Method for promoting fermentation of non-saccharomyces cerevisiae by adding Arabic gum

Abstract

The invention discloses a method for promoting non-saccharomyces cerevisiae fermentation by adding Arabic gum, and belongs to the technical field of fermentation engineering. The invention discloses a method for promoting fermentation of non-saccharomyces cerevisiae by adding Arabic gum, fermentation of the non-saccharomyces cerevisiae in grape wine is promoted by adding the Arabic gum before fermentation, and a new method and a new thought are provided for solving the problem of difficult fermentation of the non-saccharomyces cerevisiae. The fermentation method provided by the invention is simple, convenient, easy to operate, natural, green and environment-friendly, and can quickly and easily achieve the purpose compared with other methods.

Description

Technical Field

[0001] The invention relates to the technical field of fermentation engineering, in particular to a method for promoting the fermentation of non-brewer's yeast by adding gum arabic. Background Art

[0002] Yeast plays an important role in the fermentation of wine and other fruit wines. It can be divided into Saccharomyces cerevisiae and non-Saccharomyces cerevisiae according to its functions. The aroma of wine is an important parameter for evaluating the quality of wine (Renault P et al. 2015: 44-45). Non-Saccharomyces cerevisiae has a strong ability to produce aroma, and can produce high amounts of esters, higher alcohols, terpenes and other substances that improve the aroma of wine. It can also stabilize the color of wine by forming pyranoanthocyanins (Jolly N P et al. 2014: 220-222; Padilla B et al. 2016: 7-10; Wang Chunxiao et al., 2023: 535-538). Therefore, some non-Saccharomyces cerevisiae yeasts with certain winemaking characteristics have been screened and commercialized, such as the thermotolerant Kluyveromyces cerevisiae with high lactic acid production and the Deleusporon yeast with increased taste mellowness. However, non-Saccharomyces yeast has poor fermentation ability and cannot dominate the entire process of alcohol fermentation, which often causes fermentation stagnation. Therefore, the wine produced is low in alcohol and high in sugar, which is not conducive to the storage and aging of wine. In the fermentation process, the assistance of Saccharomyces yeast is often required. At present, the application of non-Saccharomyces yeast is mainly mixed with Saccharomyces cerevisiae to improve the quality of wine, so as to recognize the contribution of non-Saccharomyces yeast. It is one-sided to understand non-Saccharomyces yeast through this method. It cannot ensure that the improvement of wine quality is brought about by the metabolic advantages of non-Saccharomyces yeast itself (Wang Chunxiao et al., 2023:543). Therefore, it is necessary to study its pure fermentation and the causes of its fermentation stagnation.

[0003] Gum arabic is a water-soluble dietary fiber derived from the viscous exudate of the stems and branches of acacia trees (Huang Hongjie, 2020), and is the most widely used plant gum. Gum arabic is neutral or weakly acidic and is a mixed calcium, magnesium and potassium salt of polysaccharide acids. It is a branched complex polysaccharide containing a mixture of D-galactose, D-glucuronic acid, L-rhamnose and L-arabinose. Gum arabic contains a protein core, and the protein fraction accounts for less than 2% of gum arabic (Pegg, 2012). Gum arabic can effectively prevent the occurrence of wine reduction diseases and is mainly used in the clarification and stabilization of wine.

[0004] There are many reasons for fermentation stagnation during wine fermentation, such as excessive sugar content, causing excessive osmotic pressure, ethanol and other by-products produced during the alcoholic fermentation process, lack of nutrients such as assimilable nitrogen and dissolved oxygen (Jian H et al. 2022:1), high concentration of carbon dioxide content and premature sedimentation of yeast cells (AraujoPiraine RE et al. 2022), etc.

