Method of producing tea

Abstract

FIELD: food industry.SUBSTANCE: raw material, which is made from tea stalks, is withered and twisted. Tea stalks are treated with monosodium glutamate at a concentration of 0.1-0.3 mol / l at a temperature of 20-40 °C for 30-90 minutes. Fermentation is carried out under anaerobic conditions at a temperature of 25-35 °C with pH=4.5-5.5 for 8-16 hours and stalk moisture content of 65-80% in a nitrogen atmosphere, followed by aging for 30-40 minutes and moistening to a moisture content of 35±5% at a temperature of 75-85 °C. Repeated resting is carried out for 1-1.5 hours, then flattening to a thickness of 0.9±0.3 mm and cutting in 3-5 mm increments. The material is treated with saturated water vapor at a temperature of 110-125 °C and a pressure of 0.7-1.2 MPa for 1-2 minutes with a sharp pressure release. The resulting material is dried to a residual moisture content of 4-7% at a temperature not exceeding 60 °C with subsequent separation and settling.EFFECT: increase in the utilization rate of tea raw materials.1 cl, 3 ex

Description

[0001] Technical field

[0002] The invention relates to the food industry, namely to methods for producing teas with increased biological value, in particular tea products with a high content of gamma-aminobutyric acid (GABA), obtained by improving the technology for processing tea raw materials.

[0003] According to recent research, GABA plays a vital role in the human central nervous system, as it acts as an inhibitory agent in brain cells, thereby helping to prevent overexcitation. GABA improves the dynamics of neural processes in the brain, enhances mental productivity, improves memory, normalizes blood pressure, and prevents the development of diabetes. GABA consumed directly through food cannot meet the body's physiological needs for gamma-aminobutyric acid, which is commonly found in foods. Therefore, recent attention has been focused on developing new food products rich in GABA.

[0004] Prior Art

[0005] Various methods are known for producing teas with increased biological value. One known method involves withering the tea leaves to a moisture content of 50-70%, rolling them, and fermenting them in two stages: the first stage is vacuum-conditioned at a temperature of 15-30°C for 1-12 hours, the second (aerobic) stage lasts for 0.5-12 hours, and then drying to a moisture content of 7% [I]. This method produces black tea with a relatively high GABA content.

[0006] The disadvantage of this method is the insufficient specification of the parameters (wide ranges of anaerobic (1-12 h) and aerobic (0.5-12 h) fermentation times, as well as temperatures (15-30°C) are given, without specifying optimal values ​​or justifying their selection, the lack of information on humidity control during the fermentation process, the drying conditions are described fragmentarily, which is insufficient for reliable reproduction of the industrial process.

[0007] The closest in technical essence and achieved result to the claimed invention is a method for producing tea with a high content of gamma-aminobutyric acid, characterized by the fact that raw materials from the leaves of Camellia sinensis are withered under reduced pressure of 50-350 mm Hg. with or without the addition of carbon dioxide, then the leaves are twisted, cut, fermented and dried, and in the middle of the withering stage, when the leaf moisture content reaches 60-65% and / or before the fermentation stage, the raw material is treated with a 2.5-10% solution of glutamic acid salt at the rate of 35-140 ml per 1 kg of raw material, or the raw material is treated with a 2.5-10% solution of glutamic acid salt at the rate of 35-140 ml per 1 kg of raw material, while the fermentation process is carried out at a temperature of 35 to 45 ° C for 4-12 hours under reduced pressure of 100-500 mm Hg.with the removal of gases released during the fermentation process, and in both cases the volume and concentration of substances are selected so that there is at least 3.5 g of glutamic acid salt per 1 kg of raw material [II].

[0008] The disadvantage of this method is the difficulty of the actual feasibility of the method in the stated form and its applicability only to traditional tea raw materials.

[0009] The objective of this invention is to obtain teas with increased biological value from substandard raw materials obtained during the process of collecting and processing tea leaves.

[0010] The technical result is an increase in the utilization rate of tea raw materials, an increase in the GABA content in the target product and an increase in the consumer value of tea.

[0011] Disclosure of the essence of the invention.

