Preparation method of ultralow-temperature high-quality apple ice wine

Abstract

The invention discloses a preparation method of ultralow-temperature high-quality apple ice wine, and belongs to the technical field of fruit wine preparation. The method comprises the following steps: picking naturally frozen and thawed ice apples on a fruit tree as a raw material, crushing the raw material, and sequentially carrying out pectinase treatment, squeezing and pectinase clarification at 0-4 DEG C; inoculating saccharomyces cerevisiae, and performing temperature-controlled fermentation under the ultralow temperature condition of 0-4 DEG C; and after fermentation is finished, fining clarification, membrane filtration, filling and storage are performed to obtain a finished product. Through the synergistic effect of natural freeze-thaw raw materials and ultralow-temperature fermentation, natural sugar and organic acid of apples are reserved to the maximum extent, excellent sour and sweet balance is achieved, the fragrance intensity of honey and flower fragrance is remarkably improved, the wine body is endowed with pure and fresh taste, and the wine is suitable for being drunk by people. The technical problems of high sugar consumption, flavor loss and insufficient characteristic aroma in the existing normal-temperature and low-temperature fermentation methods are solved.

Description

Technical Field

[0001] This invention belongs to the field of fruit wine preparation technology, specifically relating to a method for preparing ultra-low temperature high-quality apple ice wine. Background Technology

[0002] As a high-value sweet fruit wine, the preparation method of the base material for apple ice wine directly determines the flavor quality and market level of the final product. Currently, the industrial processing of apple ice wine base materials mainly relies on two mainstream fermentation technologies: ambient temperature fermentation and low temperature fermentation.

[0003] The ambient temperature fermentation method typically involves using fresh apples as raw material. After washing and juicing, alcoholic fermentation is carried out at a temperature range of 20°C to 26°C, followed by clarification and filtration to obtain the base material. The core of this method lies in relying on the high activity of yeast at suitable temperatures to quickly convert the sugar in the juice into alcohol. However, the drawbacks of this method are particularly significant: First, the high-temperature environment causes excessive yeast metabolism, resulting in the excessive consumption of the apple's natural sugars, with a very low retention rate, usually only maintaining 40% to 50%, severely damaging the inherent high sugar content and sweet-sour balance of apple juice; second, the large amount of heat generated during fermentation accelerates the volatilization and oxidation loss of small-molecule flavor substances such as esters and aldehydes that impart floral and fruity aromas, resulting in a base material that, while appearing full-bodied, lacks a refreshing quality in terms of aroma and taste, exhibiting a mediocre flavor profile.

[0004] To address the shortcomings of ambient temperature fermentation, low-temperature fermentation was developed. This method also uses fresh apples as raw material, and its process is similar to the ambient temperature method, but the main fermentation temperature is controlled within the range of 10℃ to 15℃. Compared to the ambient temperature method, the low-temperature environment inhibits yeast activity to some extent, slowing down the fermentation rate, thereby increasing the sugar retention rate to 60% to 70% and preserving more of the initial flavor. However, this technology still has significant limitations: firstly, the 10℃ to 15℃ temperature only mildly inhibits yeast activity, and the slow and continuous fermentation process still decomposes some of the valuable precursors that constitute the characteristic flavor of apples; secondly, and more importantly, this temperature range cannot effectively activate the endogenous enzyme activity in the apple raw material related to the formation of "honey"-like aromas, resulting in a significant weakness in the aroma dimension of the final product, with a weak honey aroma and difficulty in further improving the overall sensory quality, resulting in sensory scores generally at a medium level (75 to 80 points).

[0005] Therefore, there is an urgent need in this field for a new method for preparing apple ice wine base that can overcome the shortcomings of the two methods mentioned above. This method should be able to significantly enhance and optimize the aroma profile of the base, especially to form a pleasant honey aroma, while ensuring the refreshing and pure taste of the wine, while maximizing the preservation of the natural sugar and acidity of apples to achieve a perfect sweet and sour balance. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for preparing high-quality apple ice wine at ultra-low temperature.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing ultra-low temperature high-quality apple ice wine includes the following steps: (1) Raw material harvesting and pretreatment: Harvest ripe ice apples that have undergone natural freeze-thaw cycles. Freeze-thaw conditions: average daily temperature ≤ -8℃ for at least 7 days; the harvesting conditions for the ice apples are: ambient temperature between -8℃ and 0℃ during harvesting. (2) Low-temperature crushing and pulp enzyme treatment: The ice apples obtained in step (1) are crushed and pulped, the material temperature is controlled at 0~4℃, and pulp enzyme is added to carry out the action; (3) Juice extraction and preservation: Sulfur dioxide is added to the fruit pulp after step (2), and juice is obtained by pressing and the temperature is controlled at 0~4℃; (4) Juice clarification: Add pectinase to the juice obtained in step (3) for clarification treatment until the pectin test is negative, and take the supernatant; (5) Low temperature controlled fermentation: The clarified juice obtained in step (4) is inoculated with brewer's yeast and fermented at 0~4℃.

[0008] Based on the above scheme, the variety of iced apples mentioned in step (1) is Fuji, Xiangfei or Aifei; the physicochemical indicators of the iced apples are: sugar content ≥26 Brix, acidity 0.2~0.4 g / 100mL.

[0009] Based on the above scheme, the pulp enzyme mentioned in step (2) is Mzyme PL, the addition amount is 100~200 mg / kg, and the stirring action is ≥3 hours at 30~40 rpm.

