Preparation method of kiwi fruit wine

Abstract

The invention discloses a preparation method of kiwi fruit wine. According to the disclosed method, apple freeze-dried powder is added into the kiwi fruit frozen concentrated juice, so that saccharomycetes can have more precursor substances for producing metabolites through fermentation, more phenolic substances and ester substances are accumulated in the fermentation process of the kiwi fruit frozen concentrated juice, the nutritional value and aroma components are increased, and the quality of the kiwi fruit ice wine is improved; according to the method disclosed by the invention, the phenolic substances and the ester aroma substances in the kiwi fruit wine are increased, the process is simple and effective, and the phenolic substances and the ester aroma substances in the kiwi fruit wine can be increased by only adding a small amount of saccharomyces cerevisiae.

Description

Technical Field

[0001] The invention belongs to the technical field of kiwi wine brewing, relates to kiwi wine with high phenolic substance content, shortens fermentation time and is a preparation method of kiwi wine with rich aroma components. Background Art

[0002] Nutritional content and aroma are important indicators for evaluating the quality of kiwi ice wine, an important component of the typical style of kiwi ice wine, and one of the main bases for determining the type of kiwi ice wine. The aroma of kiwi ice wine is mainly composed of esters, alcohols, acids, aldehydes, etc., among which esters usually contribute the most to the aroma, with a pleasant fruity aroma. Kiwi ice wine that has been fermented with apple pomace freeze-dried powder and yeast also has rich phenolic substances and antioxidant capacity, which makes kiwi ice wine a new direction in kiwi processing. Kiwis are not resistant to storage and there are few types of processed products. Deep processing of them for nutrition and health is one of the important measures to solve the problem of overcapacity. Summary of the invention

[0003] In view of the defects or shortcomings of the prior art, the present invention provides a method for preparing kiwi wine.

[0004] To this end, the preparation method of kiwi wine provided by the present invention comprises:

[0005] Step 1, adding apple freeze-dried powder with a mass percentage concentration of 2-4% to kiwi fruit frozen concentrated juice, and then keeping it warm at 65±5°C for 10-30 minutes; the preparation method of the kiwi fruit frozen concentrated juice is: thawing the frozen kiwi fruit, peeling and squeezing the juice; then adding pectinase to the kiwi fruit juice for enzymatic hydrolysis, and then centrifuging to collect clarified juice; then completely freezing the clarified juice at -20±5°C, and then transferring it to a 4±2°C refrigerator to thaw, and collecting the thawed liquid juice as the kiwi fruit frozen concentrated juice;

[0006] Step 2, adding brewer's yeast to the insulated kiwi fruit frozen concentrated juice for fermentation until the alcohol content of the fermented juice reaches 8-11% and does not increase any more, and then the fermentation is terminated;

[0007] Step 3, collecting the supernatant in the fermented juice to obtain kiwi wine.

[0008] An optional scheme is that the method for preparing the frozen concentrated kiwifruit juice is as follows: after thawing the frozen kiwifruit, peel and squeeze out the juice; then, pectinase is added to the kiwifruit juice for enzymatic hydrolysis and then centrifuged to collect the clarified juice; then, the clarified juice is completely frozen at -20±5°C, and then transferred to a 4±2°C refrigerator to thaw, the thawed liquid juice is collected, the liquid juice is completely frozen again at -20±5°C and then thawed at 4±2°C, the clarified juice is frozen and thawed 2-3 times, and the collected liquid juice is used as the frozen concentrated kiwifruit juice.

[0009] An optional solution is that the preparation method of the apple freeze-dried powder is: freezing the apple pomace after squeezing the juice at -20±5°C, then drying it under vacuum freezing conditions of -50±5°C and 4-6Pa pressure, and then powdering the pomace and passing it through a 40-mesh sieve to obtain the apple freeze-dried powder.

[0010] An optional solution is that the brewer's yeast uses brewer's yeast CGMCC NO.2786, and the fermentation time is 8 days.

