Preparation method for reducing advanced yeast flocculation factors in beer malt

Abstract

The invention discloses a preparation method for reducing advanced yeast flocculation factors in beer malt, and belongs to the technical field of beer brewing. The method comprises the following steps: selecting barley according to a red value in barley color difference indexes, then carrying out NaCO3 reinforced wheat washing, and sequentially carrying out wheat steeping, germination, drying and grubbing to obtain beer malt with low yeast advanced flocculation factor activity; according to the method disclosed by the invention, proper barley raw materials are screened by adopting a chromaticity difference sorting technology, and a NaCO3 enhanced wheat washing process is combined, so that the loading capacity of fusarium graminearum in a wheat making process is reduced, the generation of PYF factors in the beer malt is effectively reduced, the PYF value of the beer malt is greater than or equal to 0.96, and the brewing quality of the beer malt is improved.

Description

Technical Field

[0001] This invention relates to the field of beer brewing technology, specifically to a method for preparing a product that reduces the pre-flocculation factor of yeast in beer malt. Background Technology

[0002] Beer is a carbonated, effervescent, low-alcohol fermented beverage made primarily from malt and water, with the addition of hops (including hop products), and fermented by yeast. In normal beer fermentation, yeast fully utilizes the fermentable sugars in the wort to produce ethanol and various flavor compounds, which then naturally and slowly settle—a process known as yeast flocculation. This flocculation plays a crucial role in the separation, recovery, and reuse of yeast cells. However, during beer fermentation, sometimes yeast begins to settle rapidly and in large quantities before the fermentable sugars are fully utilized. This phenomenon, called premature yeast flocculation (PYF), leads to defects such as excessively high residual sugar, excessively low alcohol content, and abnormal flavor in the final beer, causing significant economic losses to beer producers.

[0003] Although pre-fermentation yeast (PYF) occurs during beer fermentation, its origin can be traced back to the malt itself. Research indicates that microbial contamination of barley in the field and during malting is the primary cause of PYF, with *Fusarium graminearum* being the main microorganism contributing to its production. Therefore, there is an urgent need for methods to reduce pre-fermentation yeast (PYF) in beer malt, thereby decreasing the *Fusarium graminearum* load on the malting barley. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing a method for reducing yeast pre-flocculation factors in beer malt. By employing color difference sorting technology to screen suitable barley raw materials and combining it with NaCO3-enhanced malting washing process, the load of Fusarium graminearum during malting is reduced, thereby reducing the generation of yeast pre-flocculation factors in beer malt.

[0005] To achieve the above objectives, this invention proposes a method for preparing a product that reduces the pre-flocculation factor of yeast in beer malt, comprising the following steps: S1. Barley sorting: Based on the red value in the barley color difference index, sort the barley and remove the red barley to obtain sorted barley. S2, NaCO3 enhanced wheat washing; The sorted barley is washed in washing water, and NaCO3 with a concentration of 0.5 g / kg~0.8 g / kg is added to the washing water; S3. The barley after NaCO3-enhanced washing is sequentially soaked, germinated, dried, and root-removed to obtain beer malt with low yeast pre-flocculation factor activity.

[0006] Preferably, in step S1, a color sorter is used to sort the wheat, and the red value in the sorting standard is >2.5.

[0007] Preferably, in step S2, the wheat washing time is 6-12 hours and the temperature is 12-16°C.

[0008] Preferably, in step S3, the yeast pre-flocculation value in the beer malt is ≥0.96.

[0009] Compared with the prior art, the present invention has the following beneficial effects: This invention strengthens the malt washing process by combining color sorting with the addition of NaCO3 alkali leaching during the malt washing process, thereby reducing Fusarium graminearum residue and effectively reducing the production of PYF factor in beer malt, resulting in a PYF value of beer malt ≥0.96 and improving the brewing quality of beer malt. Attached Figure Description

[0010] Figure 1 The image shows the sorting results of the barley sorting machine provided by the present invention, where A represents sorted red barley and B represents sorted barley. Detailed Implementation

[0011] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] This invention proposes a method for preparing a product that reduces the pre-flocculation factor of yeast in beer malt, comprising the following steps: S1. Barley sorting: Based on the red value in the barley color difference index, sort the barley and remove the red barley to obtain sorted barley. Specifically, using existing color sorters, the barley is sorted into two groups based on a red value > 2.5 according to the sorting criteria: a red value > 2.5, and designated as a red group and a normal group. Figure 1 As shown, the red barley after sorting is barley that did not meet the standard, while the normal barley is barley that meets the standard.