[0010] Based on the above scheme, the pectinase mentioned in step (4) is a biological complex enzyme, which is composed of NATUZYM DP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1; wherein the amount of NATUZYM DP ULTRA pectinase added is 400~600 mg / kg, and the amount of Mzyme Berry pectinase added is 200~300 mg / kg; the clarification treatment temperature is 0~4℃, and the stirring time is 30~40 rpm for ≥3 hours.

[0011] Based on the above scheme, the specific method of inoculating brewer's yeast in step (5) is to inoculate twice: the first inoculation is CECA dry yeast, with an addition amount of 200~300 mg / kg; after the yeast activity of the first inoculation is lost, the second inoculation is EC-1118 dry yeast, with an addition amount of 100~200 mg / kg.

[0012] Based on the above scheme, in step (5), before inoculating the yeast, the clarified juice is rapidly heated to 6~7℃; after the yeast starts fermentation, the fermentation temperature is lowered to 0~4℃ for temperature-controlled fermentation.

[0013] Based on the above scheme, the fermentation cycle in step (5) is 30 to 40 days; during the fermentation period, stir once at 30 to 40 rpm in the morning, noon and evening, and stir for 30 minutes each time.

[0014] Based on the above scheme, after the fermentation in step (5) is completed, a clarification step is also included: bentonite, gelatin and silica sol are added to the wine in sequence for clarification and stabilization treatment.

[0015] Based on the above scheme, the amount of bentonite added is 0.5~1.5 kg / ton, the amount of gelatin added is 30~100 g / ton, and the amount of silica sol added is 0.5~1.0 L / ton.

[0016] Based on the above scheme, after fermentation and fining clarification, a membrane filtration step is also included: the wine is filtered using an ultrafiltration system with a membrane pore size of 0.02~0.2 micrometers, then bottled under aseptic conditions and stored at a temperature below 0°C.

[0017] Advantages of the technical solution of this invention Compared with existing technologies, the ultra-low temperature high-quality apple ice wine base and processing method provided by this invention have the following significant advantages: 1. It greatly improves the retention of sugars and organic acids, achieving a natural sweet and sour balance.

[0018] The ultra-low temperature fermentation system of 0℃ to 4℃ used in this invention can significantly inhibit the metabolic activity of brewer's yeast, thereby greatly slowing down the decomposition and consumption of natural sugars in apples. Specifically, the residual sugar content of the final base material is 2 to 3 times higher than that of the room temperature fermentation method (20~26℃), and also 1 time higher than that of the low temperature fermentation method (10~15℃). At the same time, the ultra-low temperature environment effectively inhibits the growth of miscellaneous bacteria, resulting in a 60%~66% reduction in volatile acid (calculated as acetic acid) content compared to the room temperature method, and a 33%~66% reduction compared to the low temperature method. This increase and decrease perfectly preserve the high sugar content and moderate acidity of the raw apples, achieving an excellent and natural sweet and sour balance without excessive post-processing.

[0019] 2. Significantly optimized and enriched the aroma layers of the base material, especially highlighting the distinctive honey and floral notes.

[0020] The ultra-low temperature processing environment of this invention minimizes the volatilization and oxidation loss of small-molecule flavor compounds such as esters and aldehydes during fermentation. Furthermore, this specific low-temperature range activates endogenous enzymes in apple raw materials related to honey aroma formation, promoting the conversion of flavor precursors into target compounds such as ethyl decanoate (producing grape aroma) and benzophenone (producing floral aroma). Ultimately, this results in a 13-fold and 2.65-fold increase in the perceived intensity of floral and honey aromas in the base material compared to existing technologies, creating a more complex, richer, and highly recognizable aroma profile.

[0021] 3. It provides a purer and more refreshing taste experience.

[0022] The low-temperature fermentation environment not only inhibits the metabolism of sugars by yeast, but also effectively suppresses the formation of yeast metabolic byproducts—especially higher alcohols (fusel oils). These fusel oils are the main cause of the spicy, astringent taste and the "headache" sensation in the wine. By reducing their formation at the source, the apple ice wine base prepared by this invention has a clean and smooth taste, free of astringency and off-flavors, greatly improving the comfort and refreshing sensation of drinking, and providing a sensory experience far superior to similar products.

[0023] 4. While ensuring the highest quality, the feasibility of production was also taken into account.

[0024] This invention, through precise control of the core parameters of ultra-low temperature fermentation (temperature, time, and yeast addition strategy), successfully completed alcohol fermentation within a reasonable fermentation cycle of 30-40 days, achieving the aforementioned excellent technical effects. This cycle is within the acceptable range for industrial production, thus effectively unifying ultra-high quality with a reasonable production cycle, and possessing value for large-scale promotion and application. Detailed Implementation

[0025] The terminology used in this invention, unless otherwise specified, generally has the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and are not intended to limit the scope of the invention in any way.

[0026] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the experimental materials, reagents, and chemicals used in the following embodiments can be obtained through general channels.

[0027] In the following embodiments: The pulp enzyme Mzyme PL was produced by Aspergillus niger, purchased from Hunan Xinhongying Biotechnology Co., Ltd., batch number 122404007, with an enzyme activity of 15000 U / g. The pectinase Mzyme Berry producing strain was Aspergillus niger, purchased from Hunan Xinhongying Biotechnology Co., Ltd., batch number 122409009, with an enzyme activity of 14000 U / g; NATUZYM DP ULTRA pectinase is a concentrated pectinase produced by fermentation using a selected classic strain of Aspergillus niger; manufacturer: WeissBioTech GmbH, Germany; enzyme activity is not less than 600 PL per gram; EC-1118 dry yeast, Angel Yeast Co., Ltd., batch number: 2022 / 07 / 04 / F55-5, yeast viable cell rate ≥80%; CECA dry yeast, Angel Yeast Co., Ltd., batch number: 20230507-361, yeast activated cell count 39.575 billion / g.

