CN116554985B - Purple waxy wheat litchi wine and preparation method thereof - Google Patents

Abstract

The invention discloses a purple glutinous wheat lychee wine and a preparation method thereof. The invention adopts cold immersion combined with freeze concentration treatment to obtain concentrated lychee juice; anthocyanin concentrate is obtained by ultrasonic alcohol extraction, resin adsorption and freeze concentration treatment; extrusion puffing combined with saccharification treatment to obtain purple glutinous wheat enzymolyte; the obtained concentrated lychee juice, anthocyanin concentrate and purple glutinous wheat enzymolyte are mixed and activated yeast is added for fermentation, and pectin in the fermentation liquid is removed after fermentation to obtain purple glutinous wheat lychee wine. The method of the invention is adopted to prepare purple glutinous wheat lychee wine, which effectively improves the anthocyanin content, alcohol content and wine yield in the composite fruit wine while maintaining the quality of the composite fruit wine, and enhances the color of the wine, enriches the aroma and taste of the wine, reduces the methanol content to enhance the safety of the composite fruit wine, and is of great significance to improving the quality of health-care lychee wine.

Description

Purple glutinous wheat litchi wine and preparation method thereof

Technical Field

The invention belongs to the technical field of grain and fruit wine brewing, and particularly relates to purple glutinous wheat lychee wine and a preparation method thereof.

Background Art

Fruits are prone to spoilage after picking, thus losing their edible value and causing great waste. Through brewing, fruits can be transformed into fruit wines with high added value and high physiological effects, so as to strengthen the comprehensive utilization of fruit resources, increase the economic added value of perishable fruits, and promote fruit farmers to increase production and income. Fermented fruit wine uses fresh fruits as raw materials. It can retain most of the nutrients in fruits, such as polyphenols, organic acids, amino acids and various vitamins. Drinking fruit wine regularly can improve cardiovascular and cerebrovascular functions, slow down the aging process, inhibit fat accumulation in the human body, promote body metabolism and blood circulation, etc. In addition, fruit wine has the characteristics of low alcohol content, many types, strong fruity aroma, comfortable and pleasant taste, and unique wine color, which is deeply loved by consumers. Fruit wine has outstanding advantages, but its disadvantages are also obvious. According to the survey, the problems raised by consumers include insufficient impact of taste and aroma, single flavor and insufficient mellowness of the wine body. Under the influence of China's long-standing drinking culture and winemaking technology, fruit wine is far less popular than white wine in the domestic market. Compared with fruit wine, white wine uses grain as the brewing raw material and koji as the fermentation agent. It has the characteristics of rich aroma, lingering fragrance, mellow and harmonious taste and long aftertaste.

Hejiang lychee is the best of the "Three Wonders of Hejiang" in Luzhou City and is known as the "king of fruits". Its flesh is thick and juicy, crystal clear, crisp and sweet, fragrant and delicate, rich in sugar, protein and vitamins, and has the effects of relieving fatigue and nourishing the skin. Lychee wine is a fermented wine made from fresh lychees, which is washed, drained, peeled, pitted, juiced, fermented and clarified. The wine is brown in color, has the aroma of lychee fruit and wine, and tastes moderately sweet and sour, mellow and palatable, with a unique lychee wine style. However, fermented lychee wine has problems such as easy oxidation, easy browning, easy bacterial infection, low alcohol content and light taste. In traditional brewing methods, the pretreatment of litchi before fermentation is often controlled within 30 minutes to preserve the litchi aroma and prevent the loss of nutritional value. Sugar is added to the fermentation liquor to increase the alcohol content of the wine, and acid is added to inhibit the growth of bacteria and the production of volatile acids. However, the quality and grade of litchi wine brewed by these methods have not been improved.

