Method of producing tea

Abstract

FIELD: food industry.SUBSTANCE: raw material used is dried, and tea stalks are used as the raw material. The tea stalks are briefly cooled at a temperature of -20 °C with a holding time of 1-2 hours, then exposed to low-temperature plasma created in a dielectric barrier discharge at a voltage of 20-40 kV for 1-3 minutes, at a temperature not exceeding 35 °C, kept for 30-60 minutes and fermented in a nitrogen atmosphere at a temperature of 30-35 °C and humidity 65-75% for 8-10 hour, then dried at a temperature not exceeding 50 °C with a residual moisture content of no more than 6%, followed by separation and aging.EFFECT: production of a new tea drink from tea stalks.1 cl, 1 tbl, 3 ex

Description

[0001] Technical field

[0002] The invention relates to the food industry, in particular to methods for producing fermented tea, and can be used to obtain tea with an increased content of γ-aminobutyric acid (GABA) and antioxidant activity from the petioles of the tea plant (Camellia sinensis).

[0003] The tea industry is rapidly transforming from a raw material industry into an industry of specialized products aimed at consumers interested in natural, healthy beverages that are part of a modern, healthy lifestyle. One such beverage is tea. 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.

[0004] Prior Art

[0005] A method for treating tea raw materials with atmospheric cold plasma of a dielectric barrier discharge is known, applied to fresh tea leaves to increase the yield of polyphenols [1]. In this method, after treatment with nitrogen cold plasma with a power of 15 W for 15 minutes, the total content of phenolic compounds in the sample and the antioxidant activity of green tea increased by 41.14% and 41.06%, respectively. The catechin content also increased by 103.12%. In addition, tearing damage appeared on the surface of the tea leaves.

[0006] A disadvantage of this method is its limited effect on tea plant leaves; processing of tea stalks with subsequent CO2 fermentation is not considered. There is also no information on increasing GABA content or improving the sensory properties of the product.

[0007] 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 [2].

[0008] The disadvantage of this method is that it does not include preliminary stimulation of antioxidant activity, which ensures the opening of cellular structures and increases 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.

[0009] The objective of this invention is to develop a method for producing tea using tea stalks, which makes it possible to obtain tea with improved physicochemical characteristics.

[0010] The technical result is to increase the content of antioxidants and gamma-aminobutyric acid, and improve the sensory characteristics of the target product.

[0011] Brief summary of the invention

[0012] The technical result is achieved by the fact that in the method of producing tea, including withering of raw materials, fermentation and drying, tea stalks are used as raw materials, and after withering, the tea stalks are subjected to short-term cooling at a temperature of -20 ° C for 1-2 hours, then exposed to low-temperature plasma created in a dielectric barrier discharge at a voltage of 20-40 kV for 1-3 minutes, at a temperature of no more than 35 ° C, after which they are held for 30-60 minutes, and subsequent fermentation is carried out in a nitrogen atmosphere at a temperature of 30-35 ° C and a humidity of 65-75% for 8-10 hours, drying is carried out at a temperature of no higher than 50 ° C to a residual moisture of no more than 6%, 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. 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.

[0014] Disclosure of the claimed technical solution

[0015] The method is implemented as follows. Pre-selected, sifted tea stalks are withered on trays or drums at a temperature of at least 26°C for 4-6 hours until the moisture content decreases by 15-20%. The raw materials are then first placed in a cooling chamber (with a temperature of -20°C) for short-term cooling with a holding time of 1-2 hours, and then quickly transferred to a sealed chamber of a DBD plasma generator (e.g., Enercon Blown Arc Pro) with manual or belt feed of the raw materials, where they are treated with atmospheric cold plasma with the following process parameters: voltage of 20-40 kV, for 1-3 minutes, at an ambient temperature of no more than 35°C. After treatment with low-temperature plasma, the tea is held for 30-60 minutes.

[0016] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 30-35°C and a relative humidity of 65-75% for 8-10 hours. The raw material is then transferred to a low-temperature drying chamber with forced ventilation for drying at a temperature no higher than 50°C to a residual moisture content of no more than 6%. 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 18-23°C.

[0017] The withering process reduces the moisture content of tea stems to 60-75%. This increases the tissue's sensitivity to further processing. Withering initiates enzymatic reactions necessary for fermentation (activation of polyphenol oxidase, peroxidase, and glutamate decarboxylase enzymes), gentle intracellular hydrolysis of carbohydrates occurs, and the natural accumulation of glutamic acid, a precursor of GABA, begins.

[0018] Short-term cooling of tea stems slows metabolism and makes the tea plant cells more receptive to plasma exposure. Enzymatic processes are temporarily suspended but not irreversibly stopped. After thawing (or gradual warming to 25-30°C), they resume with increased potency due to increased substrate availability. Microdamage to the cell walls after freezing enhances the effects of plasma (increased cell permeability and stimulation of enzymatic reactions).

[0019] Treatment of tea stems with low-temperature plasma also damages the cell walls, creating micropores and microcracks that facilitate the subsequent release of intracellular components (e.g., GABA precursors and phenolic compounds). Low-temperature plasma exposure also induces oxidative / abiotic stress, which promotes the synthesis of protective substances (GABA, rutin, catechins, etc.) and the activation of glutamate decarboxylase. Increased tissue permeability facilitates subsequent gasification (N2) and preparation for efficient fermentation in a controlled environment.