[0028] In the following embodiments, the bentonite needs to be prepared into an aqueous suspension and fully hydrated before use. The specific method is as follows: the bentonite is slowly added to 10 to 15 times (w / w) of water while stirring, and after being fully dispersed, it is hydrated at room temperature for 10 to 12 hours under continuous stirring to obtain a homogeneous bentonite suspension for use.

[0029] Before use, the gelatin needs to be prepared into a solution. The specific method is as follows: add the gelatin to five times its weight of cold water while stirring, allow it to swell for 30-60 minutes, then heat to 45-50°C to completely dissolve it, obtaining a gelatin solution for later use. Maintain the gelatin solution temperature at no less than 35°C to prevent gelation.

[0030] In the following examples, alcohol content was determined using an alcohol meter; residual sugar was determined using a direct titration method; total acidity was determined using an indicator method; and volatile acidity was determined using an indicator method.

[0031] A method for preparing ultra-low temperature high-quality apple ice wine, comprising the following steps: (1) Raw material harvesting and pretreatment In late December, frozen apples that have undergone natural freeze-thaw cycles on the fruit trees are harvested. The freeze-thaw conditions are: an average daily temperature of ≤-8℃ for at least 7 consecutive days (freezing at night and thawing naturally after sunrise); the varieties of the frozen apples are Fuji, Xiangfei, or Aifei, and the harvesting conditions are: an ambient temperature of -8℃ to 0℃ at the time of harvesting; the physicochemical properties of the frozen apples are: sugar content ≥26 Brix, and acidity of 0.2~0.4 g / 100mL.

[0032] Harvesting must be completed before noon, and diseased or rotten fruit must be removed during the process.

[0033] (2) Low-temperature crushing and pulp enzyme treatment The frozen apples obtained in step (1) were pulped using a hammer crusher with a screen aperture of 10mm×20mm. The resulting pulp was collected in an insulated tank, and the material temperature was controlled at 0~4℃ throughout the process. Subsequently, 100~200 mg / kg of pulp enzyme Mzyme PL was added to the pulp, and the mixture was stirred at 30~40 rpm for 3 hours.

[0034] (3) Juice extraction and preservation Add 40 mg / L of sulfur dioxide to the fruit pulp after step (2), stir evenly, and then press it using a belt press; transfer the obtained juice into a temperature-controlled insulated tank, and set and maintain the juice temperature at 0~4℃ for later use.

[0035] (4) Juice clarification Add bio-complex enzyme to the juice obtained in step (3) for clarification treatment; the bio-complex enzyme is composed of NATUZYMDP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1, wherein the amount of NATUZYMDP ULTRA pectinase added is 400~600 mg / kg and the amount of Mzyme Berry pectinase added is 200~300 mg / kg.

[0036] Stir at 30-40 rpm for ≥3 hours at 0-4℃ until the pectin test is negative; then let stand for 1 hour, and transfer the supernatant to a fermenter.

[0037] (5) Ultra-low temperature controlled fermentation The clarified juice obtained in step (4) was rapidly heated to 6-7°C, and then inoculated with brewer's yeast in two stages: the first inoculation was with CECA dry yeast at a dosage of 200-300 mg / kg; after the yeast activity of the first inoculation was lost, the second inoculation was with EC-1118 dry yeast at a dosage of 100-200 mg / kg. After the yeast started fermentation, the fermentation temperature was lowered to 0-4°C and temperature-controlled fermentation was carried out for a fermentation period of 35 days; during the fermentation period, the mixture was stirred once at 30-40 rpm for 30 minutes each time in the morning, noon and evening.

[0038] (6) Clarification and stabilization treatment of the colloid After fermentation is complete, add the clarifying agent in the following order and manner: Bentonite treatment: Add 0.5~1.5 kg / ton of bentonite SIHA PURANIT® UF to the wine while stirring, and continue stirring for 15 minutes; Gelatin treatment: Subsequently, add 30~100 g / ton of gelatin SIHA-GELATINE and stir continuously for 10 minutes; Silica sol treatment: Finally, add 0.5~1.0 L / ton of silica sol SIHA-Becosol 30, stir continuously for 20 minutes, and then let stand for 0.5~1 hour; After completing the above steps, the resulting wine will proceed to the next process.

[0039] (7) Membrane filtration The wine liquid treated in step (6) is filtered using an ultrafiltration system, wherein the pore size of the ultrafiltration membrane is in the range of 0.02~0.2 micrometers.

[0040] (8) Aseptic filling The filtered wine is bottled under aseptic conditions.

[0041] (9) Finished product storage The filled products are stored at temperatures below 0°C.

[0042] Example 1 A method for preparing ultra-low temperature high-quality apple ice wine, comprising the following steps: (1) Raw material harvesting and pretreatment The apples are Aifei, Xiangfei, and Fuji ice apples that have ripened on the fruit trees and undergone natural freeze-thaw cycles. The freeze-thaw conditions are: average daily temperature ≤ -8℃ for at least 7 days; ambient temperature at the time of harvest is -8℃ to 0℃; the physicochemical properties of the ice apples are: sugar content ≥ 26Brix, acidity 0.2~0.4 g / 100mL.

[0043] Harvesting must be completed before noon, and diseased or rotten fruit must be removed during the process.