[0005] To solve the problem of wine fermentation stagnation, the main traditional methods currently adopted are adding nutrients and secondary inoculation. Studies have shown that mixed fermentation of non-Saccharomyces cerevisiae with S.cerevisiae can reduce the unpleasant flavor caused by pure fermentation of non-Saccharomyces cerevisiae, so a large number of studies are still focused on mixed fermentation of non-Saccharomyces cerevisiae with S.cerevisiae. Mixed fermentation of T.delbrueckii and S.cerevisiae can reduce the content of alcohol, acetaldehyde and acetic acid, and increase the content of aromatic substances such as glycerol and 2-phenylethanol. Research on pure fermentation of T.delbrueckii mainly focuses on low-alcohol wine. It is difficult to complete fermentation when the sugar content in grape juice is high. L.thermotolerans has the characteristics of high L-lactic acid production (pure fermentation can reach 9.6g / L). When mixed fermentation with S.cerevisiae, it can significantly reduce pH, reduce volatile acid, increase total acid, and increase glycerol and 2-phenylethanol content. In theory, mixed fermentation cannot distinguish whether the improvement of wine quality is really from the metabolic advantages of non-Saccharomyces yeast itself. Therefore, research on pure fermentation of non-Saccharomyces cerevisiae is very necessary. Summary of the invention

[0006] The purpose of the present invention is to provide a method for promoting the fermentation of non-brewer's yeast by adding gum arabic, so as to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is the use of gum arabic in promoting the fermentation of non-brewer's yeast.

[0009] The second technical solution of the present invention is the use of gum arabic in the preparation of products that promote the fermentation of non-brewer's yeast.

[0010] The third technical solution of the present invention is a product for promoting the fermentation of non-brewer's yeast, comprising gum arabic at a concentration of 2.5% to 10%.

[0011] A fourth technical solution of the present invention is a method for promoting the fermentation of non-brewer's yeast, comprising adding gum arabic at a concentration of 2.5% to 10% to the fermentation medium of the non-brewer's yeast to promote the fermentation of the non-brewer's yeast.

[0012] A fifth technical solution of the present invention is a method for preparing wine, which comprises fermenting the wine using non-brewer's yeast and adding gum arabic to the fermentation liquid to promote fermentation.

[0013] A sixth technical solution of the present invention is the wine prepared by the preparation method.

[0014] Based on the above technical solution, the present invention has the following technical effects:

[0015] The present invention discloses a method for promoting the fermentation of non-brewer's yeast by adding gum arabic, and the method of adding gum arabic before fermentation promotes the fermentation of non-brewer's yeast in wine, providing a new method and new idea for the problem of difficult fermentation of non-brewer's yeast. The fermentation method provided by the present invention is simple, easy to operate, natural and green and environmentally friendly, and can achieve the purpose quickly and easily compared with other methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 For the technology roadmap.

[0018] Figure 2 Sugar fermentation curves of grape juice inoculated with a38 (a) and grape juice inoculated with R12 (b).

[0019] Figure 3 Comparison of glucose and fructose in grape juice before and after fermentation. A is fermentation with a38 inoculation, and B is fermentation with R12 inoculation.

[0020] Figure 4 The content of ethanol and glycerol in grape juice after fermentation. Among them, a is the fermentation with inoculation of a38, and b is the fermentation with inoculation of R12.

[0021] Figure 5 Comparison of organic acids in grape juice before and after fermentation. A is fermentation with a38 inoculation, and B is fermentation with R12 inoculation.

[0022] Figure 6 The total phenol, tannin and anthocyanin content of grape juice before and after fermentation. Among them, a is the fermentation with inoculation a38, and b is the fermentation with inoculation R12.

[0023] Figure 7 Correlation analysis between CIElab parameters and phenolic substances in wine samples.

[0024] Figure 8 This is a sensory analysis chart of wine samples. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0031] The embodiment of the present invention provides the use of gum arabic in promoting the fermentation of non-brewer's yeast.

[0032] In some specific embodiments, the non-Saccharomyces yeast includes Kluyveromyces thermotolerans and Torulaspora delavayces.

