Preparation method of cold-brew instant matcha liquid

Abstract

This invention discloses a method for preparing cold-extracted instant matcha liquid, belonging to the field of tea beverage processing technology. Addressing the problems of difficulty in cold water dispersion, easy sedimentation, and flavor loss during heat processing in existing matcha liquids, the method provided by this invention includes: mixing matcha powder with water at 0-10℃ at a mass ratio of 1:10 to 1:20, and soaking and extracting at 4-10℃ for 30-90 minutes; adding tea saponin and / or soybean lecithin to the cold-extract liquid at a rate of 0.1%-0.5% of the matcha powder mass, and wet-milling to a particle size D90≤500nm; gradually freezing and concentrating at -10℃ to 0℃ with a freezing rate of 180-240kg / h·m, concentrating to 10%-20% solids; adding gellan gum, curdlan gum, and / or xanthan gum at a rate of 0.05%-0.2% of the concentrate mass to form a weak gel system; and finally cold-sterilizing and filling. The matcha liquid prepared by this invention is completely dispersed when stirred in cold water at 0-10℃ for 5-10 seconds, and there is no sediment after standing for 24 hours. The turbidity is ≤25NTU, and it retains its bright green color and aroma. It is suitable for freshly made tea drinks such as matcha latte and matcha smoothie.

Description

Technical Field

[0001] This invention relates to the field of tea beverage processing technology, specifically a method for preparing cold-extracted instant matcha liquid. Background Technology

[0002] Tea concentrate is a liquid product made primarily from tea leaves, through water extraction and subsequent physical removal of some of the water. Due to its ease of use and stable quality, it has become an important ingredient in the modern tea beverage industry. Matcha concentrate, as a special type of tea concentrate, retains the unique bright green color, delicate taste, and complete nutritional components of matcha, making it widely used in freshly made tea drinks such as matcha lattes and matcha smoothies.

[0003] However, existing matcha concentrate products suffer from the following technical problems in practical applications. First, traditional matcha concentrates often employ hot water extraction or hot concentration processes, resulting in products that are difficult to disperse in cold water, easily leading to clumping and incomplete dissolution. Tea shops often need to pre-dissolve the matcha in a small amount of hot water before mixing it with ice water or milk, a cumbersome process that makes it difficult to ensure consistent flavor. This is mainly because matcha particles have a highly hydrophobic surface, and the further agglomeration during heat processing significantly reduces their wettability and dispersibility in cold water.

[0004] Secondly, the turbidity and precipitation that occurs in tea beverages during storage (i.e., "cold-induced turbidity") is a long-standing common problem in the industry. Studies have shown that the chemical components of tea precipitation mainly include tea polyphenols, caffeine, and proteins. These three types of components form large molecular complexes through non-covalent interactions such as hydrogen bonds. When the temperature of the tea infusion decreases, their solubility decreases, leading to the formation of visible precipitation. Among these, ester-type catechins (such as EGCG and ECG), due to their higher galloyl and hydroxyl groups, are more prone to participating in precipitation formation compared to non-ester-type catechins. This problem is particularly prominent in concentrated matcha liquids, as the increased frequency of intermolecular collisions in high-concentration systems significantly exacerbates the rate and extent of precipitation formation.

[0005] To control sedimentation, existing technologies mostly employ physical removal (such as centrifugation and filtration) or chemical dissolution (such as adding alkali). However, physical removal, while removing sediment, also results in the loss of some flavor compounds and nutrients; chemical dissolution may alter the pH of the tea infusion, affecting the final product's taste. For example, Chinese patent CN111149893A discloses a production process for high-concentration, sediment-free concentrated tea juice, which involves boiling extraction, filtration, concentration, and dissolution. However, this method involves high-temperature boiling, which significantly damages heat-sensitive aroma compounds and chlorophyll, making it difficult to meet the requirements of matcha products for retaining their vibrant green color and high aroma.

