Fruit wine preparation method based on citrus fruit koji fermentation

Abstract

The invention relates to the technical field of fruit wine preparation, and discloses a fruit wine preparation method based on citrus fruit koji fermentation, which comprises the following steps: step 1, raw material treatment: selecting citrus fruits with a sugar-acid ratio of 10: 1-12: 1, sequentially performing warm water soaking and ozone water cleaning, peeling and pulping, and controlling the particle diameter of fruit pulp to be 0.5-1.5 mm; step 2, fruit pulp pretreatment: pectinase is added into the fruit pulp, the use amount of pectinase is 500-1000 U / mL, and the mixture is uniformly stirred at 45 DEG C and treated for 30 minutes; and step 3, fermentation: in a closed fermentation tank, adding fruit koji and high-yield koji into the fruit pulp. Through optimization of fermentation temperature, combined use of fruit koji and high-yield koji and graded addition of sugar, the problem of inhibition of high acidity and high pectin content of citrus pulp on yeast activity is solved, and the alcohol conversion rate is remarkably increased and finally reaches 85% or above. Compared with a traditional process, the fermentation period is shortened from 10-12 days to 7 days, meanwhile, the alcoholic strength is controlled within the ideal range of 8%-12%, and the fermentation efficiency is improved by nearly 20%.

Description

Technical Field

[0001] The invention relates to the technical field of fruit wine preparation, in particular to a method for preparing fruit wine based on citrus fruit koji fermentation. Background Art

[0002] Fruit wine is widely favored by consumers for its unique flavor and nutritional value, especially citrus wine, which has gradually become one of the hot categories in the fruit wine market with its refreshing sweet and sour taste and rich citrus aroma. Citrus, as a widely planted economic crop, is rich in sugar, acidity and aromatic substances, providing a high-quality raw material basis for fruit wine brewing. The development of citrus wine can not only increase the added value of citrus, but also broaden the industrial chain of citrus deep processing, with significant economic benefits and market prospects.

[0003] The existing citrus wine preparation technology mainly converts the sugar in citrus pulp into alcohol through fermentation, and completes the product brewing by combining clarification and storage processes. However, due to the high acidity, rich pectin and suspended matter content of citrus pulp, the yeast activity is easily inhibited during the fermentation process, and the alcohol conversion rate is low. At the same time, the unique aromatic substances of citrus are easily volatilized and lost during the wine brewing process, resulting in a single flavor and lack of layering. In addition, traditional clarification treatment methods are difficult to completely remove suspended particles in the pulp, resulting in poor transparency of the wine, affecting the quality of the final product and consumer acceptance.

[0004] The main problem in the citrus wine brewing process of the prior art is that due to the high acidity and high pectin content of citrus pulp during the fermentation process, the yeast metabolic activity is inhibited, the alcohol conversion rate is low, and it is difficult to improve the fermentation efficiency. The alcohol content and flavor of the final product are insufficient. This problem not only affects the industrial production efficiency of citrus wine, but also limits its market competitiveness. Therefore, there is an urgent need for a citrus wine preparation method that can optimize the fermentation process and improve the alcohol conversion efficiency to better meet production needs and market expectations. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing fruit wine based on citrus fruit koji fermentation, which solves the problem that the high acidity and high pectin content of citrus pulp during the fermentation process inhibits the metabolic activity of yeast and leads to a low alcohol conversion rate, making it difficult to improve the fermentation efficiency.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing fruit wine based on citrus fruit koji fermentation, comprising the following steps: Step 1, raw material processing: select citrus fruits with a sugar-acid ratio of 10:1 to 12:1, soak them in warm water and wash them with ozone water, peel them and pulp them, and control the diameter of the pulp particles to 0.5-1.5 mm; Step 2: Pretreatment of fruit pulp: Add pectinase to the fruit pulp, the dosage of pectinase is 500-1000 U / mL, stir evenly and treat at 45°C for 30 minutes; Step 3, fermentation: in a closed fermentation tank, add fruit koji and high-yield koji to the fruit pulp, where the fruit koji is 500g / 100kg of fruit pulp, the high-yield koji is 50g / 100kg of fruit pulp, and 15kg of white sugar is added / 100kg of fruit pulp. The fermentation is divided into the following two stages: Step 4: Initial fermentation stage: ferment at 28-30℃ for 3 days; Step 5, main fermentation stage: cool down to 25-28℃ and continue fermentation for 4 days; Step 6: Clarification: After fermentation is completed, cool the wine to 5-10°C, add gelatin and silica sol for clarification, the amount of gelatin is 0.02%-0.05%, the amount of silica sol is 0.01%-0.03%, and let it stand for 12-24 hours; Step 6: Filtration and filling: After filtering through a 200-mesh screen and a 0.45-micron microporous membrane, fill in a sterile environment.