[0011] An optional solution is that after adding the apple freeze-dried powder in step 1, the sugar content of the kiwi fruit frozen concentrated juice is 19-20° Brix and the pH is 3-4.

[0012] The method of the present invention adds apple freeze-dried powder to kiwi fruit frozen concentrated juice, so that yeast can have more precursor substances for fermenting and producing metabolites, and more phenolic substances and ester substances are accumulated in the fermentation process of kiwi fruit frozen concentrated juice, thereby increasing the nutritional value and aroma components and improving the quality of kiwi fruit ice wine; wherein the kiwi fruit juice obtained by freezing, freezing, thawing and clarifying has the advantage of better maintaining the nutritional components and flavor of kiwi fruit, smaller volume and longer shelf life.

[0013] The method of the invention increases the phenolic substances and ester aroma substances in the kiwi fruit wine, the process is simple and effective, and only a small amount of brewer's yeast is added to increase the phenolic substances and ester aroma substances in the kiwi fruit wine.

[0014] In the scheme of the present invention, apple freeze-dried powder is added to shorten the fermentation time of kiwi ice wine from 12 days to 8 days, and the kiwi ice wine is rich in phenolic substances and ester substances. DETAILED DESCRIPTION

[0015] Unless otherwise specified, the scientific and technical terms used herein are understood according to the knowledge of ordinary technicians in the relevant fields.

[0016] The following are examples provided by the inventor to further explain the technical solution of the present invention. The following examples all use Xuxiang kiwifruit from Zhouzhi County, Xi'an City, Shaanxi Province as raw materials.

[0017] Embodiment 1:

[0018] This example uses apple freeze-dried powder as a nutritional enhancer, and uses Luochuan apples from Luochuan County, Yan'an City, Shaanxi Province as raw materials; uses brewer's yeast CGMCC NO.2786 to ferment and produce kiwi ice wine; uses Xuxiang kiwi fruits with emerald green flesh and eighty-mature, removes moldy fruits and impurities, and selects slightly mature and soft kiwi fruits for use. The steps are as follows:

[0019] (1) Preparation of frozen concentrated kiwifruit juice: the fruit is placed at room temperature for 2-3 days to soften, and then placed in a cold storage at about -20±5°C for 10 days to completely freeze the fruit and complete the enrichment of sugar. The sorted frozen fruit is thawed naturally at 4±2°C, peeled and cut into pieces, and juice is squeezed at low temperature using a wall breaking machine to increase the concentration of nutrients in the juice; then 20 mg / L pectinase is added and the fruit is placed in a 30±5°C water bath for 60 minutes; then centrifuged in a high-speed refrigerated centrifuge for 10 minutes at a speed of 5000 rpm to remove the bottom pomace to obtain clarified juice; then the clarified juice is frozen in a -20±5°C refrigerator to completely freeze it, the frozen juice is transferred to a 4±2°C cold storage room to slowly thaw, the thawed liquid juice is collected, the liquid juice is completely frozen again at -20±5°C and then slowly thawed in a 4±2°C cold storage room, and the above freezing, thawing and collection processes are repeated, and the liquid juice obtained by the third operation is used as kiwifruit frozen concentrated juice.

[0020] (2) Specific preparation method of apple freeze-dried powder: After the apples are juiced, the remaining pomace is collected and evenly spread on a pre-freezing plate, and pre-frozen in a freezing chamber at -20±5°C for 12 hours to form uniform ice crystals; after the pre-freezing is completed, the pomace is quickly transferred to a vacuum freeze dryer set at -50±5°C and a pressure of 5Pa, and dried for 48 hours to allow the water to directly sublimate and dry; the dried pomace is powdered and sieved through a 40-mesh sieve to obtain apple freeze-dried powder.

[0021] (3) Preparation of frozen concentrated kiwifruit juice: add 3% apple freeze-dried powder to the frozen concentrated kiwifruit juice to make the sugar content 19.5° Brix and the pH value about 3.5. After preparation, place the mixture in a constant temperature water bath at 65±5°C for 20 minutes and finally place the mixture in a sterile fermentation bottle.