[0033] Non-brewer's yeast has the characteristics of high production of glycerol, lactic acid, higher alcohols and aromatic esters, which can greatly improve the characteristics of wine. However, non-brewer's yeast has poor fermentation ability and it is difficult to complete alcohol fermentation alone. Research on non-brewer's yeast is mainly based on mixed fermentation with brewer's yeast (S.cerevisiae), and there are few studies on its pure strain fermentation. Delbrueckii (T.delbrueckii) and thermotolerans (L.thermotolerans) have been used as two commonly used commercial non-brewer's yeasts due to their outstanding characteristics. Gum arabic belongs to plant gums and is mainly used for clarification and stabilization of the color of wine in wine. There are few studies on the use of its cell immobilization to promote the fermentation of non-brewer's yeast. Therefore, the present invention aims to achieve its fermentation promotion effect on Delbrueckii R12 and thermotolerans a38 by adding different concentrations of gum arabic, thereby solving the problem of slow and stagnant fermentation of non-brewer's yeast.

[0034] The embodiments of the present invention also provide the use of gum arabic in preparing a product for promoting the fermentation of non-brewer's yeast.

[0035] The embodiment of the present invention further provides a product for promoting the fermentation of non-brewer's yeast, comprising gum arabic with a concentration of 2.5% to 10%.

[0036] The embodiment of the present invention also provides a method for promoting the fermentation of non-brewer's yeast, which includes adding gum arabic at a concentration of 2.5% to 10% to the fermentation medium of the non-brewer's yeast to promote the fermentation of the non-brewer's yeast.

[0037] The embodiment of the present invention also provides a method for preparing wine, which uses non-brewer's yeast to ferment the wine, and adds gum arabic to the fermentation liquid to promote fermentation.

[0038] In some specific embodiments, the added amount of gum arabic is 2.5% to 10%, preferably 2.5% or 10%.

[0039] In some specific embodiments, the non-Saccharomyces yeast includes Kluyveromyces thermotolerans and Torulaspora delavayces.

[0040] The embodiment of the present invention also provides wine prepared by the preparation method.

[0041] The invention discloses a method for promoting the fermentation of non-brewing yeast by adding gum arabic, wherein the fermentation is carried out by using Torulopsis delavayci and Kluyveromyces thermotolerant, and the fermentation ability of non-brewing yeast in wine is improved by adding gum arabic of different concentrations, thereby solving the problem of the difficulty of fermentation of non-brewing yeast. The method can be further studied and applied to the production and fermentation of fruit wine.

[0042] In some specific embodiments, the fermentation progress of the strain is monitored based on the consumption of reducing sugars.

[0043] Take samples every 24 hours to monitor the sugar content. Take 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00 ml of 4 mg / ml glucose standard solution in a 25 ml stoppered test tube, add distilled water to 1 ml, add 1.5 ml of DNS and mix well, keep in a boiling water bath for 5 minutes, cool to room temperature with running water, add 4 ml of distilled water, mix well, let stand for 20 minutes, detect the absorbance at a wavelength of 562 nm, and draw a standard curve. Take 1 ml of the original sample or diluted sample (dilute the sugar to between 0-4g), and the operation method is the same as above. After the absorbance of the sample reducing sugar is detected, substitute it into the glucose standard curve to calculate the sugar content.

[0044] In some specific implementation schemes, the physical and chemical indicators of wine are based on the results of high performance liquid chromatography.

[0045] Samples before and after fermentation were taken to measure basic physical and chemical indicators, including glucose, fructose, citric acid, malic acid, succinic acid, lactic acid, acetic acid, tartaric acid, glycerol, ethanol, etc. Standard glucose and fructose were prepared into a series of standard solutions with mass concentrations of 0.6, 0.4, 0.2, 0.1, 0.05, and 0.01 g / L, standard ethanol was prepared into a series of standard solutions with mass concentrations of 2, 1.5, 1, 0.5, 0.1, and 0.05 g / L, and six kinds of organic acids were prepared into a series of standard solutions with mass concentrations of 1, 0.8, 0.6, 0.4, 0.2, 0.1, 0.05, and 0.01 g / L, respectively. After filtration with a 0.22 μm water filter, they were used for HPLC testing. The samples before fermentation were diluted 200 times with ultrapure water, and the samples after fermentation were diluted 100 times with ultrapure water, filtered with a 0.22 μm organic filter membrane, and used for Agilent 1260 InfinityⅡHPLC analysis. Chromatographic conditions: The chromatographic column was BioRad Aminex HPX 87-H (300 mm × 7.8 mm), the mobile phase was 5 mmol / L H2SO4 solution, the flow rate was 1.0 mL / min, the column temperature was 60 °C, the injection volume was 20 μL, and the detection wavelength was 210 nm.