[0007] Preferably, the citrus fruit is sweet orange, grapefruit or kumquat.

[0008] Preferably, the peeled citrus fruits are soaked in a 0.1% ascorbic acid solution.

[0009] Preferably, the addition of white sugar is carried out in two times, with 12 catties / 100 kg of fruit pulp added for the first time and 3 catties / 100 kg of fruit pulp added on the 4th day.

[0010] Preferably, during the fermentation process, stirring is performed for 10 minutes every 4 hours to mix the fermented material.

[0011] Preferably, the sugar content, pH value and alcohol content of the wine are monitored during the fermentation process, the sugar content is reduced to 1%-2%, and the pH value is maintained in the range of 3.2-3.6.

[0012] Preferably, the added amount of gelatin is 0.03%, and the added amount of silica sol is 0.02%.

[0013] Preferably, the filtering device comprises a 200 mesh screen and a 0.45 micron polyethersulfone microporous membrane.

[0014] Preferably, the bottled fruit wine is stored in a constant temperature environment of 10-15° C. for at least 30 days.

[0015] Preferably, a low-speed pulper is used for pulping, the rotation speed does not exceed 3000 rpm, and the diameter of the pulp particles is controlled in the range of 0.5-1.0 mm.

[0016] The present invention provides a method for preparing fruit wine based on citrus fruit koji fermentation. It has the following beneficial effects: 1. The present invention solves the problem of high acidity and high pectin content of citrus pulp inhibiting yeast activity by optimizing fermentation temperature, combining fruit koji with high-yield koji, and adding sugar in batches, significantly improving the alcohol conversion rate to more than 85%. Compared with the traditional process, the fermentation cycle is shortened from 10-12 days to 7 days, while the alcohol content is controlled within the ideal range of 8%-12%, and the fermentation efficiency is improved by nearly 20%.

[0017] 2. The present invention adopts a segmented temperature control strategy and a closed fermentation environment during the fermentation process, which significantly reduces the volatilization loss of characteristic aromatic substances such as citrus aldehyde and limonene due to high temperature, ensuring that the wine has a strong citrus aroma. In addition, the flavor enzyme in the fruit koji further strengthens the aroma level of the fruit wine, making the product more unique in the market competition.

[0018] 3. The present invention uses a combination of cooling sedimentation and gelatin and silica sol as a clarifier to effectively remove suspended matter, colloidal substances and fine particles in the wine, so that the light transmittance of the final product reaches more than 95%, and the wine is clear and transparent, meeting the appearance requirements of high-end fruit wine. This clarification treatment scheme also reduces the risk of precipitation during storage and extends the shelf life of the product.

[0019] 4. The present invention adds pectinase to decompose pectin in the pulp pretreatment stage, combines the natural progress of esterification reaction during the addition of sugar and aging, and ensures the alcohol content while achieving an ideal balance between the sourness and sweetness of the wine. After storage, the fruit wine has a smoother taste, a mellow wine structure and a pleasant aftertaste.

[0020] 5. The present invention adopts 0.45 micron polyethersulfone microporous membrane filtration in the filtration and filling stages, combined with nitrogen filling protection and sealing optimization during filling, which reduces the probability of oxidation reaction and inhibits the growth of bacteria, ensuring that the wine has no precipitation and no odor changes during storage, and has a shelf life stability of more than 12 months. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Embodiment 1: Please see attached Figure 1The present invention provides a method for preparing fruit wine based on citrus fruit koji fermentation, comprising the following steps: Regarding step S1, the first step in the preparation of citrus wine is raw material processing, the main purpose of which is to ensure the quality of raw materials and provide suitable basic conditions for subsequent processes through scientific screening and cleaning processes. In the context, the selection and processing of citrus fruits are not only related to the efficiency of the fermentation process, but also directly affect the flavor and quality of the final wine. The steps involved in step S1, such as fruit selection, cleaning, and peeling, are key pre-processes for optimizing the flavor of the wine and ensuring fermentation stability.

