A method for evaluating malt solubility

Abstract

The application discloses a malt solubility evaluation method and belongs to the field of malt evaluation. The technical scheme comprises the following steps: defining the malt solubility according to a malt solubility index, and the lower the malt solubility index is, the better the malt solubility is. The application is applied to the field of malt solubility evaluation, solves the problems of multi-index dependence, low detection efficiency and group mean distortion of existing methods, realizes rapid and accurate quantitative detection of the malt solubility index, and meets the urgent needs of rapid evaluation of the malt solubility and rapid adjustment of a malting process in mass production.

Description

Technical Field

[0001] This invention belongs to the field of malt evaluation, and particularly relates to a method for evaluating malt solubility. Background Technology

[0002] Malt, the core raw material for beer brewing, is a product obtained from barley through malting. During malting, barley absorbs water and germinates, and the embryo secretes gibberellin, which stimulates the aleurone layer to produce various hydrolytic enzymes. These hydrolytic enzymes are transported to the endosperm and continuously break down large molecules, increasing the amount of soluble low-molecular-weight sugars and nitrogenous substances. This causes the entire endosperm structure to change from tough to loose, a phenomenon known as malt dissolution [Guan Dunyi, Beer Industry Handbook [M], Beijing: China Light Industry Press, 2007]. Solubility is a key indicator for measuring malt quality, directly determining the quality, cost, and flavor stability of beer. Poorly dissolved malt contains more glassy particles, has low enzyme activity, slow saccharification, and low extract, resulting in beer with poor non-biological stability. Overly dissolved malt grows vigorously, with significant root and shoot loss, leading to a weak beer flavor and poor foam. Moderately dissolved malt has good brewing characteristics and is fundamental to stable beer quality.

[0003] Currently, there is a lack of unified evaluation methods and standards for determining malt solubility. During the germination stage, experienced malt growers often use their thumb and forefinger to rub green malt to judge its solubility. If the endosperm disperses into a powdery form, it indicates good solubility; if it forms a clump that cannot be broken apart, it indicates poor solubility. For finished malt, it is usually judged by taste. If the malt is loose and easily broken, it is considered well-dissolved; if the grains are hard and difficult to bite, it indicates poor solubility. All of these methods are highly subjective, cannot provide quantitative assessment, and are only suitable for rough, empirical judgments.

[0004] The malt solubility evaluation system covers multiple dimensions of indicators, including indicators such as starch solubility (brittleness, difference between coarse and fine flour, saccharification power, etc.); indicators such as protein solubility (Courbach value, α-amino nitrogen); and indicators such as cell solubility (β-glucan, viscosity, etc.). Ozka Ra et al. [R.Ozka Ra, A. Basman, H. Koksel, et al. Effects of cultivarand environment on β-glucan content and malting quality of Turkishbarleys. Journal of the Institute of Brewing. 1998, 104(4):217-220] believe that β-glucan is a key indicator linking varietal characteristics and malt quality. Its content changes are significantly correlated with physical indicators such as brittleness and viscosity, as well as chemical indicators such as the Courbach index, and can be used as an important reference for assessing malt solubility. High β-glucan content may correspond to lower brittleness (insufficient endosperm solubility) or higher viscosity (insufficient cell wall degradation). By detecting β-glucan content, key indicators such as crispness (correlation coefficient -0.899*), Kurbach value (correlation coefficient -0.734*), fineness difference (correlation coefficient 0.675*), and viscosity (correlation coefficient 0.755*) can be indirectly assessed, providing data support for barley variety selection, planting area optimization, and malting process adjustment. Gastl et al. [M. Gastl, M. Kupetz, and T. Becker, Determination of Cytolytic Malt Modification – Part II Impact on Wort Separation. Journal of The American Society of Brewing Chemists. 2021, VOL.79, NO.1, 66–74] believe that crispness, viscosity, and β-glucan content are the main analytical indicators for assessing malt cell lysis in malt quality control. Cell lysis describes the enzymatic breakdown of polysaccharides in grain cell walls, mainly β-glucan and arabinoxylan. Xu Jufei et al. [Xu Jufei, Kang Jian, Gu Fanghong et al. Key malting parameters affecting malt solubility and parameter optimization, Food and Fermentation Industries, 2015, 41(8):332] believe that fluorescent staining can more realistically reflect the solubility of malt and is relatively simple and intuitive. Malt grains are cut longitudinally and stained. Because Calcofluor fluorescent whitening agent can specifically bind to β-glucan, the undissolved cell walls show blue fluorescence after staining, while the dissolved parts show light blue. The malt solubility can be obtained by calculating the staining ratio.However, this method requires specialized cutting equipment and fluorescence detector software, making it relatively cumbersome to operate and subject to subjective errors. Measuring malt β-glucan content using the Megazyme kit can indirectly evaluate the degree of endosperm cell wall degradation. However, the β-glucan measured by this method includes partially degraded small molecules and undegraded large molecules, failing to accurately reflect malt solubility. Edney et al. [MJ Edney, JK Eglinton, HM Collins, et al. Importance of Endosperm Modification for Malt Wort Fermentability, The Institute of Brewing & Distilling, 2007, 113(2)] argue that the endosperm dissolution process is very complex and influenced by a series of barley characteristics, including genetics, growth conditions, and malt processing conditions. Each barley variety has its specific dissolution mode and rate, and barley growth conditions also affect the endosperm dissolution potential. Drought, excessive nitrogen, or other environmental factors leading to high protein levels can severely alter the dissolution properties of barley samples, and hard grains also show a slower dissolution rate than floury grains.

[0005] Currently, most breweries comprehensively evaluate malt solubility by testing malt crispness, fineness difference, saccharification power, Courbach value, α-amino nitrogen, and β-glucan content. Studies have shown that crispness (>80), fineness difference (<2.0%), saccharification power (>250 WK), and Courbach value (42%-45%) are key parameters for measuring the balance between starch and protein breakdown, while β-glucan content (<110 mg / 100g) reflects the uniformity of cell wall degradation. However, the solubility characteristics of different barley varieties vary considerably.

