A method for evaluating the tenderness of new shoots of tea trees

Abstract

The present invention belongs to the field of tea tree detection, and specifically relates to a method for quickly evaluating the tenderness of new shoots of different tea tree germplasm resources, comprising the following steps: taking new shoots of tea trees to be tested; removing stems and grinding the new shoots after drying; using a particle size analyzer to measure the particle size distribution of the ground tea powder to obtain the D 50 Data; Using the judgment criteria, according to the D 50 The tenderness grade of the new shoots of the tea germplasm to be tested is obtained by using the data. The tenderness of the new shoots of different tea germplasm resources can be evaluated and graded by the method of the present invention.

Description

Technical Field

[0001] The invention belongs to the field of tea tree detection, and in particular relates to a method for rapidly evaluating the tenderness of new shoots of different tea tree germplasm resources. Background Art

[0002] Tea trees are important economic crops in my country. They are evergreen woody plants, and their new shoots are the raw materials for tea processing. The quality of new shoots determines the quality of finished tea. There are two main indicators for measuring the quality of tea shoots: tenderness and tenderness retention. The tenderness of new shoots is usually expressed by their growth period or leaf expansion, such as single bud, one bud and one leaf, one bud and two leaves, etc. In the same season, new shoots with different tenderness can be processed into tea of ​​different grades. For example, single bud or one bud and one leaf can be processed into famous green tea, one bud and two or three leaves can be processed into bulk tea, and coarser and older new shoots can be used to make black tea. Tenderness is not only related to the growth period of new shoots, but also closely related to the characteristics of the variety. For new shoots of the same season and the same variety with different growth periods, tenderness is easy to judge and evaluate, that is, the tenderness of a single bud is higher than that of a bud and one leaf, the tenderness of a bud and one leaf is higher than that of a bud and two leaves, and one bud and two leaves is higher than one bud and three leaves, and so on. However, for different varieties or germplasm resources in the same season and the same growth period, the tenderness of new shoots often varies significantly due to different genetic backgrounds. In tea production, the tenderness of new shoots has a significant impact on the harvesting method and efficiency. Generally speaking, tenderer new shoots are more suitable for manual picking, while new shoots with lower tenderness are more suitable for mechanical harvesting. In addition, tenderness also has an important impact on the shaping of tea products. New shoots with high tenderness are easier to shape, and can also effectively reduce the broken tea rate of tea products, and improve production efficiency and benefits. Therefore, in the process of variety selection and promotion, varieties with high tenderness of new shoots in the same season and the same growth period are more popular.

[0003] Tea germplasm resources are an important cornerstone for the healthy and sustainable development of my country's tea industry. The scientific evaluation of germplasm traits is a prerequisite for the efficient use of germplasm resources. The existing methods for evaluating the tenderness of new shoots are mainly measured by researchers testing the physical characteristics of buds and leaves. When the detection methods are limited, researchers often use subjective perception methods to measure the tenderness of new shoots, such as testing the softness of buds and leaves by twisting, rubbing, and lifting them by hand. This method is greatly affected by the experience of researchers and is difficult to standardize. With the development of detection technology, researchers use physics, biochemistry, molecular biology and other means to measure the tenderness of new shoots. For example, the shear force of the leaves is used to measure the tenderness of tea shoots, that is, the leaves and stems of the tea shoots are cut by a texture analyzer, and the tenderness of the new shoots is measured with the minimum shear force. The greater the minimum shear force, the lower the tenderness.

[0004] This method is most consistent with subjective perception, but due to issues such as equipment cost, its current scope of application is very limited. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for evaluating the tenderness of new shoots of tea trees. The present invention evaluates the tenderness of new shoots of different germplasm resources by grinding dry tea of ​​new shoots of tea trees into particle sizes.

[0006] In order to solve the above technical problems, the present invention provides a method for evaluating the tenderness of new shoots of tea trees, comprising the following steps:

[0007] 1) Sampling:

[0008] Take the new shoots of the tea tree to be tested (new shoots of the tea tree germplasm to be tested);

[0009] 2) Preparation of dry tea powder:

[0010] Place the new shoots in a microwave oven and heat at 800±50W for 1.5min~2min, then dry at 80±10℃ until the moisture content is less than 5% (drying time is about 4h~6h);

[0011] The obtained new shoot dry sample is destemmed (i.e., retaining buds and leaves), and then ground to obtain tea powder (tea powder sample);

[0012] Note: Generally, for a microwave oven at 800±50W, the amount of fresh leaves processed each time is ≤25g.

