Vaccinium bracteatum thunb leaf fermented tea cake and making method thereof

Abstract

The invention relates to the technical field of food industry, and discloses a vaccinium bracteatum thunb leaf fermented tea cake and a making method thereof. According to the method, hot air withering and light supplementing withering technologies are added in the withering process, so that the fragrance, flavor and nutrient content of the product are improved to a certain extent; secondly, the fermentation process of endogenous enzyme and exogenous enzyme is added, so that the cell wall structure can be effectively destroyed, the release of inclusions is promoted, protein is decomposed to generate amino acid, and good effects on enhancing the fresh and cool feeling, enhancing the concentration of tea soup and improving the taste are achieved; finally, a punching cake making technology is creatively adopted, so that the vaccinium bracteatum thunb tea product is easier to store and transport, and the vaccinium bracteatum thunb tea is of great significance to industrial development of the vaccinium bracteatum thunb tea.

Description

Technical Field

[0001] The invention relates to the technical field of food industry, and more particularly to a black rice leaf fermented tea cake and a preparation method thereof. Background Art

[0002] Vaccinium bracteatum (Vaccinium bracteatum Thunb.), also known as southern candle and dyeing bean, is an evergreen shrub or small tree in the genus Vaccinium of the Ericaceae family. Vaccinium bracteatum has strong ecological adaptability, is drought-tolerant, cold-resistant, and resistant to infertility, preferring both sun and shade. It is a unique tree species that combines medicinal, health-promoting, and ornamental properties, with broad prospects for development and utilization. Vaccinium bracteatum has a long history of medicinal use. Traditional Chinese Medicine believes that its leaves are mild in nature and have a light flavor. Its fruits and branches are used as medicine to benefit the kidneys and strengthen essence, strengthen the tendons and improve eyesight, relieve drowsiness, relax blood vessels, improve blood circulation, and treat chronic diarrhea and dysentery. Vaccinium bracteatum leaves can also be used directly to make a drink or added to beverages to prevent diseases such as arteriosclerosis and diabetes.

[0003] The production of tea cakes has a long history. Making tea into tea cakes makes it easier to store and transport. This is particularly true for the production of black rice leaf tea. Black rice leaf leaves are very fragile after being made into tea, which seriously affects the quality of the tea. Therefore, making black rice leaf tea into tea cakes greatly facilitates the storage and transportation of the tea.

[0004] Chinese Patent Publication No. CN 114009559 A discloses a process for preparing black rice tea and its preparation. The process includes preparing the raw material, air-drying the surface, rapidly inactivating enzymes, maintaining color and aroma, disrupting cells, moistening the pulp, shaping, drying, selecting, packaging, and inspecting. However, the resulting black rice tea has a certain astringency and bitterness, and the flavor needs improvement. Furthermore, the dried black rice leaves are quite brittle and easily crumble under pressure, affecting the appearance and making them inconvenient to store.

[0005] Therefore, improving the traditional processing technology of the leaves of the blueberry tree is of great significance for increasing the value of the leaves of the blueberry tree. Summary of the Invention

[0006] In light of this, the present invention provides a fermented tea cake made from black rice leaf and a method for making it. Compared to existing technologies, the present invention incorporates hot air and light-assisted withering techniques during the withering process, significantly improving the aroma, flavor, and nutrient content of the product. Furthermore, the fermentation process incorporates both endogenous and exogenous enzymes, effectively disrupting the cell wall structure, promoting the release of internal contents and breaking down proteins into amino acids. This has a significant effect on enhancing the freshness, concentration, and flavor of the tea. Finally, the present invention innovatively utilizes a punching and cake-pressing technique, making black rice leaf tea products easier to store and transport, which is of great significance to the development of the tea industry.

[0007] One of the purposes of the present invention is to provide a method for preparing a fermented tea cake of black rice leaf, comprising the following steps:

[0008] (1) Raw material collection: From the end of April to the beginning of May, collect 1 bud and 2 leaves or 1 bud and 3 leaves from the new shoots of the black rice tree. The collected young shoots need to be placed in a breathable basket or net bag to avoid mechanical damage and heating and reddening of the raw materials.