[0020] Fermentation under anaerobic conditions in a nitrogen atmosphere 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.

[0021] In a nitrogen atmosphere, the activity of oxidative enzymes is suppressed, preserving antioxidants and amino acids. Fermentation activates the flavonoid complex (especially thearubigins and theaflavins).

[0022] The combination of temperature of 30-35°C, relative humidity of 65-75% and process duration of 8-10 hours also provides optimal conditions for the activity of glutamic acid decarboxylase.

[0023] Anaerobic conditions and slow fermentation prevent oxidation and breakdown of aromatic substances, especially theanine, linalool, geraniol and other volatile components.

[0024] The combination of low-temperature plasma treatment of tea stalks with N2 fermentation enhances biochemical processes, promotes maximum activation of glutamate decarboxylase, and achieves high GABA levels while maintaining a soft texture and delicate flavor.

[0025] Gentle drying at a temperature not exceeding 50°C allows preserving heat-labile antioxidants.

[0026] The claimed method for producing tea from tea stems yields tea with a high content of γ-aminobutyric acid and antioxidants. Furthermore, the claimed integrated technology of treating pre-frozen tea stems with low-temperature plasma, fermenting them under anaerobic conditions, and optimal drying allows for the release of extractive substances, which also enhances the unique woody flavor and removes the specific aroma of tea stems, thereby improving the sensory characteristics of the tea. Thus, the combination of the claimed features of the invention enables the achievement of the technical result.

[0027] The author of the declared technical solution has produced experimental samples of tea from tea stalks of the “Colchis” variety, the production method of which is explained with examples of specific implementation.

[0028] Examples of specific implementation

[0029] Example 1. Pre-screened tea stalks (1,000 g) are withered on trays at a temperature of at least 26°C to a moisture content of approximately 75%. The raw materials are then briefly cooled at -20°C for 2 hours, quickly transferred to a sealed chamber of a DBD plasma generator, and treated with atmospheric cold plasma using the following process parameters: 30 kV for 1 minute, at an ambient temperature of 30°C. After treatment with low-temperature plasma, the tea stalks are held for 40 minutes.

[0030] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 30°C and a relative humidity of 75% for 10 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 45°C to a residual moisture content of no more than 6%. 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 maturation in a ventilated area until it reaches a temperature of 23°C.

[0031] The physicochemical and sensory properties of the obtained product are given in the table.

[0032] Example 2. Pre-screened tea stalks (1,000 g) are withered on trays at a temperature of at least 26°C to a moisture content of approximately 60%. The raw materials are then briefly cooled at -20°C for 1 hour, quickly transferred to a sealed chamber of a DBD plasma generator, and treated with atmospheric cold plasma at a voltage of 20 kV for 2 minutes at an ambient temperature of 28°C. After treatment with low-temperature plasma, the tea stalks are held for 30 minutes.

[0033] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 33°C and a relative humidity of 70% for 8 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 48°C to a residual moisture content of no more than 6%. 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 maturation in a ventilated area until it reaches a temperature of 18°C.

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

[0035] Example 3. Pre-screened tea stalks (1,000 g) are withered on trays at a temperature of at least 26°C to a moisture content of approximately 70%. The raw materials are then briefly cooled at -20°C for 1.5 hours, quickly transferred to a sealed chamber of a DBD plasma generator, and treated with atmospheric cold plasma at a voltage of 40 kV for 2 minutes at an ambient temperature of 34°C. After treatment with low-temperature plasma, the tea stalks are held for 60 minutes.

[0036] Following this, fermentation takes place in an anaerobic fermentation chamber under a nitrogen atmosphere at a temperature of 35°C and a relative humidity of 65% for 9 hours. The raw material is then transferred to a drying chamber for drying at a temperature of 43°C to a residual moisture content of no more than 6%. 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 22°C.

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

[0038]

[0039]

[0040] Industrial applicability

[0041] 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.

[0042] SOURCES OF INFORMATION

[0043] 1. Maryam Keshavarzi. Enhancement of polyphenolic content extraction rate with maximum antioxidant activity from green tea leaves by cold plasma / J Food Sci. Oct 2020; 85(10):3415-3422. doi: 10.1111 / 1750-3841.15448. Epub 2020 Sep 27. https: / / pubmed.ncbi.nlm.nih.gov / 32984963 /

[0044] 2. Patent WO 2006021317 A1 for the invention “Method for preparing tea” (published 02.03.2006).

Claims

A method for producing 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 subjected to short-term cooling at a temperature of -20°C for 1-2 hours, then exposed to low-temperature plasma created in a dielectric barrier discharge at a voltage of 20-40 kV for 1-3 minutes, at a temperature not exceeding 35°C, after which they are held for 30-60 minutes, and subsequent fermentation is carried out in a nitrogen atmosphere at a temperature of 30-35°C and a humidity of 65-75% for 8-10 hours, drying is carried out at a temperature not exceeding 50°C to a residual humidity of not more than 6%, followed by separation and aging.

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