[0024] In this embodiment, step S1 "raw material processing" includes the following specific operations: 1. Raw material selection: According to the process requirements, select citrus fruits with a sugar-acid ratio (TSS / TA) of 10:1 to 12:1, preferably sweet orange (Citrus sinensis), grapefruit (Citrus maxima) or kumquat (Fortunella margarita). These varieties have high sugar content and moderate acidity, which can provide suitable fermentation substrates and flavor bases. When selecting fruits, the fruit maturity is required to reach 80%-90%, and there is no obvious mechanical damage or pests on the surface of the peel. Rotten or substandard fruits are removed.

[0025] 2. Cleaning process: To ensure that the surface of citrus fruits is clean and free from microbial contamination, the following two-step cleaning process is used: The first step is to soak the fruit in warm water at 50-60℃ for 3 minutes to remove dust, dirt and pesticide residues on the surface of the fruit. The choice of water temperature is based on the comprehensive consideration of decontamination efficiency and avoiding damage to the appearance of the fruit.

[0026] The second step is to place the fruit in an ozone aqueous solution (ozone concentration is 10 ppm) and clean it for 2 minutes. The bactericidal effect of ozone is used to reduce the number of microorganisms on the surface of the fruit and avoid the influence of miscellaneous bacteria on the subsequent fermentation process.

[0027] 3. Peeling: Peeling is a necessary step to prevent bitter substances (such as limonin) and volatile oils in citrus peels from affecting fermentation. In this embodiment, mechanical peeling equipment is used to treat the fruit. The peeling efficiency is controlled during the peeling process to ensure that the peel residue does not exceed 2%. After peeling, the pulp is quickly soaked in a 0.1% ascorbic acid solution (treatment time is 2 minutes). This treatment can effectively prevent oxidative browning of the pulp and maintain the bright color of the fruit.

[0028] 4. Special fruit processing instructions: For citrus varieties with thin peels (such as kumquats), in addition to ensuring that the peels are peeled, extra attention should be paid to the complete peeling to prevent the peels from entering the pulp and increasing the burden of impurities. For citrus fruits with a sugar-acid ratio slightly lower than the required range, high-sugar fruits can be appropriately mixed to improve the overall raw material quality.

[0029] Regarding step S2, the preparation and pretreatment of pulp is an important link in the preparation process of citrus wine. Its purpose is to further process the washed and peeled citrus fruits into pulp suitable for fermentation, and optimize the physical and chemical properties of the pulp through pretreatment, so as to provide more efficient reaction conditions for saccharification and alcohol conversion in the subsequent fermentation stage. The pulping and pectinase treatment technology involved in step S2 directly affects the viscosity, ingredient availability and fermentation efficiency of the pulp, and is closely related to the raw material quality control of step S1 and the fermentation process of step S3.

[0030] In this embodiment, step S2 "preparation and pretreatment of fruit pulp" includes the following specific operations: 1. Preparation of fruit pulp: The peeled citrus pulp is pulped using a low-speed pulper. The speed of the pulper is controlled below 3000 rpm to avoid pulp oxidation and flavor loss caused by high-speed shearing.

[0031] During the pulping process, the equipment parameters are set to control the diameter of the pulp particles between 0.5-1.5 mm. This particle size range can ensure the uniform distribution of the pulp material and provide good conditions for the attachment and saccharification of subsequent fermentation bacteria.

[0032] After pulping is completed, the pulp is immediately sealed and stored to prevent oxidation and discoloration caused by exposure to air.

[0033] 2. Pectinase pretreatment: Heat the pulp to 45°C to accelerate the enzyme activity reaction speed. Then add pectinase according to the mass ratio of the pulp, and the added amount of pectinase is 500-1000 U / mL.

[0034] After adding, the pulp is mixed evenly by a stirring device, and the stirring time is set to 10 minutes to ensure that the pectinase is fully in contact with the pulp material.

[0035] After stirring, let it stand for 30 minutes to decompose the pectin into soluble sugars and oligosaccharides, while reducing the viscosity of the pulp and providing a more suitable environment for subsequent fermentation bacteria.

[0036] 3. Parameter control and detection: During the pectinase treatment process, the temperature of the pulp was always maintained at 45°C to avoid excessively high temperatures that would cause enzyme inactivation or excessively low temperatures that would reduce decomposition efficiency.

[0037] The initial sugar content (TSS) of the pulp should be detected as 10%-12%, and the pH value should be maintained in the range of 3.0-3.5 to ensure the adaptability of subsequent fermentation conditions.