[0006] Chinese patent CN 112924337 B provides a method for evaluating malt solubility. This method uses the wheat grains below the dry soaking layer before the end of the dry soaking step as an indirect evaluation target for malt solubility. At least 50 wheat grain samples are randomly selected before the end of each dry soaking step, their surface moisture is wiped dry, and they are longitudinally cut. The number of wheat grains is counted based on the solubility of the cut surface, and then the soaking index (IT) is calculated. When the IT is less than 300, it reflects good malt solubility; when the IT is between 300 and 350, it reflects poor malt solubility; and when the IT is greater than 350, it reflects very poor malt solubility. This method is suitable for real-time determination of malt solubility during the soaking stage in large-scale production processes, allowing for timely process adjustments. However, the testing process is cumbersome, the judgment of the cut surface is subjective, and it is only applicable to the soaking process, not for judging the finished malt.

[0007] As can be seen from the above, existing malt solubility evaluation technologies have the following shortcomings:

[0008] 1. Defects of relying on multiple indicators: Current solubility evaluation requires comprehensive consideration of multiple key indicators, such as brittleness, stock value, β-glucan, etc. The indicators are complicated and there is a lack of unified judgment standards in the industry.

[0009] 2. Low detection efficiency: Traditional methods include six key indicators such as saccharification power, library value, and β-glucan. Before detection, the malt must be prepared into wort, which is a complicated process. In addition, different instruments are required for the detection of each indicator, resulting in high detection costs, time and labor costs, and low detection efficiency.

[0010] 3. Population Mean Distortion: The test results of conventional malt quality indicators reflect the population mean, which is actually the average of a mixture of 50g of malt (approximately 1200-1400 grains) after grinding. This means it is subject to averaging. The ground mixture cannot reflect the true solubility of individual malt grains, nor can it reflect the differences in solubility between different grains. For example, mixing and grinding 600 under-dissolved malt grains with 600 over-dissolved malt grains may show good solubility and meet quality standards, but the solubility of individual malt grains may not meet requirements, potentially leading to misleading results.

[0011] 4. Production lag: Malt plants typically feed raw materials continuously during large-scale production. Routine malt index testing takes 36 hours to complete. By the time abnormal malt indexes are detected, raw materials have already been fed continuously, which may result in multiple batches of products failing to meet quality standards. There is a lag in testing.

[0012] In summary, existing methods for evaluating malt solubility suffer from problems such as dependence on multiple indicators, low detection efficiency, and distortion of population mean, making it difficult to meet the needs of large-scale production for rapid, accurate, and quantitative detection. Summary of the Invention

[0013] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to overcome the problems of multi-index dependence, low detection efficiency and population mean distortion in the existing malt solubility evaluation methods. In order to meet the needs of large-scale production for rapid detection and accurate quantification of malt solubility, a malt solubility index evaluation method with speed, simplicity and accuracy is proposed.

[0014] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows:

[0015] This invention provides a method for evaluating malt solubility, defining malt solubility based on a malt solubility index, wherein a lower malt solubility index indicates better malt dissolution; the malt solubility index is calculated using the following method:

[0016] MI=5.867-0.031×ALI-0.026×FD;

[0017] In the above formula, MI is the malt solubility index, ALI is the leaf bud index, and FD is the single grain crushing degree.

[0018] Solubility is a crucial indicator for evaluating malt quality. For malt mills, it serves as a metric for assessing the suitability of their malting processes; for breweries, it is a vital reference for developing saccharification processes. Figure 1 As shown, the above-mentioned malt solubility evaluation method innovatively introduces two parameters—bud index (morphological index) and single-grain crushing degree (physical index)—to replace the traditional multi-biochemical index detection system, significantly simplifying the evaluation process of malt solubility while improving detection efficiency and accuracy. Specific beneficial effects are shown in Table 1.

[0019] Table 1. Comprehensive comparison of detection methods

[0020]

[0021]

[0022] This invention significantly improves the efficiency and accuracy of malt solubility detection by simplifying detection indicators, optimizing evaluation formulas, and enhancing detection resolution. Compared with traditional methods, this invention not only greatly reduces detection time and costs but also significantly improves the representativeness and reliability of detection results through single-grain-level detection and a low coefficient of variation. These innovations and technological advantages provide malt plants and breweries with a more efficient and accurate tool for evaluating malt quality, better meeting the needs of real-time process adjustments during production.

[0023] Furthermore, the R-squared value of the above formula model is 0.893, indicating that the leaf bud index and single grain crushing degree can explain the variation of 89.3% in the malt solubility index.

[0024] Preferably, when 0.50 < MI ≤ 1.00, the malt dissolves well; when 1.00 < MI ≤ 1.50, the malt dissolves insufficiently; and when MI > 1.50, the malt dissolves poorly.

[0025] Preferably, the leaf bud index is calculated using the following formula:

[0026]

[0027] In the above, N1, N2, N3, N4, and N5 represent the number of malt grains whose leaf bud length accounts for 0 to 1 / 4, 1 / 4 to 1 / 2, 1 / 2 to 3 / 4, 3 / 4 to 1, and >1, respectively.

[0028] Preferably, the leaf bud index is obtained by the following method: boiling the malt sample, cooling the grains until the epidermis is transparent, observing the length of the leaf buds through the epidermis, analyzing the proportion of the leaf bud length to the grain length of each malt grain, and classifying them according to 0-1 / 4, 1 / 4-1 / 2, 1 / 2-3 / 4, 3 / 4-1, and >1, and statistically obtaining N1, N2, N3, N4, and N5.

[0029] Preferably, the leaf bud index is obtained by the following method:

[0030] Sample preparation: Select 100 malt grains as a sample, place them in a beaker, and add 100 mL of distilled water;

[0031] Boiling treatment: Place the beaker on an electric stove and boil for 5-6 minutes, then let it cool at room temperature for 30 minutes.

