Preparation method of low-caffeine tea water and low-caffeine tea powder

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a treatment method for removing caffeine from tea water, in particular to a preparation method of low-caffeine tea water capable of effectively reducing the caffeine content in the tea water and well keeping original flavor substances of tea leaves, and a preparation method of low-caffeine tea powder prepared on the basis of the method. The method specifically comprises the following steps: taking tea leaf powder as a raw material, soaking the tea leaf powder in cold water, extracting and removing caffeine in tea water by using dichloromethane to obtain low-caffeine tea water, and finally removing water to obtain the low-caffeine instant tea powder. The method is low in production cost and easy to industrially popularize and apply.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a method for preparing low-caffeine tea and low-caffeine tea powder, particularly a method for preparing low-caffeine tea that can effectively reduce the caffeine content in tea while better preserving the original flavor substances of tea leaves, and a method for preparing low-caffeine tea powder based on this method. Background Technology

[0002] As one of the most consumed beverages globally, tea's rich functional components have always been a research hotspot. Modern medical and nutritional studies have shown that tea contains polyphenols (with epigallocatechin gallate, or EGCG, as its core active ingredient), tea polysaccharides, tea pigments, theanine, and tea proteins, which possess unique aroma and flavor, as well as multiple health benefits. Tea polyphenols can exert antioxidant effects by scavenging free radicals in the body, thus slowing down the aging process of cells. Theanine can regulate the activity of the central nervous system, relieving anxiety and improving sleep quality. Tea polysaccharides have a certain auxiliary effect in regulating blood sugar and blood lipid levels. Simultaneously, the active ingredients in tea can inhibit the growth of harmful bacteria, maintain the balance of the intestinal microecology, and have shown the potential to inhibit the proliferation of some tumor cells in in vitro experiments.

[0003] However, tea naturally contains high levels of caffeine, reaching around 2% in many types. As a central nervous system stimulant, excessive short-term caffeine intake can lead to symptoms such as insomnia, palpitations, and anxiety. The long-term cumulative harm is even more significant: clinical studies have confirmed a link between long-term high caffeine intake and an increased risk of hypertension, potentially causing blood pressure fluctuations by affecting vasoconstriction. For middle-aged and elderly individuals, caffeine can interfere with calcium absorption and metabolism, increasing the probability of osteoporosis. Furthermore, research indicates that long-term excessive caffeine intake may cause chronic damage to the central nervous system, leading to memory loss, poor concentration, and even sexual dysfunction in some individuals. For pregnant women, excessive caffeine may cross the placental barrier, affecting fetal development and increasing the risk of premature birth or low birth weight. Therefore, the widely popular tea beverage also poses potential health risks to consumers.

[0004] With the popularization of the global health consumption concept, consumers' demand for tea drinks has gradually shifted from "flavor pursuit" to "health suitability". In certain occasions or in the development of food and beverages for specific groups, there is also a need for low-caffeine or caffeine-free tea products. Therefore, the market demand for low-caffeine tea drinks continues to rise.

[0005] Traditional methods for preparing decaffeinated tea have several shortcomings. For example, some processes use high-temperature extraction, leading to a significant loss of heat-sensitive nutrients such as EGCG and damaging the original flavor of the tea. Currently, common decaffeination technologies rely on multiple hot water washes or supercritical carbon dioxide extraction. Supercritical carbon dioxide extraction requires large equipment investments and is costly, making it difficult to popularize. While hot water extraction is relatively safe, it often results in a significant loss of flavor compounds (such as tea polyphenols, amino acids, and aroma components), resulting in a weak, unpleasant-tasting decaffeinated tea product with a low caffeine removal rate (more than 10% residue). Therefore, developing a method for preparing decaffeinated tea that effectively reduces caffeine content while maximizing the preservation of the original color, aroma, flavor, and nutrients of the tea is of significant practical importance. Simultaneously, the large-scale production of decaffeinated tea and the further development of derivative decaffeinated tea powder are also key areas of technological development.

[0006] Focusing on the above issues, we developed a method that can efficiently remove caffeine and leave low solvent residue while preserving the nutrition and flavor of tea. This method enables the large-scale production of low-caffeine tea, which in turn produces cold-water instant low-caffeine tea powder. This solves a key problem in the field of food science and is of great significance for promoting the upgrading of the tea beverage industry towards health and convenience. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing low-caffeine tea and low-caffeine tea powder. This method optimizes water treatment and extraction conditions to obtain as many water-soluble components of tea as possible, effectively removes caffeine from the tea through solvent extraction, and significantly reduces the loss of tea flavor substances and other effective components. Furthermore, by removing water from the tea, a low-temperature, instant-dissolving low-caffeine tea powder is obtained.

