Lemongrass and passion fruit beer and preparation method thereof

Abstract

The preparation method comprises the following steps: preparing malt flour, a lemongrass extracting solution and passion fruit juice, saccharifying and filtering wort, boiling the wort and fermenting the wort, namely uniformly mixing yeast and the cooled wort according to a mass ratio, standing and activating, and introducing into a fermentation tank for main fermentation; when the sugar degree is reduced to 5 + / -0.2 degree P, adding an auxiliary material with a second addition amount, sealing the tank, increasing the pressure to 0.12 + / -0.01 MPa, and carrying out secondary fermentation; when the sugar degree during secondary fermentation is reduced to 3.5 degree P or is kept unchanged, gradually cooling, and when the temperature is reduced to 5 DEG C, starting to discharge the yeast, and keeping the pressure to store the beer, so as to obtain the lemongrass passion fruit beer. Compared with the prior art, the low-temperature fermentation method is adopted while the sugar degree is controlled, the time of secondary fermentation is prolonged, the beer has the high foam holding property, it is ensured that volatile aroma components in fruit juice can be better combined with the beer, and therefore the lasting time of fruity aroma is prolonged, and the aroma is prevented from being separated from a beer body in the later period of fermentation.

Description

Technical Field

[0001] The invention relates to the field of beer brewing, in particular to a citronella passion fruit beer and a preparation method thereof. Background Art

[0002] Beer has a long history of brewing. It is mainly made of malt, yeast, hops and water. The main traditional production processes can be roughly divided into three processes: malt making, beer brewing, and beer bottling. It is a low-alcohol wine rich in CO2 that is brewed through fermentation.

[0003] Fruit beer is an alcoholic beverage made by adding fruit as an auxiliary ingredient to beer for fermentation. On the one hand, it gives the beer a unique fruit aroma, and on the other hand, it makes the beer have potential health benefits.

[0004] However, most of the existing fruit beer brewing processes directly add fruit juice concentrate into beer for fermentation, which results in a short duration of fruity aroma, and the flavor consistency and stability of the product cannot be guaranteed, thus failing to meet consumers' drinking needs for fruit beer. Summary of the invention

[0005] The invention aims to provide a citronella passion fruit beer and a preparation method thereof, which prolongs the second fermentation time by adopting a low-temperature fermentation method while controlling the sugar content, so that the beer has a higher foam retention.

[0006] To solve the above problems, the first aspect of the present invention provides a method for preparing lemongrass passion fruit beer, comprising: preparing malt powder, lemongrass extract and passion fruit juice;

[0007] Saccharification and filtration of wort: putting the malt powder into a saccharification pot for staged saccharification, and filtering after saccharification to obtain clarified wort;

[0008] Boiling wort: adding at least two kinds of hops and auxiliary materials with a first addition amount to the wort in batches during the boiling stage until boiling is completed and then cooling, wherein the auxiliary materials include: the lemongrass extract and the passion fruit juice;

[0009] Fermentation of wort: the yeast and the cooled wort are mixed evenly in a mass ratio of 0.25 to 0.28:10, left to stand for activation, and then introduced into a fermentation tank for primary fermentation; when the sugar content drops to 5±0.2°P, the auxiliary material with the second addition amount is added, the tank is sealed and the pressure is increased to 0.12±0.01MPa for secondary fermentation;

[0010] When the sugar content during the secondary fermentation drops to 3.5°P or remains unchanged, the temperature is gradually lowered. When the temperature drops to 5°C, the yeast is discharged and the beer is stored at a pressure maintained to obtain the lemongrass passion fruit beer.

[0011] Preferably, the malt powder comprises: barley malt, wheat malt and light char malt; the mass ratio of the barley malt, wheat malt and light char malt is: 25:14:5.

[0012] Preferably, the method for extracting the lemongrass extract comprises: selecting dry lemongrass and extracting it with water at a mass ratio of 1:5 at 90-95° C. for 1-1.5 hours;

[0013] The preparation method of the passion fruit juice comprises: beating passion fruit pulp with water in a ratio of 1:0.8-1.2, adding 0.1-0.3% by weight of pectinase and cellulase, and obtaining clarified passion fruit juice after enzymolysis and filtration.