[0032] Observation and classification: After the wheat grains are cooled, the epidermis becomes transparent. The length of the leaf buds is observed through the epidermis. The proportion of the leaf bud length to the length of the wheat grain is calculated and classified according to 0 to 1 / 4, 1 / 2 to 3 / 4, 3 / 4 to 1, and >1. The results are statistically obtained as N1, N2, N3, N4, and N5.

[0033] Calculation of leaf bud index.

[0034] The proportion of leaf bud length reflects the overall solubility of malt. Grains with a leaf bud length ratio of 0-1 / 4 indicate ungerminated or slow-growing malt with poor solubility; 1 / 4-1 / 2 indicates insufficient solubility; 1 / 2-3 / 4 indicates good solubility; 3 / 4-1 indicates good solubility; and a length ratio >1 indicates potential over-saturation. Therefore, a leaf bud index is obtained through weighted calculation of 100 malt grains, comprehensively reflecting the overall solubility of malt.

[0035] Preferably, the particle size distribution is calculated using the following formula:

[0036] Single-particle pulverization degree FD = [1 - (M_residual / M_total)] × 100%;

[0037] In the above, M_residual refers to the total mass of whole grains, half grains, and broken grains remaining in the sieve; M_total refers to the total mass of the malt initially weighed.

[0038] Preferably, the particle size distribution is obtained by the following method:

[0039] Sample preparation: Weigh the malt sample and record its total mass as M_total;

[0040] Single-grain grinding process: Each grain of malt is placed into a centrifuge tube, steel balls are added, and the single grain of malt is ground using a grinder;

[0041] Observation of the degree of grinding: After grinding, observe the degree of grinding of the wheat grains in the centrifuge tube. Well-dissolved wheat grains will be fine powder after grinding; ungerminated or insufficiently dissolved wheat grains contain glassy or semi-glassy particles and cannot be completely ground, and may leave whole or half grains or other large particles; summarize the centrifuge tubes that were not completely ground, and count the number of tubes with whole grains and half grains. The more tubes, the worse the uniformity of dissolution.

[0042] Residue treatment: For wheat grains that are not completely crushed, collect whole grains, half grains, broken grains, husks and wheat flour in the tube into a sieve for sieving. Fine powder and small particles are sieved out, while large particles are retained on the sieve.

[0043] Residue weighing: Collect all whole, half and broken particles from the sieve into a weighing dish, weigh and record the mass of the residue as M_residue;

[0044] Calculation of particle size: Based on the mass of the residue and the total number of whole and half particles, a comprehensive evaluation is conducted to calculate the particle size of each particle.

[0045] Preferably, each malt grain is placed into a 2.0ml centrifuge tube, and a 7mm diameter steel ball (stainless steel) is added. The single malt grain is then pulverized using a high-throughput tissue homogenizer at a frequency of 1000-1200 rpm / min for 30-40 seconds. For malts that are readily soluble and easy to pulverize, such as malt obtained from two-row barley, the pulverizing frequency can be controlled at 1000 rpm / min for 30 seconds. For malts that are difficult to dissolve or have hard, difficult-to-pulverize grains, such as malt obtained from six-row barley or high-protein barley, the pulverizing frequency is increased to 1200 rpm / min, and the pulverizing time is extended to 40 seconds.

[0046] Preferably, for wheat grains that are not completely crushed, the broken grains, husks, and flour in the tube are collected into a sieve with a mesh size of 0.2 × 0.2 mm, and the sieve is gently tapped to allow the flour to fall into the collection box. Fine powder and small particles can pass through the 0.2 × 0.2 mm sieve, while whole grains, half grains, and other large particles remain on the sieve, representing the less soluble portion of the wheat grain, which is used for calculating the degree of crushing.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] This invention provides a method for evaluating malt solubility. This method innovatively introduces two parameters: leaf bud index (morphological index) and single-grain powderiness (physical index), replacing the traditional multi-biochemical index detection system. This simplifies the evaluation process and enables rapid determination of malt solubility. Compared with traditional methods, this invention has the following advantages:

[0049] (1) Streamlined testing indicators: The number of key testing indicators has been reduced from 6 to 2. Only two indicators, leaf bud index and single grain crushing degree, need to be measured, replacing the original multi-indicator comprehensive evaluation and establishing a unified malt solubility index judgment standard.

[0050] (2) High detection efficiency: The detection time is reduced from 36 hours to 3 hours; the operation is simple and does not require expensive precision instruments; the detection cost is significantly reduced, making it more suitable for large-scale production.

[0051] (3) Strong representativeness: Compared with the population mean of malt mixed grinding in traditional testing, the evaluation results of single grain testing can better reflect the true degree of dissolution of wheat grains, which is more representative and facilitates horizontal comparison between different varieties or different batches of the same variety.

[0052] (4) High practicality: It is conducive to the timely adjustment of malting process in malt factories, facilitates the rapid formulation of saccharification process in breweries, improves production efficiency, and ensures the consistency of product quality. Attached Figure Description

[0053] Figure 1 This invention provides a comparison of the detection indicators between the conventional method and the method of this invention. Detailed Implementation

[0054] The technical solutions in specific embodiments of the present invention will now be described in detail and completely with reference to the accompanying drawings. Obviously, the described embodiments are merely some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0055] The above-mentioned technical solution of the present invention, the process of determining and verifying the technical solution are as follows:

[0056] Step 1: Barley Cleaning

[0057] (1) Preliminary selection: Use a wind-powered preliminary selector to remove larger impurities (stones, ropes, straw, burlap sacks) and very small impurities (sand, dust, etc.).

[0058] (2) Fine selection: A deawning machine is used to remove awns, an electromagnetic iron separator to remove iron impurities, a destoner to remove stones of varying sizes mixed in, and a mesh sorter to remove impurities from the wheat grains. The barley / wheat used for feeding after processing must be free of iron filings, soil, stones, and other harmful impurities. The purity rate of barley / wheat is ≥99.5%.