[0038] 4. Special handling instructions: If the pectin content of the citrus variety in the raw material is high (such as grapefruit), the amount of pectinase added can be appropriately increased to the upper limit of 1000 U / mL, and the processing time can be extended to 40 minutes to further reduce the viscosity and optimize the uniformity of the pulp.

[0039] If the color of the pulp shows a tendency to brown, additional 0.05%-0.1% ascorbic acid solution can be added to adjust it to keep the color of the pulp stable.

[0040] Regarding step S3, fermentation is the core link in the preparation of citrus wine, and its main purpose is to convert sugar in the pulp into alcohol through microbial metabolism and generate unique flavor substances. The fermentation process is directly affected by the quality of the previous pulp treatment and plays an important role in the subsequent clarification and quality stability. In this step, the synergistic effect of fruit koji and high-yield koji, segmented temperature control, sugar addition and other operating points all play a key role in the fermentation efficiency and wine flavor, and have a linking significance between the past and the future.

[0041] In this embodiment, step S3 "fermentation" includes the following specific operations: 1. Ratio and preparation of fermentation raw materials: Add the following ingredients to every 100 catties of citrus pulp: 500g fruit koji: rich in saccharifying enzymes and flavor enzymes, used to break down complex sugars in the fruit pulp and optimize the fermentation flavor.

[0042] 50g high-yield koji: Contains acid-resistant yeast strains that adapt to the high acid environment of citrus pulp and promote alcohol conversion.

[0043] 15 pounds of white sugar: used to supplement the fermentation substrate, 12 pounds of which are added during the initial fermentation, and the remaining 3 pounds are added on the 4th day of the main fermentation.

[0044] After mixing, stir evenly to ensure that the koji and sugar are fully dispersed in the fruit pulp.

[0045] 2. Fermentation equipment and conditions: Fermentation equipment: Use a closed fermentation tank with a gas valve installed on the top to discharge the carbon dioxide produced during the fermentation process and prevent external contamination.

[0046] Environmental control: The initial temperature is set at 28-30°C and the fermenter is placed in a constant temperature controlled environment to ensure the metabolic activity of the yeast.

[0047] 3. Fermentation stage and parameter control: Primary fermentation stage (days 1-3): The temperature is maintained at 28-30°C to promote rapid yeast proliferation and initial alcohol production.

[0048] Stir for 10 minutes every 4 hours to ensure uniform contact between the fermentation substrate and the bacteria.

[0049] Main fermentation stage (Day 4-7): The temperature drops to 25-28℃, reducing the loss of volatile aromatic substances and extending the fermentation period.

[0050] On the 4th day, add 3 catties of remaining sugar per 100 kg of fruit pulp. By adding it in batches, the yeast activity can be continued to avoid premature termination of fermentation.

[0051] The stirring frequency was adjusted to 5 minutes every 6 hours to avoid local overheating of the fermentation liquid.

[0052] 4. Fermentation process monitoring: Sugar content monitoring: Use a refractometer to measure the sugar content of the fermentation liquid daily. The initial value is 10%-12%, and gradually decreases to 1%-2% as the criterion for determining the end of fermentation.

[0053] Alcohol Measurement: Using gas chromatography, the alcohol content of the wine is measured daily, with a target of 8%-12%.

[0054] pH monitoring: Use a precision pH meter to measure. The pH value during fermentation should be maintained in the range of 3.2-3.6 to ensure the stability of the yeast metabolic environment.

[0055] 5. Special variety adaptability: For citrus varieties with a slightly lower sugar-acid ratio in the pulp (such as certain grapefruit varieties), the initial sugar addition amount can be appropriately increased to 13 catties per 100 kg of pulp during the initial fermentation to ensure sufficient sugar substrate.

[0056] For high-acid citrus varieties (such as kumquat), the amount of high-yield koji added can be appropriately increased to 60 grams per 100 kilograms of pulp to balance the fermentation efficiency.

[0057] Regarding step S4, clarification is an important step in the late fermentation stage. Its purpose is to remove the suspended matter, pomace and tiny particles remaining in the fermentation liquid through sedimentation and the application of clarifiers, improve the clarity of the wine, and lay the foundation for subsequent filtration and filling. This step plays a key role in the fermentation stage and stabilizing the quality of the wine in the context. The operation method and parameter control directly affect the appearance quality and flavor performance of the final fruit wine.

[0058] In this embodiment, step S4 “clarification process” includes the following specific operations: 1. Natural Settlement: Cooling operation: After fermentation is completed, the wine in the fermentation tank is cooled to 5-10℃, and the fermentation residue and suspended particles are quickly settled by lowering the temperature. The cooling process uses an external circulation cooling system, and the temperature reduction rate is controlled at 1-2℃ / hour to avoid the wine cooling too fast and affecting the flavor stability.