[0014] Preferably, the saccharification step comprises: putting the malt powder and water in a mass ratio of 1:3.5-4 into a saccharification pot with hot water at 50-55°C;

[0015] In the first stage, the temperature rises to 50-55°C, heating is stopped and timing begins, and saccharification lasts for 10 minutes;

[0016] In the second stage, the temperature rises to 60-63℃, heating is stopped and timing begins, and saccharification lasts for 30 minutes;

[0017] In the third stage, the temperature rises to 65-68℃, heating is stopped and timing begins, and saccharification lasts for 20 minutes;

[0018] In the fourth stage, the temperature rises to 70-72°C, heating is stopped and timing begins, and saccharification lasts for 10 minutes;

[0019] In the fifth stage, the temperature rises to 75-78°C, heating is stopped and timing begins. Saccharification lasts for 5 minutes, and saccharification ends.

[0020] Preferably, the filtering step comprises:

[0021] First filtration: After saccharification, the mash formed in the saccharification pot is pumped into the filter tank to stand, and then refluxed until the wort is clear, and the filtration is repeated until clear wort is obtained;

[0022] Second filtration: Add the slop washing water preheated to 76-78°C into the filter tank, and the tank washing time is 30-60 minutes.

[0023] Preferably, the saccharification step further comprises: before the saccharification begins, pouring saccharification water at 50-55° C. in the saccharification pot into the filter tank; the mass ratio of the saccharification water to the slop washing water is 1-1.25:1.

[0024] Preferably, the boiling step comprises:

[0025] Pumping the clarified wort into a boiling pot, heating the wort to 95-98° C., and keeping the wort in a boiling state for a period of time to make the wort have a first sugar content;

[0026] Meanwhile, add the Peller hops for the first time at the beginning of the boil;

[0027] Add Peller hops for the second time when boiling for 25-30 minutes;

[0028] When boiling for 60 to 65 minutes, add Saaz hops, and at the same time, mix the lemongrass extract and the passion fruit juice and add them until the boiling is finished.

[0029] Preferably, the first sugar content is 8-12°P; and the yeast is A01 ale yeast or lager yeast.

[0030] Preferably, in the first added amount, the lemongrass extract and passion fruit juice account for 60% to 80% of the total added amount;

[0031] In the second added amount, the lemongrass extract and passion fruit juice account for 20% to 40% of the total added amount;

[0032] The addition amounts of the citronella extract and passion fruit juice are calculated based on the wort and are respectively 2-3 g / L and 30-50 g / L.

[0033] According to a second aspect of the present invention, there is provided a lemongrass passion fruit beer, which is brewed according to the above method and comprises the following components and raw materials in weight fractions:

[0034] 125-130 parts of barley malt, 70-75 parts of wheat malt, 25-30 parts of light char malt, 0.3-0.4 parts of Peller hops, 0.5-0.6 parts of Saaz hops, 2-2.5 parts of lemongrass, 4-4.5 parts of passion fruit, 1450-1500 parts of water, and 0.25-0.3 parts of yeast.

[0035] The above technical solution of the present invention has the following beneficial technical effects:

[0036] The present invention prolongs the time of the second fermentation by adopting a low-temperature fermentation method while controlling the sugar content, so that the beer has a higher foam retention, ensuring that the volatile aroma components in the fruit juice can be better combined with the beer, thereby prolonging the duration of the fruity aroma and avoiding the separation of the aroma from the beer in the late fermentation period. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0038] In the description of the present application, it should be noted that the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] Citronella, also known as lemongrass, is a perennial herbaceous plant of the genus Cymbopogon in the Poaceae family. It is a medicinal and edible spice plant with a lemon aroma. Citronella contains rich aldehydes, alcohols, and esters, and has biological activities such as antibacterial, anti-inflammatory, anxiety-relieving, and antioxidant.