Purple glutinous wheat 168 is a purple all-glutinous wheat variety suitable for large-scale planting and mechanized harvesting. It is high-yielding and disease-resistant, suitable for high-altitude planting, and can be rotated with glutinous sorghum in the hilly areas of Luzhou. While meeting the needs of agricultural planting, purple glutinous wheat 168 meets the characteristics of high-quality brewing raw materials because the content of amylopectin in the grains is greater than 98%. Xiaoqu liquor brewed with purple glutinous wheat 168 as a single raw grain has the characteristics of high wine yield, short cellaring period and mellow flavor. In addition, the seed coat of purple glutinous wheat 168 is rich in anthocyanins and has high nutritional and ornamental value. The traditional liquor brewing process includes the infiltration, cooking, saccharification, fermentation and distillation of raw materials. The high temperature generated by cooking and distillation will cause the degradation of anthocyanins. It is necessary to find a brewing method that can retain the anthocyanins of purple glutinous wheat 168. In addition, the infiltration and cooking processes have a long processing time, low efficiency, high energy consumption and large sewage discharge.

In summary, finding a method for preparing composite fruit wine that can maintain the quality of fruit wine while improving the nutritional value, alcohol content and yield of fruit wine, enhancing the color of the wine, enriching the aroma and taste of the wine, and enhancing safety is of vital importance in the field of grain and fruit wine brewing technology.

Summary of the invention

In view of the above-mentioned deficiencies in the prior art, the present invention provides a purple glutinous wheat lychee wine and a preparation method thereof, which can effectively improve the anthocyanin content, alcohol content and wine yield in the compound fruit wine while maintaining the quality of the compound fruit wine, enhance the color of the wine, enrich the aroma and taste of the wine, and reduce the methanol content to enhance the safety of the compound fruit wine.

The present invention adopts the following technical solutions:

A method for preparing purple glutinous wheat lychee wine comprises the following steps:

(1) mixing litchi pulp with water to obtain litchi pulp, and then macerating, filtering, and freeze-concentrating to obtain concentrated litchi juice;

(2) subjecting the purple glutinous wheat to ultrasonic alcohol extraction, adsorption and concentration to obtain anthocyanin concentrate;

(3) extruding and puffing the purple glutinous wheat, and then adding saccharifying enzyme to perform enzymolysis to obtain a purple glutinous wheat enzymolysis solution;

(4) mixing the concentrated lychee juice obtained in step (1), the anthocyanin concentrate obtained in step (2), and the purple glutinous wheat enzymatic hydrolyzate obtained in step (3), adding activated yeast to ferment to obtain a fermentation liquid, allowing the mixture to stand, filtering, and collecting the filtrate;

(5) adding a clarifier to the filtrate obtained in step (4) for clarification, allowing to stand, and filtering to obtain purple glutinous wheat litchi wine.

By adopting the above technical solution, the beneficial effects of the present invention are as follows:

The purple glutinous wheat litchi wine of the invention is a composite fruit-grain wine prepared by mixed fermentation of concentrated litchi juice, anthocyanin concentrate and purple glutinous wheat enzymolyzate. The fruit-grain wine has high alcohol content, high nutritional value, beautiful color, three-dimensional and full taste and aroma, and effectively solves the problems of insufficient taste and aroma impact, single flavor and low nutritional content of existing litchi wine.

Furthermore, the above-mentioned mixing and beating is carried out at 5-10°C, preferably 5°C, and the mass ratio of litchi pulp to water is 1:1-2, preferably 1:1; the above-mentioned litchi pulp is immersed at 5-15°C for 3-5 days, preferably 5°C, for 3 days; the above-mentioned freeze concentration is to concentrate the filtered filtrate at -20 to -10°C, preferably -20°C; the crystallization rate is controlled to be 50-60%, preferably 60%, so that the sugar content of litchi juice is 220-300g/L, preferably 300g/L.

