High-temperature heat treatment storage method for researching flavor stability of tea beverage

Abstract

The invention relates to a high-temperature heat treatment storage method for researching flavor stability of tea drinks, which comprises the following steps: 1) weighing green tea, adding pure water, extracting in a water bath kettle, collecting tea soup, and cooling in an ice-water bath; (2) ensuring that the concentration of tea polyphenol in the tea soup is 450-550mg / L; 3) sterilizing the tea soup, carrying out hot filling by using a sterile bottle, sealing, and naturally cooling; and 4) storing the cooled tea beverage at the temperature of 55-95 DEG C, then quickly cooling the tea beverage in an ice-water bath to room temperature, and then storing a sample in a refrigerator at the temperature of-18 DEG C. According to the invention, the relationship between the high-temperature heat treatment of the green tea beverage and the traditional storage method is established through the visual and easy-to-observe characteristic of the color parameters (L, a, b, delta E). Compared with a traditional shelf life experiment, the sample pretreatment steps involved in the method are simpler, more convenient and more efficient, and a solid theoretical basis is provided for scientific researchers in the field of tea beverage flavor stability research.

Description

Technical Field

[0001] The invention belongs to the technical field of tea beverage processing, and in particular relates to a high-temperature heat treatment storage method for studying the flavor stability of tea beverages. Background Art

[0002] Tea beverages are made from tea water extracts, tea concentrates and instant tea powders through a series of processing steps (filtration, concentration and sterilization, etc.). Although the processing technology is mature, green tea beverages still face challenges in terms of changes in sensory attributes and flavor quality during storage, which are mainly caused by external environmental factors such as light, temperature and oxygen.

[0003] Traditional tea beverage storage methods are usually carried out at a temperature of 35°C to simulate the actual storage environment. However, green tea beverages are extremely sensitive to these environmental factors, which can easily lead to quality degradation. Commercially available tea beverages usually have a shelf life of up to 6 to 12 months, which requires researchers to observe and analyze flavor changes over a long period of time when conducting tea beverage storage tests. This long-term observation not only increases the time cost of research, but also leads to a waste of human resources and a large consumption of material resources.

[0004] Therefore, it is particularly urgent to develop a method that can shorten the time cost and simulate the flavor deterioration of tea beverages during long-term storage. The color attribute of tea beverages, as an intuitive and easy-to-visually perceive feature, often changes more obviously than the changes in flavor substances. Based on this, the present invention proposes a high-temperature heat treatment method for green tea beverages, which is intended to replace traditional storage methods (for example, storage at 35°C for 1 week) to achieve faster and more efficient sample processing. This method can not only significantly reduce the time and resource consumption of scientific researchers in conducting tea beverage storage tests, but also provide a new technical approach for the study of tea beverage flavor stability. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a high-temperature heat treatment storage method for studying the flavor stability of tea beverages, which is specifically achieved through the following technical solutions: A high temperature heat treatment storage method for studying the flavor stability of tea beverages, the method comprising the following steps: 1) Accurately weigh a certain amount of green tea into a glass conical flask, add 70℃ pure water into the conical flask, then immerse the conical flask in a 70℃ water bath for extraction. After extraction, filter and collect the tea soup, cool the collected tea soup to 22-27℃ in an ice water bath, and make up to volume; 2) Test the mass concentration and solid content of tea polyphenols in tea soup according to the national standard GB / T 21733-2008 to ensure that the concentration of tea polyphenols in tea soup is 450-550 mg / L; 3) After the tea soup is sterilized, it is hot-filled in sterile bottles and then sealed and cooled naturally; 4) The cooled tea beverage was placed at a temperature of 55-95°C for different storage periods. After the treatment, it was placed in an ice water bath to quickly cool to room temperature. Subsequently, the sample was stored in a -18°C refrigerator.

[0006] Furthermore, in step 1), the liquid ratio of green tea to pure water is 1 g:45 mL, the extraction time is 15 min, and during the extraction process, it is manually shaken every 5 min.

[0007] Furthermore, in step 3), the sterilization temperature of the tea soup is 90° C. and the sterilization time is 20 seconds.

[0008] Furthermore, in step 4), the storage temperature of the tea beverage is 95° C. and the storage time is 20-160 min.

[0009] Furthermore, in step 4), the storage temperature of the tea beverage is 75° C. and the storage time is 1-6 hours.

[0010] Furthermore, in step 4), the storage temperature of the tea beverage is 55° C. and the storage time is 2-12 hours.