[0044] (2) Low-temperature crushing and pulp enzyme treatment The frozen apples obtained in step (1) were pulped using a hammer crusher with a screen aperture of 10mm×20mm. The resulting pulp was collected in an insulated tank, and the material temperature was controlled at 0~4℃ throughout the process. Subsequently, 100~200 mg / kg of pulp enzyme Mzyme PL was added to the pulp, and the mixture was stirred at 30~40 rpm for 3 hours at this temperature.

[0045] (3) Juice extraction and preservation Add 40 mg / L of sulfur dioxide to the fruit pulp after step (2), stir evenly, and then press it using a belt press; transfer the obtained juice into a temperature-controlled insulated tank, and set and maintain the juice temperature at 0~4℃ for later use.

[0046] (4) Juice clarification Add bio-complex enzyme to the juice obtained in step (3) for clarification treatment; the bio-complex enzyme is composed of NATUZYMDP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1, wherein the amount of NATUZYMDP ULTRA pectinase added is 400~600 mg / kg and the amount of Mzyme Berry pectinase added is 200~300 mg / kg.

[0047] Stir at 30-40 rpm for ≥3 hours at 0-4℃ until the pectin test is negative; then let stand for 1 hour, and transfer the supernatant to a fermenter.

[0048] (5) Ultra-low temperature controlled fermentation The clarified juice obtained in step (4) was rapidly heated to 6-7°C, and then inoculated with brewer's yeast in two stages: the first inoculation was with CECA dry yeast at a dosage of 200-300 mg / kg; after the yeast activity of the first inoculation was lost, the second inoculation was with EC-1118 dry yeast at a dosage of 100-200 mg / kg. After the yeast started fermentation, the fermentation temperature was lowered to 0°C and temperature-controlled fermentation was carried out for a fermentation period of 35 days; during the fermentation period, the mixture was stirred once at 30-40 rpm for 30 minutes each time in the morning, noon and evening.

[0049] (6) Clarification and stabilization treatment of the colloid After fermentation is complete, stop fermentation at -2 to -4℃; the alcohol content of the fermented wine is measured to be 6-7 vol%, and the residual sugar is 130-160 g / L; clarifying agents are added in the following order and manner for clarification and stabilization treatment, as follows: ① Under stirring conditions, add bentonite SIHA PURANIT® UF suspension to the wine at a ratio of 0.5~1.5 kg bentonite per ton of wine, and continue stirring for 15 minutes; ②Then, according to the ratio of 30~100 g of gelatin per ton of wine, add gelatin SIHA-GELATINE solution to the wine and stir continuously for 10 minutes; ③ Finally, add silica sol SIHA-Becosol 30 to the wine at a ratio of 0.5~1.0L / ton, stir continuously for 20 minutes, and then let it stand for 0.5~1 hour.

[0050] (7) Membrane filtration The wine liquid treated in step (6) is filtered using an ultrafiltration system, wherein the pore size of the ultrafiltration membrane is in the range of 0.02~0.2 micrometers.

[0051] (8) Aseptic filling The filtered wine is bottled under aseptic conditions.

[0052] (9) Finished product storage The filled products are stored at temperatures below 0°C.

[0053] Finished product specifications: Alcohol content 6-7% vol, residual sugar 130-160 g / L, volatile acid 0.2-0.25 g / L; Sensory evaluation: Clear, bright, golden yellow, with a typical fruity aroma. Round and sweet. Score 88.

[0054] Example 2 A method for preparing ultra-low temperature high-quality apple ice wine, comprising the following steps: (1) Raw material harvesting and pretreatment The apples are Aifei, Xiangfei, and Fuji ice apples that have ripened on the fruit trees and undergone natural freeze-thaw cycles. The freeze-thaw conditions are: average daily temperature ≤ -8℃ for at least 7 days; ambient temperature at the time of harvest is -8℃ to 0℃; the physicochemical properties of the ice apples are: sugar content ≥ 26Brix, acidity 0.2~0.4 g / 100mL.

[0055] Harvesting must be completed before noon, and diseased or rotten fruit must be removed during the process.

[0056] (2) Low-temperature crushing and pulp enzyme treatment The frozen apples obtained in step (1) were pulped using a hammer crusher with a screen aperture of 10mm×20mm. The resulting pulp was collected in an insulated tank, and the material temperature was controlled at 0~4℃ throughout the process. Subsequently, 100~200 mg / kg of pulp enzyme Mzyme PL was added to the pulp, and the mixture was stirred at 30~40 rpm for 3 hours at this temperature.

[0057] (3) Juice extraction and preservation Add 40 mg / L of sulfur dioxide to the fruit pulp after step (2), stir evenly, and then press it using a belt press; transfer the obtained juice into a temperature-controlled insulated tank, and set and maintain the juice temperature at 0~4℃ for later use.

[0058] (4) Juice clarification Add bio-complex enzyme to the juice obtained in step (3) for clarification treatment; the bio-complex enzyme is composed of NATUZYMDP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1, wherein the amount of NATUZYMDP ULTRA pectinase added is 400~600 mg / kg and the amount of Mzyme Berry pectinase added is 200~300 mg / kg.

[0059] Stir at 30-40 rpm for ≥3 hours at 0-4℃ until the pectin test is negative; then let stand for 1 hour, and transfer the supernatant to a fermenter.

[0060] (5) Ultra-low temperature controlled fermentation The clarified juice obtained in step (4) was rapidly heated to 6-7°C, and then inoculated with brewer's yeast in two stages: the first inoculation was with CECA dry yeast at a dosage of 200-300 mg / kg; after the yeast activity of the first inoculation was lost, the second inoculation was with EC-1118 dry yeast at a dosage of 100-200 mg / kg. After the yeast started fermentation, the fermentation temperature was lowered to 2°C and temperature-controlled fermentation was carried out for a fermentation period of 35 days; during the fermentation period, the mixture was stirred once at 30-40 rpm for 30 minutes each time in the morning, noon and evening.

