Preparation method of lactic acid synergistically brewed grape wine

Abstract

The invention discloses a preparation method of lactic acid synergistically brewed wine, and belongs to the technical field of wine brewing. Comprising the following steps: homogenizing grape mash, adding color-protecting tannin, squeezing, adding pectinase after squeezing, adding potassium metabisulfite, saccharomyces cerevisiae dry powder and lactic acid, and fermenting to obtain the grape wine after fermentation. Flavor improvement: through fine lactic acid regulation and control, the frankincense, fruit fragrance and flower fragrance of the wine are rich and lasting, unique cream and nut flavors are newly added, and the flavor level richness is improved compared with that of a traditional process. The lactic acid can adjust the balance between the total acid and the pH value of the wine, reduce the acerbity, enhance the roundness and the mellowness, and improve the average score of the taste preference. Lactic acid and metal ions are chelated, tartrate precipitation is reduced, oxidation resistance is combined, oxidation browning is delayed, the shelf life is predicted and prolonged, and the storage cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wine brewing, and in particular to a method for preparing wine brewed in a coordinated manner using lactic acid. Background Art

[0002] As a popular beverage, the quality of wine is affected by many factors. Although traditional brewing processes are relatively mature in terms of fermentation and aging, there is still room for improvement. Lactic acid is an important metabolite in the winemaking process, but existing technologies have not fully explored its role in flavor regulation, taste optimization, and stability improvement. Some patents focus on single fermentation control or the simple use of additives, failing to systematically and innovatively utilize the synergistic effects of lactic acid and various aspects of winemaking, making it difficult to meet consumers' increasingly diverse needs and pursuit of high-quality wine. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing wine by co-brewing with lactic acid, so as to solve the problems existing in the above-mentioned prior art.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a method for preparing wine by synergistic brewing with lactic acid, comprising the following steps:

[0006] After the grape mash is homogenized, color-protecting tannins are added and the mash is squeezed. After the squeezing is completed, pectinase is added, and potassium metabisulfite, brewer's yeast powder and lactic acid are added for fermentation. After the fermentation is completed, the wine can be obtained.

[0007] The second technical solution of the present invention is the wine prepared by the preparation method.

[0008] Based on the above technical solution, the present invention has the following technical effects:

[0009] Flavor enhancement: Through fine control of lactic acid, the wine's frankincense, fruity and floral aromas are made rich and long-lasting, and unique creamy and nutty flavors are added, and the flavor layering is richer than traditional processes.

[0010] Taste optimization: Lactic acid can adjust the balance of total acidity and pH value of wine, reduce sourness and astringency, enhance roundness and mellowness, and improve the average score of taste preference.

[0011] Enhanced stability: Lactic acid chelates with metal ions, reducing tartrate precipitation. Combined with its antioxidant properties, it delays oxidative browning, extending the shelf life and reducing storage costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0013] Figure 1 This is a diagram of wine fermentation kinetics. (a) shows different lactic acid additions to the mash and fermentation, as well as the control group; (b) shows different lactic acid additions two and four days after fermentation.

[0014] Figure 2 Figure 3 shows the changes in lactic acid content in the wine samples treated during fermentation. (a) Adding different amounts of lactic acid to the must; (b) Adding different amounts of lactic acid to the start of fermentation; (c) Adding different amounts of lactic acid two days into fermentation; and (d) Adding different amounts of lactic acid four days into fermentation.

[0015] Figure 3 This is a visualization of the main organic acid content in each group of wine samples. (a) shows the grape must, the wines with lactic acid added during fermentation, and the control group; (b) shows the wines with lactic acid added after two and four days of fermentation.

[0016] Figure 4 This is a visualization diagram of the CIELab parameters of the wine sample. * , b is a * , c is b * , d is C * ab , e is △E * ab , f is h * ab .

[0017] Figure 5 It is the total anthocyanin content in wine.

[0018] Figure 6 represents the content of nine monomeric anthocyanins in wine. Here, a represents Dp 3-O-Glu, b represents Cy 3-O-Glu, c represents Pt 3-O-Glu, d represents Pn 3-O-Glu, e represents Mv 3-O-Glu, f represents Pn 3-acetylglc, g represents Mv 3-acetylglc, h represents Pn 3-p-coumglc trans, and i represents Mv 3-p-coumglc trans.