[0013] 3) Tea powder D 50 analyze:

[0014] The particle size distribution of the tea powder obtained by grinding was measured by a particle size analyzer. Water was used as the medium for the measurement. The shading rate was 11%-13% (the amount of tea powder used was preferably such that the shading rate was 11%-13% during the measurement). The D 50 Data (After the determination is completed, the D of each tea powder sample is obtained according to the statistical results of the instrument 50 data);

[0015] 4) Determination of tenderness of new shoots:

[0016] Using the judgment criteria, according to the D 50 Data was collected to obtain the tenderness grade of the new shoots of the tea tree germplasm to be tested.

[0017] As an improvement of the evaluation method of the tenderness of tea tree new shoots of the present invention: the judgment criteria in step 4) are:

[0018] Grinded tea powder D 50 The tenderness of new shoots >45μm is "special grade", 40μm <D 50 The tenderness of new shoots ≤45μm is "first class", 35μm <D 50 The tenderness of new shoots ≤40μm is "secondary", 30μm <D 50The tenderness of shoots ≤ 35 μm is "Grade Three", D 50 The tenderness of shoots < 30 μm is "Grade Four".

[0019] As a further improvement of the method for evaluating the tenderness of tea tree shoots of the present invention, in the step 1):

[0020] In a tea garden with a conventional management mode, when the tea shoots grow to one bud and one leaf, one bud and two leaves, or one bud and three leaves, healthy tea shoots with consistent growth vigor are harvested. There are 3 biological replicates for each germplasm (3 biological replicates are required for one bud and one leaf, one bud and two leaves, and one bud and three leaves respectively), and each replicate has no less than 30 tea shoots.

[0021] As a further improvement of the method for evaluating the tenderness of tea tree shoots of the present invention, in the step 2):

[0022] After removing the stalks from the tea shoots, weigh 1 g of the tea sample and add it to a 10 mL grinding tube. Then add 3 grinding beads made of 304 steel with a diameter of 50 mm. Place the grinding tube on a ball mill for grinding: the grinding time is 50 s, the interval time is 10 s, the grinding times are 30 times, and the grinding frequency is 60 Hz. After grinding, take out the grinding beads and fully mix the tea powder in the grinding tube. For each tea tree germplasm, tea powder samples of one bud and one leaf, one bud and two leaves, and one bud and three leaves of the tea shoots with 3 replicates are obtained.

[0023] The present invention is a method for judging the tenderness of tea shoots of different germplasm resources by analyzing the particle size of the tea powder after grinding the dry tea made from tea tree shoots. Specifically, the present invention provides the relationship between the particle size distribution D 50 (i.e., the particle size corresponding to when the cumulative distribution percentage of the sample reaches 50%) of the tea powder after grinding the dry tea made from the tea shoots of different germplasms and the tenderness of the tea shoots. According to the measurement of the particle size of the tea powder after grinding the dry tea made from the spring tea shoots of different tea tree germplasms, the tenderness of the tea shoots of different tea tree germplasm resources can be evaluated and graded.

[0024] In the present invention, the judgment standard for the data measured by the conventional shear force method is as follows: Use a texture analyzer to detect the minimum shear force (F) of the lowest stem segment of the freshly harvested fresh tea shoots, and judge the tenderness of the tea shoots. If F ≤ 120 g, the tenderness of the tea shoots is "Extra Grade"; if 120 g < F ≤ 200 g, the tenderness of the tea shoots is "Grade One"; if 200 g < F ≤ 450 g, the tenderness of the tea shoots is "Grade Two"; if 450 g < F ≤ 1000 g, the tenderness of the tea shoots is "Grade Three"; if F > 1000 g, the tenderness of the tea shoots is "Grade Four".

[0025] Compared with the prior art, the present invention has the following technical advantages:

[0026] The method for evaluating the tenderness of tea tree shoots of the present invention has a high throughput and can identify a large number of tea tree germplasm resources at one time;

[0027] The method for evaluating the tenderness of new shoots of tea trees of the present invention is simple and quick to operate, can be standardized, and can effectively avoid subjective factors.

[0028] The present invention can be widely applied to tea germplasms with different color characteristics and different bud and leaf sizes, and has good universality;

[0029] The method for evaluating the tenderness of new shoots of tea trees of the present invention can realize sample preparation and unified measurement in multiple locations and multiple time periods, and the measurement object is particle size, and the stability is good. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0031] Note: Most of the tea germplasms in the following cases are existing conventional tea trees, while some tea germplasms (such as '5-62', Zhejiang Agricultural University 805, etc.) are newly obtained tea germplasms by the research group of the inventor of this application.