[0059] (3) Grading: Remove lean wheat grains by grading sieve. The proportion of wheat grains with an abdominal diameter of less than 2.0 mm should not exceed 1.0% in the production of barley / wheat. This creates conditions for uniform soaking and uniform germination, and improves the malt extraction rate.

[0060] Step 2: Specific steps for malt preparation (1) Malt soaking: Taking Copeland barley as an example, a three-soak, two-stage soaking process is adopted. The soaking water temperature is controlled at 15-17℃. Continuous ventilation and oxygen supply are used during the soaking process, including the first soaking stage (wet soaking for 5 hours), the first stage (dry soaking for 6 hours), the second soaking stage (wet soaking for 7 hours), the second stage (dry soaking for 6 hours), and the third soaking stage (wet soaking for 4 hours), for a total duration of 28 hours. This process needs to be appropriately adjusted according to the barley variety to ensure that the final malt degree reaches 40.5% and the germination rate exceeds 90%.

[0061] (2) Germination: The germination temperature is controlled at 16-18℃, and the germination time is 96 hours. The wheat is turned over every 12 hours, and continuous ventilation and oxygen supply are required during the germination process. The fresh air usage is 80% within 24-36 hours of germination, reduced to 60% from 48-72 hours, and further reduced to 50% from 72-96 hours.

[0062] (3) Drying: The green malt obtained in the above steps is transferred to a separate drying oven for ventilation and dehumidification. The drying process is as follows: 50℃ (5h) → 55℃ (4h) → 65℃ (4h) → 75℃ (2h), and then the temperature is raised to 84℃ and roasted at a constant temperature for 3h.

[0063] (4) Root removal: After drying, wait for the malt to cool to room temperature and remove the roots within 12 hours to obtain the finished malt.

[0064] Step 3: Testing of routine malt quality indicators

[0065] 1. Crispness

[0066] (1) Instrument preparation: Install the brittleness tester in place, press the power switch button, and preheat for more than 30 minutes.

[0067] (2) Sample weighing: Weigh 50±0.01g of the purified malt sample using a plastic liter cup, add it from the upper feeding funnel of the brittleness tester, and place the collection box at the lower discharge port at the same time.

[0068] (3) Instrument operation: Move the control handle from the upper node to the lower node, press the run switch, the run indicator light will flash, and the instrument will run for 8 minutes.

[0069] (4) Stop operation: The instrument will automatically stop operating after the set time is reached. Move the control handle from the lower node to the upper node, remove the outer cover, press and hold the copper button in the upper left corner, and remove the screen.

[0070] (5) Sample collection: Use a brush to collect the broken grains, shells and wheat flour on the pressure roller shaft into the sieve. Gently tap the sieve so that the wheat flour that can pass through the sieve holes falls into the collection box.

[0071] (6) Particle handling: Collect all the particles in the sieve (use a stiff brush to remove the particles in the sieve holes) into a plastic beaker and weigh them.

[0072] (7) Calculation of results: The formula for calculating brittleness is: F=(100-2W)÷100×100%, where: F (Friability) represents the brittleness of the sample, and W represents the weight of the remaining fragments and shells in the sieve, in grams.

[0073] 2. Inventory Value

[0074] (1) Determination of soluble nitrogen: Take two dry and clean digestion tubes, add 10 mL of wort to each tube, then add 2-3 drops of concentrated sulfuric acid to each tube, place them in a digestion furnace and carefully evaporate to dryness, then remove and set aside.

[0075] (2) Total nitrogen determination: Accurately weigh 1g of the finely powdered sample (accurate to 0.0001g) and carefully add it into the digestion tube.

[0076] (3) Digestion and distillation: Process according to conventional digestion and distillation procedures.

[0077] (4) Titration operation: Titrate the distillate with 0.1 mol / L hydrochloric acid standard solution, shaking the bottle while titrating and observing the color change until the color of the distillate changes from green to slightly red, which is the titration endpoint. Record the amount of hydrochloric acid consumed.

[0078] 3. β-glucan

[0079] (1) Sample preparation: Take 3 25ml stoppered colorimetric tubes and label them as follows: No. 1 (blank), No. 2 (sample), and No. 3 (sample), among which tubes No. 2 and No. 3 are parallel samples.

[0080] (2) Solution addition: Accurately pipette 2 ml of distilled water into tube 1 (blank), and pipette 2 ml of diluted sample into tubes 2 and 3 (samples).

[0081] (3) Constant temperature treatment: Place the three colorimetric tubes in a constant temperature water bath at (20±0.1)℃ and keep them at the constant temperature for 5 minutes.

[0082] (4) Colorimetric reaction: Add 4 ml of Congo red solution at 20°C to the blank and sample colorimetric tubes respectively, shake well, start timing, and keep warm for 10 minutes in a constant temperature water bath at (20±0.1)°C.

[0083] (5) Colorimetric determination: After keeping warm for 10 minutes, immediately use a 10mm glass cuvette to measure the absorbance of the sample at a wavelength of 550nm, with a blank cuvette as a reference.

[0084] Step 4: Development and Operational Procedures of Single-Grain Malt Detection Indicators

[0085] This invention provides two detection indicators for evaluating the solubility of a single malt grain: the bud index and the malt grain pulverization degree, aiming to achieve rapid evaluation of malt solubility. The specific operation steps are as follows:

[0086] 1. Leaf bud index:

[0087] (1) Sample preparation: Select 100 malt samples and put them into a beaker, add about 100ml of distilled water.

[0088] (2) Boiling treatment: Place the beaker on an electric stove and boil for 5-6 minutes, then cool at room temperature for 30 minutes.

[0089] (3) Observation and classification: After the wheat grains are cooled, the skin becomes transparent. Observe the length of the leaf buds through the skin and classify them according to the proportion of the leaf bud length to the whole wheat grain: 0 to 1 / 4, 1 / 4 to 1 / 2, 1 / 2 to 3 / 4, 3 / 4 to 1, and >1. For example, 0 to 1 / 4 refers to wheat grains from non-germination to leaf buds with a length less than 1 / 4 (excluding 1 / 4), 3 / 4 to 1 refers to wheat grains with leaf buds with a length from 3 / 4 to 1 (including 1), and >1 refers to wheat grains with leaf buds longer than the length of the malt.