[0012] The technical result is achieved by the fact that in the method of producing tea, including withering of raw materials, twisting, treatment with a solution of glutamic acid salt, fermentation and drying, tea stalks are used as raw materials, the treatment is carried out with monosodium salt of glutamic acid at a concentration of 0.1-0.3 mol / l at a temperature of 20-40 ° C for 30-90 minutes, and fermentation is carried out under anaerobic conditions at a temperature of 25-35 ° C with a pH of 4.5-5.5 for 8-16 hours and a stalk moisture content of 65-80% in a nitrogen atmosphere, followed by resting for 30-40 minutes and humidification to a moisture content of 35 ± 5% at a temperature of 75-85 ° C, repeated resting for 1-1.5 hours, flattening to a thickness of 0.9 ± 0.3 mm, cutting with a step of 3-5 mm, processing the material with saturated water vapor at a temperature of 110-125°C and a pressure of 0.7-1.2 MPa for 1-2 minutes with a sharp pressure release, and drying the resulting material is carried out to a residual moisture content of 4-7% at a temperature not exceeding 60°C, followed by separation and aging.

[0013] The term "tea petiole" refers to the structural part of the tea plant that connects the leaf blade to the stem. The petiole and stem are considered distinct parts of the tea plant. In traditional tea production, petioles are separated and discarded as waste, despite containing beneficial substances such as L-theanine, phenolic compounds, and fiber. They also (in tea varieties such as "Colchis," "3823," "8346," and "Kimen") contain significant amounts of glutamic acid, a precursor to GABA. With their low bitterness and rich mineral content, tea petioles are the ideal base for a smooth beverage.

[0014] Implementation of the invention.

[0015] The method is implemented as follows. Pre-screened tea stalks are withered on trays or drums at a temperature of at least 26°C to a moisture content of about 60%, twisted on rollers to destroy the tissue of the tea stalk, treated with a solution of monosodium glutamate at a concentration of 0.1-0.3 mol / l at a temperature of 20-40°C for 30-90 minutes using a spray system, fermentation is carried out in an anaerobic fermentation chamber in a nitrogen atmosphere for 8-16 hours at a temperature of 25-35°C, pH = 4.5-5.5 and a moisture content of the stalks of 65-80%. Anaerobic conditions in a nitrogen atmosphere are necessary to activate the enzyme glutamate decarboxylase, which converts glutamic acid salts into γ-aminobutyric acid. In the absence of oxygen, the metabolism of tea stem cells switches towards anaerobic decarboxylation of glutamate.A nitrogen atmosphere also minimizes oxidative processes—the oxidation of catechins and other antioxidants is slowed, preserving the beneficial properties of the raw materials. A temperature of 25-35°C and a pH of 4.5-5.5 also provide optimal conditions for the activity of glutamic acid decarboxylase, which converts glutamate to GABA. At temperatures above 37°C, enzyme activity decreases.

[0016] Tea stalks, unlike regular tea leaves, have a coarser, denser structure, which helps them better preserve their texture during fermentation. However, this prevents fermentation from always reaching the deeper layers, so it is advisable to apply the following intensive processing. After resting for 30-40 minutes, the stalks are sent to a conditioning drum, where they are treated with hot water and compressed steam to achieve a uniform moisture content of 35±5% at a temperature of 75-85°C. This intensive moistening imparts elasticity to the stalks, which is necessary for cutting and subsequent processing. The moistened and heated stalks are then placed in mixing silos for resting for 1-1.5 hours until they reach ambient temperature and the moisture is evenly distributed within the stalk structure, which is essential for ensuring the quality of the finished product.After resting, the tea stems are transferred to rollers, where they undergo a flattening process to a thickness of 0.9±0.3 mm. This mechanical treatment modifies the tea stem fibers, exposing them to breakage, deformation, and delamination without damaging them so much that their strength is significantly reduced. Flattening the tea stems also facilitates their subsequent cutting, which is carried out in increments of 3-5 mm. To ensure structure preservation and reduce juice loss, the cutting was performed at this stage, rather than during fermentation.

[0017] After cutting, the tea stems are sent to the "explosion" unit. Steam explosion involves exposing the fermented material to saturated steam at a temperature of 110-125°C and a pressure of 0.7-1.2 MPa for 1-2 minutes, followed by a sudden pressure release into a vacuum chamber. This process causes loosening of the tea stem particles due to the stretching of the cell walls, which swell and increase their volume, partially "exploding" them. The rapid expansion, stretching, and rupture of the cells under the influence of pressure and steam causes the destruction of the cell walls, the release of intracellular glutamate, and an increase in the yield of γ-aminobutyric acid. The "explosion" does not directly synthesize GABA, but creates conditions for its release and post-enzymatic synthesis, thereby improving the extraction yield.These conditions for steam explosion were selected taking into account actual data on the thermal stability of GABA (Thermal stability and degradation of amino acids studied by TGA-FTIR, Journal of Thermal Analysis and Calorimetry, 2011), according to which GABA (and related amino acids) remains stable up to a temperature of approximately 170°C during short-term heating. Below this temperature, GABA does not lose functionality, is not decarboxylated, and does not convert into toxic products. With short exposures (less than 2 min), as during steam explosion (110-125°C), GABA is not destroyed, does not lose biological activity - on the contrary, it becomes more accessible after the destruction of the cell wall, remains in the material, or is available for extraction.