[0046] In some specific implementation schemes, the method for detecting wine color and related substances is as follows:

[0047] Color parameter CIElab determination: refer to the method of (Li Yunkui et al., 2017: 297-298) for details. After the wine sample is filtered through a 0.45μm organic filter membrane, deionized water is used as a reference. Use a 1mm glass cuvette to continuously scan the absorption spectrum of the visible light region from 400 to 780nm, with a scanning interval of 1nm, and repeat twice for each wine sample. Take the absorbance measured at A450, A520, A570, and A630 and calibrate it to 1cm optical path, and calculate the CIElab parameters a* (red / green color channel), b* (yellow / blue color channel) and L* (brightness), C*ab, hab, and ΔE*ab.

[0048] Total phenol determination: Take 6 test tubes, accurately pipette 0, 0.1, 0.2, 0.3, 0.5, 1.0 mL of phenol mother solution into the test tubes, and dilute to 10 mL respectively. Take another 6 test tubes, pipette 0.1 mL of the above solution respectively, add 5 mL of water to each, add 0.5 mL of forin-Sioxacol to each, and mix thoroughly. Add 1.5 mL of 20% sodium carbonate solution within 30 seconds to 8 minutes, mix and dilute to 10 mL with water. Place the above solutions at 20°C for 2 hours, then measure the absorbance at 765 nm in a spectrophotometer, and draw a standard curve y=1085.1x-11.586, R2=0.9995. Dilute red wine 10 times and take 0.2 mL. Add 5 mL of deionized water, 0.5 mL of folin, 1.5 mL of sodium carbonate, and 2.8 mL of deionized water. Incubate at 20 °C in dark for 2 h. Measure with a cuvette at 765 nm. Substitute the result of the standard curve into the result to calculate catechins.

[0049] Tannin determination: Take 8 test tubes, take 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 mL of catechin mother solution respectively, add 10, 9.8, 9.6, 9.4, 9.2, 9, 8.8, 8.6 mL of deionized water respectively, use 10 mm quartz cuvette to measure absorbance at 280 nm wavelength, draw standard curve y = 48.665x + 0.6727, R2 = 0.9998. Take 2 test tubes, add 0.1 mL of red wine and 1.6 mL of ammonium sulfate to the control, and dilute to 8 mL with deionized water; add 0.1 mL of red wine, 2.4 mL of methylcellulose, and 1.6 mL of ammonium sulfate to the sample, and dilute to 8 mL with deionized water; stand at room temperature and avoid light for 10 minutes, measure with cuvette at 280 nm wavelength, calculate absorbance using A = A control - A sample, substitute the standard curve result to calculate catechin.

[0050] Determination of total anthocyanins: Take 0.2 mL of wine sample in two test tubes, add pH 1.0 and pH 4.5 buffer respectively, dilute to 5 mL, keep away from light for 15 to 20 minutes, and measure the absorbance at 520 nm and 700 nm in a spectrophotometer within 23 to 40 minutes. Calculate the absorbance using A = (A520-A700) pH1.0-(A520-A700) pH4.5, and calculate the W value (anthocyanin content) using W (mg / L) = (A*493.5*dilution factor*1000) / 28000. The result is calculated as delphinidin.

[0051] In some specific implementation schemes, the sensory evaluation is based on the design and regulations of the sensory evaluation form.

[0052] Referring to the method of (Qiang Wenle et al., 2024:705) and slightly modified, the sensory tasting panel compared the wines from four aspects: appearance (16 points), aroma (32 points), taste (42 points), and overall evaluation (10 points), with a total score of 100 points. A panel of 12 wine professional sensory evaluators was formed to conduct wine tasting and scoring.