[0090] (4) Calculation of leaf bud index:

[0091] The leaf bud length of malt samples was measured. Through regression analysis of various leaf bud lengths and related dissolution indices, the formula for calculating the Acrospire Length (ALI) was determined as follows:

[0092]

[0093] Among them, N1-N5 represent the number of malt grains with leaf bud lengths of 0-1 / 4, 1 / 4-1 / 2, 1 / 2-3 / 4, 3 / 4-1, and >1, respectively.

[0094] 2. Single-particle pulverization determination

[0095] The determination of single-grain pulverization is based on the indirect assessment of malt solubility through physical brittleness. Malt grains are subjected to high-frequency impact treatment with steel balls using a high-throughput tissue homogenizer. After pulverization, the degree of breakage of the grains in centrifuge tubes is observed. Well-dissolved grains are easily pulverized, resulting in a fine powder. Ungerminated or insufficiently dissolved grains contain glassy or semi-glassy particles and cannot be completely pulverized, potentially retaining whole or half grains of malt. This method, by weighing and calculating the residue after pulverization, obtains the different degrees of pulverization of single malt grains under the same frequency of steel ball impact, thereby determining the actual solubility of each single malt grain.

[0096] Single-particle pulverization determination includes:

[0097] (1) Sample preparation: Select 100 malt samples and record their total mass (denoted as M_total).

[0098] (2) Single grain grinding: Place each malt grain into a 2.0ml centrifuge tube and add a 7mm diameter steel ball (stainless steel). Grind the single malt grains using a high-throughput tissue homogenizer. The recommended grinding frequency is 1000-1200rpm / min and the grinding time is 30-40 seconds.

[0099] (3) Observation of the degree of grinding: After grinding, observe the degree of grinding of the wheat grains in the centrifuge tubes. Well-dissolved wheat grains will be fine powder after grinding; ungerminated or insufficiently dissolved wheat grains will contain glassy or semi-glassy particles and cannot be completely ground, possibly leaving whole or half grains. Summarize the centrifuge tubes that were not completely ground, and count the number of tubes with whole grains and half grains. The more tubes, the worse the uniformity of dissolution.

[0100] (4) Residue treatment: For wheat grains that cannot be completely crushed, collect the broken grains, husks and wheat flour in the tube into a sieve with a pore size of 0.2×0.2mm, and gently tap the sieve to let the wheat flour fall into the collection box.

[0101] (5) Weighing the residue: Collect all whole, half and broken particles from the sieve into a weighing dish, weigh and record the mass of the residue (denoted as M residue).

[0102] Degree of fragmentation (FD) calculation: Based on the mass of the residue, calculate the degree of fragmentation (FD) per particle using the following formula:

[0103] Single-particle pulverization degree FD=[1-(M_residual / M_total)]×100% (Equation 2)

[0104] Residue rate = M_residue / M_total, Powdering degree = 1 - Residue rate

[0105] Wherein, FD: single grain crushing degree, indicating the degree of malt crushing; M residual: the total mass of whole grains, half grains and broken grains remaining in the sieve; M total: the total mass of malt initially weighed.

[0106] 3. Formula for calculating malt solubility index

[0107] We collected 121 representative two-row barley malt samples, including commercial and micro-malt malt, covering major barley producing regions worldwide, such as Canada, Australia, France, Argentina, and China, and stored them under refrigeration. We analyzed the bud index and single-grain pulverization of the samples and established regression models between the malt dissolution index and the bud index and single-grain pulverization.

[0108] A formula for calculating the malt dissolution index (MI) was established using linear regression analysis:

[0109] MI=5.867-0.031×ALI-0.026×FD (Formula 3)

[0110] Wherein, ALI: leaf bud index; FD: single grain crushing degree; the R-squared value of the model is 0.893, indicating that the leaf bud index and single grain crushing degree can explain 89.3% of the variation in malt dissolution index.

[0111] 4. Verification of method accuracy

[0112] To verify the accuracy and reliability of the malt solubility index (MI) evaluation method proposed in this invention, another 48 batches of malt samples (16 batches of micro-malt and 32 batches of commercial malt) were selected for method validation. Correlation analysis was performed between traditional evaluation indicators such as crispness and β-glucan and the MI to determine the correlation coefficients, thereby verifying the accuracy and reliability of the method.

[0113] Verification Step (1) Routine Indicator Detection

[0114] Routine tests were performed on each batch of malt samples, including crispness, saccharification power, extractives, gluten count, α-amino nitrogen, and β-glucan. Currently, breweries mainly use crispness and coarse-to-fine powder difference to reflect the degree of starch solubility, gluten count and FAN to reflect the degree of protein solubility, and β-glucan to reflect the degree of endosperm cell wall degradation.

[0115] (2) Evaluation of malt solubility index

[0116] Malt solubility index was evaluated simultaneously on 48 batches of samples, including rapid detection of leaf bud index and single grain pulverization, calculation of malt solubility index (MI), and evaluation of malt solubility.

[0117] (3) Correlation analysis

[0118] Correlation analysis was performed on the conventional indicators (brittleness, stock value, β-glucan) and malt solubility index (MI) values ​​of 48 batches of malt samples.

[0119] Correlation analysis showed that the malt solubility index (MI) was significantly correlated with indicators such as β-glucan, gluten count, and brittleness, indicating that the malt solubility index can comprehensively reflect the starch solubility, protein solubility, and cell wall solubility of malt, and fully reflect the overall degree of malt solubility.