[0006] In the field of beverage suspension stabilization, food gums such as gellan gum have been used to suspend fruit pieces or solid particles. For example, Chinese patent CN1947559B discloses a composite food gum containing gellan gum for preparing suspended beverages to suspend solid particles such as fruit pieces. However, this type of technology is mainly aimed at suspending large particles (such as fruit granules) that are visible to the naked eye. The amount of suspending agent added is usually high. If it is directly used in matcha liquid, it will result in a product with excessive viscosity and an unpleasant taste, which does not meet the requirements of matcha lattes, smoothies, and other products for a refreshing taste. In addition, the precipitated particles in matcha liquid are in the micron or even nanometer range, and their sedimentation behavior is fundamentally different from that of large particles, making it difficult to directly apply existing suspension technologies.

[0007] Chinese patent CN114176147B discloses a method for preparing tea concentrate for blending alcoholic beverages. It employs a progressive freeze-concentration technique to preserve the aroma of tea and removes unstable molecules through stabilization treatment with a similar equiproportional alcohol system and adsorbent precipitation, thus solving the precipitation problem in tea-infused alcohol blending. However, this method involves an ethanol treatment step, resulting in a final product containing ethanol or requiring dealcoholization. Furthermore, its application is limited to blending tea-infused alcoholic beverages and is not suitable for direct use in tea shops to prepare non-alcoholic drinks such as matcha lattes and smoothies. Additionally, this method does not address the nano-processing of matcha particles, failing to resolve the issue of the matcha liquid's instant solubility in cold water.

[0008] Therefore, developing a method for preparing cold-extracted instant matcha liquid that is instantly soluble in cold water, does not precipitate over a long period, retains its flavor well, and has a refreshing taste has significant market value and technical significance. Summary of the Invention

[0009] The purpose of this invention is to overcome the aforementioned technical difficulties and provide a method for preparing cold-extracted instant matcha liquid.

[0010] To achieve the above objectives, the technical solution adopted is: a method for preparing cold-extracted instant matcha liquid, comprising the following steps: (1) Cold extraction step: Mix matcha powder with water at 0-10℃ at a mass ratio of 1:10~1:20, and soak and extract at 4-10℃ for 30-90 minutes to obtain cold extract; (2) Nano-grinding step: Add a natural stabilizer to the cold extract obtained in step (1). The natural stabilizer is one or more of tea saponin and soybean lecithin. The amount added is 0.1%-0.5% of the mass of matcha powder. Then perform wet media grinding so that the particle size D90 of the ground matcha particles is ≤ 500 nm. (3) Gradual freezing concentration step: The matcha liquid ground in step (2) is gradually frozen and concentrated at -10℃ to 0℃, with a freezing rate of 180-240 kg / h•m. The unfrozen concentrate is collected and concentrated until the solid content is 10%-20%. (4) Suspension stabilization step: Add a natural polysaccharide suspending agent to the concentrate obtained in step (3), wherein the natural polysaccharide suspending agent is one or more of gellan gum, guar gum, and xanthan gum, and the amount added is 0.05%-0.2% of the mass of the concentrate to form a weak gel system; (5) Cold sterilization and filling steps: The matcha liquid obtained in step (4) is cold sterilized and filled.

[0011] Furthermore, in step (2) the nano-grinding step, the particle size D90 of the ground matcha particles is ≤ 300 nm.

[0012] Furthermore, in step (2) the nano-grinding step, the natural stabilizer is tea saponin, and the amount added is 0.2%-0.4% of the mass of matcha powder.

[0013] Furthermore, in the progressive freezing and concentration step (3), the freezing temperature is -5℃ to 0℃, the freezing rate is 200-220 kg / h•m, and the concentration is made up to a solid content of 12%-15%.

[0014] Furthermore, in step (4) the suspension stabilization step, the natural polysaccharide suspending agent is a compound of gellan gum and guar gum, wherein the amount of gellan gum added is 0.05%-0.1% of the mass of the concentrate, and the amount of guar gum added is 0.02%-0.05% of the mass of the concentrate.