[0018] The next section, the drying column, is used to reduce the moisture content to 4-7% at a temperature no higher than 60°C. The dried tea stalks are then separated from the air-steam mixture in a cyclone separator. From the drying chamber, the tea stalks are fed to an air separator, after which the finished product is placed in a storage silo for aging until it reaches a temperature of 18-23°C.

[0019] The claimed method for producing tea from tea stems simultaneously solves the problem of waste disposal, enabling waste-free production, and produces tea with a high content of γ-aminobutyric acid. Furthermore, the claimed integrated technology of treating tea stems with a glutamic acid salt solution, anaerobic fermentation, and thermomechanical pressure treatment releases extractive substances, enhancing the unique "woody" flavor and removing the specific aroma of tea stems, thereby increasing not only the γ-aminobutyric acid content but also improving the taste and consumer characteristics of tea. Thus, the combination of the claimed features of the invention enables the achievement of a technical result.

[0020] The author of the declared technical solution has produced experimental samples of tea from tea stalks of the "Colchis" tea variety, the production method of which is explained with examples of specific implementation.

[0021] Examples of specific implementation.

[0022] Example 1. Pre-screened tea stalks in the amount of 1000 g are withered on trays or drums at a temperature of at least 26°C to a humidity of 62%, twisted on rollers, treated using a spray system with 300 ml of 0.1 M solution of monosodium glutamate at a temperature of 40°C for 60 minutes, fermentation is carried out in an anaerobic fermentation chamber in a nitrogen atmosphere for 16 hours at a temperature of 30°C, pH = 5.

[0023] After resting for 30 minutes, the tea stalks are sent to a conditioning drum, where they are treated with hot water and compressed steam to achieve a uniform moisture content of 40% at a temperature of 80°C. The moistened and heated stalks are then transferred to mixing silos for resting for 1 hour. After resting, the stalks are flattened on rollers to a thickness of 0.6 mm, followed by cutting at 4 mm intervals.

[0024] After cutting, the tea stems are sent to the "explosion" unit. Steam explosion involves exposing the fermented material to saturated steam at a temperature of 115°C and a pressure of 1.0 MPa for 2 minutes, followed by a sudden pressure release into a vacuum chamber.

[0025] The next section, the drying column, is used to dry the tea stalks to reduce moisture content to 4% at a temperature no higher than 60°C. The dried tea stalks are then separated from the air-steam mixture in a cyclone separator. From the drying chamber, the tea stalks are fed to an air separator, after which the finished product is placed in a storage silo for storage until it reaches a temperature of 23°C.

[0026] The γ-aminobutyric acid content in the target product was determined by HPLC with preliminary derivatization with orthophthalaldehyde and detection at 254 nm. The average GABA content was 228 mg / 100 g dry matter.

[0027] As studies have shown, the obtained tea stem samples contain 35% water-soluble extractive substances and 25% coarse fiber, which will also significantly increase the value of teas made from them.

[0028] Example 2. Pre-screened tea stalks in the amount of 1000 g are withered on trays or drums at a temperature of at least 26°C to a humidity of 60%, twisted on rollers, treated using a spray system with 300 ml of 0.2 M solution of monosodium glutamate at a temperature of 20°C for 90 minutes, fermentation is carried out in an anaerobic fermentation chamber in a nitrogen atmosphere for 18 hours at a temperature of 25°C, pH = 5.5.

[0029] After resting for 40 minutes, the tea stalks are sent to a conditioning drum, where they are treated with hot water and compressed steam to achieve a uniform moisture content of 35% at a temperature of 85°C. The moistened and heated stalks are then transferred to mixing silos for resting for 1.5 hours. Afterwards, the stalks are flattened on rollers to a thickness of 0.9 mm, followed by cutting at 3 mm increments.

[0030] After cutting, the tea stems are sent to the "explosion" unit. Steam explosion involves exposing the fermented material to saturated steam at a temperature of 125°C and a pressure of 0.7 MPa for 1.5 minutes, followed by a sudden pressure release into a vacuum chamber.