The beneficial effects of adopting the above further technical solution are:

Fresh lychees are peeled, pitted and immediately frozen, and lychee juice is obtained by pulping with cold water, cold soaking and freeze concentration. The low-temperature operation throughout the process can not only inhibit the browning and oxidation of lychees to retain the original natural flavor of lychees, but also prolong the pre-treatment processing time of lychees to facilitate industrial production, and reduce the contamination of foreign bacteria in the production process to improve product safety; at the same time, soaking lychee pulp at low temperature can also enhance the color intensity and stability of fruit wine, increase the content of phenolic substances in fruit wine and improve the sensory evaluation score of fruit wine, and the freeze concentration treatment of filtered lychee juice can increase the sugar content of lychee juice before fermentation to 220-300g/L to increase the alcohol content of fruit wine, thereby solving the problems of low alcohol content, insufficient body and light taste of traditional lychee wine.

Furthermore, the conditions for the ultrasonic alcohol extraction are as follows: adding a citric acid-containing ethanol solution to purple glutinous wheat at a solid-liquid ratio of 1:3-5 at 40-60°C, ultrasonically extracting for 1-2 hours, and then centrifuging to collect the supernatant; wherein the volume fraction of ethanol in the ethanol solution is 70-90%, and the mass fraction of citric acid is 0.5-1.5%; preferably, adding a citric acid-containing ethanol solution at a solid-liquid ratio of 1:4 at 50°C, ultrasonically extracting for 1 hour, and then centrifuging to collect the supernatant; wherein the volume fraction of ethanol in the ethanol solution is 90%, and the mass fraction of citric acid is 1%.

Furthermore, the adsorption in step (2) is to use a resin to adsorb the supernatant for 2 to 3 hours at a pH value of 3 to 5 and a temperature of 25 to 35°C, and then elute with an ethanol solution containing citric acid, and desorb for 1 to 2 hours to obtain an eluate, wherein the volume fraction of ethanol in the ethanol solution is 70 to 90%, and the mass fraction of citric acid is 0.5 to 1.5%; the concentration is to concentrate the eluate at 40 to 55°C and a pressure of 0.007 to 0.015 MPa for 30 to 60 minutes to obtain anthocyanin concentrated solution; preferably, at a pH of 4 and a temperature of 30°C, the supernatant is adsorbed for 2 hours by a macroporous resin, and then eluted with an ethanol solution containing citric acid, and desorbed for 2 hours to obtain an eluate, wherein the volume fraction of ethanol in the ethanol solution is 90%, and the mass fraction of citric acid is 1%; the concentration is to concentrate the eluate at 40°C and a pressure of 0.008 MPa for 40 minutes.

The beneficial effects of adopting the above further technical solution are:

Anthocyanins are easily degraded, and ultrasonic alcohol extraction, resin purification, and vacuum low-temperature concentration can be used to extract and retain anthocyanins to the greatest extent. In addition, since pectin is insoluble in alcohol solution, the purple glutinous wheat powder is treated with ultrasonic alcohol extraction to remove pectin from the purple glutinous wheat concentrate while satisfying the dissolution of anthocyanins, thereby reducing the formation of methanol in fruit and grain wine.

Furthermore, in the above step (3), the extrusion puffing is performed by extruding the purple glutinous wheat flour with a water content of 12% to 25% at a temperature of 120 to 180° C., a spiral diameter of 50 to 60 mm, and a spindle speed of 300 to 500 r/min, and then cooling to 60 to 65° C. after puffing; the mass fraction of the saccharifying enzyme added in the above step (3) is 0.1 to 0.2%, and the enzymolysis time is 3 to 6 hours; preferably, the purple glutinous wheat flour with a water content of 20% is extruded at a temperature of 150° C., a spiral diameter of 50 mm, and a spindle speed of 400 r/min, and then cooling to 60° C. after puffing; the mass fraction of the saccharifying enzyme added is 0.1%, and the enzymolysis time is 4 hours.

The beneficial effects of adopting the above further technical solution are:

In order to promote the conversion of starch, the starch is gelatinized and saccharified through extrusion puffing and saccharifying enzyme respectively, so as to increase the fermentable sugars and improve the alcohol content and wine yield. At the same time, extrusion puffing treatment replaces traditional steaming, which can not only save energy and simplify the process, but also shorten the fermentation cycle, reduce bacterial contamination and improve the flavor of the wine.