[0019] Figure 7 This is the principal component analysis diagram of aroma substances.

[0020] Figure 8This is a radar chart of sensory tasting scores. A shows different lactic acid levels added to the mash, B shows different lactic acid levels added during fermentation, C shows different lactic acid levels added after two days of fermentation, and D shows different lactic acid levels added after four days of fermentation, along with the control group. DETAILED DESCRIPTION

[0021] 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 rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0023] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice 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 any conflict with any incorporated document, the contents of this specification shall prevail.

[0024] 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 without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] Unless otherwise specified, the technical solutions described in the present invention are all conventional solutions in the field, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0027] The embodiment of the present invention provides a method for preparing wine by synergistic brewing of lactic acid, comprising the following steps:

[0028] After the grape mash is homogenized, color-protecting tannins are added and the mash is squeezed. After the squeezing is completed, pectinase is added, and potassium metabisulfite, brewer's yeast powder and lactic acid are added for fermentation. After the fermentation is completed, the wine can be obtained.

[0029] In some specific embodiments, the amount of the color-protecting tannin added is 200 mg / L; the amount of the pectinase added is 40 mg / L; and the amount of the potassium metabisulfite added is 20 mg / L.

[0030] In some specific embodiments, the added amount of the cerevisiae dry powder is 200 mg / L.

[0031] In some specific embodiments, the amount of lactic acid added is 1.5 g / L.

[0032] In some specific embodiments, the fermentation temperature is 18-25°C.

[0033] In some specific embodiments, the fermentation is completed when the residual sugar content is less than 4 g / L.

[0034] The embodiment of the present invention also provides wine prepared by the preparation method.

[0035] The present invention aims to accurately add and regulate the content of lactic acid during the winemaking process to produce high-quality wine.

[0036] Based on the raw grape variety characteristics and maturity, this invention explores the innovative use of lactic acid gradient control technology to add appropriate amounts of lactic acid during four stages of wine fermentation. This method adjusts the wine's acidity and optimizes the fermentation environment. Microbial community succession is analyzed by measuring changes in lactic acid content during fermentation. Basic physical and chemical indicators, CIELab parameters, anthocyanin content, and volatile aroma compounds are measured, and sensory tasting analysis is performed. Taking all these parameters into consideration, the optimal lactic acid addition stage and amount during fermentation yields the highest quality wine.

[0037] Example 1

[0038] 1.1 Raw material preparation

[0039] Grapes: High-quality Cabernet Sauvignon grapes collected from Chateau Changyu Baron Balboa in Shihezi, Xinjiang. Grape physical and chemical indicators: Sugar: 247g / L, total acid: 4.22g / L; pH: 4.13; Volatile acid: 0.02g / L; Free SO 2： 19.64mg / L.

[0040] Brewing yeast: The local brewing yeast strain CECA comes from Professor Liu Yanlin of the College of Enology at Northwest Agriculture and Forestry University.

[0041] Lactic acid: Food grade: L-lactic acid, purity over 97%.

[0042] 1.2. Preprocessing stage

[0043] Under a sterile environment, the grapes were destemmed, crushed, and squeezed to obtain 190L of grape mash, which was then transferred to a 200L fermenter for homogenization. During the squeezing process, 38g of color-protecting tannins at 200mg / L and 7.6g of pectinase at 40mg / L were added to ensure consistency of basic properties. The mash was then transferred to 25 10L fermenters, with 0.4g of potassium metabisulfite added at 20mg / L to each tank to achieve approximately 40mg / L of free sulfur dioxide to prevent bacterial contamination. The mash was then macerated for 24 hours to promote the dissolution of pigments and flavor compounds.

[0044] 1.3. Lactic acid addition experiment

[0045] CECA dry yeast powder was added directly to each fermenter at an inoculum of 200 mg / L to start fermentation. 1.5 g / L, 2 g / L, and 2.5 g / L of lactic acid (A) were added to the grape mash (before yeast addition) (A), at the start of fermentation (B), two days after fermentation (C), and four days after fermentation (D). 1.5 , A2, A 2.5 、B 1.5 , B2, B 2.5 、C 1.5 , C2, C 2.5 、D 1.5 , D2, D 2.5) 13 experiments were conducted in a control group (CK) without acid addition. The caps were pressed every morning and evening, and 50 mL samples were taken every 12 hours to monitor the fermentation progress. The specific gravity of each fermentation vessel was measured to maintain a stable fermentation temperature of 18-25°C. Fermentation was continued until the residual sugar level was <4g / L.