[0040] Passion fruit, also known as purple passion fruit, Brazil nut, and egg fruit, is a herbaceous vine of the genus Passiflora in the Passifloraceae family. It grows in tropical areas and is native to Brazil. It has a sweet and sour taste and a strong aroma. It is rich in vitamins, carotenoids, phenolic compounds and other nutrients. It has the effects of eliminating fatigue, lowering blood lipids and blood pressure, reducing inflammation and removing spots, protecting the liver and nourishing the skin. It plays an important role in beverages such as fruit tea and compound beverages.

[0041] Currently, there is no fruit beer made from lemongrass and passion fruit, and existing fruit beers of the same type all have problems such as short duration of fruity aroma and separation of aroma from the beer in the late fermentation stage.

[0042] The first embodiment of the present invention provides a method for preparing lemongrass passion fruit beer, comprising:

[0043] Step S1, preparing malt powder, lemongrass extract and passion fruit juice;

[0044] Specifically, the method for extracting the lemongrass extract comprises: selecting dry lemongrass with complete leaves and strong aroma, washing and cutting into small pieces, and extracting the lemongrass with water at a mass ratio of 1:5 at 90-95° C. for 1-1.5 hours;

[0045] The preparation method of passion fruit juice comprises: beating passion fruit pulp with water in a ratio of 1:0.8-1.2, adding 0.1-0.3% by weight of pectinase and cellulase, obtaining clarified passion fruit juice after enzymolysis and filtration, and refrigerating for later use.

[0046] Furthermore, the malt powder includes: barley malt, wheat malt and light char malt; preferably, the mass ratio of barley malt, wheat malt and light char malt is 25:14:5.

[0047] The invention adopts three kinds of malt to prepare wort, among which barley malt is rich in starch and enzyme, can provide strong malt aroma and complex flavor for beer, and is the main beer malt; by adding a proper amount of wheat malt, a relatively refreshing and light taste is brought to the beer; by adding light coke malt, the mellowness of the beer, as well as the caramel and malt aroma in the beer are enhanced.

[0048] The sugars and enzymes in malt can promote the growth and fermentation of beer yeast, making the beer ferment more fully and perfectly. Secondly, the sugars in malt will provide the alcohol content of beer, and will also affect the sweetness and flavor of beer. Finally, the protein and amino acids in malt can provide the nutrition and protection needed by beer yeast.

[0049] Therefore, when performing step S2, the process of wort saccharification, this embodiment performs the following staged saccharification steps in the saccharification pot:

[0050] The malt powder prepared in step S1 is mixed with water in a mass ratio of 1:3.5-4, and then put into a saccharification pot with hot water at 50-55°C;

[0051] In the first stage, the temperature rises to 50-55℃, the heating is stopped and the timing is started. After saccharification for 10 minutes, the temperature is raised and the second stage of saccharification begins. This stage can promote the hydrolysis of protein by aminopeptidase, R enzyme, limit dextrinase and carboxypeptidase in malt to generate a large amount of amino acids.

[0052] The second stage: when the temperature rises to 60-63℃, stop heating and start timing. After saccharification for 30 minutes, heat up and start the third stage of saccharification. This stage is used to promote β-amylase to hydrolyze starch, thereby generating a large amount of maltose and a small amount of dextrin.

[0053] The third stage, when the temperature rises to 65-68℃, stop heating and start timing. After saccharification for 20 minutes, heat up and start the fourth stage of saccharification. This stage is used to promote α-amylase to hydrolyze starch, thereby producing a large amount of dextrin.

[0054] In the fourth stage, the temperature rises to 70-72℃ and the heating is stopped and the timing starts. After saccharification for 10 minutes, the temperature is raised and the fifth stage of saccharification begins. This stage promotes the production of fermentable sugars. This process produces a large amount of maltose and a small amount of dextrin.

[0055] In the fifth stage, the temperature rises to 75-78°C, heating is stopped and timing begins. Saccharification lasts for 5 minutes, a large amount of dextrin is generated, and saccharification ends.

