" using the following formula: LCL R =0 in, This represents the average content of the same amino acid in high-temperature Daqu (a type of Chinese liquor) produced at different production sites in different production plants. R is the average moving range, where: R = |X i+1 -X i |,X i This represents the content of the i-th amino acid in high-temperature Daqu (a type of Chinese liquor).

4. The method as described in claim 2, characterized in that, The qualified and unqualified areas of the amino acid content in high-temperature koji at different key nodes are determined by the center CL value, upper control UCL value, and lower control LCL value of the control index. If the amino acid content is not within the range of the quality control chart, it is determined that the quality of the high-temperature koji is abnormal. If the amino acid content is within the range of the quality control chart, it is determined that the quality of the high-temperature koji is normal.

5. The method as described in claim 1, characterized in that, The preprocessing includes the following steps: Sample sieving; Extraction: Add extraction reagent to the sieved sample, mix well, and sonicate; the addition ratio of extraction reagent to sample is 200ml-500ml:1g, calculated in ml / g; the extraction reagent is ultrapure water; Centrifugation; Filtration: The supernatant after centrifugation is filtered through a 0.22 μm aqueous PES syringe filter membrane to obtain the test solution.

6. The method as described in claim 1, characterized in that, The reference amino acid is L-lysine.

7. The method as described in claim 5, characterized in that, The sieve aperture is 0.1-1 mm.

8. The method as described in claim 5, characterized in that, The centrifugation conditions are: 8000rpm~15000rpm, centrifugation for 3-6min.

9. The method as described in claim 5, characterized in that, The extraction reagent is added in a ratio of 250ml to 400ml to 1g relative to the sample, measured in ml / g.

10. The method as described in claim 5, characterized in that, The extraction reagent is added in a ratio of 280ml to 350ml to 1g relative to the sample, measured in ml / g.

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