[0053] The strains used in the embodiments of the present invention are:

[0054] Lachancea thermotolerans a38, isolated from Qilian Winery, Gansu, with a deposit number of CGMCC No.21713, has been disclosed in patent CN113667611A;

[0055] Torulaspora delbrueckii R12 was isolated in Jingyang, Shaanxi. This strain has been disclosed in patent CN108342333A.

[0056] The method of the present invention is also applicable to thermotolerant Kluyveromyces and Torulella delavayi from other commercial sources.

[0057] The solutions and culture media used in the embodiments of the present invention are as follows:

[0058] Solution:

[0059] (1) 0.85% saline: Add 0.85 g of sodium chloride to 100 mL of distilled water.

[0060] (2) DNS reagent: 6.5 g 3,5-dinitrosalicylic acid in a water bath at 42°C until completely dissolved, 325 ml 2 mol / L NaOH, 45 g propylene glycol, dilute to 1 L with distilled water, place in a brown bottle (wrapped with tin foil) at 4°C and protect from light during preparation.

[0061] (3) 20% saturated sodium carbonate solution: Weigh 200 g of anhydrous sodium carbonate and dissolve it in 1 L of boiling water. After cooling to room temperature, add a few pieces of crystalline sodium carbonate crystals and filter after 24 hours.

[0062] (4) 0.5% phenol mother solution: Weigh 0.500 g of gallic acid (dry gallic acid), dissolve it in water, pour it into a 100 mL volumetric flask, i.e. 5 mg / mL, and make up to volume.

[0063] (5) 0.04% methylcellulose solution: Weigh 0.4 g of methylcellulose and slowly add it to a 1 L beaker containing 300 mL of 80°C deionized water. Stir until completely dissolved. Add the remaining 0-5°C deionized water to the beaker and stir at 0-5°C (ice bath) for 20-40 min. Remove from the ice bath and continue shaking until the solution becomes clear. Allow the solution to reach room temperature and make up to 1 L with deionized water.

[0064] (6) Saturated ammonium sulfate solution: Add 300 mL of deionized water to a 500 mL thread-capped bottle. Then add ammonium sulfate crystals until 1.5 cm of ammonium sulfate is precipitated at the bottom of the bottle.

[0065] (7) 5 g / L catechin stock solution: Accurately weigh 0.25 g of catechin and dissolve it in water to make up to 50 mL.

[0066] (8) 0.5 mg / mL catechin solution: Pipette 10 mL of 5 g / L catechin stock solution and dilute to 100 mL.

[0067] (9) pH = 1.0 KCl buffer: Weigh 1.86 g KCl and add it to 980 mL distilled water. Adjust the pH to 1.0 (±0.05) with HCl (about 6.3 mL) and make up to volume in a 1 L volumetric flask.

[0068] (10) pH = 4.5 CH3CO2 Na·3H2O (sodium acetate) buffer: weigh 54.43 g CH3CO2 Na·3H2O, add 960 mL distilled water, adjust pH to 4.5 (±0.05) with HCl (about 20 mL), and make up to volume with a 1 L volumetric flask.

[0069] Culture medium:

[0070] (1) YPD medium: 10 g / L yeast extract powder, 20 g / L peptone, 20 g / L glucose. Add 20 g / L agar to the solid mixture.

[0071] (2) Grape juice: Meili grape juice picked in August 2023 and collected from Yangling District, Xianyang City, Shaanxi Province.

[0072] Example 1

[0073] The technical roadmap of the present invention is as follows: Figure 1 shown.

[0074] 1 Wine fermentation with gum arabic

[0075] 1.1 Strain fermentation test

[0076] Heat-resistant Kluyveromyces a38 and Dale spore circle R12 were inoculated into YPD solid culture medium, cultured at 30℃ for 24h, and single colonies were picked and inoculated into 100mL YPD liquid culture medium, activated at 26℃ and 150r / min for 12h.

[0077] 200 mg / L yeast fungicide DMDC (dimethyl dicarbonate) was added to the Meili grape juice and allowed to stand for 12 hours for sterilization. The sterilized grape juice was divided into 250 mL conical flasks, with 100 mL of grape juice in each conical flask.