Furthermore, the mass ratio of the concentrated lychee juice, anthocyanin concentrate and purple glutinous wheat enzymatic hydrolysate is 1:0.5-1.5:2-5, preferably 1:1:3; the mass percentage of activated yeast added is 1-2%, preferably 1%; the fermentation process is first fermented at 25-30°C for 1-3 days, then fermented at 15-18°C until the total sugar content is 3.5-4.5g/L, preferably fermented at 25°C for 2 days, and then fermented at 15°C until the total sugar content is 4g/L.

The beneficial effects of adopting the above further technical solution are:

Purple glutinous wheat enzymatic hydrolysate is added for mixed fermentation. Purple glutinous wheat contains a large amount of starch, which can make up for the low sugar content of litchi pulp.

Furthermore, in step (4), the filtration is performed by keeping the fermentation broth at 4-8°C, preferably at 4°C, until the gel on the upper layer of the broth stops increasing, filtering with a filter having a pore size of 20-80 mesh, preferably 40 mesh, and collecting the filtrate.

The beneficial effects of adopting the above further technical solution are:

By standing and filtering, part of the pectin in the fermentation liquid can be removed, which is beneficial to reducing the methanol content in the finished wine.

Furthermore, the clarifier is a mixture of pectinase, chitosan and gelatin in a mass ratio of 1:1 to 3:1, preferably 1:2:1.

Furthermore, the clarification is performed by adding a clarifier to the filtrate at a concentration of 0.5-0.6 mg/mL, preferably 0.6 mg/mL, standing for 2-4 days, preferably 3 days, and filtering to obtain purple glutinous wheat lychee wine.

The beneficial effects of adopting the above further technical solution are:

Chitosan and gelatin were used as clarifiers for clarification, and pectinase was subsequently added to the clarifier to degrade residual pectin, thereby achieving the purpose of clarification and helping to reduce the methanol content in the finished wine.

The purple glutinous wheat lychee wine is prepared by the preparation method of the purple glutinous wheat lychee wine.

In summary, the beneficial effects of the present invention are:

The present invention adds anthocyanin concentrate of purple glutinous wheat 168 for mixed fermentation on the basis of traditional litchi wine fermentation, which makes up for the defect of less anthocyanin in litchi pulp, and reasonably utilizes the characteristic of purple glutinous wheat 168 being rich in anthocyanin, and the pectin content in purple glutinous wheat 168 is low, while litchi contains a large amount of pectin, which will be converted into methanol after continuous high temperature and fermentation. Methanol has a great toxic effect on the human body, and when the content is too high, it will inhibit the central nervous system, leading to retinal damage, optic nerve atrophy, vision loss and even blindness. In fruit wine brewing, the commonly used method for removing pectin is to add pectinase, and pectinase is generally a complex enzyme system composed of multiple enzymes, among which pectinesterase can randomly cut off the ester bond between methoxyl group and galacturonic acid in water-soluble pectin molecules to produce methanol and free hydroxyl groups, that is, adding pectinase to achieve the decomposition of pectin will inevitably produce methanol, and according to the characteristic that the boiling point of methanol is 64.5°C, the methanol in liquor or fruit wine is usually removed by steaming. The invention takes into account the retention of high anthocyanins and is not suitable for removing methanol by high-temperature cooking. The concentrated lychee juice that has not been hydrolyzed by pectinase and the purple glutinous wheat hydrolyzate that has been extruded, puffed and saccharified are mixed, and the pectin and methanol contents in the fruit-grain wine are reduced by low-temperature fermentation with activated yeast and filtering after low-temperature standing. This is because lychee contains rich monosaccharides and can be directly fermented by yeast to produce wine without the need for decomposition by saccharifying enzymes or distiller's yeast. The purple glutinous wheat can convert starch into sugars that can be fermented by yeast through extrusion, puffing and saccharification. During the fermentation period, activated dry yeast can be added to produce wine. At the same time, the concentrated lychee juice is in a low-temperature environment during preparation and mixed fermentation. Only adding yeast is not enough to cause pectin degradation. The fermented liquid is subjected to low-temperature standing treatment to condense and precipitate pectin in the form of macromolecules. Subsequently, pectinase is added to a clarifier to degrade the residual pectin, thereby achieving the purpose of clarification.

