Method for producing fermented tea

Abstract

FIELD: food industry.SUBSTANCE: raw material used is dried, and tea stalks are used as the raw material. Tea stalks are treated with ozone in the gas phase at a concentration of 0.05-0.3 ppm for 5-15 minutes at a temperature of 15-25 °C and relative humidity 65-75%. The gas environment is purged until the residual ozone disappears. The stalks are sprayed with an aqueous solution of L-glutamate in an amount of 0.1-0.3 wt.% per mass of raw material for uniform distribution. Afterwards, the food strain Lactobacillus brevis DSM 20054 is inoculated in an amount of 107 -109 CFU / g. Fermentation is carried out in a nitrogen atmosphere at a temperature of 28-32 °C, pH 4.5-6.0 and relative humidity 75-85% for 12-24 hours. Drying is carried out at a temperature not exceeding 50 °C with a residual moisture content of no more than 6%, followed by separation and aging.EFFECT: expansion of the range of tea drinks.1 cl, 1 tbl, 3 ex

Description

[0001] Technical field.

[0002] The invention relates to the food industry, namely to methods for processing tea raw materials in order to obtain fermented tea with an increased content of biologically active substances.

[0003] The tea industry is rapidly transforming from a raw material industry into an industry of specialized, consumer-focused products. Modern consumers are interested in natural, healthy beverages that are part of a healthy lifestyle. Fermented tea is one such beverage. According to recent research, the antioxidant activity of tea made from the leaves, stems, and petioles of Camellia sinensis has scientifically proven physiological and biochemical effects aimed at protecting the body from oxidative stress and its consequences. Therefore, special attention is being paid to the production of products rich in antioxidants and high in gamma-aminobutyric acid (GABA).

[0004] Prior art.

[0005] A known method of processing tea raw materials is by exposing them to an ozone-air mixture with an ozone concentration of 0.03-0.04 ppm (0.06-0.08 mg / m 3 ) at a relative humidity of 95-98% and a temperature of 22-24°C for 40-50 min [I].

[0006] A disadvantage of this method is the relatively prolonged exposure of the tea leaves to ozone, which subsequently leads to a decrease in the quality of the raw material—the destruction of L-theanine, amino acids, and vitamin C, a deterioration in aroma, and cell damage. There is also no evidence of an increase in GABA content or an improvement in the sensory properties of the product.

[0007] A method of fermenting green tea with the L. brevis GTL79 strain with the addition of glucose and monosodium glutamate [II] is also known. After 3-5 days of fermentation, the GABA content increased by more than 230%, and its antioxidant activity also increased to 94% (DPPH).

[0008] The disadvantage of this method is the use of traditional leaf biomass, a rapid peak increase in GABA (up to ~19-30 μg / mL) after one day of fermentation, but then further increase is insignificant; a decrease in the total polyphenol content, which will reduce the antioxidant value of the final product.

[0009] The closest in technical essence and achieved result to the claimed invention is a method for preparing tea with an increased content of amino acids, including collecting the source material for the production of tea, including stems and leaves, physically separating the stem material from the leaf material in order to obtain a tea plant with a large number of stems, processing the source material using at least one of the traditional methods of processing tea, including withering, maceration, grinding, steaming, fermentation, drying [III].

[0010] The disadvantage of this method is that it doesn't aim to stimulate biochemical changes. It doesn't pre-stimulate antioxidant activity, which would open up cellular structures and increase the efficiency of enzymatic conversion. Furthermore, the fermentation conditions are general and not optimized for temperature and humidity, and drying at elevated temperatures can reduce catechin levels.

[0011] The objective of this invention is to develop a method for producing tea using tea stalks, which makes it possible to obtain a target product with improved physicochemical characteristics.

[0012] The technical result is an increase in antioxidant activity and the content of gamma-aminobutyric acid, and an improvement in the sensory characteristics of the target product.

[0013] Brief summary of the invention.