[0078] The activated strain was sampled and placed in a 96-well plate with 200 μL of bacterial solution. The absorbance was measured at 600 nm using an ELISA reader, and the bacterial volume was calculated. The activated bacterial solution was centrifuged at 6000 r / min for 5 min, and 0.85% saline was added to wash it, and the process was repeated twice. The volume was adjusted to 1×10 6 The inoculum size of CFU / mL was inoculated into 100 mL of grape juice.

[0079] Gum arabic with a mass concentration of 0%, 2.5%, 5% and 10% was added to the inoculated grape juice, and the juice was placed in a constant temperature incubator for constant temperature fermentation at 26°C. Samples were taken every 24 hours to monitor the sugar content until the fermentation stopped.

[0080] 1.2 Monitoring of fermentation process

[0081] The grape juice inoculated with a38 and R12 was fermented for 20 days. Figure 2 As shown in the figure, the fermentation rate of grape juice inoculated with a38 and R12 was significantly accelerated when 10% gum arabic was added compared with other concentrations, and the residual sugar left after fermentation was lower than that of other concentrations. Figure 2 As shown in a, the sugar content of grape juice inoculated with a38 showed a downward trend when different concentrations of gum arabic were added 15 days before fermentation. After the 15th day, the sugar content of 0%, 2.5%, and 5% gum arabic concentrations remained basically unchanged, while the sugar content of 10% gum arabic concentration showed a slow downward trend. After the fermentation, the sugar content of 0%, 2.5%, 5%, and 10% gum arabic concentrations dropped to 155.3g / L, 171.6g / L, 154.6g / L, and 118.5g / L, respectively. Figure 2As shown in Figure b, the sugar content of grape juice inoculated with R12 showed a downward trend after adding different concentrations of gum arabic 13 days before fermentation. After the 13th day, the sugar content of 0%, 2.5%, and 5% gum arabic remained basically unchanged, while the sugar content of 10% gum arabic showed a slow downward trend. After the fermentation, the sugar content of 0%, 2.5%, 5%, and 10% gum arabic dropped to 157.3g / L, 156.4g / L, 168.7g / L, and 132.5g / L, respectively.

[0082] 2 Effects of gum arabic on basic physical and chemical parameters of wine

[0083] 2.1 Reducing sugar

[0084] like Figure 3 It can be seen that the remaining fructose content after fermentation is significantly higher than the glucose content. Figure 3 As shown in a, in the grape juice inoculated with a38, the glucose and fructose contents in the grape juice with 10% concentration of arabic gum added were the lowest, 39.68 g / L and 78.81 g / L, respectively. The glucose and fructose contents in the grape juice with 2.5% concentration of arabic gum added were the highest, 67.52 g / L and 104.14 g / L, respectively. Figure 3 As shown in middle b, in the grape juice inoculated with R12, there was no significant difference in the glucose and fructose contents between those with 2.5% and 5% gum arabic added and those without gum arabic added, while the glucose and fructose contents in the juice with 10% gum arabic added were the lowest, which were 46.11 g / L and 86.35 g / L, respectively.

[0085] 2.2 Ethanol and glycerol

[0086] like Figure 4 As shown in a, the alcohol content of the grape juice inoculated with a38 at the end of fermentation was 6.82%vol~7.69%vol, and the glycerol content was 5.77g / L~7.46g / L. The alcohol content was the highest when 10% gum arabic was added, but the glycerol content was the lowest. The alcohol content was the lowest when 2.5% gum arabic was added, and the glycerol content was the highest when no gum arabic was added. Figure 4 As shown in b, the alcohol content of the grape juice inoculated with R12 at the end of fermentation was 6.27%vol~9.03%vol, and the glycerol content was 3.16g / L~4.14g / L. The glycerol content was the highest when 2.5% gum arabic was added, the alcohol content was the highest when 10% gum arabic was added, and the alcohol and glycerol contents were the lowest when 5% gum arabic was added. It can be seen that a38 has a stronger ability to produce glycerol than R12, but a weaker ability to produce ethanol than R12.