[0011] The present invention accelerates the storage of tea beverages by adopting high-temperature heat treatment technology, establishes a connection between traditional storage experiments and high-temperature heat treatment storage experiments, and achieves color parameters similar to those of traditional storage methods in a significantly shortened time period. The implementation of this method improves storage efficiency, shortens the experimental cycle, and enhances cost-effectiveness. It provides certain conveniences for scientific researchers to carry out flavor stability research related to tea beverages, and has important scientific research and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The color and appearance changes (A) of the samples treated at 35°C and 95°C in Example 1, as well as the changes in the color difference parameters L value (B), a value (C), b value (D), and △E value (E) (different letters on BE indicate that there are significant differences between the A and D treatment groups and the CK treatment group (p ≤ 0.05)); Figure 2 for Figure 1 Fitting curve of ∆E changing with different treatment time; Figure 3The color and appearance changes (A) of the samples treated at 35°C and 75°C in Example 2, as well as the changes in the color difference parameters L value (B), a value (C), b value (D), and △E value (E) (different letters on BE indicate that there are significant differences between the A and C treatment groups and the CK treatment group (p ≤ 0.05)); Figure 4 for Figure 3 Fitting curve of ∆E changing with different treatment time; Figure 5 The color and appearance changes (A) of the samples treated at 35°C and 55°C in Example 3, as well as the changes in the color difference parameters L value (B), a value (C), b value (D), and △E value (E) (different letters on BE indicate that there are significant differences between the A and B treatment groups and the CK treatment group (p ≤ 0.05)); Figure 6 for Figure 5 Fitting curve of ∆E changing with different treatment time. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with specific embodiments. Example 1

[0014] A high temperature heat treatment storage method for studying the flavor stability of tea beverages, comprising the following specific steps: Step 1: Accurately weigh 5.00 g of Longguan Longjing tea and place it in a 250 mL glass conical flask. Then, add 225 mL of 70℃ pure water to the flask. Then immerse the conical flask in a 70℃ water bath for 15 min, and shake it manually every 5 min. After the extraction is completed, filter the tea soup through a 300-mesh gauze while it is hot into a 250 mL volumetric flask, then use an ice water bath as a cooling medium to quickly cool the tea soup to about 25℃ and fix the volume.

[0015] Step 2: According to the national standard (GB / T 21733-2008 Tea Beverages), test the mass concentration (mg / L) and solid concentration (Brix) of tea polyphenols in the tea soup, and dilute the tea soup to a tea polyphenol concentration of about 500 mg / L.

[0016] Step 3: The tea soup is sterilized at 90°C (the temperature is confirmed by infrared gun test) for 20 seconds, and then hot-filled in sterile bottles. The filled and sealed tea beverage is allowed to cool naturally.

[0017] Step 4: The cooled tea beverages were placed in a 35°C incubator for 1 (A1), 3 (A2), 5 (A3), and 7 days (A4); and heat-treated in a 95°C water bath for 20 (D1), 40 (D2), 80 (D3), and 160 min (D4). The tea beverages that were not treated by storage were used as the control group (CK). After the treatment, the tea beverages were quickly removed from the incubator or water bath and immediately placed in an ice water bath to quickly cool to room temperature. Subsequently, the samples were stored in a -18°C refrigerator.

[0018] HunterLab's colorimeter system was used to accurately measure the color coordinates of the samples based on the CIE color space (Lab and Lch values). The total color difference (ΔE) was calculated using the L, a, and b values, and this parameter is widely used in the color evaluation of food and beverages. The calculation formula for ΔE is as follows:

[0019] Among them, L t , a t , b t represents the color parameters of the tea beverage at the end of the processing time t, and L0, a0, b0 represent the color parameters of the initial tea beverage.

[0020] The sensory evaluation of the samples was completed by a panel of five professionally trained members (three women and two men from the Tea Research Institute of the Chinese Academy of Agricultural Sciences). Before the evaluation, 50 mL of the tea beverage was accurately measured into the evaluation cup. The evaluation cup was then covered and placed in a 35°C water bath for 20 minutes to ensure that the sample achieved a consistent and stable overall flavor. The panel members then conducted a sensory evaluation of the color of the tea beverage in accordance with the "Tea Sensory Evaluation Method" (GB / T 23776-2018).