[0008] In order to achieve the above objectives,

[0009] Its characteristic is that it is achieved through the following technical route, as shown in the appendix. Figure 1 As shown: A method for preparing decaffeinated tea and decaffeinated tea powder includes the following steps: Add tea leaves or tea powder to room temperature water and steep them according to a certain ratio of tea leaves to water. At room temperature, after soaking for a certain period of time, filter out the tea leaves to obtain tea water; repeat the process of soaking the tea leaves and filtering, and combine the filtered tea water. Low-caffeine tea was prepared by centrifuging tea with food-grade dichloromethane at a certain volume ratio and rotation speed. The tea was analyzed by high-performance liquid chromatography to determine the caffeine removal results. The residual dichloromethane content was detected by gas chromatography to meet relevant food requirements. Desolvation technology was used to dehydrate low-caffeine tea to obtain yellow low-caffeine instant tea powder.

[0010] In step A above, the raw material can be ordinary tea leaves or tea powder, preferably tea powder with a size of 20-120 mesh; In step A, the ratio of tea powder to water is 1:20-1:40 (g / mL), with a preferred ratio of 1:30 (g / mL); the water temperature is room temperature. In step B above, the soaking time is 12h-48h, preferably 24h; the number of soaking times is 1-3, preferably 2 extraction times; In step C above, the volume ratio of tea to dichloromethane is 1:0.5 - 1:1.5, preferably 1:1; the centrifugal extractor speed is 1960-2240 rpm, preferably 2100 rpm; In step D above, the dehydration treatment can be carried out by spray drying, air drying, freeze drying, oven drying and microwave drying, etc., with spray drying being the preferred method.

[0011] The low-caffeine tea was tested by high performance liquid chromatography. The results showed that the caffeine content in the low-caffeine tea was equivalent to 3.79±0.15mg of caffeine per gram of tea leaves, which is only about 2.75% of the caffeine content in the raw tea leaves.

[0012] The residual dichloromethane content in low-calorie tea and low-calorie instant tea powder was detected by gas chromatography. The results showed that dichloromethane was not detected in either the tea or the tea powder.

[0013] Highly efficient caffeine removal: Through a two-step process of "room temperature water soaking extraction" and "solvent extraction", most of the active ingredients in the tea leaves are first dissolved in water at a lower temperature. Then, caffeine is mainly extracted with dichloromethane, which effectively avoids the loss of other active ingredients and greatly reduces the caffeine content in the final product (tea water and tea powder) by up to 97.25% (compared to the original tea leaves).

[0014] Excellent flavor retention: The "room temperature water soaking extraction" step retains the volatile aroma components in tea to the maximum extent. The extraction of dichloromethane does not affect the content of tea polyphenols, amino acids, and soluble sugars in the tea water, resulting in a low-caffeine tea with a clear color, fresh and mellow taste, and rich and natural aroma, overcoming the defects of weak and bland tea soup caused by traditional decaffeine methods.

[0015] Simple process and low cost: The equipment and raw materials used in this invention are simple and readily available. The centrifugal extractor is easy to operate and does not require expensive organic solvents or complex supercritical extraction equipment. The production cost is low and it is easy to promote and apply industrially.

[0016] High safety: The entire process uses water as the main medium, and the centrifugal extraction method can efficiently separate dichloromethane. The analysis results show that there is no risk of chemical solvent residue, and the product is highly safe.

[0017] The product comes in various forms: The low-caffeine tea preparation method obtained in this invention can be combined with a subsequent dehydration process to conveniently prepare low-caffeine instant tea powder, which is easy to store and transport, thus expanding the application range of low-caffeine tea. This tea powder can also be quickly dissolved in cold water. Attached Figure Description

[0018] Figure 1 A process route for preparing low-caffeine instant tea. Figure 2 The image shows the high-performance liquid chromatogram of the tea obtained in step B.

[0019] Figure 3 The high-performance liquid chromatogram of the low-caffeine tea obtained in step C is shown.

[0020] Figure 4 The gas chromatogram of the low-caffeine tea obtained in step C is shown.

[0021] Figure 5 The gas chromatogram of the low-caffeine instant tea powder obtained in step D.