[0087] 2.3 Organic acids

[0088] like Figure 5 As shown in the figure, the acid content before fermentation is malic acid>tartaric acid>citric acid, and these acids decrease to varying degrees after fermentation. However, fermentation acids such as lactic acid increase, especially succinic acid, which is at a high level, but acetic acid is at a low level (<1.2g / L). Figure 5 As shown in Figure a, in the grape juice inoculated with a38, as the concentration of gum arabic increased, the content of succinic acid gradually decreased, while the content of lactic acid increased significantly compared with before the start of fermentation. The lactic acid content of the grape juice with 5% concentration of gum arabic added was the highest at 2.2 g / L. Figure 5 As shown in Figure b, in the grape juice inoculated with R12, as the concentration of gum arabic increased, the content of succinic acid gradually decreased, and both lactic acid and acetic acid were at a lower level. This shows that the ability of a38 to produce lactic acid is stronger than that of R12.

[0089] The changes in basic physical and chemical indicators of grape juice before and after fermentation are shown in Tables 1-2.

[0090] Table 1

[0091]

[0092] Note: 1. Different letters for the same strain in the same column indicate statistically significant differences (P<0.05); 2. SF indicates the sample at the beginning of fermentation, and the rest are samples after the end of fermentation.

[0093] Table 2

[0094]

[0095] 3 Effect of gum arabic on wine color and related substances

[0096] 3.1 Total phenols, tannins, and anthocyanins

[0097] like Figure 6 As shown in the figure, the anthocyanin content at the end of fermentation is lower than that before fermentation. Figure 6 As shown in a, in the grape juice inoculated with a38, there was no significant difference in the total phenol content before and after fermentation. The tannin content after fermentation was lower than that at the beginning of fermentation. The tannin content of the 5% concentration of gum arabic was the highest at 1082.59 g / L, and the tannin content of the 10% concentration was the lowest at 958.4 g / L. The color of red wine just after fermentation is mainly determined by monomer anthocyanins, and the color is mainly purple-red. Figure 6As shown in b, in the grape juice inoculated with R12, the total phenol content after fermentation was higher than that before fermentation, and there was a significant difference between the two. The tannin content after fermentation was lower than that at the beginning of fermentation. The tannin content was the highest at 1088.89 g / L when 2.5% gum arabic was added, and the lowest at 1013.62 g / L when 10% gum arabic was added. The tannin content of both strains was the lowest when 10% gum arabic was added.

[0098] 3.2 Wine CIElab parameters

[0099] As shown in Tables 3 and 4, the L* of each sample after the fermentation is higher than that at the beginning of the fermentation. The lightness value of the treated wine samples after the fermentation is 43.9-47.33, indicating that the wine has good gloss. The a* after the fermentation is 41.07-51.05, indicating that the red content of the treated wine samples is large, and the difference between them is significant. The largest is the wine sample inoculated with a38 strain without adding gum arabic, and the smallest is the wine sample inoculated with R12 strain and adding 10% gum arabic; b* after the fermentation is 12.87-20.36, indicating that the yellow content of the wine color of the treated wine samples is large, and the difference between them is significant. The largest is the wine sample inoculated with a38 strain and adding 10% gum arabic, and the smallest is the wine sample inoculated with R12 strain without adding gum arabic. After the fermentation, C*ab was between 44.65 and 53.81, indicating that the color saturation of the wine was high. The largest one was the wine sample inoculated with a38 strain without adding gum arabic, and the smallest one was the wine sample inoculated with R12 strain and adding 10% gum arabic. Hab* after the fermentation was between 0.25 and 0.46, indicating that the color of the treated wine samples was mainly purple-red. Taking the wine samples at the beginning of fermentation as a reference, the ΔE*ab of the treated wine samples after the fermentation was completed was greater than 6, indicating that the color was significantly different from the wine samples at the beginning of fermentation. The ΔL* of the treated wine samples after the fermentation was completed was negative, indicating that the colors of these treated wine samples were brighter than the reference samples. The Δa* of the treated wine samples after the fermentation was completed was positive and the △b* was negative, indicating that the red hue of all colors was significantly lower than the reference sample, and the yellow hue was significantly higher than the reference sample.