[0021] In this example, as the storage time increases, the color of the sample treated at 35°C gradually changes from light yellow-green to orange-yellow, and the color of the sample treated at 95°C gradually changes from light yellow-green to yellow ( Figure 1 During the heat treatment, the L value and △E value decreased significantly, and the a value and b value increased significantly ( Figure 1BE in the color chart). It was found through the color plate that the colors of A1 and D1 are relatively close, and the colors of A2 and D4 are relatively close. The L value (98.025 / 98.11) and △E value (98.307 / 98.323) of A1 / D1 are relatively close. The L value (95.77 / 95.915) and △E value (96.756 / 96.744) of A2 and D4 are relatively close. Using the color parameter ΔE as a measurement indicator, the curve fitting of the ΔE changes at different treatment times at 35℃ and 95℃ was performed, and the points with the same ordinates of the two curves were taken as the similarity points of the color difference parameters ( Figure 2 ). In the fitting curve, the fitting ΔE values ​​of A1 / D1 are 98.233 / 98.418, and the fitting ΔE values ​​of A2 / D4 are 96.965 / 96.739. Through calculation, it was found that the color changes of storage at 35℃ for 1 day and heat treatment at 95℃ for 27.5 min (near D1) were basically the same, the color changes of storage at 35℃ for 2 days and heat treatment at 95℃ for 61 min (D2-D3) were basically the same, and the color changes of storage at 35℃ for 3 days and heat treatment at 95℃ for 104 min (D3-D4) were basically the same. Example 2

[0022] The difference between this embodiment and implementation 1 is only in step 4), and step 4) is specifically as follows: The cooled tea beverages were placed in a 35°C incubator for 1 (A1), 3 (A2), 5 (A3), and 7 days (A4); and heat-treated in a 75°C water bath for 1 (C1), 2 (C2), 4 (C3), and 6 hours (C4). The tea beverages that were not treated with storage were used as the control group (CK). After the treatment, the tea beverages were quickly removed from the incubator or water bath and immediately placed in an ice water bath to quickly cool to room temperature. Subsequently, the samples were stored in a -18°C refrigerator.

[0023] The color coordinates of the samples were accurately measured based on the CIE color space (Lab and Lch values) using HunterLab's colorimeter system. The total color difference (ΔE) was calculated from the L, a and b values, a parameter that is widely used in food and beverage color evaluation.

[67] The calculation formula of ΔE is as follows:

[0024] Among them, L t , a t , b t represents the color parameters of the tea beverage at the end of the processing time t, and L0, a0, b0 represent the color parameters of the initial tea beverage.

[0025] The sensory evaluation of the samples was completed by a panel of five professionally trained members (three women and two men from the Tea Research Institute of the Chinese Academy of Agricultural Sciences). Before the evaluation, 50 mL of the tea beverage was accurately measured into the evaluation cup. The evaluation cup was then covered and placed in a 35°C water bath for 20 minutes to ensure that the sample achieved a consistent and stable overall flavor. The panel members then conducted a sensory evaluation of the color of the tea beverage in accordance with the "Tea Sensory Evaluation Method" (GB / T 23776-2018).

[0026] In this example, as the storage time increases, the color of the sample treated at 35°C gradually changes from light yellow-green to orange-yellow, and the color of the sample treated at 75°C gradually changes from light yellow-green to yellow ( Figure 3 During the heat treatment, the L value and △E value decreased significantly, and the a value and b value increased significantly ( Figure 3 BE in the color chart). It is found from the color plate that the colors of A1 and C2 are relatively close. The L value (98.025 / 97.72) and △E value (98.307 / 98.062) of A1 / C2 are relatively close. Using the color parameter ΔE as a measurement index, the curve fitting of the ΔE change at different treatment times at 35℃ and 75℃ is performed, and the points with the same ordinates of the two curves are taken as the similarity points of the color difference parameters ( Figure 4 ). In the fitting curve, the fitting ΔE value of A1 / C2 is 98.233 / 98.214. Through calculation, it is found that the color change of storage at 35℃ for 1 day and heat treatment at 75℃ for 116.5 min (near C2) is consistent, and the color change of storage for 2 days and heat treatment at 75℃ for 268 min (near C3) is consistent. Example 3

[0027] The difference between this embodiment and embodiment 1 is only in step 4). Step 4) is as follows: the cooled tea beverage is placed in a 35°C incubator for storage for 1 (A1), 3 (A2), 5 (A3), and 7 days (A4); and heat-treated in a 55°C water bath for 2 (B1), 4 (B2), 6 (B3), and 12 hours (B4). The tea beverage without storage treatment is used as the control group (CK). After the treatment, the tea beverage is quickly removed from the incubator or water bath and immediately placed in an ice water bath to quickly cool to room temperature. Subsequently, the sample is stored in a -18°C refrigerator.