[0009] (2) Light supplement and withering: Spread the collected tea leaves evenly in the withering trough with a thickness of 2cm to 5cm. Use air blowing to wither for 2-4 hours. The air volume should be such that the leaf layer is not blown away. Shake the leaves every 30 minutes. When shaking, the hands should be light, shake them loosely, turn them thoroughly, and spread them evenly to avoid damaging the buds and leaves. At the same time, use monochromatic LED lights for light supplement to activate oxidase and accelerate the degradation of chlorophyll to improve the aroma quality of the fermented tea products made from black rice leaves.

[0010] (3) Rolling: Use a rolling machine or hand-rolling to roll the tea leaves into strips in a stable environment in three steps, following the order of light-heavy-light, to destroy the cell structure and promote the overflow and oxidation of the black rice juice.

[0011] (4) Fermentation: A fermentation machine can be used for fermentation to ensure a stable fermentation environment. The tea leaves are piled up to a thickness of 10 cm to 15 cm in an environment with a temperature of 25°C to 30°C, a relative humidity of not less than 90%, and sufficient oxygen. After fermentation for 4 hours, the tea leaves are taken out and the exogenous enzyme mixture is evenly sprayed on the surface of the leaves for secondary fermentation. The fermentation is carried out until the grass smell disappears, the floral and fruity aroma begins to appear, and the leaves are preferably orange-red in color.

[0012] The beneficial effects achieved by the above technical means are: secondary fermentation is carried out by adding exogenous enzymes, which promotes the release of contents and enhances the flavor of the product.

[0013] (5) Initial drying: Spread the leaves to a thickness of about 1 cm and treat at 80°C for about 20 minutes until the moisture content of the leaves is about 20% and they feel prickly when held.

[0014] (6) Spread out to cool: Spread out the tea leaves in time to cool them down and dissipate the heat. The cooling time is 30 to 60 minutes.

[0015] (7) Re-drying: Spread the leaves to a thickness of about 2cm to 3cm, treat at 70℃ to 80℃ for about 15 minutes, dry until the moisture content is no more than 6%, and grind into powder by hand.

[0016] (8) Refining: Use screening, stem picking, air separation and other equipment to remove the tendons, stems, flakes and powder of tea leaves, and use static electricity to remove light impurities such as hair and dust.

[0017] (9) Re-steaming and softening: Put the tea leaves into a wet steaming barrel and steam them at a steam temperature of 100-105℃ for 1min-2min to raise the moisture content of the leaves to 12%-15%.

[0018] (10) Punching and pressing: Put the tea leaves into the mold and press the hydraulic press at a pressure of 15-20 tons for 5-10 minutes;

[0019] The effect of adopting the above technical means is: using a hydraulic press for pressing, high efficiency and strong compactness.

[0020] (11) Drying and shaping: Cool the leaf cake to room temperature and package it after it is completely cooled to prevent the uncooled leaf cake from deforming.

[0021] Preferably, the weather on the day of collection in step (1) and 1-2 days before collection should be sunny and rainless, and fresh, tender, uniform, and free of pests and diseases should be collected.

[0022] Preferably, the operation of the air withering in step (2) is as follows: the air flow temperature at the air outlet is 28°C to 32°C, the humidity is 70% to 75%, and the air is stopped for 10 minutes every hour; 15 minutes to 30 minutes before the end of withering, the hot air is stopped and replaced with natural air.

[0023] Preferably, the peak wavelength of the monochromatic light in step (2) is: λ = 480nm, half width: Δλ = 20nm, and luminous flux: Φ = 150μmol·m -2 ·s -1 .

[0024] Preferably, the requirements for environmental stability in step (3) are: temperature 20-24° C., humidity 85-90%.