[0014] The technical result is achieved by the fact that in the method for producing fermented tea, including withering of raw materials, fermentation and drying, tea stalks are used as raw materials, and after withering, the tea stalks are treated with ozone in the gas phase at a concentration of 0.05-0.3 ppm for 5-15 minutes at a temperature of 15-25 ° C and a relative humidity of 65-75%, after which the gas environment is purged until the residual ozone disappears, then the stalks are sprayed with an aqueous solution of L-glutamate in an amount of 0.1-0.3 wt. % per weight of raw materials for uniform distribution, after which they are inoculated with the food strain Lactobacillus brevis DSM 20054 in an amount of 10 7 -10 9 CFU / g, fermentation is carried out in a nitrogen atmosphere at a temperature of 28-32°C, pH 4.5-6.0 and relative humidity of 75-85% for 12-24 hours, and drying is carried out at a temperature not exceeding 50°C until the residual moisture content is no more than 6%, followed by separation and aging.

[0015] The term "tea petiole" refers to the structural part of the tea plant that connects the leaf blade to the stem. In traditional brewing methods, petioles are separated and discarded as waste, despite containing beneficial substances such as L-theanine, phenolic compounds, and fiber. They also contain significant amounts of glutamic acid, a precursor to GABA.

[0016] Disclosure of the claimed technical solution.

[0017] The method is implemented as follows. Pre-selected and sifted tea stalks are withered on trays or drums at a temperature of at least 26-30°C for 6-8 hours until the moisture content is reduced by 25-35%. The raw materials are then placed in an ozonizer with a static treatment chamber containing an air cooling system and treated with gaseous ozone at a concentration of 0.05-0.3 ppm for 5-15 minutes at a temperature of 15-25°C and a relative humidity of 65-75%. The gaseous environment is then purged until residual ozone disappears.

[0018] After this, the raw material is removed from the ozonizer and sprayed with an aqueous solution of L-glutamate at a rate of 0.1-0.3% by weight of the raw material, evenly distributing it over the entire surface. Then, a pre-prepared culture of the Lactobacillus brevis strain DSM 20054 is inoculated (by propagation in a liquid medium (1% glucose, 0.5% peptone) at a temperature of 37°C for 24 hours) by spraying over the tea petioles at a rate of 5-10 ml of suspension per 1 kg of petioles. Fermentation is carried out in a sealed chamber in a nitrogen atmosphere at a temperature of 28-32°C, pH 4.5-6.0 and relative humidity of 75-85% for 12-24 hours. The raw material is then fed into a convective drying chamber with forced ventilation for drying at a temperature not exceeding 50°C to a residual moisture content of no more than 6%.From the drying chamber, the tea stalks are fed into an air separator to remove dust and unwanted particles, after which the finished product is sent to a storage silo for storage in a ventilated area until it reaches a temperature of 18-23°C.

[0019] The withering process reduces the moisture content of tea stems to 65-70%, thereby softening the tissues, preparing them for further processing. Withering initiates enzymatic reactions necessary for fermentation (activation of endogenous enzymes, oxidation of polyphenols, etc.).

[0020] Tea stalks are treated with ozone to gently destroy cell walls (increase permeability), inactivate unwanted microflora, and activate polyphenol oxidase, without significantly damaging amino acids. Ozonation is carried out in a sealed chamber in the gas phase at an ozone concentration of 0.05-0.3 ppm for 5-15 minutes at a temperature of 15-25°C and a relative humidity of 65-75%. At high temperatures (>30°C) or prolonged exposure (>30 min), oxidation of theanine, amino acids, and vitamin C may occur. Excess moisture in the form of condensation also creates unfavorable conditions for further fermentation. Petioles are less sensitive to this treatment than tea buds and leaves (as they contain less chlorophylls, but more lignin and fiber).

[0021] Therefore, ozone at a concentration of 0.05-0.3 ppm during short-term treatment of petioles will not destroy the beneficial components, but rather will help improve fermentation (by damaging tissue and inactivating pathogenic microflora). Overall, ozone plays a regulatory role – it activates the antioxidant system without destroying phenols, which is an unobvious use, as it is typically used as a disinfectant.