[0028] HunterLab's colorimeter system was used to accurately measure the color coordinates of the samples based on the CIE color space (Lab and Lch values). The total color difference (ΔE) was calculated using the L, a, and b values, and this parameter is widely used in the color evaluation of food and beverages. The calculation formula for ΔE is as follows:

[0029] Among them, L t , a t , b t represents the color parameters of the tea beverage at the end of the processing time t, and L0, a0, b0 represent the color parameters of the initial tea beverage.

[0030] The sensory evaluation of the samples was completed by a panel of five professionally trained members (three women and two men from the Tea Research Institute of the Chinese Academy of Agricultural Sciences). Before the evaluation, 50 mL of the tea beverage was accurately measured into the evaluation cup. The evaluation cup was then covered and placed in a 35°C water bath for 20 minutes to ensure that the sample achieved a consistent and stable overall flavor. The panel members then conducted a sensory evaluation of the color of the tea beverage in accordance with the "Tea Sensory Evaluation Method" (GB / T 23776-2018).

[0031] In this example, as the storage time increases, the color of the sample treated at 35°C gradually changes from light yellow-green to orange-yellow, and the color of the sample treated at 55°C gradually changes from light yellow-green to light yellow ( Figure 5 During the heat treatment, the L value and △E value decreased significantly, and the a value and b value increased significantly ( Figure 5 BE in the color chart). It is found from the color plate that the colors of A1 and B3 are relatively close. The L value (98.025 / 98.125), a value (-0.365 / -0.3), b value (7.43 / 7.11), and △E value (98.307 / 98.383) of A1 / B3 are relatively close. Using the color parameter ΔE as a measurement indicator, the curve fitting of the ΔE change at different treatment times at 35℃ and 55℃ is performed, and the points with the same ordinates of the two curves are taken as the similarity points of the color difference parameters ( Figure 6 ). In the fitting curve, the fitting ΔE values ​​of A1 / B3 are 98.233 / 98.216. Through calculation, it is found that the color changes of storage at 35℃ for 1 day and heat treatment at 55℃ for 233.5 min (near B3) are consistent.

Claims

1. A high temperature heat treatment storage method for studying the flavor stability of tea beverages, characterized in that: The method comprises the following steps: 1) Accurately weigh a certain amount of green tea into a glass conical flask, add 70℃ pure water into the conical flask, then immerse the conical flask in a 70℃ water bath for extraction. After extraction, filter and collect the tea soup, cool the collected tea soup to 22-27℃ in an ice water bath, and make up to volume; 2) Test the mass concentration and solid content of tea polyphenols in tea soup according to the national standard GB / T 21733-2008 to ensure that the concentration of tea polyphenols in tea soup is 450-550 mg / L; 3) After the tea soup is sterilized, it is hot-filled in sterile bottles and then sealed and cooled naturally; 4) The cooled tea beverage was placed at a temperature of 55-95°C for different storage periods. After the treatment, it was placed in an ice water bath to quickly cool to room temperature. Subsequently, the sample was stored in a -18°C refrigerator.

2. A high temperature heat treatment storage method for studying the flavor stability of tea beverages as claimed in claim 1, characterized in that Step 1), the liquid ratio of green tea to pure water is 1g:45mL, the extraction time is 15min, and during the extraction process, it is manually shaken once every 5min.

3. A high temperature heat treatment storage method for studying the flavor stability of tea beverages as claimed in claim 1, characterized in that In step 3), the sterilization temperature of the tea soup is 90°C and the sterilization time is 20s.

4. A high temperature heat treatment storage method for studying the flavor stability of tea beverages as claimed in claim 1, characterized in that In step 4), the storage temperature of the tea beverage is 95° C. and the storage time is 20-160 min.

5. A high temperature heat treatment storage method for studying the flavor stability of tea beverages as claimed in claim 1, characterized in that In step 4), the storage temperature of the tea beverage is 75° C. and the storage time is 1-6 hours.

6. A high temperature heat treatment storage method for studying the flavor stability of tea beverages as claimed in claim 1, characterized in that In step 4), the storage temperature of the tea beverage is 55° C. and the storage time is 2-12 hours.

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