[0013] S2, NaCO3 enhanced wheat washing; the sorted barley is washed in washing water, and NaCO3 is added to the washing water at a concentration preferably of 0.5 g / kg to 0.8 g / kg, for example, 0.5 g / kg, 0.6 g / kg, 0.7 g / kg, or 0.8 g / kg; Specifically, the normal barley from the sorted barley is washed in a washing solution containing NaCO3 for an enhanced time of 6 to 12 hours and at a temperature of 12 to 16°C.

[0014] S3. After washing with NaCO3, the barley is soaked, germinated, dried and root-removed in sequence to obtain beer malt with low activity of yeast pre-flocculation factor.

[0015] Specifically, during the malting process, ventilation and spraying are alternated. The malting water temperature is 16℃, the malting time is 20 hours (11 hours of water soaking and 9 hours of dry soaking), and the malting method is long-term water interruption. After malting, the malting degree reaches 39-41%. During the germination process, malting is carried out at 14-18℃ for 4-6 days to obtain green sprouts. The green sprouts are sent to a drying oven for drying, dehumidification for 14 hours, drying at 50-65℃ for 4 hours, and roasting at 80-85℃ for 2 hours until the moisture content is reduced to below 5%. Finally, the roots are removed to obtain beer malt.

[0016] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the experimental methods described below are conventional methods; unless otherwise specified, the materials and reagents used in the embodiments described below are commercially available.

[0017] Example 1 A method for preparing a product with reduced yeast pre-flocculation factor in beer malt includes the following steps: S1. Barley selection: Barley is sorted according to the red value in the color difference index. Red barley is removed and becomes the red group. The sorted barley is the normal group. Barley that is not sorted is the control group. S2. The normal group of barley was washed in washing water containing NaCO3 at a concentration of 0.8 g / kg for 8 hours at a temperature of 15℃.

[0018] S3. After washing with NaCO3, the barley is sequentially soaked, germinated, dried, and de-rooted. During the soaking process, ventilation and spraying are alternated. The soaking water temperature is 16℃, the soaking time is 20 hours (11 hours of water soaking and 9 hours of dry soaking), and the soaking method is long-term water interruption. After soaking, the degree of malting reaches 39-41%. During the germination process, germination is carried out at 15℃ for 6 days to obtain green sprouts. The green sprouts are sent to the drying oven for drying, dehumidification for 14 hours, drying at 65℃ for 4 hours, and roasting at 80℃ for 2 hours until the moisture content is reduced to below 5%. Finally, the roots are removed to obtain beer malt.

[0019] Comparative Example 1 A method for preparing beer malt includes the following steps: S1 involves washing unsorted barley in a washing solution containing NaCO3 at a concentration of 0.8 g / kg for 8 hours at a temperature of 15℃.

[0020] S2. After being fortified with NaCO3, the barley was subjected to soaking, germination, drying, and root removal in sequence. During the soaking process, ventilation and spraying were alternated. The soaking water temperature was 16℃, the soaking time was 20 hours, including 11 hours of water soaking and 9 hours of dry soaking. The soaking method was long-term water interruption. After soaking, the degree of malting reached 39-41%. During the germination process, the barley was germinated at 15℃ for 6 days to obtain green sprouts. The green sprouts were sent to a drying oven for drying. The moisture was removed for 14 hours, the barley was dried at 65℃ for 4 hours, and the barley was roasted at 80℃ for 2 hours until the moisture content was reduced to below 5%. Finally, the roots were removed to obtain beer malt.