[0059] Standing time: The cooled wine is left to stand in a low temperature environment for 7-10 days, during which time large suspended particles gradually sink to the bottom of the tank to form a sedimentation layer.

[0060] 2. Addition of clarifier: Use of gelatin: Add 0.02%-0.05% gelatin according to the mass ratio of the wine as one of the clarifiers to bind protein impurities and macromolecular colloids in the wine. Gelatin should be dissolved in 40℃ warm water before use, with a dissolution ratio of 1:10, and then evenly added to the wine and stirred.

[0061] Use of silica sol: Add 0.01%-0.03% silica sol at the same time, its main function is to absorb fine suspended particles and pectin substances. After adding silica sol, the wine needs to be stirred evenly and left to stand for 12-24 hours.

[0062] 3. Agitation and sedimentation control: Agitation: After the clarifier is added, use a slow stirring device (speed <50 rpm) to mix the wine. The stirring time is set to 10 minutes to ensure that the clarifier is evenly distributed in the wine.

[0063] Settling time: After stirring, let the wine stand for another 12-24 hours to allow the clarifier to fully react with the impurities in the wine to form settleable particles.

[0064] 4. Parameter monitoring: Wine turbidity measurement: Use a turbidity meter to test the wine before and after treatment to ensure that the turbidity of the wine after clarification is reduced to below 3.2 NTU.

[0065] Transmittance measurement: Use an optical density meter to measure the transmittance. The transmittance of the treated wine should be above 95%.

[0066] 5. Special handling instructions: For high-pectin citrus varieties with more fermentation residues (such as grapefruit), the amount of gelatin can be appropriately increased to the upper limit of 0.05%, and the proportion of silica sol can be adjusted to 0.03%.

[0067] For wine that is still slightly turbid after standing, the sedimentation time can be extended to 48 hours based on low-temperature standing to further remove tiny particles.

[0068] Regarding step S5, filtration and filling are post-processing stages of citrus wine preparation, the purpose of which is to further remove tiny particles and impurities in the wine, ensure the clarity and microbial safety of the wine, and maintain the flavor stability of the wine and extend the shelf life through the filling process. Step S5 is closely connected with the clarification treatment of step S4, and is a necessary process for achieving standardization and commercialization of fruit wine products. The filtration accuracy and filling conditions during the operation are directly related to the product quality.

[0069] In this embodiment, step S5 "filtration and filling" includes the following specific operations: 1. Filtration process: Primary filtration: The clarified wine is first filtered through a 200-mesh screen to remove large particles of sediment and agglomerates in the wine. The screen is made of food-grade stainless steel to maintain a stable liquid flow rate during the filtration process to avoid excessive particle disturbance.

[0070] Precision filtration: After primary filtration, the wine enters the precision filtration unit and undergoes secondary filtration using a 0.45 micron polyethersulfone microporous membrane. This step is mainly used to remove the remaining tiny particles, colloids and microorganisms in the wine, ensuring that the wine is clear and transparent and has microbial safety for long-term storage.

[0071] Equipment cleaning and verification: The filtration equipment must be CIP (clean in place) cleaned before each batch of use. It must be rinsed with a dilute alkaline solution for 10 minutes and then cleaned with pure water to ensure that there is no secondary contamination during the filtration process.

[0072] 2. Filling process: Filling environment: Filling is carried out in a sterile workshop with a cleanliness level of ISO 7 (10,000) to prevent the quality of the wine from deteriorating due to environmental pollution during the filling process.

[0073] Filling method: Use an automatic filling machine to inject the filtered fruit wine into a glass bottle that has been sterilized at high temperature. The filling capacity control accuracy is ±0.5%.

[0074] Nitrogen filling protection: Nitrogen is filled into the wine bottle before filling, with a concentration of more than 99%, to replace the air in the bottle, reduce the oxidative effect of oxygen on the wine, and extend the shelf life of the product.

[0075] 3. Packaging and sterilization: Packaging: After filling, the glass bottle is immediately sealed with an aluminum screw cap. The screw capping pressure and torque are calibrated according to the bottle cap specifications to ensure tightness.

[0076] Bottle disinfection: The sealed wine bottles are sterilized on the surface using ultraviolet disinfection equipment. The ultraviolet wavelength is 254 nm and the irradiation time is 2 minutes.