[0015] Furthermore, in step (5) cold sterilization and filling, the cold sterilization is carried out by microfiltration membrane filtration or ultra-high pressure sterilization; the pore size of the microfiltration membrane is 0.22-0.45 μm, and the pressure of the ultra-high pressure sterilization is 400-600 MPa.

[0016] Furthermore, a cold-extracted instant matcha liquid is prepared using the preparation method described in any one of claims 1-6.

[0017] Furthermore, the matcha liquid is completely dispersed when stirred in cold water at 0-10℃ for 5-10 seconds, and no visible sediment is observed after standing for 24 hours, with a turbidity ≤ 25 NTU.

[0018] The beneficial effects of adopting the above scheme are as follows: After applying this cold-extraction instant matcha liquid preparation method, the matcha particles are ground to a D90 ≤ 500 nm (preferably ≤ 300 nm) through the combination of cold extraction and nano-grinding steps. This significantly reduces the particle size and increases the specific surface area, resulting in a substantial improvement in the wettability and dispersibility of the matcha particles in cold water. The resulting matcha liquid can be completely dispersed in cold water at 0-10℃ with stirring for 5-10 seconds, without the need for pre-dissolving in hot water. It can be directly used in the preparation of beverages such as matcha lattes and matcha smoothies, simplifying the operation process of tea shops and helping to ensure the consistency of product flavor.

[0019] A gradual freeze-concentration process is employed to concentrate the matcha liquid at low temperatures, avoiding flavor loss and particle agglomeration caused by heat concentration. Simultaneously, a natural polysaccharide suspending agent (one or more of gellan gum, curdlan gum, and xanthan gum) is added during the suspension stabilization step to form a weak gel system that effectively suspends nano-sized matcha particles, preventing sedimentation. Testing showed that the resulting matcha liquid exhibited no visible sedimentation after 24 hours of standing, with a turbidity ≤ 25 NTU, demonstrating superior long-term storage stability compared to matcha liquid prepared using traditional methods.

[0020] The entire process employs low-temperature technology: the cold extraction step is carried out at 4-10℃, the nano-grinding step is carried out at room temperature or low temperature, the gradual freeze concentration step is carried out at -10℃ to 0℃, and the cold sterilization step uses microfiltration membrane filtration or ultra-high pressure sterilization, all of which avoid the damage to heat-sensitive components caused by high-temperature treatment. Compared with traditional hot concentration processes, the matcha liquid prepared in this application can better retain the bright green color of chlorophyll and the natural aroma of tea leaves, with a refreshing taste and low bitterness.

[0021] In the suspension stabilization step, the amount of natural polysaccharide suspending agent added is only 0.05%-0.2% of the concentrate mass, far lower than the amount of suspending agent used in traditional suspended beverages (usually around 0.5%). This low addition amount is sufficient to form a weak gel system to suspend nano-sized particles, without causing the product to become too viscous. The resulting matcha liquid has a refreshing taste and does not affect the original taste of matcha lattes, smoothies, and other beverages, meeting the requirements of tea shops for raw material quality.

[0022] Cold extraction, nano-grinding, progressive freeze concentration, suspension stabilization, and cold sterilization can all be performed on conventional food industry equipment, without the need for special or expensive equipment. The entire process operates at low temperatures, resulting in controllable energy consumption. Furthermore, it does not use organic solvents or chemical additives, aligning with consumer trends towards clean labels and natural products, and thus possesses promising prospects for industrial application. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. The described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example

[0024] This embodiment provides a method for preparing cold-extracted instant matcha liquid, which specifically includes the following steps.

[0025] (1) Cold extraction step Take 1 kg of commercially available steamed green matcha powder (D90 ≤ 20 μm, origin: Guizhou) and add 15 kg of pure water (conductivity ≤ 5 μS / cm), maintaining the water temperature at 4-6℃. Slowly add the matcha powder to the water while stirring continuously at 300 rpm. After addition, allow the mixture to stand and soak at 6-8℃ for 60 minutes to obtain a cold extract.