[0120] 5. Range of malt solubility and malt solubility index

[0121] The malt solubility index is defined based on different degrees of malt solubility, as follows:

[0122] Good solubility: 0.50 < MI ≤ 1.00

[0123] Insufficient dissolution: 1.00 < MI ≤ 1.50

[0124] Poor solubility: MI > 1.50

[0125] Comprehensive evaluation capability: The malt solubility index provides a more comprehensive and accurate method for evaluating malt solubility, solving the problems of multi-indicator dependence, cumbersome operation, and lack of unified standards in traditional evaluation methods.

[0126] Reliability verification: Through analysis and verification of a large number of malt samples, the reliability and accuracy of the malt solubility index have been fully demonstrated, providing strong support for malt quality control and production optimization.

[0127] To provide a clearer and more detailed description of the malt solubility evaluation method provided in the embodiments of the present invention, specific embodiments will be described below.

[0128] Example 1

[0129] By using the malt solubility index to replace traditional testing methods, the malting process can be quickly adjusted.

[0130] In theory, the quality indicators of barley of the same variety should be consistent, and the malting process and malt quality should also remain stable. However, as an agricultural crop, barley is inevitably affected by climate and soil conditions, and quality fluctuations are unavoidable. Differences may also exist between different batches of the same variety. In actual production, it is necessary to adjust the production process in a timely manner according to the barley quality and malting performance to ensure the consistency of malt quality.

[0131] Malt, the main raw material for beer, is obtained from barley through processes such as soaking, germination, drying, and de-rooting. Typically, a single malting cycle is about 168 hours. After obtaining the malt, quality analysis should be performed as soon as possible. If the indicators are within acceptable limits, the malting process is suitable, and production can continue. If the malt indicators are unacceptable, the cause must be investigated and the production process adjusted promptly to ensure malt quality. Conventional malt quality evaluation indicators are numerous, resulting in cumbersome operations, long testing cycles, and high costs. Malt plants typically operate in continuous malting production, with input volumes of hundreds of tons. Traditional quality testing is often delayed; by the time quality problems are discovered, multiple batches of substandard malt have already been produced, severely affecting product quality consistency.

[0132] This patent proposes a method for evaluating malt solubility, which innovatively introduces two parameters: leaf bud index (morphological index) and single grain crushing degree (physical index), to replace the traditional multi-biochemical index detection system. The detection can be completed in just 3 hours, which can quickly evaluate malt solubility. The detection time is reduced by 91.7% compared with the traditional method. It can realize real-time adjustment of malt production process, especially the rapid optimization of soaking and germination processes.

[0133] Step 1: Evaluation of malt solubility index and rapid adjustment of malting process.

[0134] The malting process of Australian Spartacus barley on a certain ship was tracked. The bud index and single grain pulverization of each batch of malt were tested. The malt solubility was quickly determined based on the solubility index, enabling real-time adjustments to the large-scale production process. A total of 26 batches of malt samples were tracked, and the test results of some malts are shown in Table 2.

[0135] Table 2. Solubility evaluation of selected batches of Australian Spartacus malt.

[0136] Leaf bud index ≥86 89 80 90 94 87 92 Single-particle grinding degree ≥84 84 81 86 85 82 87 Solubility Index 0.50-1.00 0.92 1.28 0.84 0.78 1.04 0.75 Solubility evaluation / Soluble well Insufficient dissolution Soluble well Soluble well Insufficient dissolution Soluble well

[0137] Results analysis:

[0138] As shown in the table, 24 out of 26 batches of Spartacus malt had a solubility index below 1.00, indicating good solubility; 2 batches had a solubility index above 1, indicating insufficient solubility. The malt solubility index of batch 12 was 1.28, with both the leaf bud index and single-grain fineness below the standard range. The number of tubes containing whole and half grains after single-grain crushing was twice that of batch 11, indicating significantly insufficient malt solubility, specifically insufficient starch and protein dissolution. After discovering the abnormality, the malt factory promptly adjusted the malting process, extending the first soaking time by 2 hours and increasing the germination temperature by 2°C from 24 to 72 hours to promote the dissolution of malt endosperm cells as much as possible. After the process adjustment, the leaf bud index of batch 13 increased from 80% to 90%, the single-grain fineness increased from 81% to 86%, and the malt solubility index decreased from 1.28 to 0.84, indicating normal malt solubility. As production continued, the malt solubility index of batch 25 was 1.04, indicating low single-grain fineness. The number of whole and half grains after single-grain fineness increased by 20% compared to batch 24, suggesting insufficient starch dissolution. The malt factory adjusted the soaking process again, extending the third soaking time by 2 hours while maintaining the germination temperature. After the adjustment, the single-grain fineness of batch 26 improved from 82% to 87%, and the malt solubility index decreased from 1.04 to 0.75, returning to normal. This demonstrates that the process adjustment was reasonable and effective.

[0139] Step 2: Perform routine malt quality evaluation and verify the results.

[0140] In the later stage, the above 26 batches of malt were retested using conventional methods. The results of the malt solubility index were verified using conventional testing indicators to ensure the reliability of the malt solubility index. The test results of some batches are shown in Table 3.

[0141] The routine test results of 6 batches

[0142] Table 3. Routine Quality Indicators of Australian Spartacus Malt

[0143] Moisture% ≤4.5 4.1 3.8 4 4.1 4.5 4.5 Extract% ≥80.0 82.2 81.7 81.3 81.2 80.6 81.5 WK glycation power ≥240 307 316 314 303 307 277 Saccharification time (min) ≤10 8 9 9 8 10 9 Crispness % ≥80 97 74 97 94 75 88 Difference between coarse and fine powder % ≤1.5 1.1 1.3 0.8 0.7 1.4 0.8 Library value % 43.5±2 45.5 40.1 45.3 43.5 42.5 44.5 Amino nitrogen g / 100g 155±15 162 158 152 155 143 151 β-glucan mg / 100g ≤110 78 92 86 91 98 66 Filtering time Min ≤40 33 47 36 30 38 31 Total acid (ml / 100ml) ≤1.15 0.92 0.92 0.89 0.92 0.87 0.9 Colorimetric EBC 4.0±1.0 4.2 3.7 3.5 3.9 3.8 4.7 Boiling color EBC 8.0±1.0 7.8 7.8 7.6 7.7 7.9 7.8

[0144] Results analysis:

[0145] Analysis of routine indicators shows that 24 out of 26 batches of Spartacus malt had normal indicators and good solubility. Batch 12 had a malt crispness of 74% and a storage value of 40.1%, indicating insufficient dissolution of starch and protein, consistent with the malt solubility index results. Batch 25 had a malt crispness of 75%, below the standard, requiring improvement in starch solubility, consistent with the malt solubility index results.