[0061] (6) Clarification and stabilization treatment of the colloid After fermentation is complete, stop fermentation at -2 to -4℃; the alcohol content of the fermented wine is measured to be 7-8% vol, and the residual sugar is 110-125 g / L; clarifying agents are added in the following order and manner for clarification and stabilization treatment, as follows: ① Under stirring conditions, add bentonite SIHA PURANIT® UF suspension to the wine at a ratio of 0.5~1.5 kg bentonite per ton of wine, and continue stirring for 15 minutes; ②Then, according to the ratio of 30~100 g of gelatin per ton of wine, add gelatin SIHA-GELATINE solution to the wine and stir continuously for 10 minutes; ③ Finally, add silica sol SIHA-Becosol 30 to the wine at a ratio of 0.5~1.0L / ton, stir continuously for 20 minutes, and then let it stand for 0.5~1 hour.

[0062] (7) Membrane filtration The wine liquid treated in step (6) is filtered using an ultrafiltration system, wherein the pore size of the ultrafiltration membrane is in the range of 0.02~0.2 micrometers.

[0063] (8) Aseptic filling The filtered wine is bottled under aseptic conditions.

[0064] (9) Finished product storage The filled products are stored at temperatures below 0°C.

[0065] Finished product specifications: alcohol content 7-8% vol, residual sugar 110-125 g / L, volatile acidity 0.2-0.27 g / L; sensory evaluation: clear, slightly dull, golden yellow, prominent fruity aroma, mellow and pleasant. Score: 86.

[0066] Example 3 A method for preparing ultra-low temperature high-quality apple ice wine, comprising the following steps: (1) Raw material harvesting and pretreatment The apples are Aifei, Xiangfei, and Fuji ice apples that have ripened on the fruit trees and undergone natural freeze-thaw cycles. The freeze-thaw conditions are: average daily temperature ≤ -8℃ for at least 7 days; ambient temperature at the time of harvest is -8℃ to 0℃; the physicochemical properties of the ice apples are: sugar content ≥ 26Brix, acidity 0.2~0.4 g / 100mL.

[0067] Harvesting must be completed before noon, and diseased or rotten fruit must be removed during the process.

[0068] (2) Low-temperature crushing and pulp enzyme treatment The frozen apples obtained in step (1) were pulped using a hammer crusher with a screen aperture of 10mm×20mm. The resulting pulp was collected in an insulated tank, and the material temperature was controlled at 0~4℃ throughout the process. Subsequently, 100~200 mg / kg of pulp enzyme Mzyme PL was added to the pulp, and the mixture was stirred at 30~40 rpm for 3 hours at this temperature.

[0069] (3) Juice extraction and preservation Add 40 mg / L of sulfur dioxide to the fruit pulp after step (2), stir evenly, and then press it using a belt press; transfer the obtained juice into a temperature-controlled insulated tank, and set and maintain the juice temperature at 0~4℃ for later use.

[0070] (4) Juice clarification Add bio-complex enzyme to the juice obtained in step (3) for clarification treatment; the bio-complex enzyme is composed of NATUZYMDP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1, wherein the amount of NATUZYMDP ULTRA pectinase added is 400~600 mg / kg and the amount of Mzyme Berry pectinase added is 200~300 mg / kg.

[0071] Stir at 30-40 rpm for ≥3 hours at 0-4℃ until the pectin test is negative; then let stand for 1 hour, and transfer the supernatant to a fermenter.

[0072] (5) Ultra-low temperature controlled fermentation The clarified juice obtained in step (4) was rapidly heated to 6-7°C, and then inoculated with brewer's yeast in two stages: the first inoculation was with CECA dry yeast at a dosage of 200-300 mg / kg; after the yeast activity of the first inoculation was lost, the second inoculation was with EC-1118 dry yeast at a dosage of 100-200 mg / kg. After the yeast started fermentation, the fermentation temperature was lowered to 4°C and temperature-controlled fermentation was carried out for a fermentation period of 35 days; during the fermentation period, the mixture was stirred once at 30-40 rpm in the morning, noon and evening.

[0073] (6) Clarification and stabilization treatment of the colloid After fermentation is complete, stop fermentation at -2 to -4℃; the alcohol content of the fermented wine is measured to be 8.5-9% vol, and the residual sugar is 90-100 g / L; clarifying agents are added in the following order and manner for clarification and stabilization treatment, as follows: ① Under stirring conditions, add bentonite SIHA PURANIT® UF suspension to the wine at a ratio of 0.5~1.5 kg bentonite per ton of wine, and continue stirring for 15 minutes; ②Then, according to the ratio of 30~100 g of gelatin per ton of wine, add gelatin SIHA-GELATINE solution to the wine and stir continuously for 10 minutes; ③ Finally, add silica sol SIHA-Becosol 30 to the wine at a ratio of 0.5~1.0L / ton, stir continuously for 20 minutes, and then let it stand for 0.5~1 hour.

[0074] (7) Membrane filtration The wine liquid treated in step (6) is filtered using an ultrafiltration system, wherein the pore size of the ultrafiltration membrane is in the range of 0.02~0.2 micrometers.

[0075] (8) Aseptic filling The filtered wine is bottled under aseptic conditions.

[0076] (9) Finished product storage The filled products are stored at temperatures below 0°C.