[0026] (2) Nano-grinding steps The cold extract obtained in step (1) was initially filtered through a 200-mesh filter cloth to remove undispersed large fiber particles. Tea saponin (purity ≥80%, added at 0.3% of the matcha powder mass, i.e., 3 g) was added to the filtrate and stirred evenly. The mixture was then ground using a media mill (zirconia beads, 0.3 mm diameter) at 10-12℃ for 90 minutes. The particle size of the ground matcha particles was measured using a laser particle size analyzer; the particle size D90 was 280 nm.

[0027] (3) Gradual freezing and concentration steps The matcha liquid ground in step (2) was transferred to a progressive freeze concentration apparatus. The freezing temperature was set to -5°C to -3°C, and the freezing rate was 200 kg / h·m. Concentration was stopped when the solid content of the concentrate reached 13%, and the unfrozen concentrate was collected, yielding a total of approximately 3.5 kg of concentrate.

[0028] (4) Suspension stabilization steps Add gellan gum to the concentrate obtained in step (3) at a rate of 0.08% of the concentrate mass (i.e., 2.8 g), and stir at low speed (150 rpm) for 30 minutes until completely dissolved to form a weak gel system.

[0029] (5) Cold sterilization and filling steps The matcha liquid obtained in step (4) was sterilized by microfiltration membrane with a pore size of 0.22 μm. Under aseptic conditions, it was filled into light-proof containers at a low temperature of 6-8℃ to obtain the finished cold-extracted instant matcha liquid.

[0030] The applicant conducted performance tests on the obtained product: Dissolving time in cold water: Add 10 mL of product to 90 mL of 4℃ cold water and stir gently for 5 seconds until completely dispersed without clumping.

[0031] Precipitation: After standing for 24 hours, no precipitate was visible to the naked eye.

[0032] Turbidity: Measured using a turbidimeter, the turbidity was 18.5 NTU.

[0033] Color: Measured with a colorimeter, L* = 42.3, a* = -12.8, b* = 18.6, showing a bright green color.

[0034] Solid content: 12.8%. Example

[0035] This embodiment is basically the same as Embodiment 1, except that the parameters of each step are different.

[0036] (1) Cold extraction step Take 1 kg of matcha powder, add 10 kg of pure water, water temperature 8-10℃, soak and extract for 90 minutes, extraction temperature 8-10℃.

[0037] (2) Nano-grinding steps Add soybean lecithin (0.5% of the matcha powder mass, i.e., 5 g) to the cold extraction liquid, and grind it for 60 minutes using a media mill (zirconia beads, 0.5 mm diameter). The particle size after grinding is D90 = 450 nm.

[0038] (3) Gradual freezing and concentration steps Freezing temperature: -8℃ to -5℃, freezing rate: 180 kg / h·m, concentration stopped when solid content reaches 18%, and the concentrate collected.

[0039] (4) Suspension stabilization steps Add guar gum to the concentrate at a rate of 0.15% of the concentrate's mass, and stir at low speed until completely dissolved.

[0040] (5) Cold sterilization and filling steps Ultra-high pressure sterilization is used, with a pressure of 500 MPa and a processing time of 5 minutes, followed by low-temperature filling.

[0041] The applicant conducted performance tests on the product obtained in Example 2: Dissolving time in cold water: 8 seconds for complete dispersion.

[0042] Precipitation: No visible precipitation was observed after standing for 24 hours.

[0043] Turbidity: 22.3 NTU.

[0044] Color: L* = 41.5, a* = -11.2, b* = 19.1.

[0045] Solid content: 17.5%. Example

[0046] This embodiment is basically the same as Embodiment 1, except that a compound suspending agent is used in the suspension stabilization step.

[0047] (1) The cold extraction procedure is the same as in Example 1.

[0048] (2) The nano-grinding steps are the same as in Example 1, and the particle size D90 after grinding is 275 nm.

[0049] (3) The gradual freezing and concentration steps are the same as in Example 1, and the solid content is concentrated to 12.5%.