[0022] Spraying with an aqueous solution of L-glutamate (0.1-0.3 wt%) ensures uniform distribution of the solution without overwetting the petioles. This enhances the surface penetration of the amino acid into the tissue, especially after withering and slight damage to the cell membranes (they become more permeable). A localized glutamate reserve is also created in the intercellular space and on the surface of the petioles. During subsequent anaerobic fermentation (under N2), glutamate becomes readily accessible to Lactobacillus brevis, which has an active glutamate decarboxylase enzyme system. L-glutamate imparts a slight umami flavor and enhances the sensation of sweetness in the finished tea.

[0023] Inoculation with Lactobacillus brevis strain promotes active production of GABA from glutamate naturally found in petioles.

[0024] Fermentation is carried out under anaerobic conditions in a nitrogen atmosphere at a temperature of 28-32°C for 12-24 hours and a relative humidity of 75-85%. This is necessary to activate the enzyme glutamate decarboxylase, which converts glutamic acid salts into γ-aminobutyric acid, promotes the accumulation of GABA, and reduces the oxidative breakdown of polyphenols, increasing the antioxidant activity of tea.

[0025] In a nitrogen atmosphere, the activity of oxidative enzymes is suppressed, preserving antioxidants and amino acids. Fermentation also activates the flavonoid complex (especially thearubigins and theaflavins).

[0026] Anaerobic conditions and slow fermentation prevent oxidation and breakdown of aromatic substances, especially theanine, linalool, geraniol and other volatile components.

[0027] Complex biotechnological treatment of tea stalks with ozone, an aqueous solution of L-glutamate and Lactobacillus brevis bacteria enhances biochemical processes, promotes maximum activation of glutamate decarboxylase, and achieves high GABA levels while maintaining a soft texture and delicate taste.

[0028] Gentle drying at a temperature not exceeding 45°C allows preserving heat-labile antioxidants.

[0029] The claimed method for producing tea from tea stems yields tea with a high content of γ-aminobutyric acid and antioxidants. Furthermore, the claimed comprehensive biotechnological processing technology of the stems allows for the release of extractive substances, which also enhances the unique woody flavor and removes the specific aroma of tea stems, thereby producing a functional product enriched with γ-aminobutyric acid (GABA), theanine, antioxidants, and improved sensory properties. Thus, the combination of the claimed properties is not obvious and leads to a synergistic effect, enabling the achievement of the technical result.

[0030] The author of the declared technical solution has produced experimental samples of tea from tea stalks of the "Kimyn" variety, the production method of which is explained with examples of specific implementation.

[0031] Examples of specific implementation.

[0032] Example 1. Pre-screened tea stalks in the amount of 10 kg are withered on trays at a temperature of 27 ° C for 6 hours to a humidity of about 70%. The raw materials are then subjected to treatment in an ozone chamber under the following parameters: O3 - 0.2 ppm, holding time 15 min, at a temperature of 20 ° C and a relative humidity of 75%. Then, the gas environment is purged until the residual ozone disappears. After that, the stalks are sprayed, evenly distributing them, with an aqueous solution of L-glutamate in an amount of 0.1 wt. % of the weight of the raw material. L. brevis (strain DSM 20054) is prepared, 100 ml of suspension per 10 kg (titer 10 8 CFU / g) and sprayed over the raw material.

[0033] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 30°C, pH 6.0, and a relative humidity of 85% for 18 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 45°C for 4 hours until the residual moisture content reaches no more than 5.2%. From the drying chamber, the tea stalks are fed to an air separator to remove dust and unwanted particles, after which the finished product is placed in a storage silo for storage in a ventilated area until it reaches a temperature of 23°C.

[0034] The physicochemical and sensory properties of the obtained product are given in the table.