[0032] Example 1

[0033] 1) In tea gardens managed under conventional management, healthy new shoots of tea germplasms 'Huangjinya', 'Zhe Nong 805', 'Yingshuang', 'Xiaoxiang No. 1', 'Fuding Dabaicha' and '5-62' when they had just developed to 1 bud and 1 leaf, 1 bud and 2 leaves, and 1 bud and 3 leaves were harvested in the spring of 2022. Each germplasm had 3 biological replicates (1 bud and 1 leaf, 1 bud and 2 leaves, and 1 bud and 3 leaves required 3 biological replicates respectively), and each replicate had no less than 30 new shoots.

[0034] Healthy new shoots refer to new shoots that are free from pests and diseases and mechanical damage.

[0035] 2) The minimum shear force of the lowest stem segment of each newly harvested shoot is measured using the known shear force method, and the tenderness of each sample is determined accordingly.

[0036] 3) The harvested new shoots were sterilized in a microwave oven at 800W for 1.5min-2min, and then dried at 80°C for 6 hours to reduce the moisture content of the leaves to less than 5%.

[0037] After the obtained new shoot dry sample was destemmed (i.e., retaining the buds and leaves), 1.000g of tea sample was accurately weighed and added to a 10mL grinding tube, and then 3 304 steel grinding beads with a diameter of 50mm were added. The grinding tube was placed on a ball mill for grinding. The grinding conditions were as follows: grinding time, 50s; interval time, 10s; grinding times, 30 times; grinding frequency, 60Hz. After the grinding, the grinding beads were taken out and the tea powder in the grinding tube was fully mixed. For each tea tree germplasm, tea powder samples with 1 bud and 1 leaf, 1 bud and 2 leaves, and 1 bud and 3 leaves were obtained.

[0038] 4) Add sufficient water to the circulating water pump of the laser particle size analyzer. After starting the circulation, check the instrument background, and then zero the background of the instrument. Add tea powder to the measuring cell, ultrasonicate for 1 min, and control the light shielding rate to be (12 ± 1)%. Start the measurement after the light shielding rate is stable, and save the measurement results to obtain D of each sample 50 . After each measurement, clean the instrument twice with circulating water and then proceed with the next sample measurement.

[0039] 5) The measurement results are shown in Table 1. The average values of D of the one-bud-one-leaf dry tea powder of 'Golden芽', 'Zhenong 805', 'Yingshuang', 'Xiaoxiang No. 1', 'Fuding Dabaicha', and '5 - 62' are 50 45.15 μm, 46.44 μm, 45.16 μm, 46.03 μm, 45.42 μm, and 41.47 μm respectively; the average values of D of the one-bud-two-leaf dry tea powder are 50 41.49 μm, 41.87 μm, 39.81 μm, 37.79 μm, 38.37 μm, and 37.80 μm respectively; the average values of D of the one-bud-three-leaf dry tea powder are 50 39.82 μm, 38.31 μm, 38.94 μm, 33.59 μm, 33.43 μm, and 34.26 μm respectively.

[0040] Table 1

[0041]

[0042] 6) Judgment method:

[0043] For the present invention: For the tea powder D after grinding, 50 if the new shoot tenderness is "super grade" when D > 45 μm, "first grade" when 40 μm < D 50 ≤ 45 μm, "second grade" when 35 μm < D 50 ≤ 40 μm, "third grade" when 30 μm < D 50 ≤ 35 μm, and "fourth grade" when D 50 ≤ 30 μm.

[0044] For the conventional shear force method: If F ≤ 120 g, the new shoot tenderness is "super grade", if 120 g < F ≤ 200 g, the new shoot tenderness is "first grade", if 200 g < F ≤ 450 g, the new shoot tenderness is "second grade", if 450 g < F ≤ 1000 g, the new shoot tenderness is "third grade", and if F > 1000 g, the new shoot tenderness is "fourth grade".

[0045] The obtained results are:

[0046] In the spring of 2022, the tenderness of new shoots with 1 bud and 1 leaf of 'Golden Bud', 'Zhe Nong 805', 'Ying Shuang', 'Xiaoxiang No. 1', 'Fuding Da Baicha', and '5-62' were respectively special, special, special, special, special, and first grade; the tenderness of new shoots with 1 bud and 2 leaves were respectively first grade, first grade, second grade, second grade, second grade, and second grade; the tenderness of new shoots with 1 bud and 3 leaves were respectively second grade, second grade, second grade, third grade, third grade, and third grade (Table 2). It can be seen that the results obtained by this method are consistent with those obtained by the conventional shear force method.