[0031] The next section, the drying column, is used to reduce the moisture content to 6% at a temperature no higher than 60°C, and the dried tea stalks are separated from the air-steam mixture in a cyclone separator. From the drying chamber, the tea stalks are fed to an air separator, after which the finished product is placed in a storage silo for storage until it reaches a temperature of 20°C.

[0032] The γ-aminobutyric acid content of the target product was determined by HPLC with preliminary derivatization with orthophthalaldehyde and detection at 254 nm. The average GABA content was 296 mg / 100 g dry matter.

[0033] In the obtained tea stem samples, the content of water-soluble extractive substances is 32% and the content of coarse fibers is 23%, which will also significantly increase the value of teas using them.

[0034] Example 3. Pre-screened tea stalks in the amount of 1000 g are withered on trays or drums at a temperature of at least 26°C to a humidity of 60%, twisted on rollers, treated using a spray system with 300 ml of 0.3 M solution of monosodium glutamate at a temperature of 30°C for 30 minutes, fermentation is carried out in an anaerobic fermentation chamber in a nitrogen atmosphere for 12 hours at a temperature of 35°C, pH = 4.5.

[0035] After resting for 35 minutes, the tea stalks are sent to a conditioning drum, where they are treated with hot water and compressed steam to achieve a uniform moisture content of 30% at a temperature of 75°C. The moistened and heated stalks are then transferred to mixing silos for resting for 75 minutes. Afterwards, the stalks are flattened on rollers to a thickness of 1.2 mm, followed by cutting at 5 mm increments.

[0036] After cutting, the tea stems are sent to the "explosion" unit. Steam explosion involves exposing the fermented material to saturated steam at a temperature of 110°C and a pressure of 1.2 MPa for 1 minute, followed by a sudden pressure release into a vacuum chamber.

[0037] The next section, the drying column, is used to dry the tea stalks to reduce moisture content to 7% at a temperature no higher than 60°C. The dried tea stalks are then separated from the air-steam mixture in a cyclone separator. From the drying chamber, the tea stalks are fed to an air separator, after which the finished product is placed in a storage silo for storage until it reaches a temperature of 18°C.

[0038] The γ-aminobutyric acid content of the target product was determined by HPLC with preliminary derivatization with orthophthalaldehyde and detection at 254 nm. The average GABA content was 342 mg / 100 g dry matter.

[0039] In the obtained tea stem samples, the content of water-soluble extractive substances is 33% and the content of coarse fibers is 24%, which will also significantly increase the value of teas using them.

[0040] The proposed method also allows for sensory characteristics comparable to those of classic loose leaf tea.

[0041] Industrial applicability.

[0042] The proposed technical solution is implemented using commercially available devices and materials and can be implemented at any tea processing facility. The use of tea stalks, a secondary raw material and waste product from tea harvesting and processing, allows for the production of new tea products with a high content of gamma-aminobutyric acid. Thus, the proposed technology increases the utilization rate of tea raw materials by an average of 15-20%, while the quality of tea stalks will also improve due to their increased biological value, positively impacting the consumer value of the product. Implementing the principles of waste-free production and sustainable processing of agricultural raw materials, traditionally considered waste, will increase the profitability of tea production.

[0043] SOURCES OF INFORMATION.

[0044] I. CN Patent No. 103005020, for the invention “Red tea with a high content of gamma-aminobutyric acid (GABA) for maintaining health” (published on 03.04.2013).

[0045] II. Patent RU No. 2785107 C1 for the invention "Method for producing tea with a high content of gamma-aminobutyric acid" (published 02.12.2022).

Claims

A method for producing tea comprising withering raw materials, twisting, treatment with a solution of glutamic acid salt, fermentation and drying, characterized in that tea stalks are used as raw materials, the treatment is carried out with monosodium glutamic acid salt at a concentration of 0.1-0.3 mol / l at a temperature of 20-40 ° C for 30-90 minutes, and fermentation is carried out under anaerobic conditions at a temperature of 25-35 ° C with a pH of 4.5-5.5 for 8-16 hours and a stalk moisture content of 65-80% in a nitrogen atmosphere, followed by resting for 30-40 minutes and humidification to a moisture content of 35 ± 5% at a temperature of 75-85 ° C, repeated resting for 1-1.5 hours, flattening to a thickness of 0.9 ± 0.3 mm, cutting with a step of 3-5 mm, processing the material with saturated water vapor at a temperature of 110-125°C and a pressure of 0.7-1.2 MPa for 1-2 minutes with a sharp pressure release, and drying of the resulting material is carried out to a residual moisture content of 4-7% at a temperature not exceeding 60°C, followed by separation and aging.