[0025] Preferably, the specific operation of light-heavy-light in step (3) is:

[0026] Initial kneading: Press lightly for 15-30 minutes to make the tea leaves into initial strips, but avoid excessive leaf breakage.

[0027] Repeated kneading: gradually increase the pressure and knead for 30-60 minutes, so that the cell breakage rate reaches more than 80%, the cells are fully broken, and the juice overflows;

[0028] Second light kneading: sieve out the clumped leaves to make them evenly distributed and dissipate heat.

[0029] Preferably, the exogenous enzyme mixture in step (4) is a mixture containing 0.1% by mass concentration of pectinase and 0.05% by mass concentration of protease.

[0030] Preferably, the amount of the exogenous enzyme mixture in step (4) is 5-10 mL sprayed per kilogram of tea leaves.

[0031] Preferably, the temperature, humidity and oxygen conditions of the secondary fermentation in step (4) are the same as those of the primary fermentation, and the fermentation time is 30 min to 1 h.

[0032] The second object of the present invention is to provide a fermented tea cake made from blackberry leaves.

[0033] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention utilizes enzymatic fermentation technology to ferment the blueberry leaves through the polyphenol oxidase in the leaves and exogenously added cellulose and protease, thereby creating a new process for producing blueberry leaf tea, thereby improving the flavor quality of the blueberry tea product. In addition, the microwave hot air withering and light supplement withering technologies used in the process also have a certain benefit in improving the nutritional components and flavor of the blueberry tea product. Finally, the punching and cake-making technology makes the blueberry tea product easier to preserve. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0036] Figure 1 These are the results of the nutrient content of the leaves of the black rice tree under different LED light qualities in comparative example 1.

[0037] Figure 2 The following is the taste comparison result of fermentation and non-fermentation in comparative example 2. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] A method for preparing a fermented tea cake of black rice leaves, comprising the following specific steps:

[0041] 1) Raw material collection:

[0042] The collection time is from the end of April to the beginning of May. The weather should be sunny and rainless on the day of collection and 1-2 days before collection. Choose 1 bud and 2 leaves or 1 bud and 3 leaves from the new shoots of the black rice tree.

[0043] 2) Fill in the light and wither

[0044] The leaves are evenly spread in the withering trough with a thickness of 2cm to 5cm. The air flow temperature at the blast outlet is 28℃ to 32℃ and the humidity is 70% to 75%. The blast is stopped for 10 minutes every hour. 15min to 30min before the end of withering, the hot air is stopped and replaced with natural air. The withering time is 2-4h. The leaves are shaken every 30min. At the same time, a monochromatic LED light is used for supplementary lighting (peak wavelength: λ = 480nm, half width: Δλ = 20nm, luminous flux: Φ = 150μmol·m-2·s-1).

[0045] 3) Rolling

[0046] The room temperature is maintained at 20-24°C and the humidity is 85-90%. The kneading is carried out in three steps in the order of light-heavy-light. The first kneading is light pressure for 15-30 minutes to make the black rice leaves initially into strips, and it is necessary to avoid excessive leaf breakage; the second kneading is to gradually increase the pressure and knead for 30-60 minutes to fully rupture the cells and overflow the juice. The cell breakage rate must reach more than 80%; the second light kneading is to screen out the agglomerated leaves, make the leaves evenly distributed, and dissipate heat.

[0047] 4) Fermentation

[0048] The temperature of the fermentation place is 25℃~30℃, the relative humidity is not less than 90%, the fermented leaves are evenly stacked with a thickness of 10cm~15cm, and the fermentation space is kept with sufficient oxygen. Fermentation is carried out in a fermentation machine to ensure a stable fermentation environment. After the first fermentation for 4 hours, the leaves are taken out, and a mixture of pectinase (0.1%) and protease (0.05%) is prepared. The surface of the leaves is evenly sprayed for secondary fermentation. 5mL of the mixture is sprayed per kilogram of leaves. The secondary fermentation time is controlled between 30min and 1h. Fermentation is carried out until the grass smell disappears, the floral and fruity fragrance begins to appear, and the leaf color is preferably orange-red.