[0050] (4) Suspension stabilization steps Add a mixture of gellan gum and guar gum to the concentrate, wherein the amount of gellan gum added is 0.06% of the mass of the concentrate and the amount of guar gum added is 0.03% of the mass of the concentrate, and stir at low speed for 30 minutes until completely dissolved.

[0051] (5) The cold sterilization and filling steps are the same as in Example 1.

[0052] The applicant conducted performance tests on the product obtained in Example 3: Dissolving time in cold water: 4 seconds for complete dispersion.

[0053] Precipitation: No visible precipitation was observed after standing for 48 hours.

[0054] Turbidity: 16.2 NTU.

[0055] Color: L* = 43.0, a* = -13.2, b* = 17.9.

[0056] Solid content: 12.3%.

[0057] Comparative Example 1: This comparative example is basically the same as Example 1, except that the nano-grinding step is omitted.

[0058] (1) The cold extraction procedure is the same as in Example 1.

[0059] (2) Omit the nano-grinding step: After the cold extract is filtered through a 200-mesh filter cloth, it directly enters the progressive freeze concentration step without wet media grinding. At this time, the particle size D90 of the matcha is about 18 μm.

[0060] (3) The gradual freezing and concentration steps are the same as in Example 1.

[0061] (4) The suspension stabilization steps are the same as in Example 1.

[0062] (5) The cold sterilization and filling steps are the same as in Example 1.

[0063] The applicant conducted performance tests on the product obtained from Comparative Example 1: Dissolving time in cold water: If there are still obvious lumps after stirring for 30 seconds, it is necessary to continue stirring for about 60 seconds to basically disperse them.

[0064] Sedimentation: Obvious sedimentation appeared after standing for 2 hours, and the sediment layer was about 5 mm thick after 24 hours.

[0065] Turbidity: 58.7 NTU.

[0066] Color: L* = 40.2, a* = -8.5, b* = 20.3, dark green.

[0067] Solid content: 12.5%.

[0068] Comparative Example 2: This comparative example is basically the same as Example 1, except that the suspension stabilization step is omitted.

[0069] (1) The cold extraction procedure is the same as in Example 1.

[0070] (2) The nano-grinding steps are the same as in Example 1, and the particle size D90 after grinding is 282 nm.

[0071] (3) The gradual freezing and concentration steps are the same as in Example 1.

[0072] (4) Omit the suspension stabilization step: Do not add any polysaccharide suspending agent and proceed directly to the sterilization step.

[0073] (5) The cold sterilization and filling steps are the same as in Example 1.

[0074] The applicant conducted performance tests on the product obtained from Comparative Example 2: Dissolving time in cold water: 6 seconds for complete dispersion.

[0075] Precipitation: Precipitation began to appear after standing for 4 hours, and the precipitate layer was about 2 mm thick after 24 hours.

[0076] Turbidity: 35.6 NTU.

[0077] Color: L* = 42.1, a* = -11.9, b* = 18.8.

[0078] Solid content: 12.6%.

[0079] Comparative Example 3: This comparative example uses a traditional thermal concentration process to prepare matcha liquid as a control.

[0080] (1) Hot water extraction Take 1 kg of matcha powder, add 15 kg of 80℃ hot water, soak and extract at 75-80℃ for 30 minutes, stirring at 300 rpm.

[0081] (2) Filtering It uses a 200-mesh filter cloth to remove tea residue.

[0082] (3) Thermal concentration The mixture was concentrated under reduced pressure at 60-65°C using a rotary evaporator until the solid content reached approximately 13%, yielding approximately 3.6 kg of concentrated liquid.

[0083] (4) Heat sterilization filling High-temperature instantaneous sterilization (UHT) is used, which involves treatment at 135°C for 10 seconds, followed by hot filling (approximately 70°C).

[0084] The applicant conducted performance tests on the product obtained from Comparative Example 3: Dissolving time in cold water: If lumps still form after stirring for about 45 seconds, they need to be dissolved in hot water beforehand.

[0085] Precipitation: Obvious precipitation appeared after standing for 1 hour, and the precipitation layer was about 6 mm thick after 24 hours.