[0022] (4) Activation culture of Saccharomyces cerevisiae: 500 μL of yeast culture medium was added to 50 mL of sterile YPD liquid culture medium and cultured in a constant temperature shaking incubator at 28±5°C for 24 h.

[0023] (5) Fermentation of frozen concentrated kiwifruit juice: The activated brewer's yeast was inoculated into the prepared frozen concentrated kiwifruit juice at a volume ratio of 5%, and the juice was fermented at a constant temperature of 20±2°C for 8 days; no bubbles were generated in the fermentation bottle, and there was a clear fermentation aroma. The alcohol content reached 8-11% and did not rise any more, and the fermentation was terminated.

[0024] (6) Collection of kiwifruit ice wine: centrifuge the fermentation liquid at 5000 rpm for 10 minutes in a high-speed refrigerated centrifuge, take the supernatant, and remove the raw material residue and yeast precipitate at the bottom.

[0025] Comparative Example 1:

[0026] Different from the above-mentioned Example 1, this comparative example uses sucrose to prepare the frozen concentrated kiwifruit juice, so that the sugar content of the frozen concentrated kiwifruit juice is 19.5° Brix, the pH is fixed at 3.5, and after preparation, it is bathed in a constant temperature water bath at 65°C for 20 minutes and finally placed in a sterile fermentation bottle; and the fermentation time is 12 days.

[0027] The kiwi ice wine prepared in the above-mentioned Example 1 and Comparative Example 1 was tested, and three parallel tests were conducted. The following tests and evaluations were performed on the fruit wines of the example, comparative example 1 (fermentation for 8 days) and comparative example 1 (fermentation for 12 days), respectively.

[0028] (1) Sensory evaluation criteria are shown in Table 1.

[0029] Table 1 Sensory evaluation standards for kiwi ice wine

[0030]

[0031]

[0032] (2) Chroma detection: The chroma of kiwi ice wine was determined by colorimetry, and the colorimeter Lab system was used, with ultrapure water as the control, to accurately measure the chroma value of the sample. L* value (brightness, reflecting the brightness of the color), a* value (positive number represents red, negative number represents green), b* value (positive number represents yellow, negative number represents blue), the test was repeated 3 times. In the test, the L*, a*, and b* value mode was used to measure and evaluate the color of the juice. 20 mL of each example was taken in a colorimetric dish, and the colorimeter was placed close to the plastic wrap, and the L*, a*, and b* values ​​were measured using a colorimeter.

[0033] (3) Soluble solid content detection: Referring to the determination method of soluble solid content in NY / T 2637-2014, the soluble solid content (SSC) of kiwifruit juice was determined using a refractometer (unit: °Brix).

[0034] (4) Total sugar detection: refer to GB / T15038-2006, use Fehling's reagent direct titration method, and the total sugar content is calculated as glucose.

[0035] (5) Total acid detection: refer to GB12456-2021, the determination standard of total acid in food, and adopt the acid-base indicator titration method.

[0036] (6) Total phenol detection: The total phenol content of kiwi ice wine was determined by Folin phenol spectrophotometry. The test should be carried out in a dark environment. Within a certain concentration range, the absorbance is proportional to the content of phenolic compounds, and the unit is gGAE / L, where GAE represents gallic acid equivalent.

[0037] (7) Alcohol content detection: refer to GB5009.225-2016 Determination of ethanol concentration in wine, and use the alcohol meter method to determine the alcohol content of kiwi ice wine, the unit is (% vol).

[0038] (8) pH detection: Referring to GB10468-89, pH determination method for fruit and vegetable products, the pH value of kiwi ice wine was determined using a pH meter.

[0039] (9) Organic acid detection: With reference to GB5009.157-2016 Determination of organic acids in food, high performance liquid chromatography was used to determine the organic acids in kiwi ice wine.