[0049] 5) Initial baking

[0050] The temperature is controlled at 80℃, the leaf thickness is about 1cm, and the treatment takes about 20 minutes to dry until the leaf moisture content is about 20% and it feels prickly when held by hand.

[0051] 6) Let it cool

[0052] Spread out the leaves in time to cool down and dissipate heat, the time is 30 minutes to 60 minutes.

[0053] 7) Re-drying

[0054] The temperature is 70℃~80℃, the leaves are spread to a thickness of about 2cm~3cm, and the process is carried out for about 15 minutes and dried until the moisture content is no more than 6%, and then ground into powder by hand.

[0055] 8) Refining

[0056] Use screening, stem picking, air separation and other equipment to remove ribs, stems, flakes and powder, and use static electricity to remove light impurities such as hair and dust.

[0057] 9) Re-steaming and softening

[0058] Put the leaves into the wet steaming barrel, adjust the steam temperature to 100-105℃, and the time is 1min-2min, so that the moisture content of the leaves returns to 12%-15%.

[0059] 10) Punching and pressing cakes

[0060] Place a 5g blade into the mold in advance, control the hydraulic press pressure at 15 to 20 tons for stamping, and control the stamping time at 5-10 minutes.

[0061] 11) Drying and setting

[0062] After stamping, take out the leaf cake and place it in a special shaping rack to cool at room temperature for 30 minutes. After it is completely cooled, take it out and package it to prevent the uncooled leaf cake from deforming.

[0063] Comparative Example 1

[0064] Effects of different LED light qualities on the nutrient content of black rice tree leaves

[0065] For step 2) supplementary light withering in Example 1, five light qualities were set, namely white light control (W), red light (R), yellow light (Y), blue light (B) and ultraviolet light (UV-A) to treat the blueberry seedlings, and the remaining steps were the same as in Example 1.

[0066] Test results see Figure 1 Different experiments showed that the total flavonoids content in the leaves of the black rice seedlings under blue light and ultraviolet light treatment was 45.23 mg / g and 33.02 mg / g, respectively, which increased by 49.08% and 8.83% compared with white light (control). The results showed that blue light has a significant advantage in the accumulation of flavonoids content in the leaves.

[0067] Comparative Example 2

[0068] Taste comparison between fermented and non-fermented

[0069] For step 4) fermentation in Example 1, a comparative example without fermentation was set, and the remaining steps were the same as in Example 1.

[0070] The taste of unfermented and fermented black rice leaf tea was tested by electronic tongue, and the results are shown in Table 1 and Figure 2 Under the influence of fermentation, the bitterness and astringency of the black rice leaf tea were significantly reduced, and the sweetness and sourness increased. The test results showed that fermentation can significantly adjust the taste of the black rice leaf tea.

[0071] Table 1

[0072] sweet acid bitter astringent No fermentation 0.87 -14.21 7.91 4.16 Fermentation 10.41 0.51 -2.32 -2.21

[0073] Comparative Example 3

[0074] Comparison of nutrients between fermented and non-fermented

[0075] The nutrients in the unfermented and fermented black rice leaf tea in Comparative Example 2 were tested. The results are shown in Table 2. The black rice leaf significantly increased the content of most substances during the fermentation process, especially sugars and some amino acids, while organic acids also increased.

[0076] Table 2

[0077]

[0078] Result analysis:

[0079] Sugars (glucose, fructose, sucrose):

[0080] The content increased significantly after fermentation, among which fructose increased the most (19.21→41.63 mg / g) and sucrose increased the most significantly (1.13→13.68 mg / g).

[0081] This suggests that fermentation may promote the decomposition of polysaccharides or the accumulation of sugars, thereby enhancing the sweetness of black rice leaf tea.

[0082] Organic acids (tartaric acid, citric acid):

[0083] The content increased significantly after fermentation, with tartaric acid (42.43→92.30μg / g) and citric acid (8.17→18.81mg / g) both doubling.