[0046] 1.4 Index determination

[0047] 1.4.1 Determination of basic physical and chemical indicators of wine

[0048] The determination methods of basic physical and chemical indicators such as total acid (calculated as tartaric acid), volatile acid (calculated as acetic acid), total SO2, pH, alcohol content, and residual sugar refer to GB / T 15038-2006 "General Analytical Methods for Grape and Fruit Wine", and each indicator is measured three times.

[0049] 1.4.2 Determination of organic acid content

[0050] Organic acids were determined using HPLC (Shimadzu, Kyoto, Japan). Sample preparation: After the sample was centrifuged at 8000 rpm and 4°C for 2 min, the supernatant was taken and diluted with pure water to a residual sugar content of about 1 g. The supernatant was then filtered through a 0.22 μm organic filter membrane and used for Agilent 1260 Infinity II HPLC analysis.

[0051] Chromatographic conditions: Column: Bio R adAminex 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.

[0052] Quantitative method: With the peak area as the abscissa and the organic acid concentration as the ordinate, draw the organic acid standard curve, and calculate the contents of the six organic acids in the sample according to the regression equation.

[0053] 1.4.3 Determination of CIELab parameters

[0054] The wine color analyzer is used for measurement and deionized water is used as reference for calibration. Using a specific glass cuvette, the instrument can directly obtain the CIELab parameter a by continuously scanning the UV-Visible spectrum of 400 to 780 nm in the visible light region. * 、b * and L * 、C * ab 、h * ab and ΔE * ab .

[0055] 1.4.4 Determination of anthocyanins

[0056] The content of individual and total anthocyanins was determined using an LC-20AT high-performance liquid chromatography (HPLC) system (Shimadzu, Kyoto, Japan). Wine samples were filtered through a 0.22 μm organic filter membrane before analysis. A Synergi hydrorp C18 column (250 mm × 4.6 mm, 4 μm) was used with a mobile phase consisting of solvent A (purified water:acetonitrile:formic acid, 32:4:1, v / v / v) and solvent B (purified water:acetonitrile:formic acid, 16:20:1, v / v / v) at a flow rate of 1.0 mL / min. The gradient program was: 0–35% B (≥45 min), 35–100% B (≥1 min), 100% B (≥4 min), and 100–0% B (≥1 min). The injection volume was 20 μL, the detection wavelength was 520 nm, and the column was maintained at 35°C. Anthocyanidin species were identified by retention time, and the concentration of monomeric anthocyanins was calculated using a standard curve generated using malvidin-3-O-gluco-side. The total anthocyanin content was determined by integrating the total peak area.

[0057] 1.4.5 Determination of volatile substances

[0058] GC-MS was used for qualitative and quantitative analysis.

[0059] Sample preparation: Weigh 1.0 g of NaCl and add it to a 20 mL headspace vial, then add 5.0 mL of the wine sample and 10 μL of the internal standard (1000 mg / L 4-methyl-2-pentanol).

[0060] GC-MS analysis: PAL automatic sampler, the sample bottle is placed in the heating chamber, shaken and balanced at 400 rpm below 140°C for 30 minutes, and the extraction head is inserted into the sample and adsorbed at 40°C and 250 rpm for 30 minutes for injection.

[0061] Qualitative and quantitative analysis: The compounds were identified by comparing the retention index (RI) with the NIST Chemical webbook using the NIST14 spectral library. The compounds were quantified using the standard curve method. 2 Above 0.99.

[0062] 1.4.6 Sensory Tasting

[0063] Conducted at the College of Enology at Northwest Agriculture and Forestry University, the tasting panel consisted of 12 experienced wine tasting professionals (aged 19-25, 6 men and 6 women) who had undergone uniform training. The wine samples were divided into four groups based on the time of lactic acid addition and collectively underwent a comprehensive sensory evaluation in a professional tasting room. The sensory evaluation included 10 sensory attributes: appearance (color), aroma (aroma intensity, creamy aroma, floral aroma, fruity aroma, and unpleasant odors), taste (acidity, aftertaste, and harmony), and an overall evaluation. Each attribute in the sensory tasting evaluation was scored on a 5-point scale, with 0 to 5 indicating increasing intensity. Each taster was then asked to select their favorite wine.