[0146] Comparative analysis shows that the malt solubility index (MSI) results are largely consistent with conventional indicators, but the detection time is reduced from 36 hours to 3 hours, a reduction of 91.7%, and the detection cost is lowered by 95.8%. Multiple rounds of experimental verification have shown that this method is accurate and reliable, effectively supporting real-time quality control in malt production. The MSI has significant application value in adjusting production processes and ensuring malt quality.

[0147] Example 2

[0148] By using the malt solubility index to replace traditional testing methods, saccharification formulas and saccharification processes can be quickly adjusted.

[0149] We are tracking two newly delivered batches of purchased Canadian two-row barley malt, namely Copeland and Churchill. During the peak beer production season, malt indicators should be tested as soon as possible after the malt arrives at the warehouse. Based on the quality characteristics of the malt, appropriate saccharification formulas and processes should be developed to ensure the consistency of beer quality.

[0150] Step 1: Develop a saccharification process using standard malt quality evaluation methods.

[0151] Following traditional methods, the two batches of malt were tested for routine malt indicators, including crispness, storage value, and β-glucan solubility. The tests for both batches of malt were completed within 36 hours.

[0152] The quality indicators of the two batches of malt are shown in Table 4 below.

[0153] Table 4. Routine quality indicators of two batches of malted barley.

[0154] Moisture% ≤4.5 4.3 4.4 Extract% ≥80 81.0 81.1 WK glycation power ≥300 330 269 Saccharification time Min ≤10 9 9 Crispness % ≥80 88 75 Difference between coarse and fine powder % ≤1.5 1.1 1.3 Library value % 42.5±2 43.6 41.3 Amino nitrogen mg / 100g 160±15 165 151 β-glucan mg / 100g ≤110 65 98 Filtering time Min ≤40 30 33 Total acid (ml / 100L) ≤1.15 1.12 1.04 Colorimetric EBC 4.0±1 4.5 3.9 Boiling color EBC 8.0±1 8.5 7.5

[0155] Results analysis:

[0156] As shown in the table, Copeland malt meets the requirements for conventional indicators such as crispness, gluten count, and β-glucan content. Churchill malt falls below the standard in two key indicators, saccharification power and crispness, while meeting the requirements for gluten count and β-glucan content, indicating insufficient starch dissolution. Therefore, when developing the saccharification process, amylase activity can be increased by adding amylase preparations, or extending the saccharification time and lowering the saccharification temperature can be considered to promote starch dissolution. In summary, different saccharification formulations were developed for the two malt-added products based on their dissolution characteristics, as shown in Table 5 below.

[0157] Table 5 Saccharification Formulas and Saccharification Schemes 1

[0158] malt Malt is available Copeland, Canada Churchill Malt Formula Canadian wheat:Australian wheat 2:1 Canadian wheat:Australian wheat 2:1 Canadian wheat:Australian wheat 2:1 Saccharification process 65℃ for 60 minutes 65℃ for 60 minutes 65℃ for 70 minutes

[0159] Because Copeland malt dissolves well, the saccharification process in Experiment 1 was consistent with the control. However, Churchill malt exhibited low saccharifying enzyme activity, low brittleness, insufficient starch dissolution, and generally low malt solubility. Therefore, when formulating the saccharification formula, the saccharification time could be extended from 60 min to 70 min to enhance enzyme activity. Monitoring of the subsequent saccharification process revealed that saccharification at 65℃ for 60 min resulted in a first-run wort filtration time of 70 min and a cold wort turbidity of 0.5 EBC, indicating low saccharifying enzyme activity and slow speed. Extending the saccharification time to 70 min reduced the first-run wort filtration time to 60 min, decreased the cold wort turbidity to 0.27 EBC, and ensured that other wort quality indicators remained normal, indicating that the saccharification formula and process were appropriate and could meet the requirements of large-scale production.

[0160] Option 2: Use the malt solubility index to replace traditional methods and quickly develop the saccharification process.

[0161] The bud index and single-grain crushing degree of two batches of malted Copeland and Churchill were tested respectively. The malt solubility was quickly determined based on the malt solubility index, which only took 3 hours, saving 91.3% compared with the traditional test method of 36 hours.

[0162] The malt solubility index results are shown in Table 6.

[0163] Table 6 Solubility index of two batches of malted barley

[0164] Leaf bud index ≥86 88 87 Single-particle grinding degree ≥84 87 81 Solubility Index 0.50-1.00 0.88 1.06 Solubility evaluation / Soluble well Insufficient dissolution

[0165] Results analysis:

[0166] The results show that the Copeland malt solubility index is 0.88, indicating good solubility. However, the solubility index of Churchill malt is 1.06, indicating insufficient solubility. Further analysis revealed that while the bud index of the malt was normal, the fineness of individual grains was below standard, and the number of tubes in both whole and half grains was significantly increased compared to Copeland, indicating lower solubility and thus insufficient starch dissolution. When formulating the saccharification formula and process, starch dissolution can be promoted by extending the saccharification time or adding enzymes. Therefore, to address the issue of insufficient starch dissolution in Churchill malt, saccharification scheme two, as shown in Table 7, was developed.