[0040] (10) Polyphenol detection: The phenolic compounds in the example were separated by ethyl acetate extraction, and the polyphenols in kiwi ice wine were determined by high performance liquid chromatography.

[0041] (11) Detection of aroma components: The aroma components are enriched by headspace-solid phase microextraction (HS-SPME) technology using a GC-MS system. The unknown compounds in the sample are identified using GC / MS solution software and matched with the NIST14 mass spectral library to identify the unknown volatile substances. Only identification results with a similarity greater than 90% are reported. The retention time and mass spectrum information of the unknown compound are compared with the standard. The internal standard method is used to quantitatively analyze the volatile substances after qualitative analysis.

[0042] (12) Amino acid detection: With reference to GB5009.124-2016 Determination of amino acids in food, the amino acids in kiwi ice wine were determined using an amino acid analyzer.

[0043] The results are as follows:

[0044] Table 2 Chroma of kiwifruit ice wine of Comparative Example 1 fermented for 12 days and Example 1 fermented for 8 days

[0045] Ice wine L* a* b* ΔE* Comparative Example 1 (12 days) 89.91 -2.48± 33.68±0.06 35.40±0.06 Comparative Example 1 (8 days) 86.47 -2.62± 32.44±0.03 32.04±0.00 Example 1 91.27 -1.95± 39.04±0.01 40.20±0.01

[0046] As shown in Table 2, the L* of Example 1 is larger, indicating that the color of the wine sample is clearer, brighter, and easier to get a higher evaluation in the color item of sensory evaluation. In the chromaticity, the b value represents the yellow-blue degree, and the b* values ​​of the two wine samples are positive, showing a pleasant light yellow color, which meets the sensory requirements of kiwi ice wine.

[0047] Table 3 Sensory and physical and chemical indicators of kiwi ice wine of comparative example 1 fermented for 12 days and example 1 fermented for 8 days

[0048]

[0049] As shown in Table 3, the total phenol content of Example 1 with the addition of apple freeze-dried powder is 4.68gGAE / L, which has a higher total phenol content. According to the provisions of QBT5476-2020 General Technical Requirements for Fruit Wine, the alcohol content of fruit wine at 20°C should be ≥2.0%vol. The alcohol content of Comparative Example 1 and Example 1 are 9.01%vol and 8.97%vol, respectively, both of which meet the standards. In terms of sensory scores, Example 1 is 5.25 points higher than that of Comparative Example 1, which may have higher consumer satisfaction and help improve product market competitiveness.

[0050] Table 4 Organic acid content of kiwifruit ice wine in Comparative Example 1 fermented for 12 days and Example 1 fermented for 8 days

[0051] Organic Acid Comparative Example 1 (12 days) Comparative Example 1 (8 days) Example 1 oxalic acid 0.21±0.00 0.22±0.02 0.29±0.01 tartaric acid 0.60±0.03 0.55±0.05 1.22±0.02 Quinic acid 11.11±0.02 11.13±0.03 11.28±0.11 Malic Acid 1.46±0.11 1.03±0.08 11.89±0.11 Pyruvate 1.33±0.12 1.15±0.04 2.43±0.01 L-(+)-Lactic Acid 9.10±0.40 8.97±0.09 11.13±0.08 Acetic acid 0.79±0.13 0.81±0.03 0.97±0.03 Alpha-ketoglutarate 0.11±0.01 0.10±0.03 0.09±0.01 Succinic acid 0.02±0.00 0.04±0.01 1.40±0.07 Citric Acid 0.42±0.01 0.36±0.02 0.33±0.01

[0052] As shown in Table 4, the content of quinic acid in Comparative Example 1 is the highest, 11.11 mg / mL, followed by lactic acid 9.10 mg / mL. The content of malic acid in Example 1 is the highest, 11.89 mg / mL, followed by quinic acid 11.28 mg / mL.