[0056] Compared with the three-stage saccharification method of 50℃-65℃-78℃ in the prior art, this embodiment

[0057] First, the wort is directly put into a saccharification pot with hot water at 50-55°C to accelerate the leaching of enzymes in the malt and increase the activity of the enzymes;

[0058] Secondly, the five-stage temperature increase maximizes the activity of the enzyme, improves the saccharification efficiency and the quality of the wort, and gradually increases the temperature from low to high to prevent the enzyme from being destroyed, which reduces the generation of by-products.

[0059] Step S3, filtering process;

[0060] Before saccharification begins, hot water at 50-55°C in the saccharification pot is introduced into the filter tank to prepare for subsequent filtration. The concentration of the original wort is controlled, and the mass ratio of saccharification water to slop water is 1-1.25:1. After saccharification is completed, the mash formed in the saccharification pot is pumped into the filter tank, first allowed to stand for 10 minutes, then refluxed for 15 minutes until the wort is clear, and the first filtration begins. When a certain volume of clear wort is obtained by filtration, the filtration is stopped.

[0061] Then add a certain volume of hot water (waste water) preheated to 76-78°C into the filter tank to start the second filtration (waste washing); the second filtration time is controlled within 30-60 minutes, and finally collect the clarified wort;

[0062] In this step, by controlling the time of the second filtration, it is possible to avoid insufficient utilization of raw materials, low soluble sugar content, low wort sugar content and high wort turbidity due to too short a time, and to avoid too long a time, which will cause the wort sugar content to decrease and affect fermentation.

[0063] Step S4: boiling of wort

[0064] The clarified wort obtained by filtering in step S3 is pumped into a boiling pot, and the wort is heated to 95-98°C, and the wort is kept in a boiling state for 65-70 minutes, so that the wort has a first sugar content. In addition, Peller hops are added at the beginning of boiling; Peller hops are continued to be added after boiling for 30 minutes; when the wort is boiled for 65 minutes, Saaz hops are added and a mixture of citronella extract and passion fruit juice having a first addition amount is added to the wort until the boiling is completed.

[0065] Preferably, the lemongrass extract and passion fruit juice are added 5 minutes before the boiling is terminated.

[0066] In this step, the enzyme is inactivated by heating the wort to maintain the ratio of maltose and dextrin. By boiling, various fungi in the wort are eliminated to avoid spoilage during fermentation and ensure the quality of the final product; and by keeping it in a boiling state for a certain period of time, excess water can be evaporated during the boiling process to concentrate the wort to the required concentration, and the duration can be adjusted according to the required sugar content, preferably the first sugar content is 8-12°P;

[0067] Furthermore, hop oils are highly volatile and tend to "evaporate" during a long cooking process. Therefore, adding Peller hops at the beginning of the boiling process can maximize the extraction of hops and ensure full isomerization. Adding Saaz hops at a later stage helps to maintain the subtle flavor and aroma of hops produced by hop oils.

[0068] Furthermore, in order to perfectly combine the flavors of the two raw materials, lemongrass and passion fruit, Peller hops and Saaz hops were selected. Peller hops are aroma hops with an α-acid content of 4-9%. They have a slight spicy, floral and high-quality bitterness, a prominent hop aroma and a high linalool content, which is suitable for highlighting the fruity aroma in fruity beer. However, α-acid is the main source of bitterness in beer. The α-acid content in Peller hops is higher, and a longer boiling time will lead to more α-acid isomerization, increasing bitterness.

[0069] Saaz hops are aroma hops with an α-acid content of 2-6%. They contain balanced oils and more polyphenols. They have a good antioxidant effect on beer and can extend the shelf life of beer flavor. In order to avoid the volatilization of aroma, they are added later.

[0070] Before the wort fermentation in step S5, the method further includes: introducing the boiled wort into a whirlpool settling tank for heat coagulant precipitation and separation, and cooling the hot wort after whirlpool settling through a plate heat exchanger.

[0071] Step S5, fermentation of wort, including: a primary fermentation stage and a secondary fermentation stage.