[0077] Finished product specifications: Alcohol content 8.5~9% vol, residual sugar 90~100 g / L, volatile acidity 0.2~0.3 g / L. Sensory evaluation: Clear, no sediment, slightly yellow, fruity and floral aromas, honey aroma. Round, sweet, and with a long finish. Score: 92 points.

[0078] Example 4 A method for preparing ultra-low temperature high-quality apple ice wine, comprising the following steps: (1) Raw material harvesting and pretreatment The apples are Aifei, Xiangfei, and Fuji ice apples that have ripened on the fruit trees and undergone natural freeze-thaw cycles. The freeze-thaw conditions are: average daily temperature ≤ -8℃ for at least 7 days; ambient temperature at the time of harvest is -8℃ to 0℃; the physicochemical properties of the ice apples are: sugar content ≥ 26Brix, acidity 0.2~0.4 g / 100mL.

[0079] Harvesting must be completed before noon, and diseased or rotten fruit must be removed during the process.

[0080] (2) Low-temperature crushing and pulp enzyme treatment The frozen apples obtained in step (1) were pulped using a hammer crusher with a screen aperture of 10mm×20mm. The resulting pulp was collected in an insulated tank, and the material temperature was controlled at 0~4℃ throughout the process. Subsequently, 100~200 mg / kg of pulp enzyme Mzyme PL was added to the pulp, and the mixture was stirred at 30~40 rpm for 3 hours at this temperature.

[0081] (3) Juice extraction and preservation Add 40 mg / L of sulfur dioxide to the fruit pulp after step (2), stir evenly, and then press it using a belt press; transfer the obtained juice into a temperature-controlled insulated tank, and set and maintain the juice temperature at 0~4℃ for later use.

[0082] (4) Juice clarification Add bio-complex enzyme to the juice obtained in step (3) for clarification treatment; the bio-complex enzyme is composed of NATUZYMDP ULTRA pectinase and Mzyme Berry pectinase in a mass ratio of 2:1, wherein the amount of NATUZYMDP ULTRA pectinase added is 400~600 mg / kg and the amount of Mzyme Berry pectinase added is 200~300 mg / kg.

[0083] Stir at 30-40 rpm for ≥3 hours at 0-4℃ until the pectin test is negative; then let stand for 1 hour, and transfer the supernatant to a fermenter.

[0084] (5) Ultra-low temperature controlled fermentation The clarified juice obtained in step (4) was rapidly heated to 6-7°C, and then inoculated with brewer's yeast in two stages: the first inoculation was with CECA dry yeast at a dosage of 200-300 mg / kg; after the yeast activity of the first inoculation was lost, the second inoculation was with EC-1118 dry yeast at a dosage of 100-200 mg / kg. After the yeast started fermentation, the fermentation temperature was lowered to 6°C and temperature-controlled fermentation was carried out for a fermentation period of 35 days; during the fermentation period, the mixture was stirred once at 30-40 rpm for 30 minutes each time in the morning, noon and evening.

[0085] (6) Clarification and stabilization treatment of the colloid After fermentation is complete, stop fermentation at -2 to -4℃; the alcohol content of the fermented wine is measured to be 8.5-10.5% vol, and the residual sugar is 80-120 g / L; clarifying agents are added in the following order and manner for clarification and stabilization treatment, as follows: ① Under stirring conditions, add bentonite SIHA PURANIT® UF suspension to the wine at a ratio of 0.5~1.5 kg bentonite per ton of wine, and continue stirring for 15 minutes; ②Then, according to the ratio of 30~100 g of gelatin per ton of wine, add gelatin SIHA-GELATINE solution to the wine and stir continuously for 10 minutes; ③ Finally, add silica sol SIHA-Becosol 30 to the wine at a ratio of 0.5~1.0L / ton, stir continuously for 20 minutes, and then let it stand for 0.5~1 hour.

[0086] (7) Membrane filtration The wine liquid treated in step (6) is filtered using an ultrafiltration system, wherein the pore size of the ultrafiltration membrane is in the range of 0.02~0.2 micrometers.

[0087] (8) Aseptic filling The filtered wine is bottled under aseptic conditions.

[0088] (9) Finished product storage The filled products are stored at temperatures below 0°C.

[0089] Finished product specifications: alcohol content 8.5~10.5% vol, residual sugar 80~120 g / L, volatile acid 0.3~0.4 g / L; sensory evaluation: clear, slightly hazy, straw yellow, fruity and honey aroma, refreshing and palatable. Score 85.

[0090] Comparative Example 1 A method for preparing cider, comprising the following steps: Ripe Aifei, Xiangfei, and Fuji ice apples (non-freeze-thawed apples) were harvested from the fruit trees. Following the method in Example 3: after washing, crushing, pulping, enzymatic hydrolysis, addition of sulfur dioxide, and juicing, the sugar content was measured to be 18.5 Brix and the acidity to be 0.35~0.5 g / 100g. Low-temperature fermentation was then carried out according to the method in Example 3, and fermentation was terminated at -2~-4℃ after completion. The alcohol content of the fermented wine was measured to be 7~9.5% vol and the residual sugar to be 20~45 g / L. After clarification and stabilization treatment and membrane filtration according to the method in Example 3, the finished product indicators were measured to be: alcohol content 7~9.5% vol, residual sugar 20~45 g / L, total acid 3.5~5.0 g / L, and volatile acid 0.3~0.45 g / L. Sensory evaluation: a fresh fruity aroma mixed with a faint honey sweetness; a slightly bubbly, sweet and sour, and mellow taste; lacking the firmness and rich layers of ice apples, a score of 80.