[0064] 2 Experimental results

[0065] 2.1 Wine fermentation kinetics

[0066] The alcohol fermentation process of 13 bottles of wine was tested by hydrometry. The results are as follows Figure 1 As shown. The specific gravity was measured every 12 hours to monitor the fermentation dynamics. The fermentation duration ranged from 192 to 264 hours (8 to 11 days), and alcoholic fermentation was eventually completed, with slight differences. From the beginning of fermentation, the specific gravity of the 13 bottles of wine showed a sharp downward trend, with CK, A 1.5 , A2, A 2.5 、B 1.5 , B2, C 1.5 The eight groups of B and C2 completed fermentation on the 8th day. 2.5 、C 2.5 Fermentation was completed on the 9th day, D 1.5 , D2 completed fermentation on the 10th day, and D 2.5 Fermentation was completed on the 11th day, and the residual sugar was less than 4g / L, indicating insufficient fermentation power.

[0067] It can be seen that compared with the control group, the addition of lactic acid has a greater impact on the entire fermentation process. Fermentation lag occurs in many groups, and this phenomenon becomes more significant the later the lactic acid is added. It may be that the number of yeast is low in the later stage of fermentation, and the addition of lactic acid changes the environmental pH, which inhibits yeast activity and significantly reduces the sugar consumption rate.

[0068] 2.2 Basic physical and chemical indicators of wine

[0069] As shown in Table 1, the total acid content of the 12 lactic acid-added wine samples ranged from 5.17 to 6.68 g / L. The total acid content and pH of the lactic acid-added wine samples also showed a gradient over the same period. Compared to the control group, the total sulfur dioxide content of all 12 experimental groups was slightly lower, and the alcohol content (13.17% to 14.26% vol) was similar across the groups.

[0070] Table 1 Basic physical and chemical indicators of wine

[0071]

[0072] Depend on Figure 2 It can be seen that after adding lactic acid during the fermentation process, the lactic acid content measured on the second day showed a slight decrease. This may be because certain microorganisms in the wine consume some of the lactic acid during metabolism, and the lactic acid content then tends to stabilize. The day before the end of alcoholic fermentation, the lactic acid content shows a decrease again. The reason for this may be that the content of aroma substances (such as esters) in the wine is high in the late stage of alcoholic fermentation, which combine with lactic acid to form lactic acid esters.

[0073] Depend on Figure 3 As can be seen, the contents of the five organic acids—tartaric, malic, citric, succinic, and acetic—did not differ significantly across the wine samples. Comparing the lactic acid content of the wine samples at different times and at the same dosage revealed that the later the acid was added, the higher the lactic acid content and total acid content in the finished wine, indicating better acid retention.

[0074] 2.3 Effect of lactic acid regulation on wine color

[0075] The numerical values ​​of the CIELab parameters of the wine samples are shown in Table 2.

[0076] Table 2 CIELab parameters of wine samples

[0077]

[0078] L * The value reflects the glossiness of the wine sample, ranging from 0 (black) to 100 (white). * The range of brightness is between 42.64 and 57.00, and the glossiness of different wine samples varies greatly. 1.5 )L * The highest value is 57.00, wine sample 4 (B 1.5 )L * This to some extent explains that the colors of the two wine samples are brighter overall, while wine sample 12 (D 2.5 ) has the lowest glossiness, at 42.64, but is still within the bright range.

[0079] a * Represents the red and green color of the wine sample, Figure 4 It can be seen that compared with the control group, all wine samples * The values ​​of the two groups increased, indicating that the addition of lactic acid can improve the red hue of the wine samples to a certain extent. 1.5 ) * The highest value is 49.05, which indicates that the wine sample has more red components. * Represents the yellow-blue color of the wine sample, b* The smaller the value, the lower the yellow hue. * The value range is between 14.24 and 17.76, and the difference between the wine samples is not big. Wine sample 12 (D 2.5 )b * The highest value is 17.76, indicating that the wine sample has more yellow content; while wine sample 4 (B 1.5 )b * The lowest value.

[0080] Chroma C * ab Indicates the color saturation of the wine sample, which is a * and b * As a result of the combined effect, the larger the value, the higher the color saturation. Figure 4 It can be seen that compared with the control group, the chromaticity C * ab There was an increase in all of them, especially in sample 4 (B 1.5 ) and wine sample 6 (B 2.5 ) has the best color saturation. Hue h * ab Reflects the color tendency of the wine sample.