[0077] 4. Parameter control: Filtration accuracy: The transparency of the filtered wine is measured using an optical density meter, and the transmittance must reach more than 95% to ensure that it meets the appearance requirements of high-quality fruit wine.

[0078] Filling loss rate: The liquid loss rate during each filling process shall not exceed 1%, and waste shall be reduced by optimizing equipment operation efficiency.

[0079] 5. Special conditions adaptation: If the flow rate decreases during the filtration process, the microporous membrane can be replaced in time to ensure the filtration efficiency.

[0080] If the viscosity of the wine is high (such as fruit wine made from high-sugar fruit pulp), the screen size can be appropriately increased to 150 mesh during primary filtration to prevent excessive blockage.

[0081] Regarding step S6, storage and aging are the final steps in the preparation of citrus wine. Its main purpose is to achieve the sweet and sour balance, flavor mellowing and further optimization of the wine structure in a stable environment through low-temperature storage and appropriate aging time. Step S6 is closely related to the aforementioned filtration and filling (S5). Through scientific storage condition control, it ensures that the product reaches the best drinking quality before circulation and achieves quality consistency in industrial mass production.

[0082] In this embodiment, step S6 "storage and aging" includes the following specific operations: 1. Storage conditions: Temperature control: After filling, the wine is transferred to a constant temperature storage warehouse, and the storage temperature is set within the range of 10-15°C. This temperature range can effectively slow down the rate of biochemical reactions in the wine, while avoiding the influence of low-temperature crystallization on the uniformity of the wine.

[0083] Humidity control: The relative humidity of the storage warehouse is controlled at 65%-75% to prevent excessive humidity from causing the wine bottle labels to fall off or excessive humidity from causing the corks to dry out and deform, affecting the product's sealing.

[0084] Storage away from light: The storage environment must avoid direct sunlight, use dim light or no light environment to prevent photooxidation reaction from destroying the aromatic substances in the wine.

[0085] 2. Aging time: The aging time of fruit wine storage is set at least 30 days. During this period, the esterification reaction in the wine is further carried out, which improves the sour and sweet balance of the fruit wine and makes the flavor more harmonious.

[0086] For products with higher requirements for specific flavors, the aging time can be extended to 60-90 days to obtain a more complex aroma and a smoother taste.

[0087] 3. Aging process monitoring: Physical and chemical indicators: The physical and chemical indicators of the wine are tested once every 10 days, including alcohol content, pH value, total acid content, etc., to ensure the stability of the quality of the fruit wine during storage.

[0088] Sensory evaluation: Sensory evaluation was conducted on the 30th and 60th days of storage, with professional wine tasters scoring the aroma, taste and body structure of the fruit wine to evaluate the aging effect.

[0089] 4. Bottle status inspection: Regularly check the seal of the bottle and the status of the label to ensure that the bottle cap has not loosened during storage, the wine has not leaked, and the label and packaging have not been damaged by humidity or temperature changes.

[0090] 5. Adaptability adjustment for special varieties: For citrus wines with higher acidity (such as wine made from kumquats), the storage temperature can be adjusted to the upper limit of 12-15°C to accelerate the esterification reaction of some acidic substances and balance the sour and sweet ratio.

[0091] For citrus wine with high sugar content, the aging time can be appropriately extended to make its flavor fuller.

[0092] Embodiment 2: This embodiment provides a method for preparing fruit wine based on citrus fruit koji fermentation, which is basically the same as the process flow of Example 1, but the fermentation temperature is adjusted in step S3 "fermentation" to compare the effects of different fermentation temperatures on alcohol conversion rate, wine flavor and transparency. This embodiment reduces the initial fermentation temperature setting and evaluates its effect on fermentation efficiency and final product quality to prove that the effect of Example 1 is better.

[0093] 1. Raw material processing (step S1): Similar to the first embodiment, the citrus fruits are selected, cleaned and peeled in strict accordance with the requirements of step S1 to ensure the consistency of the fruit raw material quality and subsequent processes.

[0094] 2. Pulp preparation and pretreatment (step S2): Similar to Example 1, citrus fruits were made into pulp using a low-speed pulper, and the physical properties and fermentation substrate composition of the pulp were optimized by pectinase treatment. The pulp particle diameter was controlled in the range of 0.5-1.5 mm, the pectinase addition amount was 500-1000 U / mL, and the treatment temperature was 45°C.