[0086] Turbidity: 68.3 NTU.

[0087] Color: L* = 38.5, a* = -3.8, b* = 22.1, yellowish-brown.

[0088] Solid content: 12.8%. Example

[0089] The applicant has summarized and compared the performance of Examples 1-3 and Comparative Examples 1-3 as follows:

[0090] The comparison above shows that the cold-extracted instant matcha liquids prepared in Examples 1-3 are significantly superior to those in Comparative Examples 1-3 in terms of cold water dissolution time, precipitation, turbidity, and color. Specifically, Comparative Example 1, by omitting the nano-grinding step, experienced a significantly prolonged dissolution time and severe precipitation, indicating that nano-grinding is crucial for achieving instant dissolution in cold water and reducing precipitation. Comparative Example 2, by omitting the suspension stabilization step, although exhibiting a shorter dissolution time, showed precipitation after standing, demonstrating the irreplaceable role of the weak gel system in long-term suspension stability. Comparative Example 3, using a traditional hot concentration process, produced a product with a yellowish-brown color, high turbidity, and severe precipitation, failing to meet the requirements for a bright green color and high quality in matcha liquid.

[0091] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0092] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing cold-extracted instant matcha liquid, characterized by: Includes the following steps: (1) Cold extraction step: Mix matcha powder with water at 0-10℃ at a mass ratio of 1:10~1:20, and soak and extract at 4-10℃ for 30-90 minutes to obtain cold extract; (2) Nano-grinding step: Add a natural stabilizer to the cold extract obtained in step (1). The natural stabilizer is one or more of tea saponin and soybean lecithin. The amount added is 0.1%-0.5% of the mass of matcha powder. Then perform wet media grinding so that the particle size D90 of the ground matcha particles is ≤ 500 nm. (3) Gradual freezing concentration step: The matcha liquid ground in step (2) is gradually frozen and concentrated at -10℃ to 0℃, with a freezing rate of 180-240 kg / h·m. The unfrozen concentrate is collected and concentrated until the solid content is 10%-20%. (4) Suspension stabilization step: Add a natural polysaccharide suspending agent to the concentrate obtained in step (3), wherein the natural polysaccharide suspending agent is one or more of gellan gum, guar gum, and xanthan gum, and the amount added is 0.05%-0.2% of the mass of the concentrate to form a weak gel system; (5) Cold sterilization and filling steps: The matcha liquid obtained in step (4) is cold sterilized and filled.

2. The method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: In step (2) of the nano-grinding process, the particle size D90 of the ground matcha particles is ≤ 300 nm.

3. The method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: In step (2) nano-grinding, the natural stabilizer is tea saponin, and the amount added is 0.2%-0.4% of the mass of matcha powder.

4. The method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: In step (3) of the progressive freezing and concentration step, the freezing temperature is -5℃ to 0℃, the freezing rate is 200-220 kg / h·m, and the concentration is made up to a solid content of 12%-15%.

5. The method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: In step (4) of the suspension stabilization step, the natural polysaccharide suspending agent is a compound of gellan gum and guar gum, wherein the amount of gellan gum added is 0.05%-0.1% of the mass of the concentrate, and the amount of guar gum added is 0.02%-0.05% of the mass of the concentrate.

6. The method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: In step (5) cold sterilization and filling, the cold sterilization is carried out by microfiltration or ultra-high pressure sterilization; the pore size of the microfiltration membrane is 0.22-0.45 μm, and the pressure of ultra-high pressure sterilization is 400-600 MPa.

7. A cold-extracted instant matcha liquid prepared according to the method for preparing cold-extracted instant matcha liquid according to claim 1, characterized in that: It is prepared by the preparation method according to any one of claims 1-6.

8. The cold-brewed instant matcha liquid according to claim 7, characterized in that: The matcha liquid is completely dispersed when stirred in cold water at 0-10℃ for 5-10 seconds, and no visible sediment is observed after standing for 24 hours, with a turbidity ≤ 25 NTU.

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