The purple glutinous wheat litchi wine prepared by the invention is prepared by mixed fermentation of concentrated lychee juice, purple glutinous wheat anthocyanin concentrate and purple glutinous wheat enzymolysis solution, and has the advantages of high alcohol content, high nutritional value, beautiful color, three-dimensional and full taste and aroma, and effectively solves the problems of insufficient taste and aroma impact, single flavor and low nutritional content of existing litchi wine.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flow chart for the preparation of purple glutinous wheat litchi wine.

DETAILED DESCRIPTION

The principles and features of the present invention are described below in conjunction with the embodiments, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

Example 1

This embodiment provides a method for preparing purple glutinous wheat litchi wine, comprising the following steps:

(1) selecting fresh, ripe, non-deteriorated and non-moldy lychees, and immediately storing the lychee pulp at 5° C. after peeling and removing the core, and then mixing all the pulp with 5° C. water in a mass ratio of 1:1 to obtain lychee pulp;

(2) placing the litchi pulp obtained in step (1) in a sealed impregnation tank and impregnating at 5° C. for 3 days to obtain an impregnation liquid; subsequently filtering the impregnation liquid, separating the filtrate and the filter residue, squeezing the filter residue and mixing the squeezed liquid with the filtrate, standing at 10° C. for 24 hours, and then filtering again to obtain a litchi stock solution, concentrating the litchi stock solution at -20° C., controlling the crystallization rate to 60% during the freezing time, and performing two crystallization-filter pressing separation operations to obtain litchi juice, so that the sugar content of the litchi juice is 300 g/L;

(3) The purple glutinous wheat was crushed and sieved through a 50-mesh sieve to obtain purple glutinous wheat fine powder, and a 90% ethanol solution containing 1% citric acid was added at a solid-liquid ratio of 1:4, and ultrasonic alcohol extraction was performed at 50°C for 1 h, and then centrifuged at 8000 r/min for 10 min, and the supernatant was collected;

(4) using a macroporous resin to adsorb the supernatant obtained in step (3), with an adsorption pH value of 4, an adsorption temperature of 30° C., an adsorption time of 2 h, and eluting with a 90% ethanol solution containing 1% citric acid, desorbing for 2 h to obtain an eluate, and concentrating the eluate at 40° C. and 0.008 MPa for 40 min to obtain an anthocyanin concentrate;

(5) After removing impurities from the whole purple glutinous wheat, the purple glutinous wheat was crushed into 40 meshes, and water was added to adjust the moisture content of the raw material to 20%. The extrusion puffing treatment was performed under the conditions of a puffing temperature of 150° C., a screw diameter of 50 mm, and a spindle speed of 400 r/min. Subsequently, the puffed raw material was placed in a saccharification pot and cooled to 60° C., and 0.1% of the raw material weight of saccharifying enzyme was added for enzymatic hydrolysis for 4 hours to obtain an enzymatic hydrolyzate;

(6) placing the lychee juice obtained in step (2), the anthocyanin concentrate obtained in step (4), and the enzymatic hydrolyzate obtained in step (5) in a fermentation tank at a weight ratio of 1:1:3, adding 1% by weight of activated yeast for fermentation, and fermenting at 25° C. for 2 days, and then continuing to ferment at 15° C., and ending the fermentation when the total sugar content reaches 4 g/L to obtain a fermentation liquid;

(7) After the fermentation is completed, the fermentation liquid obtained in step (6) is kept at 4° C. until the gel on the upper layer of the liquid stops increasing, and filtered using a filter cloth or filter screen with a pore size of 40 mesh to collect the filtrate;

(8) adding a clarifier at a concentration of 0.6 mg/mL to the filtrate obtained in step (7) for clarification, standing for 3 days, and filtering through an ultrafiltration membrane to obtain purple glutinous wheat litchi wine, wherein the mass ratio of pectinase, chitosan and gelatin in the mixed clarifier is 1:2:1.