[0100] Table 3

[0101]

[0102] Note: 1. Different letters for the same strain in the same column indicate statistically significant differences (P<0.05); 2. SF indicates the sample at the beginning of fermentation, and the rest are samples after the end of fermentation.

[0103] Table 4

[0104]

[0105] 3.3 Correlation analysis

[0106] In order to explore the intrinsic relationship between phenolic substances and CIELab parameters, Pearson correlation analysis was performed. The results are as follows: Figure 7 As shown in the figure, the results showed that there was a correlation between total phenols, tannins, anthocyanins and CIELab parameter indicators. The more * there are, the stronger the significance. L* was significantly negatively correlated with TN (tannin), TA (anthocyanin), a*, and was significantly positively correlated with TP (total phenols), h*, b*, and △Eab*; a* was significantly negatively correlated with L*, b*, h*, △Eab*, and TP, and was significantly positively correlated with C* and TN; b* was significantly negatively correlated with a*, TN, and TA, and was extremely significantly positively correlated with h*, L*, and △Eab*; C* was significantly negatively correlated with TP and was extremely significantly positively correlated with a*; h* was significantly negatively correlated with a*, TN, TA, and C*, and was significantly positively correlated with b*, △Eab*, and L*; △Eab* was significantly negatively correlated with a*, TN, and TA, and was significantly positively correlated with L*, b*, h*, and TP. Among them, h* (hue) and ΔE* (color difference) are extremely significantly positively correlated, indicating that the hue change of wine samples and the visual differences caused are synergistic. L* and TA are extremely significantly negatively correlated, mainly because anthocyanin is the main contributor to wine color. The darker the wine color, the lower the brightness. Chroma a* and h* are significantly negatively correlated, indicating that purple-red is the main hue in young red wine.

[0107] 4 Effect of gum arabic on sensory evaluation of wine

[0108] like Figure 8 As shown in the figure, with the increase of the concentration of gum arabic, the taste intensity, body and structure of the red wine inoculated with the a38 strain all showed an upward trend. In the comparison of different concentrations of gum arabic, the scores of various sensory evaluation indicators of the wine added with 2.5% gum arabic were at a higher level. The red wine inoculated with R12 strain and added with 2.5% gum arabic had the highest taste intensity, body, structure, coordination and overall evaluation.

[0109] The present invention uses thermotolerant Kluyveromyces and Torulella delbrueckii from other sources on the market as experimental subjects, adds gum arabic for fermentation, and achieves a technical effect of promoting strain fermentation equivalent to that described above.

[0110] In summary, the present invention discloses a method for promoting the fermentation of non-brewer's yeast by adding gum arabic, and the method of adding gum arabic before fermentation promotes the fermentation of non-brewer's yeast in wine, providing a new method and new idea for the problem of difficult fermentation of non-brewer's yeast. The fermentation method provided by the present invention is simple, easy to operate, natural and green and environmentally friendly, and can achieve the purpose quickly and easily compared with other methods.

[0111] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technical users in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Application of gum arabic in promoting fermentation of non-brew yeast.

2. The use according to claim 1, characterized in that: The non-brewery yeasts include Kluyveromyces thermotolerans and Torulella delavirdii.

3. The application of gum arabic in the preparation of products that promote the fermentation of non-brewer's yeast.

4. A product for promoting fermentation of non-brew yeast, characterized in that: Including gum arabic in a concentration of 2.5% to 10%.

5. A method for promoting fermentation of non-Saccharomyces cerevisiae, characterized in that: Gum arabic at a concentration of 2.5% to 10% is added to the fermentation medium of non-brewer's yeast to promote the fermentation of non-brewer's yeast.

6. A method for preparing wine, characterized in that: The wine is prepared by fermentation with non-brew yeast, and gum arabic is added to the fermentation liquid to promote fermentation.

7. The preparation method according to claim 6, characterized in that: The added amount of the gum arabic is 2.5% to 10%.

8. The preparation method according to claim 6, characterized in that: The non-brewery yeasts include Kluyveromyces thermotolerans and Torulella delavirdii.

9. Wine prepared by the preparation method according to any one of claims 6 to 8.

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