[0072] Main fermentation stage: add yeast to wort cooled to about 18°C ​​according to the mass ratio of yeast:wort = 0.25-0.28:10, stir for 5 minutes to mix evenly, and let it stand for activation for 30-35 minutes to obtain activated yeast; pass the activated yeast into the fermentation tank, and start the main fermentation by oxygenation; the sugar content of the fermentation liquid is controlled at 5±0.2°p; the fermentation time is controlled at about 5-7 days;

[0073] During the main fermentation stage, cooling the wort to around 18°C ​​can prevent high temperature from affecting yeast activity. This temperature can also keep the fermentation rate from being too fast or too slow, converting most of the fermentable sugars into ethanol and carbon dioxide and consuming most of the yeast.

[0074] Since the sugar content will affect the final alcohol content of beer, if the sugar content is too high, the fermentation will be incomplete and the alcohol content will be low; if the sugar content is too low, the alcohol content will be high, and the appropriate sugar content is conducive to balancing the bitterness of beer. Therefore, the sugar content of the fermentation liquid should be strictly controlled at 5±0.2°p during the main fermentation stage; in this embodiment, the fermentation time is controlled at about 5 to 7 days, which can enable the yeast to fully convert into sugar, avoiding the phenomenon of rough taste of beer, poor flavor, or bitterness and off-flavors.

[0075] When the sugar content drops to 5±0.2°p, the secondary fermentation stage is entered, at which time the second amount of lemongrass extract and passion fruit juice are added, the can is sealed and the pressure is increased to 0.12±0.01MPa, and the secondary fermentation begins;

[0076] The sugar content of the secondary fermentation is controlled at 3.5±0.2°P; when the sugar content drops to 3.5°P or remains unchanged, the temperature is gradually lowered to 0-1°C (2°C every 48 hours), and when the temperature drops to 5°C, the yeast is discharged and the wine is stored under pressure; the secondary fermentation time is controlled at 4-5 days;

[0077] In the secondary fermentation stage, slow cooling allows yeast that has not completely lost its activity to continue fermenting, extending the fermentation time. Slow cooling allows yeast to precipitate, making the beer clear while increasing the foam retention; low temperature can also prevent other bacteria from growing and contaminating the beer.

[0078] The step of removing yeast can increase the clarity of wort and prevent yeast autolysis from affecting the taste. This embodiment controls the fermentation time to 4-5 days, which is conducive to the diffusion and combination of the aroma of lemongrass extract and passion fruit juice, and increases the fruity aroma of beer.

[0079] In this embodiment, the first fermentation is to convert a large amount of fermentable sugar into alcohol and carbon dioxide, achieving sugar control while consuming most of the yeast; the purpose of the second fermentation is to allow the remaining yeast to continue to convert a small amount of residual sugar into alcohol and carbon dioxide at low temperature, while cleaning up some metabolic byproducts of the first fermentation stage that damage the flavor of the beer, such as diacetyl. The two fermentations are carried out in a completely closed and low-temperature environment, so the carbon dioxide produced will be retained in the beer, giving the beer a "killing" feeling when it is drunk.

[0080] In this step, by adding the citronella extract and passion fruit juice for the second time, the volatile aroma components of the two are more fully combined with the wort aroma in a low-temperature and closed environment, which is conducive to maintaining the beer aroma for a long time and improving the problem of separating the wort aroma from the special aroma of passion fruit and citronella.

[0081] Preferably, the lemongrass extract and passion fruit juice in the second added amount account for 20% to 40% of the total added amount;

[0082] The addition amounts of lemongrass extract and passion fruit juice are calculated based on wort: 2-3 g / L and 30-50 g / L respectively.

[0083] Preferably, the yeast is A01 ale yeast or lager yeast.

[0084] Step S6: After the wine is mature, the finished product is filled, sterilized, packed and shipped out.

[0085] The method of the present invention prolongs the time of the second fermentation by adopting a low-temperature fermentation method while controlling the sugar content, so that the beer has a higher foam retention, ensuring that the volatile aroma components in the fruit juice can be better combined with the beer, thereby prolonging the duration of the fruity aroma, avoiding the separation of the aroma from the beer body in the late fermentation period and providing a good taste.