Example 2

This embodiment provides a method for preparing purple glutinous wheat lychee wine, which differs from Embodiment 1 in that the immersion temperature in step (2) is 10°C.

Example 3

This embodiment provides a method for preparing purple glutinous wheat litchi wine, which differs from embodiment 1 in that the freezing time in step (2) controls the crystallization rate to 50%, and litchi juice is obtained by two crystallization-filter pressing separation operations, so that the sugar content of the litchi juice is 280 g/L.

Example 4

The present embodiment provides a method for preparing purple glutinous wheat litchi wine, which differs from embodiment 1 in that during the ultrasonic alcohol extraction in step (3), a 90% ethanol solution containing 0.5% citric acid is added to the purple glutinous wheat flour at a solid-liquid ratio of 1:4, ultrasonic alcohol extraction is performed at 50°C for 1 hour, and then centrifuged at 8000 r/min for 10 minutes to collect the supernatant.

Example 5

This embodiment provides a method for preparing purple glutinous wheat lychee wine, which differs from Embodiment 1 in that the puffing temperature in step (5) is 120°C.

Comparative Example 1

The difference between Comparative Example 1 and Example 1 is that the cold soaking step is not performed in step (2). Step (2) specifically comprises filtering the litchi pulp obtained in step (1), separating the filtrate and the filter residue, squeezing the filter residue and mixing the squeezed liquid with the filtrate, standing at 10° C. for 24 hours, and then filtering again to obtain litchi stock solution, concentrating the litchi stock solution at -20° C., controlling the crystallization rate to 60% during the freezing time, and obtaining litchi juice through two crystallization-filter pressing separation operations, so that the sugar content of the litchi juice is 300 g/L.

Comparative Example 2

The difference between Comparative Example 2 and Example 1 is that freeze concentration is not performed in step (2), and the specific steps are: placing the litchi pulp in a sealed impregnation tank, impregnating it at 5°C for 3 days to obtain an impregnation liquid, then filtering the impregnation liquid, separating the filtrate and the filter residue, squeezing the filter residue and mixing the squeezed liquid and the filtrate, standing at 10°C for 24 hours, and then filtering again to obtain the litchi stock solution.

Comparative Example 3

The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, only lychee juice and purple glutinous wheat enzymatic hydrolysate were added during the fermentation process, and no anthocyanin concentrate was added.

Comparative Example 4

The difference between Example 4 and Example 1 is that the purple glutinous wheat enzymatic hydrolysate obtained in step (5) of Example 4 is different from that in Example 1. The specific steps for obtaining the purple glutinous wheat enzymatic hydrolysate in Example 4 are as follows: take whole purple glutinous wheat, remove impurities, crush the purple glutinous wheat into 40 mesh, add water to submerge the grain surface by 5 cm, moisten the grain at 30°C for 12 hours, drain and transfer to a steamer, steam the grain for 1 hour after the steaming water boils, place the raw material in a saccharification pot after steaming and cool to 60°C, add 0.1% saccharifying enzyme by mass fraction for enzymatic hydrolysis for 4 hours, and obtain an enzymatic hydrolysate.

Test example

The alcohol content, wine yield, methanol content and anthocyanin content of the purple glutinous wheat litchi wine obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were tested, and the method was based on GB/T15308-2006 General Analysis Method for Grape and Fruit Wine, which specifically included the following steps:

(1) Determine the alcohol content of purple glutinous wheat litchi wine by alcoholometer method;

(2) The yield of purple glutinous wheat and litchi wine was determined by using the yield of raw materials;

(3) Determination of methanol content in purple glutinous wheat litchi wine by gas chromatography;

(4) Determination of anthocyanin content in purple glutinous wheat litchi wine by spectrophotometry;

The test results are shown in Table 1:

Table 1 Physical and chemical data of purple glutinous wheat litchi wine prepared in Examples 1 to 5 and Comparative Examples 1 to 4