[0095] 3. Fermentation (step S3): In this embodiment, the fermentation temperature setting is changed to evaluate the effect on the fermentation effect. The specific adjustments are as follows: Initial fermentation stage (days 1-3): The temperature was set at 25°C (3-5°C lower than 28-30°C in Example 1).

[0096] Main fermentation stage (days 4-7): The temperature was set at 22-25°C (3°C lower than 25-28°C in Example 1).

[0097] Sugar addition, stirring frequency, and fermentation monitoring method are the same as those in Example 1.

[0098] 4. Clarification treatment (step S4): Same as in Example 1, cooling sedimentation combined with a clarifier combination of gelatin and silica sol is used for treatment, the cooling temperature is 5-10°C, and the amounts of clarifiers are 0.03% and 0.02%, respectively.

[0099] 5. Filtration and filling (step S5): Similar to the first embodiment, after primary filtration through a 200-mesh screen and fine filtration through a 0.45-micron polyethersulfone microporous membrane, filling is performed in a sterile environment.

[0100] 6. Storage and aging (step S6): Same as in Example 1, the storage temperature is 10-15°C and the storage time is 30 days.

[0101] Table 1 Comparison table of embodiments 1 and 2 Comparison of alcohol conversion efficiency: Example 1 adopts a relatively high initial fermentation temperature (28-30°C) and a main fermentation temperature (25-28°C), which is more in line with the optimal activity range of yeast, and the alcohol content reaches 11.2%; while Example 2 reduces the fermentation temperature to 25°C (initial fermentation) and 22°C (main fermentation), the yeast metabolism rate slows down, and the alcohol conversion rate decreases significantly to only 9.6%.

[0102] Residual sugar content comparison: In Example 2, due to the low yeast activity, the sugar in the pulp was not completely consumed, and the residual sugar content was as high as 2.8%, making the wine taste sweet, which was slightly inferior to 1.6% in Example 1.

[0103] Comparison of wine transparency: In Example 2, due to the reduced fermentation efficiency and the large number of fermentation residues and microorganisms, the transparency of the wine after clarification was only 88%, while the transparency of Example 1 reached 95%.

[0104] Sensory evaluation comparison: Evaluation by professional wine tasters showed that the fruit wine of Example 1 had a full aroma, a balance of sweet and sour, and a smooth taste; whereas the wine of Example 2 was slightly sweet and greasy due to insufficient fermentation, and had a relatively simple flavor, and scored lower than that of Example 1.

[0105] By comparison, it can be seen that the higher primary fermentation and main fermentation temperatures in Example 1 can significantly improve the alcohol conversion rate and flavor performance, while ensuring that the transparency and sensory quality of the wine are better than those in Example 2. Therefore, the present invention recommends the use of the fermentation temperature conditions of Example 1, further demonstrating its technical superiority and practical application value.

[0106] Embodiment three: This embodiment provides a method for preparing fruit wine based on citrus fruit koji fermentation, which is basically the same as the process flow of embodiment 1, but the ratio of the clarifier is adjusted in step S4 "clarification treatment" to compare the effects of different clarifier ratios on the transparency and stability of the wine. By reducing the amount of clarifier, its effect on the clarification effect and the quality of the final product is evaluated to prove that the effect of embodiment 1 is better than that of embodiment 3.

[0107] 1. Raw material processing (step S1): Similar to the first embodiment, the citrus fruits are selected, cleaned and peeled in strict accordance with the requirements of step S1 to ensure the consistency of the fruit raw material quality and subsequent processes.

[0108] 2. Preparation and pretreatment of fruit pulp (step S2): Similar to Example 1, citrus fruits were made into pulp using a low-speed pulper, and the physical properties and fermentation substrate composition of the pulp were optimized by pectinase treatment. The pulp particle diameter was controlled in the range of 0.5-1.5 mm, the pectinase addition amount was 500-1000 U / mL, and the treatment temperature was 45°C.

[0109] 3. Fermentation (step S3): As in Example 1, the fermentation temperature is divided into two stages: the initial fermentation stage (days 1-3) is 28-30° C., and the main fermentation stage (days 4-7) is 25-28° C. Sugar is added twice, 12 catties for the first addition and 3 catties on the 4th day of the main fermentation.

[0110] 4. Clarification process (step S4): In this example, the ratio of the clarifier was adjusted to evaluate its effect on the clarification of the wine. The specific adjustments are as follows: The amount of gelatin added is 0.01% (0.03% in Example 1); The amount of silica sol added is 0.005% (0.02% in Example 1).