[0081] For red wine, the younger the wine, the higher its h * ab The smaller the value, the more purple or deep ruby ​​red the color characteristic is. As shown in Table 2, the color tone of the wine sample h * ab The difference is not big. * ab Indicates the degree of color difference between wine samples. The range of color difference that humans can observe is △E>0.5. If △E<0.5, the human eye will not be able to recognize the color difference between wine samples. Generally speaking, when △E exceeds 6, there is a strong color difference between the samples. 1.5 ) as a reference, as shown in Table 2, wine sample 3 (A 2.5 )、4(B 1.5 ) and 5(B2) were less than 6, indicating that there was no strong color difference between them and the reference wine sample, while the color differences of other wine samples were all greater than 6, which may be related to the addition time and amount of lactic acid.

[0082] Taking all parameters into consideration, wine sample 4 (B 1.5 ) has the best color, wine sample 1 (A 1.5 ) Color comes second.

[0083] 2.4 Effect of lactic acid regulation on anthocyanin content in wine

[0084] The main anthocyanins in wine have a strong absorption peak at 520nm. A total of 9 monomeric anthocyanins were detected by high performance liquid chromatography, including Dp 3-O-Glu, Cy 3-O-Glu, Pt 3-O-Glu, Pn 3-O-Glu, Mv 3-O-Glu, Pn 3-acetylglc, Mv 3-acetylglc, Pn 3-p-coumglc trans, and Mv 3-p-coumglc trans. Their contents in wine samples are as follows: Figure 6 As shown in Figure 2, the four monomer anthocyanins Dp 3-O-Glu, Pt 3-O-Glu, Mv 3-acetylglc, and Mv 3-p-coumglctrans were found in wine sample A. 1.5 The two anthocyanins Pt 3-O-Glu and Pn 3-O-Glu were found in wine sample B. 1.5 The highest content in it.

[0085] Depend on Figure 5 It can be seen that the highest total anthocyanin content is A 1.5 , is 333.41 mg / L. B 1.5 Total anthocyanin content was the next highest, at 292.92 mg / L. Sample D2 had the lowest total anthocyanin content, at only 159.77 mg / L, 44.18% less than the 286.25 mg / L total anthocyanin content in the control group, CK. This indicates that the timing and amount of lactic acid addition significantly impacted anthocyanin content, with earlier addition resulting in greater color protection.

[0086] 2.5 Correlation coefficients between anthocyanins and CIELab parameters in wines treated with different lactic acid

[0087] Anthocyanins are the main coloring substances in wine. Their content and structural stability have an important influence on the color quality of wine. During the winemaking process, changes in the composition and content of anthocyanins will affect the changes in the CIELab color parameters of wine, and the two have a certain correlation.

[0088] The correlation analysis between monomer anthocyanins and CIELab parameters in 13 groups of wine samples was performed using SPSS, and the results are shown in Table 3.

[0089] Table 3 Correlation coefficients between anthocyanins and CIELab parameters in wines treated with different lactic acid

[0090]

[0091] Note: “*” indicates significant correlation (p < 0.5); “**” indicates extremely significant correlation (p < 0.01).

[0092] It can be seen from the table that Pt 3-O-Glu and a * There was a significant negative correlation, that is, with the increase of Pt 3-O-Glu content, the wine a * The value (red hue) will be significantly reduced; Mv 3-acetylglc, Pn 3-p-coumglc trans, Mv3-p-coumglc trans and Mv 3-O-Glu are all significantly positively correlated; Mv 3-acetylglc and L * There was a very significant positive correlation between the anthocyanin and the wine sample A 1.5 The highest content and brightness in the medium, but with a * and c * There is a very significant negative correlation between L* and a * 、c * ab It is extremely significantly negatively correlated with △E; a * with c * The correlation between lactic acid and wine color is highly significant. These correlations provide a scientific basis for wine quality control, demonstrating that lactic acid addition plays a significant role in influencing wine color and hue. Precise lactic acid regulation can more precisely control wine color, thereby enhancing its market value and consumers' sensory experience.