It can be seen from Table 1 that the alcohol content and wine yield of the purple glutinous wheat lychee wine prepared in Examples 1 to 5 are respectively higher than 20% vol and 20%; the alcohol content of traditional lychee wine is 9.5-12% vol. Compared with traditional lychee wine, the alcohol content and wine yield of the purple glutinous wheat lychee wine prepared by the present invention are both increased by about one time; at the same time, the methanol content of the purple glutinous wheat lychee wine prepared in Examples 1 to 5 is lower than 250 mg/L, which meets the requirement for methanol content in GB15037-2006 wine; in addition, the purple glutinous wheat lychee wine prepared in Examples 1 to 5 has a greatly increased anthocyanin content compared with traditional lychee wine, which is about 90 mg/100 mL, due to the addition of purple glutinous wheat anthocyanin concentrate, thereby enhancing the health care function of traditional lychee wine. Compared with the embodiment, the alcohol content and wine yield of comparative examples 1, 2 and 4 decreased, and the anthocyanin content of comparative example 3 decreased significantly, proving that the cold soaking combined with freeze concentration and extrusion puffing treatment in the present invention has an effect on improving the alcohol content and wine yield, while adding purple glutinous wheat anthocyanin concentrate for mixed fermentation has an effect on improving the anthocyanin content. Taking all the embodiments and comparative examples into consideration, it can be seen that the methanol content meets the national standard requirements, proving that the treatment of first low-temperature yeast fermentation and then low-temperature standing in the present invention helps to reduce the pectin content.

Test Example 2

The sensory evaluation of the purple glutinous wheat lychee wine prepared in Experimental Examples 1 to 5 and Comparative Examples 1 to 4 was carried out, and the method referred to GB/T15308-2006 General Analysis Method for Grape Wine and Fruit Wine, GB/T33404-2016 Guidelines for Sensory Evaluation of Liquor, GB/T33405-2016 Terminology for Sensory Evaluation of Liquor and QB/T4262-2011 Lychee Wine, and specifically included the following steps:

The nine-point scale method was used to evaluate the color, texture, taste and aroma of purple glutinous wheat litchi wine, with a full score of 36 points. A total of 10 people participated in the sensory evaluation, and all of them had professional knowledge of corresponding wine brewing and tasting. The sensory evaluation indicators are shown in Table 2:

Table 2 Sensory evaluation indexes

The sensory evaluation results are shown in Table 3:

Table 3 Sensory evaluation results of purple glutinous wheat litchi wine prepared in Examples 1 to 5 and Comparative Examples 1 to 4

It can be seen from Table 3 that the sensory scores of color, texture, taste and aroma of the purple glutinous wheat lychee wine prepared in Examples 1 to 5 are all greater than 7 points and the total sensory scores are all greater than 30 points, showing excellent sensory characteristics, among which the purple glutinous wheat lychee wine prepared in Example 1 is the best; at the same time, compared with Examples 1 to 5, the purple glutinous wheat lychee wine prepared in Comparative Examples 1 to 4 is inferior in color, texture, taste and aroma, which proves that the purple glutinous wheat lychee wine prepared by cold soaking combined with freeze concentration, anthocyanin extraction and extrusion puffing treatment has better wine color and texture, as well as richer taste and aroma.

In summary, the preparation method provided by the present invention can effectively improve the anthocyanin content, alcohol content and wine yield in the compound fruit wine while maintaining the quality of the compound fruit wine, enhance the color of the wine, enrich the aroma and taste of the wine, and reduce the methanol content to enhance the safety of the compound fruit wine.