[0086] The second embodiment of the present invention provides a lemongrass passion fruit beer brewed by the method of the first embodiment.

[0087] Example 1

[0088] Step S1, weighing the following raw materials in parts by weight: 125 parts of barley malt, 70 parts of wheat malt, and 25 parts of light coke malt, mixing and crushing to obtain malt powder; weighing 0.3 parts of Peller hops, 0.5 parts of Saaz hops, 2 parts of lemongrass, 4 parts of passion fruit, 1450 parts of water, and 0.25 parts of yeast;

[0089] Select 2 portions of dried lemongrass with complete leaves and strong aroma, wash and cut into small pieces, extract the lemongrass with water at a mass ratio of 1:5 at 90-95° C. for 1-1.5 hours, and obtain a lemongrass extract;

[0090] Select fresh passion fruit, peel the fruit pulp and mix it with water in a ratio of 1:0.8-1.2, add 0.25-0.3% by weight of pectinase and cellulase, obtain clarified passion fruit juice after enzymolysis and filtration, and refrigerate for later use;

[0091] Step S2: Put the crushed malt powder into a saccharification pot at 55°C and 85L hot water for staged saccharification:

[0092] When the temperature reaches 55°C, stop heating and start timing. After saccharification for 10 minutes, start heating.

[0093] When the temperature reaches 63°C, stop heating and start timing. After saccharification for 30 minutes, start heating.

[0094] When the temperature reaches 68°C, stop heating and start timing. After saccharification for 20 minutes, start heating.

[0095] When the temperature reaches 72°C, stop heating and start timing. After saccharification for 10 minutes, start heating.

[0096] When the temperature reaches 78°C, stop heating and start timing, and saccharify for 5 minutes.

[0097] Step S3, filtration treatment: After saccharification is completed, water is spread on the bottom of the filter tank, and then the mash formed in the saccharification pot is pumped into the filter tank, first allowed to stand for 10 minutes, and then refluxed for 15 minutes until the wort is clear, and the first filtration begins;

[0098] When 50-60L of clear wort is obtained by filtration, stop filtering.

[0099] Then add 60L of hot water (waste water) preheated to 76-78℃ to the filter tank to start the second filtration (waste washing); continue filtering and introduce the filtered clarified wort into the saccharification pot; the washing time is controlled within 30-60min, and finally collect 120L-130L of clarified wort;

[0100] Step S4, boiling treatment: pump the clarified wort obtained by filtration into a boiling pot, heat the wort to 95-98° C., keep the wort in a boiling state for 65-70 minutes, and add Peller hops when it starts to boil; continue to add Peller hops when boiling for 30 minutes; when the wort is boiled for 65 minutes, add Saaz hops and mix 180 g of lemongrass extract and 2.4 kg of passion fruit juice and add them to the wort until the boiling is completed;

[0101] Cyclotonic sedimentation: After the wort is boiled, it enters the cyclotonic sedimentation tank for thermal coagulant precipitation and separation;

[0102] Cooling treatment: After cyclotron settling, the hot wort passes through a plate heat exchanger to cool down;

[0103] Step S5, fermentation of wort, comprising:

[0104] Step S5-1: Main fermentation stage: after cooling, yeast is added to wort at a mass ratio of yeast: wort = 0.25-0.28:10, stirred for 5 minutes to mix evenly, and left to stand for activation for 30-35 minutes to obtain activated yeast; the activated yeast is introduced into a fermentation tank, and oxygen is supplied to start main fermentation; the temperature is controlled at 18±0.5°C; the sugar content of the fermentation liquid is controlled at 5±0.2°p; and the fermentation time is controlled at about 7 days;

[0105] Step S5-2, secondary fermentation stage: When the sugar content drops to 5±0.2°P, add 120g of lemongrass extract and 1.6kg of passion fruit juice again, seal the can and increase the pressure to 0.12±0.01MPa to start secondary fermentation. The sugar content of secondary fermentation is controlled at 3.5±0.2°P; when the sugar content drops to 3.5°P or remains unchanged, gradually cool down to 0-1°C (2°C every 48h), and when the temperature drops to 5°C, start to discharge yeast and store the wine under pressure; the secondary fermentation time is controlled at 4-5 days;