[0093] 2.6 Effect of lactic acid regulation on wine aroma compounds

[0094] The aroma quality of wine is a crucial sensory characteristic that significantly influences its overall appeal and consumer preference. Quantitative aroma compound analysis of wine samples is presented in Table 4-13. A total of 57 aroma compounds were detected, including 23 esters, 17 higher alcohols, 6 acids, 4 ketone aldehydes, and 7 isopentenoids.

[0095] Table 4 Analysis of aroma compound content in wines treated with different lactic acid additions

[0096]

[0097] Table 5 Analysis of aroma compound content in wines treated with different lactic acid additions

[0098]

[0099] Table 6 Analysis of aroma compound content in wines treated with different lactic acid additions

[0100]

[0101] Table 7 Analysis of aroma compound content in wines treated with different lactic acid additions

[0102]

[0103] Table 8 Analysis of aroma compound content in wines treated with different lactic acid additions

[0104]

[0105] Table 9 Analysis of aroma compound content in wines treated with different lactic acid additions

[0106]

[0107] Table 10 Analysis of aroma compounds in wines treated with different lactic acid additions

[0108]

[0109] Table 11 Analysis of aroma compounds in wines treated with different lactic acid additions

[0110]

[0111] Table 12 Analysis of aroma compounds in wines treated with different lactic acid additions

[0112] RT / min Aroma substances Threshold (μg / L) OAV range Odor description 6.11 Ethyl acetate 7500.00 ＞1 Sweet, fruity 7.42 Ethyl isobutyrate 16.00 0.1～1 Candy, rubber 8.46 Isobutyl acetate 1600.00 <0.1 Banana, fruity 9.05 Ethyl butyrate 20.00 ＞1 cranberries, strawberries 9.49 Ethyl 2-methylbutyrate 18000.00 <0.1 Raw green flavor, mature water 9.96 Ethyl isovalerate 3.00 ＞1 Bananas, sweet fruits 11.70 Isoamyl acetate 30.00 ＞1 Bananas, sweet fruits 15.85 Ethyl hexanoate 10.00 ＞1 Green apple, strawberry 17.42 Hexyl acetate 670.00 <0.1 Pear, sweet and sour 20.40 Ethyl lactate 150000.00 0.1～1 Frankincense, Rubus 22.32 Methyl octanoate 200.00 <0.1 Tangerine 24.21 Ethyl octanoate 5.00 ＞1 pineapple 25.16 Isoamyl hexanoate 1400.00 <0.1 Banana, sweet 28.32 Ethyl nonanoate 1300.00 <0.1 Fruit, banana 32.38 Ethyl decanoate 200.00 0.1～1 Pleasant fat taste 33.93 Diethyl succinate 15.00 ＞1 Fruity fragrance 36.95 Geranyl acetate 100.00 0.1～1 Strawberries and flowers 37.97 Methyl salicylate 25.00 0.1～1 peaches, strawberries 39.18 Ethyl salicylate 2.00 ＞1 Floral scent 39.26 Phenethyl acetate 250.00 0.1～1 Floral, peach 39.93 Ethyl laurate 1500.00 <0.1 Fruity, floral, cheese 42.08 Oak lactone 500.00 0.1～1 Woody scent, bay leaves 53.21 Ethyl palmitate 1500.00 0.1～1 Apple, pineapple, cream Esters 8.99 n-Propanol 50000.00 ＞1 Alcohol smell 10.49 Isobutanol 40000.00 ＞1 Fusel aroma 12.28 n-Butanol 150000.00 <0.1 Rich, herbal 14.66 Isoamyl alcohol 30000.00 ＞1 Banana, fruity 15.85 n-pentanol 100000.00 0.1～1 Vanilla, almond 18.98 4-Methyl-1-pentanol 5000.00 <0.1 Raw green flavor 20.61 3-Methyl-1-pentanol 500.00 ＞1 Spicy, grassy

[0113] Table 13 Analysis of aroma compounds in wines treated with different lactic acid additions