[0035] Example 2. Pre-screened tea stalks in the amount of 10 kg are withered on trays at a temperature of 26 ° C for 8 hours to a humidity of about 70%. The raw materials are then subjected to treatment in an ozone chamber with the following parameters: O3 - 0.05 ppm, holding time 10 min, at a temperature of 25 ° C and a relative humidity of 65%. Then, the gas environment is purged until the residual ozone disappears. After that, the stalks are sprayed, evenly distributing them, with an aqueous solution of L-glutamate in an amount of 0.2 wt. % of the weight of the raw material. L. brevis (strain DSM 20054) is prepared, 50 ml of suspension per 10 kg (titer 10 9 CFU / g) and sprayed over the raw material.

[0036] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 32°C, pH 5.0, and a relative humidity of 80% for 12 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 50°C for 4 hours until the residual moisture content reaches no more than 5.8%. From the drying chamber, the tea stalks are fed to an air separator to remove dust and unwanted particles, after which the finished product is placed in a storage silo for storage in a ventilated area until it reaches a temperature of 20°C.

[0037] The physicochemical and sensory properties of the obtained product are given in the table.

[0038] Example 3. Pre-screened tea stalks in the amount of 10 kg are withered on trays at a temperature of 30 ° C for 7 hours to a humidity of about 65%. The raw materials are then subjected to treatment in an ozone chamber under the following parameters: O3 - 0.3 ppm, holding time 5 min, at a temperature of 15 ° C and a relative humidity of 65%. Then, the gas environment is purged until the residual ozone disappears. After that, the stalks are sprayed, evenly distributing them, with an aqueous solution of L-glutamate in an amount of 0.3 wt. % of the weight of the raw material. L. brevis (strain DSM 20054) is prepared, 70 ml of suspension per 10 kg (titer 10 7 CFU / g) and sprayed over the raw material.

[0039] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 28°C, pH 4.5, and a relative humidity of 75% for 24 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 48°C for 6 hours until the residual moisture content reaches no more than 5.3%. From the drying chamber, the tea stalks are fed to an air separator to remove dust and unwanted particles, after which the finished product is placed in a storage silo for storage in a ventilated area until it reaches a temperature of 18°C.

[0040] The physicochemical and sensory properties of the obtained product are given in the table.

[0041]

[0042]

[0043] Industrial applicability.

[0044] The claimed 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 and antioxidant activity.

[0045] SOURCES OF INFORMATION.

[0046] I. Patent WO 2014117228 A1 for the invention “Method for fermenting tea and device for its implementation” (published 07.08.2014)

[0047] II. Jin, Young Hun, Hong, Jong Hyoung, Lee, Jun Nee. Lactic Acid Fermented Green Tea with Levilactobacillus brevis Capable of Producing γ-Aminobutyric Acid. Springer Berlin Heidelberg, Volume 7 Issue 3 ISSN 2311-5637.

[0048] https: / / agris.fao.org / search / en / providers / 122535 / records / 65dec60a0f3e94b9e5d 12de2?utm_source=chatgpt.com (accessed 06.08.2025)

[0049] III. Patent WO20060213 17A1 for the invention “Method for preparing tea” (published 02.03.2006).

Claims

A method for producing fermented tea, including withering of raw materials, fermentation and drying, characterized in that tea stalks are used as raw materials, and after withering, the tea stalks are treated with ozone in the gas phase at a concentration of 0.05-0.3 ppm for 5-15 minutes at a temperature of 15-25 ° C and a relative humidity of 65-75%, after which the gas environment is purged until the residual ozone disappears, then the stalks are sprayed with an aqueous solution of L-glutamate in an amount of 0.1-0.3 wt. % per weight of raw materials for uniform distribution, after which they are inoculated with the food strain Lactobacillus brevis DSM 20054 in an amount of 10 7 -10 9 CFU / g, fermentation is carried out in a nitrogen atmosphere at a temperature of 28-32°C, pH 4.5-6.0 and relative humidity of 75-85% for 12-24 hours, and drying is carried out at a temperature not exceeding 50°C until the residual moisture content is no more than 6%, followed by separation and aging.

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