[0111] After the addition, the same operating steps as in Example 1 are adopted: dissolving the clarifier, slowly stirring, and standing for 12-24 hours for clarification.

[0112] 5. Filtration and filling (step S5): Similar to the first embodiment, after primary filtration through a 200-mesh screen and fine filtration through a 0.45-micron polyethersulfone microporous membrane, the mixture is filled in a sterile environment.

[0113] 6. Storage and aging (step S6): Same as in Example 1, the storage temperature is 10-15°C and the storage time is 30 days.

[0114] Table 2 Data comparison table of Examples 1 and 3 Comparison of wine transparency: In Example 3, the amount of clarifier used was significantly reduced, so the light transmittance of the wine was only 82%, which was insufficient in transparency, and there was more suspended matter (55 mg / L), which was significantly higher than that in Example 1 (15 mg / L).

[0115] Sensory evaluation comparison: Evaluation by professional wine tasters showed that the fruit wine in Example 3 had a score of only 78 due to the large amount of residual suspended matter in the wine, which resulted in a rough taste and affected the smoothness and freshness of the wine. The fruit wine in Example 1 had better clarity and consistency, with a score of 92.

[0116] Storage stability comparison: In Example 3, obvious precipitation was observed after 28 days of storage, indicating that insufficient amount of clarifier resulted in particle precipitation in the fruit wine after long-term storage. However, in Example 1, no precipitation occurred during storage, and the wine had excellent stability.

[0117] By comparison, it can be seen that Example 1 uses a higher proportion of gelatin (0.03%) and silica sol (0.02%), which can effectively remove suspended particles in the fruit wine and ensure the transparency and storage stability of the wine, while Example 3 has a significant decrease in clarity and stability of the wine due to insufficient use of the clarifier. Therefore, the present invention recommends the use of the clarifier ratio in Example 1, which further proves the superiority and repeatability of its technical solution.

[0118] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing fruit wine based on citrus fruit koji fermentation, characterized in that: The following steps are involved: Step 1, raw material processing: select citrus fruits with a sugar-acid ratio of 10:1 to 12:1, soak them in warm water and wash them with ozone water, peel them and pulp them, and control the diameter of the pulp particles to 0.5-1.5 mm; Step 2: Pretreatment of fruit pulp: Add pectinase to the fruit pulp, the dosage of pectinase is 500-1000 U / mL, stir evenly and treat at 45°C for 30 minutes; Step 3, fermentation: in a closed fermentation tank, add fruit koji and high-yield koji to the fruit pulp, where the fruit koji is 500g / 100kg of fruit pulp, the high-yield koji is 50g / 100kg of fruit pulp, and 15kg of white sugar is added / 100kg of fruit pulp. The fermentation is divided into the following two stages: Step 4: Initial fermentation stage: ferment at 28-30℃ for 3 days; Step 5, main fermentation stage: cool down to 25-28℃ and continue fermentation for 4 days; Step 6: Clarification: After fermentation is completed, cool the wine to 5-10°C, add gelatin and silica sol for clarification, the amount of gelatin is 0.02%-0.05%, the amount of silica sol is 0.01%-0.03%, and let it stand for 12-24 hours; Step 6: Filtration and filling: After filtering through a 200-mesh screen and a 0.45-micron microporous membrane, fill in a sterile environment.

2. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The citrus fruit is sweet orange, pomelo or kumquat.

3. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The peeled citrus fruits are soaked in a 0.1% ascorbic acid solution.

4. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The addition of white sugar is divided into two times, the initial addition of 12 catties / 100 kg of fruit pulp, and the addition of 3 catties / 100 kg of fruit pulp on the 4th day.

5. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: During the fermentation process, stir for 10 minutes every 4 hours to mix the fermentation material.

6. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: During the fermentation process, the sugar content, pH value and alcohol content of the wine are monitored. The sugar content drops to 1%-2% and the pH value is maintained in the range of 3.2-3.

6.

7. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The added amount of gelatin is 0.03% and the added amount of silica sol is 0.02%.

8. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The filtering device comprises a 200-mesh screen and a 0.45-micron polyethersulfone microporous membrane.

9. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The bottled wine is stored in a constant temperature environment of 10-15°C for at least 30 days.

10. The method for preparing fruit wine based on citrus fruit koji fermentation according to claim 1, characterized in that: The pulping is performed using a low-speed pulper with a rotation speed not exceeding 3000 rpm, and the diameter of the pulp particles is controlled within the range of 0.5-1.0 mm.

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