[0167] Table 7 Saccharification Formula and Saccharification Scheme II

[0168] malt Malt is available Copeland, Canada Churchill Malt Formula Canadian wheat:Australian wheat 2:1 Canadian wheat:Australian wheat 2:1 Canadian wheat:Australian wheat 2:1 Saccharification process 65℃ for 60 minutes 65℃ for 60 minutes 65℃ for 65-70 minutes

[0169] Compared to the control, the saccharification process for Copeland was the same in Experiment 1, while for Churchill, which had slightly lower solubility, the saccharification time was increased by 10 minutes or heat-resistant amylase was added to promote complete starch dissolution. Monitoring of the saccharification process showed that all wort quality indicators were normal, indicating that the saccharification formula and process were appropriate and met production requirements.

[0170] Comparative analysis

[0171] Comparing the saccharification schemes provided by traditional methods and the malt solubility index of this invention, the saccharification formulas and processes developed by the two methods are basically the same. However, the detection time of this invention is shortened by 91.3%, allowing for production adjustments to be guided 33 hours earlier. The malt solubility index evaluation technology proposed in this invention plays a significant guiding role in the formulation of saccharification formulas and processes. In actual production, the rapid evaluation technology for single malt grains can be used in conjunction with traditional methods to achieve complementary advantages. Subsequent performance in large-scale production wort and the brewing process demonstrates that adjustments to the saccharification formula and process effectively solved the problem of insufficient Churchill dissolution, ensuring smooth saccharification and fermentation. The final product's quality indicators met the requirements, and sensory evaluations were satisfactory.

[0172] In summary, the rapid evaluation technology for malt solubility index proposed in this invention can quickly and accurately detect malt solubility, significantly shortening detection time and improving detection efficiency. Through rapid detection, factories can adjust malting and saccharification processes in real time, reducing the generation of substandard products and ensuring consistent product quality. This method, combined with traditional detection methods, can better meet the needs of large-scale production, improving the overall efficiency and quality control level of malt production.

Claims

1. A method for evaluating the solubility of malt, characterized in that, Malt solubility is defined according to the malt solubility index, where a lower malt solubility index indicates better malt dissolution. The malt solubility index is calculated using the following method: MI=5.867 0.031×BUT 0.026×FD; In the above formula, MI is the malt solubility index, ALI is the leaf bud index, and FD is the single grain pulverization degree. The leaf bud index is calculated using the following formula: above, N1 , N2, N3, N4, N5 These represent the number of buds whose length accounts for 0–1 / 4, 1 / 4–1 / 2, 1 / 2–3 / 4, 3 / 4–1, and >1, respectively. The particle size distribution is calculated using the following formula: Single-particle crushing degree FD=[1 [(M residual / M total)]×100%; In the above, M_residual refers to the total mass of whole grains, half grains, and broken grains remaining in the sieve; M_total refers to the total mass of the malt initially weighed.

2. The method for evaluating malt solubility according to claim 1, characterized in that, When 0.50 < MI ≤ 1.00, malt dissolves well; when 1.00 < MI ≤ 1.50, malt dissolves insufficiently; when MI > 1.50, malt dissolves poorly.

3. The method for evaluating malt solubility according to claim 1, characterized in that, The leaf bud index was obtained by the following method: The malt samples were boiled, and after cooling, the outer skin became transparent. The length of the leaf buds was observed through the skin, and the proportion of the leaf bud length to the total grain length of each malt grain was calculated. The samples were then categorized into four groups: 0–1 / 4, 1 / 4–1 / 2, 1 / 2–3 / 4, 3 / 4–1, and >1. Statistical analysis was performed to obtain the results. N1 , N2, N3, N4, N5 .

4. The method for evaluating malt solubility according to claim 3, characterized in that, The leaf bud index was obtained by the following method: Sample preparation: Weigh 100 malt grains, place them in a beaker, and add 100 mL of distilled water; Boiling treatment: Place the beaker on an electric stove and boil for 5-6 minutes, then let it cool at room temperature for 30 minutes. Observation and Classification: After the wheat grains cool, the outer skin becomes transparent. The length of the leaf buds is observed through the outer skin. The proportion of the leaf bud length to the total grain length is calculated, and the grains are classified according to the following categories: 0–1 / 4, 1 / 4–1 / 2, 1 / 2–3 / 4, 3 / 4–1, and >1. The results are statistically obtained. N1 , N2, N3, N4, N5 ; Calculation of leaf bud index.

5. The method for evaluating malt solubility according to claim 1, characterized in that, The particle size distribution is obtained by the following method: Sample preparation: Weigh the malt sample and record its total mass as M_total; Single-grain grinding process: Each grain of malt is placed into a centrifuge tube, steel balls are added, and the single grain of malt is ground using a grinder; Observation of the degree of grinding: After grinding, observe the degree of grinding of the wheat grains in the centrifuge tube. Well-dissolved wheat grains will be fine powder after grinding; unsprouted or insufficiently dissolved wheat grains contain glassy or semi-glassy particles and cannot be completely ground, and may leave whole or half large particles; summarize the centrifuge tubes that were not completely ground, and count the number of tubes with whole grains and half grains. The more tubes, the worse the uniformity of dissolution. Residue treatment: For wheat grains that are not completely crushed, collect whole grains, half grains, broken grains, husks and wheat flour in the tube into a sieve for sieving. Fine powder and small particles are sieved out, while large particles are retained on the sieve. Residue weighing: Collect all whole, half, and broken particles from the sieve into a weighing dish, weigh them, and record the mass of the residue as M_residue; Calculation of particle size: The particle size of a single particle is calculated based on the mass of the residue. The total number of particles (whole and half) is then used for a comprehensive evaluation.

6. The method for evaluating malt solubility according to claim 5, characterized in that, Each malt grain was placed into a 2.0 ml centrifuge tube, and a 7 mm diameter steel ball was added. The single malt grain was then pulverized using a high-throughput tissue homogenizer at a frequency of 1000-1200 rpm / min for 30-40 seconds.

7. The method for evaluating malt solubility according to claim 5, characterized in that, For wheat grains that are not completely crushed, collect the whole grains, half grains, broken grains, husks and wheat flour in the tube into a sieve with a pore size of 0.2×0.2 mm, and gently tap the sieve to let the wheat flour fall into the collection box.

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