[0084] This indicates that the fermentation process may promote the production of organic acids, affecting the sourness and flavor complexity of Wufanye tea.

[0085] Amino acids (Gln, Phe, Tyr):

[0086] The content generally increased after fermentation, especially glutamine (Gln) (2.07→17.92μg / g), which increased nearly 9 times, and tyrosine (Tyr) (15.63→33.44μg / g) also increased significantly.

[0087] The increase in amino acids may enhance the umami taste and aroma of black rice leaves and make an important contribution to the flavor.

[0088] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a fermented tea cake of black rice leaf, characterized in that: The following steps are involved: (1) Raw material collection: From the end of April to the beginning of May, collect 1 bud and 2 leaves or 1 bud and 3 leaves from the new shoots of the blueberry tree; (2) Light supplement and withering: The collected tea leaves are evenly spread in the withering trough with a thickness of 2cm to 5cm. The leaves are withered with air for 2-4 hours, and shaken every 30 minutes. At the same time, a single-color LED light is used for light supplement. (3) Rolling: In a stable environment, the tea leaves are rolled into strips in three steps in the order of light-heavy-light. (4) Fermentation: Pile the tea leaves to a thickness of 10 cm to 15 cm in an environment with a temperature of 25°C to 30°C, a relative humidity of not less than 90%, and sufficient oxygen. After fermentation for 4 hours, remove the tea leaves, spray them evenly with the exogenous enzyme mixture, and then perform secondary fermentation. (5) Initial drying: spread the leaves and dry them at 80°C until the moisture content of the leaves is about 20%; (6) Spread out the tea leaves to cool for 30 to 60 minutes; (7) Re-drying: Spread the leaves and dry at 70-80°C until the moisture content is no more than 6%; (8) Refining: Use screening, stem picking, and air separation equipment to remove the tendons, stems, flakes, and powder of tea leaves, and use static electricity to remove hair and dust; (9) Re-steaming and softening: steam the tea leaves at a temperature of 100-105°C to raise the moisture content of the leaves to 12%-15%; (10) Punching and pressing: Put the tea leaves into the mold and press the hydraulic press at a pressure of 15-20 tons for 5-10 minutes; (11) Drying and shaping: Cool the leaf cake to room temperature and package it after it is completely cooled.

2. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The weather on the day of collection in step (1) and 1-2 days before collection should be sunny and rainless, and fresh, tender, uniform, and free of disease and insect pests should be collected.

3. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The operation of the air withering in step (2) is as follows: the air flow temperature at the air outlet is 28°C to 32°C, the humidity is 70% to 75%, and the air is stopped for 10 minutes every hour; 15 minutes to 30 minutes before the end of withering, the hot air is stopped and replaced with natural air.

4. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The peak wavelength of the monochromatic light in step (2) is: λ = 480nm, half width: Δλ = 20nm, and luminous flux: Φ = 150μmol·m -2 ·s -1 .

5. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The requirements for environmental stability in step (3) are: temperature 20-24° C., humidity 85-90%.

6. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The specific operation of light-heavy-light in step (3) is: Initial kneading: lightly press for 15-30 minutes to make the tea leaves initially into strips; Repeated kneading: gradually increase the pressure and knead for 30-60 minutes until the cell breakage rate reaches more than 80%; Second light kneading: sieve out the clumping leaves.

7. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The exogenous enzyme mixture in step (4) is a mixture containing 0.1% by mass concentration of pectinase and 0.05% by mass concentration of protease.

8. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The dosage of the exogenous enzyme mixture in step (4) is 5-10 mL sprayed per kilogram of tea leaves.

9. The method for making a fermented tea cake of black rice leaf according to claim 1, characterized in that: The temperature, humidity and oxygen conditions of the secondary fermentation in step (4) are the same as those of the primary fermentation, and the fermentation time is 30 minutes to 1 hour.

10. The fermented tea cake of blueberry leaves obtained by the preparation method according to any one of claims 1 to 9.

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