[0053] QBT5476.3-2023 stipulates that the volatile acid (acetic acid) content in kiwifruit wine shall not exceed 1.2 mg / mL. The acetic acid content of comparative example 1 and example 1 of this patent is relatively low, 0.97 mg / mL and 0.79 mg / mL respectively, indicating that it has a good fermentation environment.

[0054] Table 5 Polyphenol content of kiwifruit ice wine in Comparative Example 1 fermented for 12 days and Example 1 fermented for 8 days

[0055]

[0056]

[0057] As shown in Table 5, compared with Comparative Example 1, the kiwi ice wine of Example 1 has the highest catechin content, reaching 39.32 mg / L, followed by epicatechin and EGC, which are 19.11 mg / L and 19.87 mg / L, respectively. The contents of ferulic acid and caffeic acid are relatively low, not exceeding 2 mg / L. The contents of the six phenolic substances first increased and then decreased during the fermentation period, and finally stabilized. In addition, the polyphenol content of Example 1 is higher than that of the ordinary type. The addition of apple pomace freeze-dried powder increases the polyphenol content, especially chlorogenic acid, which improves the nutritional value and health function of ice wine.

[0058] The comparison shows that when the nutritional fortified kiwi ice wine of Example 1 was fermented to the eighth day, its polyphenol content was similar to that of the kiwi ice wine of Comparative Example 1 after fermentation for 12 days, or even higher, except for ellagic acid, rutin, ECG, ferulic acid and quercetin. This shows that the addition of apple freeze-dried powder can increase the polyphenol content in kiwi ice wine and shorten the fermentation time to 8 days. The polyphenol content is affected by factors such as raw material variety and brewing process. Yeast selection and fermentation temperature control are crucial to the release and conversion of polyphenols.

[0059] Table 6 Aroma component content of kiwi ice wine of Comparative Example 1 fermented for 12 days and Example 1 fermented for 8 days

[0060]

[0061]

[0062]

[0063] As shown in Table 6, a total of 80 volatile substances were detected from the kiwi ice wine of Comparative Example 1 and Example 1, and 51 substances with SI values ​​greater than 90 were semi-quantitatively analyzed, which can be divided into alcohols, aldehydes, ketones, acids, acetates, ethyl esters, other esters, and terpenes. 34 volatile substances were detected in Comparative Example 1, including 15 total phenolic contents, 9 alcohol substances, 4 aldehyde substances, 4 acid substances, 1 ketone substance, and 1 terpenoid substance. 39 volatile substances were detected in Example 1, including 23 total phenolic contents, 7 alcohol substances, 6 acid substances, and 3 aldehyde substances. The results prove that the kiwi ice wine has an ideal aroma.

[0064] Table 7 Amino acid content of kiwifruit ice wine in Comparative Example 1 fermented for 12 days and Example 1 fermented for 8 days

[0065]

[0066] As shown in Table 7, the kiwifruit ice wine of Comparative Example 1 and Example 1 has rich amino acid species, and 16 amino acids except methionine are detected, including essential amino acids and non-essential amino acids. Among the 17 amino acids detected in Comparative Example 1 and Example 1, glutamic acid has the highest content, followed by aspartic acid. Glutamic acid has a delicious taste and can make the ice wine product taste more mellow, while aspartic acid gives the kiwifruit wine a unique sweet taste, making the wine more balanced and coordinated.