[0106] Example 2

[0107] The steps are the same as those in Example 1, except that:

[0108] In step S1, lemongrass and water are extracted at a mass ratio of 1:10 at 90-95° C. for 2-3 hours to obtain a lemongrass extract;

[0109] The passion fruit pulp is mixed with water in a ratio of 1:1-1.5, and 0.2-0.25% by weight of pectinase and cellulase are added, and the clarified passion fruit juice is obtained after enzymolysis and filtration.

[0110] Example 3

[0111] The steps are the same as those in Example 1, except that:

[0112] In step S1, lemongrass and water are extracted at a mass ratio of 1:15 at 90-95° C. for 3-4 hours to obtain a lemongrass extract;

[0113] The passion fruit pulp is mixed with water in a ratio of 1:1.5-2, and 0.1-0.15% by weight of pectinase and cellulase are added, and clarified passion fruit juice is obtained after enzymolysis and filtration.

[0114] Comparative Example 1

[0115] Compared with Example 1, the step of preparing the citronella extract is eliminated, and the citronella extract is replaced by citronella powder. The rest of the formula and process are the same as those in Example 1.

[0116] Comparative Example 2

[0117] Compared with Example 1, the secondary fermentation is cancelled, and the lemongrass extract and passion fruit juice in the secondary fermentation are directly added to the main fermentation, that is, only fermentation is performed once, and the rest of the formula and process are the same as those in Example 1.

[0118] By comparing various embodiments and comparative examples, the conclusions are as follows:

[0119] Table 1 Comparison data

[0120]

[0121] Diacetyl is an intermediate metabolite of pyruvic acid and α-acetolactic acid metabolized by yeast during fermentation. The content of diacetyl will directly affect the final taste. The diacetyl content of general commercial beer is between 0.1-0.15. As shown in Comparative Example 2, the diacetyl content of beer fermented only once is high. The diacetyl content of the beer of the present invention is much lower than the general value.

[0122] Foam persistence refers to the persistence of foam. High foam persistence is usually regarded as one of the signs of good beer quality. High foam persistence usually means that the beer contains a higher concentration of surfactants, such as protein and polyphenols. These substances can be adsorbed on the gas-liquid interface when bubbles are formed, reducing the speed of bubble bursting, making the foam more stable and lasting, thereby extending the duration of the fruity aroma and avoiding the separation of the aroma from the beer body in the late fermentation period. It can be seen from Comparative Example 2 that the foam persistence rate of beer fermented only once is much lower than that of other examples.

[0123] In addition, pectinase and cellulase can not only decompose the cell walls in the juice, making the juice clearer, but also degrade pectin. As the amount of enzyme added increases, the turbidity and color of the beer decrease, the degree of beer fermentation increases, the carbon dioxide content generated increases, and there is more foam.

[0124] Therefore, the lemongrass passion fruit beer prepared in Example 1 not only has a lower diacetyl content, but also has the characteristics of low turbidity, high foam retention, etc., has a longer duration of fruity aroma, and avoids the phenomenon of separation of aroma and beer body in the late fermentation period.

[0125] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for preparing lemongrass passion fruit beer, It is characterized in that include: preparing malt powder, lemongrass extract and passion fruit juice; Saccharification and filtration of wort: putting the malt powder into a saccharification pot for staged saccharification, and filtering after saccharification to obtain clarified wort; Boiling wort: adding at least two kinds of hops and auxiliary materials with a first addition amount to the wort in batches during the boiling stage until boiling is completed and then cooling, wherein the auxiliary materials include: the lemongrass extract and the passion fruit juice; Fermentation of wort: the yeast and the cooled wort are mixed evenly in a mass ratio of 0.25 to 0.28:10, left to stand for activation, and then introduced into a fermentation tank for primary fermentation; when the sugar content drops to 5±0.2°P, the auxiliary material with the second addition amount is added, the tank is sealed and the pressure is increased to 0.12±0.01MPa for secondary fermentation; When the sugar content during the secondary fermentation drops to 3.5°P or remains unchanged, the temperature is gradually lowered. When the temperature drops to 5°C, the yeast is discharged and the beer is stored at a pressure maintained to obtain the lemongrass passion fruit beer.