[0091] The effect of different fermentation temperatures on the quality of ice cider Apple ice wine was prepared using fully matured ice apples (Aifei, Xiangfei, and Fuji varieties) fermented using ultra-low temperature fermentation (0~4℃), low temperature fermentation (10~15℃), and ambient temperature fermentation (20~26℃) methods, and after natural freeze-thaw cycles (daily average temperature ≤-8℃ for at least 7 days, harvest temperature range -8~0℃). The differences in the steps of the three fermentation methods are shown in Table 1 below.

[0092] Table 1. Differences in the main brewing steps of different fermentation methods Using fully ripe ice apples (Aifei, Xiangfei, and Fuji) that have undergone natural freeze-thaw cycles (average daily temperature ≤ -8℃ for at least 7 days, harvesting temperature range -8~0℃) as raw materials, the effects of different fermentation methods on the physicochemical properties of ice apple wine were determined and compared with the effect of low-temperature fermentation at 6℃. The results are shown in Table 2.

[0093] Table 2. Effects of different fermentation temperatures on the physicochemical properties of ice cider. Table 2 shows that higher temperatures lead to stronger yeast activity, and alcohol content increases with increasing temperature. The lowest alcohol content was observed during ultra-low temperature fermentation (0-4℃) (6-8% vol for Fuji and 5-7% vol for Xiangfei), while the highest alcohol content was observed during room temperature fermentation (20-26℃) (12.5-13% vol for Fuji and 12.5-13% vol for Aifei). Low temperatures inhibit yeast metabolism, and the residual sugar content decreases with increasing fermentation temperature. Ultra-low temperature fermentation resulted in the highest residual sugar content (110-150 g / L for Fuji and 130-160 g / L for Xiangfei), while room temperature fermentation resulted in the lowest (40-45 g / L for Fuji and 40-50 g / L for Aifei). Low temperatures slow down the decomposition of fruit acids. Fermentation at ultra-low temperatures (0-4℃) results in higher total acidity (5.5-6.0 g / L for Xiangfei and 5.5-6.5 g / L for Aifei); fermentation at room temperature results in relatively lower total acidity (3-3.7 g / L for Fuji and 3.5-4 g / L for Xiangfei). Room temperature easily breeds unwanted microorganisms, leading to increased volatile acidity (affecting flavor): ultra-low temperature fermentation results in the lowest volatile acidity (0.2-0.25 g / L for Fuji and 0.2-0.26 g / L for Xiangfei); room temperature fermentation results in the highest volatile acidity (0.6-0.7 g / L for Fuji and 0.65-0.75 g / L for Xiangfei). Overall, ultra-low temperature fermented ice cider has higher residual sugar and total acidity, lower volatile acidity, and lower alcohol content; room temperature fermentation results in higher alcohol content and lower residual sugar, but higher volatile acidity (making the flavor more susceptible to damage).

[0094] Using fully ripe Aifei apples that had undergone natural freeze-thaw cycles (average daily temperature ≤ -8℃ for at least 7 days, harvest temperature range -8~0℃) and fresh Aifei apples as raw materials, the effects of different fermentation methods on the aroma components of ice cider were determined, and the results are shown in Table 3.

[0095] Table 3. Effects of different fermentation methods on the aroma components of ice cider. Table 3 shows that the content of grape aroma, apple peel aroma, floral aroma, and honey aroma increases with decreasing fermentation temperature (from room temperature to ultra-low temperature); while the content of clove aroma decreases with decreasing fermentation temperature. Regardless of whether the apples are freeze-thawed or fresh, the content of grape aroma (ethyl decanoate), apple peel aroma (ethyl hexanoate), floral aroma (benzophenone), and honey aroma (phenylethyl alcohol) is generally higher under ultra-low temperature fermentation; while the content of clove aroma (clove) increases significantly under room temperature fermentation. The grape aroma (1.23 mg / kg) of frozen-thawed Aifei apples fermented at ultra-low temperatures is more than 14 times stronger than that of apples fermented at room temperature (0.085 mg / kg), the floral aroma (0.0052 mg / kg) is 13 times stronger, and the honey aroma (0.69 mg / kg) is 2.65 times stronger. Conversely, the clove aroma (0.52 mg / kg) of fresh Aifei apples fermented at room temperature is approximately 2.5 times stronger than that of apples fermented at ultra-low temperatures (0.21 mg / kg). At the same fermentation temperature, the aroma component content of frozen-thawed Aifei apples is generally higher than that of fresh Aifei apples. During ultra-low temperature fermentation, the grape aroma (1.23 mg / kg), clove aroma (0.25 mg / kg), and honey aroma (0.69 mg / kg) of frozen-thawed apples are all higher than those of fresh apples (1.1 mg / kg, 0.21 mg / kg, and 0.3 mg / kg, respectively).

[0096] Using fully ripe Aifei apples that had undergone natural freeze-thaw cycles (average daily temperature ≤ -8℃ for at least 7 days, harvest temperature range -8~0℃) and fresh Aifei apples as raw materials, the effects of different fermentation methods on the sensory evaluation of ice cider were determined. The results are shown in Table 4.