[0067] Combined with the results shown in Tables 2-7, in terms of sensory score and color, the L* value of Example 1 is larger, indicating that its color is clearer and brighter, and the sensory score is also higher (89.25 points), relative to 84.00 points of Comparative Example 1 (12 days) and 80.33 points of Comparative Example 1 (8 days), which may mean that Example 1 is more preferred in color and sensory evaluation. In terms of physical and chemical indicators, Example 1 has the highest soluble solids content, which may mean higher sugar content and may bring a richer taste. Example 1 has the lowest pH value, indicating that its acidity may be higher, which may affect the taste and flavor. In addition, the alcohol content of Example 1 is slightly lower than that of Comparative Example 1 (12 days), but it still meets the provisions of QBT5476-2020 General Technical Requirements for Fruit Wine. At the same time, the total sugar and total acid contents of Example 1 are higher than those of Comparative Example 1, which may affect the sweetness and acidity balance of ice wine. In terms of organic acid content, the malic acid content in Example 1 is the highest. Malic acid is one of the important organic acids that affect the flavor of fruit wine, and its high content may bring more distinct flavor characteristics. In terms of polyphenol content, the total phenol content of Example 1 is significantly higher than that of Comparative Example 1, especially the content of polyphenols such as catechins, EGC and epicatechin is higher. These substances are beneficial to health and may have a positive effect on the flavor and color of ice wine. In terms of volatile component content, the types and contents of volatile substances detected in Example 1 are higher, which may mean that its aroma is more complex and rich, which is beneficial to improving the overall sensory experience of ice wine. Finally, the amino acid content in Example 1 is similar to that in Comparative Example 1, indicating that Example 1 can also maintain the richness of amino acids in ice wine in a shorter period of time, which is important for improving the nutritional value and taste of ice wine.

[0068] In summary, compared with Comparative Example 1 fermented for 8 and 12 days, Example 1 showed higher sensory scores, richer volatile components and polyphenol content, and good physical and chemical indicators in a shorter period of time, which makes it have obvious advantages in a shorter period of time, may be more popular with consumers, and help improve the market competitiveness of the product.

Claims

1. A method for preparing kiwi wine, characterized in that: Methods include: Step 1, adding apple freeze-dried powder with a mass percentage concentration of 2-4% to kiwi fruit frozen concentrated juice, and then keeping it warm at 65±5°C for 10-30 minutes; the preparation method of the kiwi fruit frozen concentrated juice is: thawing the frozen kiwi fruit, peeling and squeezing the juice; then adding pectinase to the kiwi fruit juice for enzymatic hydrolysis, and then centrifuging to collect clarified juice; then completely freezing the clarified juice at -20±5°C, and then transferring it to a 4±2°C refrigerator to thaw, and collecting the thawed liquid juice as the kiwi fruit frozen concentrated juice; Step 2, adding brewer's yeast to the insulated kiwi fruit frozen concentrated juice for fermentation until the alcohol content of the fermented juice reaches 8-11% and does not increase any more, and then the fermentation is terminated; Step 3, collecting the supernatant in the fermented juice to obtain kiwi wine.

2. The method for preparing kiwi wine according to claim 1, characterized in that: The method for preparing the frozen concentrated kiwifruit juice comprises the following steps: thawing the frozen kiwifruit, peeling and juicing the kiwifruit; then adding pectinase to the kiwifruit juice for enzymatic hydrolysis and collecting the clarified juice by centrifugation; then completely freezing the clarified juice at -20±5°C, transferring it to a 4±2°C cold storage room for thawing, collecting the thawed liquid juice, completely freezing the liquid juice again at -20±5°C, and then thawing it at 4±2°C, repeating the freezing and thawing process for the clarified juice 2-3 times, and collecting the collected liquid juice as the frozen concentrated kiwifruit juice.

3. The method for preparing kiwi wine according to claim 1, characterized in that: The preparation method of the apple freeze-dried powder comprises: freezing the apple pomace after juicing at -20±5°C, then drying it at -50±5°C and 4-6Pa vacuum freezing conditions, and then pulverizing the pomace and sifting it through a 40-mesh sieve to obtain the apple freeze-dried powder.

4. The method for preparing kiwi wine according to claim 1, characterized in that: The brewer's yeast is brewer's yeast CGMCC NO.2786, and the fermentation time is 8 days.

5. The method for preparing kiwi wine according to claim 1, characterized in that: After the freeze-dried apple powder is added in step 1, the sugar content of the kiwi fruit frozen concentrated juice is 19-20° Brix and the pH is 3-4.

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