[0114] RT / min Aroma substances Threshold / (μg / L) OAV range Odor description 20.86 n-Hexanol 8000.00 0.1～1 Spicy, grassy 21.39 (E)-3-Hexen-1-ol 400.00 ＞1 coriander 22.03 (Z)-3-Hexen-1-ol 0.40 ＞1 Raw green flavor 24.21 1-Octen-3-ol 20.00 ＞1 Herbal, floral 25.16 Heptanol 2500.00 <0.1 Green, sweet 29.10 n-octanol 900.00 <0.1 Jasmine, lemon 35.52 3-Methylmercaptopropanol 300.00 ＞1 Sulfide and onion smell 37.32 Decyl alcohol 400.00 <0.1 Orange blossom, citrus scent 41.40 Benzyl alcohol 41.00 ＞1 Baked aroma, sweet taste 42.60 Phenylethyl alcohol 1400.00 ＞1 Floral, pollen scent Higher alcohols 25.05 Acetic acid 200000.00 0.1～1 Acetic acid 30.46 Isobutyric acid 2300.00 ＞1 Butter, cream, rancidity 34.41 Isovalerate 33.40 ＞1 Cheese, fruit 40.10 Hexanoic acid 420.00 ＞1 Woody, cheese 47.27 bitter 500.00 ＞1 spicy 53.79 Decanoic acid 10000.00 0.1～1 Fatty taste fatty acids 22.03 Nonanal 14100.00 <0.1 Herbs, toast 26.33 furfural 10.00 ＞1 leather, tallow 26.91 decanal 0.15 ＞1 spices 28.22 Benzaldehyde 5.00 ＞1 Bees, candy Ketone aldehydes 27.17 Geraniol 20.00 ＞1 Lemon, Rose 28.31 2-Methoxy-3-isobutylpyrazine 0.00500 ＞1 Green peppers, spices, soil 31.54 4-terpene alcohol 0.01 ＞1 Tangerine 34.41 α-Terpineol 250.00 <0.1 Citrus fruits 37.33 Citronellol 40.00 ＞1 Grass, lemon, cloves 38.66 Nerolidol 400.00 0.1～1 Floral, sweet 43.45 β-ionone 9.00 ＞1 Violet, sweet fruit Isopentenoids

[0115] The results showed that due to the addition of lactic acid, the content of ethyl lactate in the 12 experimental wine samples increased significantly. Its content showed a gradient change with the addition of lactic acid, and increased by 25.47 to 63.03 times compared with the control group, bringing more frankincense to the wine samples. The content of ethyl acetate also increased to a certain extent. 1.5 The highest level was 61221.27 μg / L, which enhanced the fruity and sweet aroma of the wine. In addition, isoamyl acetate, ethyl butyrate, ethyl octanoate, isoamyl alcohol, and phenylethyl alcohol were found in wine sample A. 1.5 and B 1.5 It also showed a high level.

[0116] In order to better analyze the effect of lactic acid addition on wine aroma substances, principal component analysis was performed on 26 substances with OAV>1. These 26 substances were divided into 7 major categories: acetates, short-chain fatty acid ethyl esters, medium-chain fatty acid ethyl esters, alcohols, acids, aldehydes and ketones, and isopentenoids. SIMCA was used to perform PCA analysis on their contents. The results are as follows: Figure 7 As shown in Figure 2, a total of 86.9% of the total variance was explained, of which PC1 and PC2 explained 61.1% and 25.8% of the variance respectively, and the wine samples were well distinguished. Figure 7It can be seen that aroma substances with OAV>1 are mainly distributed on the positive semi-axis of PC1. 1.5 and B 1.5 Acetates, short-chain fatty acid ethyl esters, medium-chain fatty acid ethyl esters and acids were highly accumulated in wine sample B. 1.5 The contents of higher alcohols were 61702.63, 404.76, 2347.06 and 18619.03 μg / L respectively, while the contents of higher alcohols in wine sample A were 1.5 The highest content was 577296.33 μg / L.

[0117] It can be seen that adding 1.5g / L lactic acid (A 1.5 ) and adding 1.5g / L lactic acid (B 1.5 ), which can significantly increase the content of aroma substances in wine.

[0118] 2.7 Sensory Analysis

[0119] The wine tasting panel evaluated and scored the 13 wine samples based on appearance (color), aroma (aroma intensity, creamy aroma, floral aroma, fruity aroma, unpleasant odor), taste (acidity, aftertaste, coordination), and comprehensive evaluation. The results are as follows: Figure 8 As shown by Figure 8 From a, we can see that wine sample A 1.5 The highest comprehensive score is 4.2 points; Figure 8 As can be seen in b, wine sample B 1.5 It has a high evaluation in terms of both aroma and taste, with an overall score of 4.5 points; Figure 8 As can be seen from middle c, wine sample C2 has the highest overall score of 3.5 points, but compared with the previous two periods, the positive reviews have dropped significantly; Figure 8 It can be seen from Figure d that among the three wine samples to which lactic acid was added on the fourth day of fermentation, D 1.5 The results showed a good score, but compared with the control group, the addition of lactic acid in the last two periods improved the aroma score, but the taste was obviously insufficient and bland. 1.5 The highest relative score.