[0022] Figure 6 Gas chromatogram of dichloromethane Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to these embodiments. Examples 1-7 of this invention are examples of tea infusion extraction, Examples 8-12 are examples of caffeine removal by dichloromethane extraction, and Examples 13-15 are examples of dehydration preparation of low-caffeine instant tea powder. Example

[0024] A method for preparing decaffeinated tea and decaffeinated tea powder, specifically including the following steps: Weigh 30g of tea powder and add room temperature water at a ratio of 1g / 30ml to soak and extract the tea powder. After 24 hours of soaking and extraction, the tea powder residue was filtered out, and the tea extract was recovered. The tea extract was then soaked and extracted twice under the same conditions, and the extracts were combined. The tea extract was analyzed by high performance liquid chromatography, and the EGCG content in the tea leaves was 19.52 mg / g, and the caffeine content was 152.19 mg / g.

[0025] Examples 2-7, other steps are the same as in Example 1. Example

[0026] C. The tea obtained in Example 1 was centrifuged at 2100 rpm using dichloromethane at a 1:1 volume ratio to remove caffeine, resulting in low-caffeine tea. High-performance liquid chromatography (HPLC) analysis showed that the remaining caffeine content in the treated tea was 0.126 mg / g, which is 2.75% of the original solution, with a caffeine removal rate of 97.25%. D. The low-caffeine tea obtained in step C was dehydrated and dried to obtain 8.91g of low-caffeine tea powder; the low-caffeine instant tea powder was reconstituted with cold water, and gas chromatography was used for detection. No dichloromethane residue was detected in the tea water, and the caffeine content in the tea powder was 0.425mg / g.

[0027] Examples 9-12, other steps are the same as in Example 8. Example

[0028] The 500 mL of low-caffeine tea obtained in Example 8 was dehydrated and dried using a spray dryer at a temperature of 120°C, a flow rate of 30 mL / min, a fan frequency of 80 Hz, and a needle frequency of 3 s / time. The dried tea powder was collected and weighed, yielding 1.25 g of low-caffeine dried tea powder. Example

[0029] The 500 mL of low-caffeine tea obtained in Example 8 was dehydrated and dried in a forced-air drying oven at 60°C for 12 hours. The dried tea powder was collected and weighed, yielding 0.92 g of low-caffeine dried tea powder. Example

[0030] The 500 mL of low-caffeine tea obtained in Example 8 was dehydrated and air-dried at room temperature for 24 hours. The dried tea powder was collected and weighed, yielding 0.87 g of decaffeinated dried tea powder.

Claims

1. A method for preparing decaffeinated tea and decaffeinated tea powder, characterized in that: It includes the following steps: A. Add tea leaves or tea powder to room temperature water and soak them according to a certain ratio of tea leaves to water; B. At room temperature, after soaking for a certain period of time, filter out the tea leaves to obtain tea water; repeat the process of soaking the tea leaves and filtering, and combine the filtered tea water. C. Using food-grade dichloromethane at a certain volume ratio and rotation speed, tea is centrifuged and extracted to obtain low-caffeine tea. The obtained tea is analyzed by high-performance liquid chromatography to determine the caffeine removal results. The residual dichloromethane content is detected by gas chromatography to meet relevant food requirements. D. Using desolvation technology, low-caffeine tea is dehydrated to obtain yellow low-caffeine instant tea powder.

2. The method for preparing low-caffeine tea and low-caffeine tea powder according to claim 1, characterized in that: In step A, the ratio of tea powder to cold water is 1:10-1:40 (g / mL), preferably 1:30 (g / mL); the soaking time is 12h-48h, preferably 24h.

3. The method for preparing low-caffeine tea and low-caffeine tea powder according to claim 1, characterized in that: In step B, the soaking and extraction are performed 1-3 times, preferably 2 times; the temperature is room temperature.

4. The method for preparing low-caffeine tea and low-caffeine tea powder according to claim 1, characterized in that: In step C, the volume ratio of tea to dichloromethane is 1:0.5 - 1:1.5, preferably 1:1; the centrifugal extractor speed is 1960-2240 rpm, preferably 2100 rpm.

5. The method for preparing low-caffeine tea and low-caffeine tea powder according to claim 1, characterized in that: In step D, the dehydration process can be carried out by spray drying, air drying, freeze drying, oven drying and microwave drying, with spray drying being the preferred method.

6. The method for preparing low-caffeine tea and low-caffeine tea powder according to claim 1, characterized in that: In step D, a spray dryer is used for drying, with a selected temperature of 120°C, a flow rate of 30 ml / min, a fan frequency of 80 Hz, and a needle frequency of 3 s / time.

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