[0021] Comparative Example 2 S1 performs routine washing of unsorted barley, adding food-grade sodium hydroxide for disinfection during the washing process; S2. After washing, the barley is soaked, germinated, dried, and root-removed in sequence. During the soaking process, ventilation and spraying are alternated. The soaking water temperature is 16℃, the soaking time is 20 hours, 11 hours of water soaking and 9 hours of dry soaking. The soaking method is long-term water interruption. After soaking, the degree of malting reaches 39-41%. During the germination process, germination is carried out at 15℃ for 6 days to obtain green sprouts. The green sprouts are sent to the drying oven for drying. The moisture is removed for 14 hours, the malt temperature is 65℃ for 4 hours, and the malt temperature is 80℃ for 2 hours to char. Finally, the moisture content is reduced to below 5%. Finally, the roots are removed to obtain beer malt.

[0022] Comparative Example 3 A method for preparing beer malt includes the following steps: S1. Barley selection: Barley is sorted according to the red value in the barley color difference index, and the sorted barley is the normal group. S2. Wash the normal group of barley as usual, and add food-grade sodium hydroxide for disinfection during the washing process. S3. After washing, the barley is sequentially soaked, germinated, dried, and root-removed. During the soaking process, ventilation and spraying are alternated. The soaking water temperature is 16℃, the soaking time is 20 hours (11 hours of water soaking and 9 hours of dry soaking), and the soaking method is long-term water interruption. After soaking, the degree of malting reaches 39-41%. During the germination process, germination is carried out at 15℃ for 6 days to obtain green sprouts. The green sprouts are sent to the drying oven for drying, dehumidification for 14 hours, drying at 65℃ for 4 hours, and roasting at 80℃ for 2 hours until the moisture content is reduced to below 5%. Finally, the roots are removed to obtain beer malt.

[0023] Comparative Example 4 A method for preparing beer malt includes the following steps: S1. Barley selection: Based on the red value in the barley color difference index, the red barley obtained is the red group. S2. The red group of barley was washed in a washing water containing NaCO3 at a concentration of 0.8 g / kg for 8 hours at a temperature of 15℃.

[0024] S3. After washing with NaCO3, the barley is sequentially soaked, germinated, dried, and de-rooted. During the soaking process, ventilation and spraying are alternated. The soaking water temperature is 16℃, the soaking time is 20 hours (11 hours of water soaking and 9 hours of dry soaking), and the soaking method is long-term water interruption. After soaking, the degree of malting reaches 39-41%. During the germination process, germination is carried out at 15℃ for 6 days to obtain green sprouts. The green sprouts are sent to the drying oven for drying, dehumidification for 14 hours, drying at 65℃ for 4 hours, and roasting at 80℃ for 2 hours until the moisture content is reduced to below 5%. Finally, the roots are removed to obtain beer malt.

[0025] The PYF value and fungal content of the malt from Example 1 and Comparative Examples 1-4 were determined: (1) Determination of malt PYF value: The yeast cells preserved on slant were inoculated into maltose-YPD liquid medium and cultured for two generations. Yeast cells in the late logarithmic growth stage (36 h) were collected, washed once with deionized water, and then treated with 100 mmol·L⁻¹ water. -1 Wash twice with EDTA at pH 8.0, then twice with deionized water, and then incubate the yeast cells in 50 mmol·L⁻¹ solution. -1 Resuspend the sample in NaAc-0.1%CaCl2 (pH 4.0) buffer until the final A600 value is 3.0. Then, add 2.6 mL of this suspension and 400 μL of sample to a cuvette, invert and mix 40 times, and then incubate at room temperature for 30 min. Gently invert the cuvette 10 times and measure the A600 value at 3 min. 600 PYF value. The PYF value is defined as the difference between the added sample and the added deionized water. 600 The ratio, i.e., the PYF value, = A 600 Sample / A 600 Deionized water. The lower the PYF value, the higher the PYF activity (the higher the PYF value, the lower the PYF activity); a PYF value less than 0.8 is defined as having flocculation activity, less than 0.7 is defined as having strong flocculation activity, and less than 0.6 is defined as severe flocculation.