2. The method according to claim 1, It is characterized in that The malt powder comprises: barley malt, wheat malt and light coke malt; the mass ratio of the barley malt, wheat malt and light coke malt is: 25:14:

5.

3. The method according to claim 1, It is characterized in that The method for extracting the citronella extract comprises: selecting dry citronella and extracting it with water at a mass ratio of 1:5 at 90-95° C. for 1-1.5 hours; The preparation method of the passion fruit juice comprises: beating passion fruit pulp with water in a ratio of 1:0.8-1.2, adding 0.1-0.3% by weight of pectinase and cellulase, and obtaining clarified passion fruit juice after enzymolysis and filtration.

4. The method according to claim 1, It is characterized in that The saccharification step comprises: putting the malt powder and water in a mass ratio of 1:3.5-4 into a saccharification pot with hot water at 50-55°C; In the first stage, the temperature rises to 50-55°C, heating is stopped and timing begins, and saccharification lasts for 10 minutes; In the second stage, the temperature rises to 60-63℃, heating is stopped and timing begins, and saccharification lasts for 30 minutes; In the third stage, the temperature rises to 65-68℃, heating is stopped and timing begins, and saccharification lasts for 20 minutes; In the fourth stage, the temperature rises to 70-72°C, heating is stopped and timing begins, and saccharification lasts for 10 minutes; In the fifth stage, the temperature rises to 75-78°C, heating is stopped and timing begins. Saccharification lasts for 5 minutes, and saccharification ends.

5. The method according to claim 1, It is characterized in that The filtering step comprises: First filtration: After saccharification, the mash formed in the saccharification pot is pumped into the filter tank to stand, and then refluxed until the wort is clear, and the filtration is repeated until clear wort is obtained; Second filtration: Add the slop washing water preheated to 76-78°C into the filter tank, and the tank washing time is 30-60 minutes.

6. The method according to claim 5, It is characterized in that The saccharification step also includes: before the saccharification begins, pouring saccharification water at 50-55° C. in the saccharification pot into the filter tank; the mass ratio of the saccharification water to the sludge washing water is 1-1.25:

1.

7. The method according to claim 1, It is characterized in that The boiling step comprises: Pumping the clarified wort into a boiling pot, heating the wort to 95-98° C., and keeping the wort in a boiling state for a period of time to make the wort have a first sugar content; Meanwhile, add the Peller hops for the first time at the beginning of the boil; Add Peller hops for the second time when boiling for 25-30 minutes; When boiling for 60 to 65 minutes, add Saaz hops, and at the same time, mix the lemongrass extract and the passion fruit juice and add them until the boiling is finished.

8. The method according to claim 7, It is characterized in that The first sugar content is 8-12°P; the yeast is A01 ale yeast or lager yeast.

9. The method according to claim 1, It is characterized in that In the first addition amount, the lemongrass extract and passion fruit juice account for 60% to 80% of the total addition amount; In the second added amount, the lemongrass extract and passion fruit juice account for 20% to 40% of the total added amount; The addition amounts of the citronella extract and passion fruit juice are calculated based on the wort and are respectively 2-3 g / L and 30-50 g / L.

10. A lemongrass passion fruit beer, It is characterized in that Brewing according to the method described in any one of claims 1 to 9, comprising the following raw materials with the following components and weight fractions: 125-130 parts of barley malt, 70-75 parts of wheat malt, 25-30 parts of light char malt, 0.3-0.4 parts of Peller hops, 0.5-0.6 parts of Saaz hops, 2-2.5 parts of lemongrass, 4-4.5 parts of passion fruit, 1450-1500 parts of water, and 0.25-0.3 parts of yeast.

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