[0120] 3 Conclusion

[0121] The addition of lactic acid has a great impact on the entire fermentation process. Fermentation lag occurs in many groups. This phenomenon is more obvious the later the lactic acid is added. It may be that the yeast population is low in the late fermentation stage. The addition of lactic acid changes the pH of the environment, which inhibits yeast activity and significantly reduces the sugar consumption rate. The content of lactic acid in each group of wine samples with the same addition amount at different times shows that the later the acid is added, the higher the lactic acid content in the finished wine, the higher the total acid content, and the better the acidity is maintained. Through CIELab parameter analysis, wine sample 1 (A 1.5 )L* The highest value is 57.00, wine sample 4 (B 1.5 )L * Secondly, all wine samples * The values ​​of the two groups increased, indicating that the addition of lactic acid can improve the red hue of the wine samples to a certain extent. 1.5 ) * The highest value is 49.05. Considering all the parameters, wine sample 4 (B 1.5 ) has the best color performance, wine sample 1 (A 1.5 ) followed by wine sample A. 1.5 , is 333.41 mg / L. B 1.5 The total anthocyanin content was second, at 292.92 mg / L. The total anthocyanin content in wine sample D2 was the lowest, at only 159.77 mg / L, which was 44.18% less than the total anthocyanin content of the control group CK (286.25 mg / L). This shows that the time and amount of lactic acid addition have a significant effect on the anthocyanin content. The earlier the addition period, the better the color protection effect. Correlation analysis showed that Mv 3-acetylglc, Pn 3-p-coumglc trans, Mv3-p-coumglc trans and Mv 3-O-Glu were all significantly positively correlated; Mv 3-acetylglc and L * There was a very significant positive correlation between the anthocyanin and the wine sample A 1.5 The highest content and brightness in the medium, but with a * and c * There is a very significant negative correlation between L* and a * 、c * ab It is extremely significantly negatively correlated with △E; a * with c * There is a very significant positive correlation. 1.5 and B 1.5 Acetates, short-chain fatty acid ethyl esters, medium-chain fatty acid ethyl esters and acids were highly accumulated in wine sample B. 1.5 The contents of higher alcohols were 61702.63, 404.76, 2347.06 and 18619.03 μg / L respectively, while the contents of higher alcohols in wine sample A were 1.5 The highest content is 577296.33μg / L. It can be seen that when 1.5g / L lactic acid (A 1.5 ) and adding 1.5g / L lactic acid (B 1.5 ), which can significantly increase the content of aroma substances in wine. 1.5 The relative score was the highest, indicating a high preference for aroma and taste.

[0122] In summary, experimental group B 1.5 The wine quality is the best, that is, adding 1.5g / L lactic acid during fermentation can obtain higher quality wine. Through precise lactic acid regulation, a scientific basis is provided for wine quality control.

[0123] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing wine by synergistically brewing lactic acid, characterized in that: The following steps are involved: After the grape mash is homogenized, color-protecting tannins are added and the mash is squeezed. After the squeezing is completed, pectinase is added, and potassium metabisulfite, brewer's yeast powder and lactic acid are added for fermentation. After the fermentation is completed, the wine can be obtained.

2. The preparation method according to claim 1, characterized in that The added amount of the color-protecting tannin is 200 mg / L; the added amount of the pectinase is 40 mg / L; and the added amount of the potassium metabisulfite is 20 mg / L.

3. The preparation method according to claim 1, characterized in that The added amount of the saccharomyces cerevisiae dry powder is 200 mg / L.

4. The preparation method according to claim 1, characterized in that The added amount of the lactic acid is 1.5 g / L.

5. The preparation method according to claim 1, characterized in that The fermentation temperature is 18-25°C.

6. The preparation method according to claim 1, characterized in that The fermentation is completed when the residual sugar content is less than 4g / L.

7. Wine prepared according to the preparation method according to any one of claims 1 to 6.

Images