Although the specific implementation method of the present invention has been described in detail, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims (8)

1. The preparation method of the purple waxy wheat litchi wine is characterized by comprising the following steps of:

(1) Mixing litchi pulp with water, pulping to obtain litchi pulp, soaking, filtering, and freeze concentrating to obtain concentrated litchi juice; the mixing and pulping is carried out at the temperature of 5-10 ℃, and the mass ratio of litchi pulp to water is 1: 1-2; immersing the litchi pulp for 3-5 days at the temperature of 5-15 ℃; the freezing concentration is that the filtered filtrate is concentrated at the temperature of minus 20 to minus 10 ℃, the crystallization rate is controlled to be 50 to 60 percent, and the sugar content of the litchi juice is 220 to 300 g/L;

(2) Carrying out ultrasonic alcohol extraction on the purple waxy wheat, adsorbing and concentrating to obtain anthocyanin concentrated solution;

(3) Extruding and puffing the purple waxy wheat, and then adding saccharifying enzyme for enzymolysis to obtain purple waxy wheat enzymolysis liquid;

(4) Mixing the concentrated litchi juice obtained in the step (1), the anthocyanin concentrated solution obtained in the step (2) and the purple waxy wheat enzymatic hydrolysate obtained in the step (3), adding activated yeast for fermentation to obtain fermentation liquor, standing, filtering and collecting filtrate;

(5) Adding a clarifying agent into the filtrate obtained in the step (4) for clarifying, standing and filtering to obtain the purple waxy wheat lychee wine; the clarifying agent is pectase, chitosan and gelatin, and the mass ratio is 1: 1-3: 1.

2. The method for preparing the purple waxy wheat lychee wine according to claim 1, wherein the ultrasonic alcohol extraction process is as follows: under the condition of 40-60 ℃, the purple waxy wheat is prepared by the following steps of: 3-5, adding an ethanol solution containing citric acid, carrying out ultrasonic alcohol extraction for 1-2 hours, and centrifuging to collect supernatant; wherein the volume fraction of ethanol in the ethanol solution is 70-90%, and the mass fraction of citric acid is 0.5-1.5%.

3. The preparation method of the purple waxy wheat lychee wine according to claim 1, wherein in the step (2), adsorption is carried out by adopting resin to adsorb supernatant for 2-3 hours under the condition that the pH value is 3-5 and the temperature is 25-35 ℃, eluting with ethanol solution containing citric acid, and desorbing for 1-2 hours to obtain eluent, wherein the volume fraction of ethanol in the ethanol solution is 70-90%, and the mass fraction of citric acid is 0.5-1.5%; and concentrating the eluent at 40-55 ℃ under the pressure of 0.007-0.015 MPa for 30-60 min to obtain anthocyanin concentrated solution.

4. The preparation method of the purple waxy wheat lychee wine according to claim 1, which is characterized in that the extrusion and puffing in the step (3) are carried out on the purple waxy wheat flour with the water content of 12% -25% under the conditions that the temperature is 120-180 ℃, the spiral diameter is 50-60 mm, the main shaft rotating speed is 300-500 r/min, and the temperature is cooled to 60-65 ℃ after puffing; and (3) adding 0.1-0.2% of saccharifying enzyme by mass percent, and performing enzymolysis for 3-6 hours.

5. The preparation method of the purple waxy wheat lychee wine according to claim 1, wherein the mass ratio of the concentrated lychee juice to the anthocyanin concentrate to the purple waxy wheat enzymatic hydrolysate is 1:0.5 to 1.5: 2-5; the mass percentage of the added activated yeast is 1-2%; the fermentation process is that the fermentation is carried out for 1-3 days at 25-30 ℃, and then the fermentation is carried out at 15-18 ℃ until the total sugar content is 3.5-4.5 g/L.

6. The method for preparing the purple waxy wheat lychee wine according to claim 1, wherein in the step (4), the fermentation liquor is kept still at 4-8 ℃ until gel on the upper layer of the feed liquor stops increasing, and a filter with the pore diameter of 20-80 meshes is adopted for filtering.

7. The method for preparing the purple waxy wheat lychee wine according to claim 1, wherein the clarification is to add a clarifying agent into the filtrate at a concentration of 0.5-0.6 mg/mL for clarification, standing for 2-4 days, and filtering to obtain the purple waxy wheat lychee wine.

8. The purple waxy wheat lychee wine prepared by the preparation method of the purple waxy wheat lychee wine according to any one of claims 1-7.