[0026] (2) Ergosterol content determination: Preparation of ergosterol standard solution: Ergosterol standard was dissolved in chromatographically pure ethanol to prepare 500 μg·mL -1 The ergosterol stock solution should be stored at -20°C. Dilute with ethanol to 2-500 μg / mL. -1This was used for HPLC analysis to plot the ergosterol standard curve. Preparation of alkaline potassium hydroxide solution: 20 g of potassium hydroxide was dissolved in 50 mL of pure methanol and 180 mL of anhydrous ethanol. Extraction and determination of ergosterol: 2 g of crushed barley was placed in a 50 mL centrifuge tube, and 10 mL of alkaline potassium hydroxide solution was added. The mixture was saponified at 70°C for 1 h. After naturally cooling to room temperature, 2.5 mL of distilled water and 10 mL of n-hexane were added, and the mixture was vortexed for 10 s. The mixture was centrifuged at 6000 × g for 10 min, and the upper n-hexane layer was collected in a new centrifuge tube. The lower layer was extracted twice with 10 mL of n-hexane. The collected n-hexane layers were combined and evaporated to dryness by rotary evaporation. The mixture was then reconstituted with 1 mL of anhydrous ethanol and filtered through a 0.22 μm organic syringe filter for HPLC analysis. HPLC analysis: Column: Agilent Eclipse XDB-C18, 0.5 μm 4.6 × 250 mm; Mobile phase: methanol; Flow rate: 1 mL·min -1 Column temperature: 30°C; injection volume: 20 μL; detection wavelength: 282nm.

[0027] (3) Isolation and identification of fungi: Barley suspension was serially diluted in 0.9% sodium chloride and inoculated onto PDA medium. After incubation at 30°C for 72 h, colonies were selected from the highest dilution. Genomic DNA of the selected fungal strains was extracted using a fungal genomic DNA extraction kit and amplified by PCR using universal primers ITS1 and ITS4. Sanger sequencing was performed by Shanghai Tianlin Biotechnology Co., Ltd., and the DNA sequences were then assembled. High-quality double-stranded sequence data were retrieved from the NCBI GenBank database for identification of Fusarium graminearum.

[0028] The measurement results are shown in Table 1: Table 1. Measurement results of PYF value and Fusarium graminearum content.

[0029] Based on the measurement results in Table 1, it is evident that the beer malt prepared in Example 1, after sorting and NaCO3-enhanced washing, has a PYF value of 0.96, indicating almost no flocculation activity. The beer malt prepared in Comparative Example 1 (without sorting) and Comparative Example 3 (without NaCO3-enhanced washing) has PYF values ​​of 0.86 and 0.82, respectively, indicating a small amount of flocculation activity. Comparative Example 2, using conventional beer malt preparation methods without sorting and NaCO3-enhanced washing, has a PYF value of 0.7, indicating strong flocculation activity. Comparative Example 4, which involves NaCO3-enhanced washing of sorted red barley, has a PYF value of 0.76, indicating strong flocculation activity.

[0030] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0031] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0032] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a product that reduces yeast pre-flocculation factors in beer malt, characterized in that, Includes the following steps: S1. Barley sorting: Based on the red value in the barley color difference index, sort the barley and remove the red barley to obtain sorted barley. S2 and NaCO3 enhance wheat washing; The sorted barley is washed in a washing solution containing NaCO3 at a concentration of 0.5 g / kg to 0.8 g / kg. S3. The barley after NaCO3-enhanced washing is sequentially soaked, germinated, dried, and root-removed to obtain beer malt with low activity of yeast pre-flocculation factor.

2. The preparation method for reducing yeast pre-flocculation factor in beer malt according to claim 1, characterized in that, In step S1, a color sorter is used to sort the wheat, and the red value in the sorting standard is >2.

5.

3. The preparation method for reducing yeast pre-flocculation factor in beer malt according to claim 1, characterized in that, In step S2, the wheat washing time is 6~12 hours and the temperature is 12~16℃.

4. The preparation method for reducing yeast pre-flocculation factor in beer malt according to claim 1, characterized in that, In step S3, the yeast pre-flocculation value in the beer malt is ≥0.96.

Images