[0097] Table 4. Effects of different fermentation methods on the sensory evaluation of ice cider. Table 4 shows that, regardless of whether the apples were frozen-thawed or fresh, ultra-low temperature fermentation scored the highest (92 points for frozen-thawed apples, 90 points for fresh apples), while room temperature fermentation scored the lowest (both 80 points). Furthermore, ultra-low temperature fermented cider has a clear and glossy appearance, exhibiting typical varietal aromas and a rich, mellow flavor with a balanced sweet and sour taste, resulting in a round and full-bodied overall flavor. In contrast, room temperature fermented cider appears hazy / has sediment, has a slightly off-flavor, and a raw / slightly bitter taste, exhibiting poor balance. Low temperature fermented cider falls in between, with a moderate appearance, aroma, and taste, and a natural transition between sweet and sour. At the same temperature, frozen-thawed apples scored slightly higher than fresh apples (92 vs 90 for ultra-low temperature, 87 vs 86 for low temperature), but both scored the same at room temperature (80 points). Freeze-thaw treatment can enhance the release of flavor compounds from apples, making the aroma and flavor fuller in ultra-low temperature fermented cider more prominent. Therefore, ultra-low temperature is the optimal fermentation temperature for making ice cider from "Aifei" apples, which can maximize the appearance, aroma and taste of the wine; while fermentation at room temperature will significantly degrade the sensory quality of the wine.

[0098] In summary, the impact of the three fermentation methods on the final product is mainly reflected in the following aspects: Flavor and Aroma: Low-temperature and ultra-low-temperature fermentation better preserves the fresh fruit aromas of the fruit and promotes the production of more and more elegant esters (especially ethyl esters) by yeast. These substances often bring pleasant aromas such as floral and fruity notes. In contrast, room-temperature fermentation, due to the active metabolism of yeast, often produces more higher alcohols. If the amount is too high, it may mask the fruit aromas. At the same time, the formation of esters may also be different, and the wine body is usually more full-bodied and exuberant.

[0099] Fermentation efficiency and control: Room temperature fermentation is the fastest and most efficient. Low temperature and ultra-low temperature fermentation are slower, requiring more patience, but also making it easier to control the fermentation process and reduce the risk of contamination by other microorganisms.

[0100] Body and taste: Fruit wines fermented at low and ultra-low temperatures generally have a more delicate and mellow taste, a crisper acidity, and a purer overall feel. Fruit wines fermented at room temperature may have a fuller taste due to more metabolic byproducts, but if not properly controlled, they may also have a more pungent alcohol taste or a slightly rougher texture.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing an ultra-low temperature high-quality apple ice wine, characterized in that, The method comprises the following steps: (1) Raw material picking and pretreatment: picking mature and naturally freeze-thawed ice apples, freeze-thawing condition: daily average temperature ≤-8℃ for at least 7 days; the picking condition of the ice apples is that the ambient temperature is-8℃ to 0℃ when picking; (2) Low-temperature crushing and fruit pulp enzyme treatment: crushing and pulping the ice apples obtained in step (1), controlling the material temperature to be 0-4℃, and adding fruit pulp enzyme for action; (3) Juice extraction and preservation: adding sulfur dioxide to the fruit pulp treated in step (2), and obtaining juice after pressing and controlling the temperature to be 0-4℃; (4) Juice clarification: adding pectinase to the juice obtained in step (3) for clarification treatment until the pectin test is negative, and taking the supernatant; (5) Ultra-low temperature controlled fermentation: inoculating the clarified juice obtained in step (4) with Saccharomyces cerevisiae for controlled fermentation at 0-4℃.

2. The process for the preparation of ultra-low temperature high quality apple ice wine according to claim 1, characterized by, The variety of the ice apples in step (1) is Fuji, Xiangfei or Aifei; the physicochemical indexes of the ice apples are: sugar content ≥ 26 Brix, acidity 0.2-0.4 g / 100 mL.

3. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 1 wherein, The fruit pulp enzyme in step (2) is Mzyme PL, and the addition amount is 100-200 mg / kg, and the stirring action is 30-40 rpm for ≥3 hours.

4. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 1 wherein, The pectinase in step (4) is a biological compound enzyme, which is compounded by NATUZYM DP ULTRA pectinase and Mzyme Berry pectinase at a mass ratio of 2:1; wherein the addition amount of NATUZYM DP ULTRA pectinase is 400-600 mg / kg, and the addition amount of Mzyme Berry pectinase is 200-300 mg / kg; the clarification treatment temperature is 0-4℃, and the stirring action is 30-40 rpm for ≥3 hours.

5. The method of claim 1, wherein the ultra-low temperature high quality apple ice wine is prepared by the steps of: The specific way of inoculating Saccharomyces cerevisiae in step (5) is twice inoculation: first inoculating CECA dry yeast with an addition amount of 200-300 mg / kg; after the activity of the first inoculated yeast is lost, secondly inoculating EC-1118 dry yeast with an addition amount of 100-200 mg / kg.

6. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 5, wherein, In step (5), before inoculating the yeast, the clarified juice is rapidly warmed to 6-7℃; after the yeast starts fermentation, the fermentation temperature is reduced to 0-4℃ for controlled fermentation.

7. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 1 wherein, The fermentation period in step (5) is 30-40 days; during the fermentation period, the juice is stirred at 30-40 rpm once a day, and each stirring lasts for 30 minutes.

8. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 1 wherein, After the fermentation in step (5) is completed, a gelation clarification step is further included: adding bentonite, gelatin and silica sol to the wine in sequence for clarification and stabilization treatment.

9. The process for the preparation of ultra-low temperature high quality apple ice wine according to claim 8, characterized by, The addition amount of the bentonite is 0.5-1.5 kg / ton, the addition amount of the gelatin is 30-100 g / ton, and the addition amount of the silica sol is 0.5-1.0 L / ton.

10. The process for the preparation of ultra-low temperature high quality apple ice wine as claimed in claim 1 wherein, After the fermentation and gelation clarification, a membrane filtration step is further included: an ultrafiltration system with a membrane pore size of 0.02-0.2 microns is used to filter the wine, and then the wine is filled under sterile conditions and stored under a temperature lower than 0℃.

Images