[0047] Table 2

[0048]

[0049] Example 2

[0050] 1) In tea gardens managed under conventional management, healthy new shoots of tea germplasms 'Fuding Da Baicha', 'Huang Jin Ya', 'Ying Shuang', 'Zhe Nong 301', 'Chun Yu 2' and 'Long Jing 43' that had just developed to 1 bud 1 leaf, 1 bud 2 leaves and 1 bud 3 leaves were harvested in the spring of 2023, with 3 biological replicates for each germplasm and no less than 30 new shoots in each replicate.

[0051] 2) The minimum shear force of the lowest stem segment of each newly harvested shoot is measured using the known shear force method, and the tenderness of each sample is determined accordingly.

[0052] 3) The harvested new shoots were subjected to the withering, drying and grinding methods described in Example 1 to prepare tea powder samples of various tea germplasm.

[0053] 4) According to the method described in Example 1, each tea powder sample D 50 Carry out determination.

[0054] 5) The test results are shown in Table 3. 1 bud 1 leaf dry tea powder D of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2' and 'Longjing 43' 50 The average values ​​are 46.18μm, 45.44μm, 48.81μm, 47.96μm, 44.09μm, 48.25μm; 1 bud 2 leaves dry tea powder D 50 The mean values ​​are 37.58μm, 40.78μm, 39.83μm, 38.32μm, 39.49μm, 43.34μm; 1 bud 3 leaves dry tea powder D 50 The average values ​​are 34.45μm, 37.44μm, 38.45μm, 34.85μm, 36.91μm, and 39.74μm.

[0055] Table 3

[0056]

[0057]

[0058] 6) According to the determination method of Example 1, in the spring of 2023, the tenderness of 1 bud and 1 leaf of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2', and 'Longjing 43' was respectively special grade, special grade, special grade, special grade, first grade, and special grade; the tenderness of 1 bud and 2 leaves of various qualities was respectively second grade, first grade, second grade, second grade, second grade, and first grade; the tenderness of 1 bud and 3 leaves of various qualities was respectively third grade, second grade, second grade, third grade, second grade, and second grade (Table 4). It can be seen that this method is consistent with the results obtained by the conventional shear force method.

[0059] Table 4

[0060]

[0061] Example 3

[0062] 1) In the tea garden under conventional management mode, the healthy new shoots of tea germplasms 'Fuding Da Baicha', 'Huangjin Ya', 'Yingshuang', 'Zhe Nong 301', 'Chun Yu 2' and 'Longjing 43' that had just developed to 1 bud and 2 leaves and 1 bud and 4 leaves were harvested in the summer of 2023, with 3 biological replicates for each germplasm and no less than 30 new shoots in each replicate.

[0063] 2) The shear force method was used to measure the minimum shear force of the lowest stem segment of each newly harvested shoot, and the tenderness of each sample was determined accordingly.

[0064] 3) The harvested new shoots were subjected to the withering, drying and grinding methods described in Example 1 to prepare tea powder samples of various tea germplasm.

[0065] 4) According to the method described in Example 1, each tea powder sample D 50 Carry out determination.

[0066] 5) The test results are shown in Table 5. Particle size D of tea powder of 1 bud and 2 leaves of new shoots of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2' and 'Longjing 43' 50 The average values ​​are 36.58μm, 41.42μm, 37.69μm, 35.88μm, 36.32μm, and 35.52μm; the particle size D of the tea powder of 1 bud and 4 leaves new shoots 50 The average values ​​are 28.45μm, 33.56μm, 30.41μm, 29.11μm, 27.39μm, and 28.57μm.

[0067] Table 5

[0068]

[0069] 6) According to the determination method of Example 1, in the autumn of 2023, the tenderness of new shoots with 1 bud and 2 leaves of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2', and 'Longjing 43' was Grade 2, Grade 1, Grade 2, Grade 2, Grade 2, and Grade 2 respectively; the tenderness of new shoots with 1 bud and 4 leaves was Grade 4, Grade 3, Grade 3, Grade 4, Grade 4, and Grade 4 respectively (Table 6). It can be seen that the results obtained by this method are consistent with those obtained by the conventional shear force method.

[0070] Table 6

[0071]

[0072] Example 4

[0073] 1) In the tea garden under conventional management mode, the healthy new shoots of tea germplasms 'Fuding Da Baicha', 'Huangjin Ya', 'Yingshuang', 'Zhe Nong 301', 'Chun Yu 2' and 'Longjing 43' that had just developed to 1 bud 1 leaf, 1 bud 2 leaves and 1 bud 3 leaves were harvested in the autumn of 2023, with 3 biological replicates for each germplasm and no less than 30 new shoots in each replicate.

[0074] 2) The shear force method was used to measure the minimum shear force at the lowest stem segment of each newly harvested shoot, and the tenderness of each sample was determined accordingly.

[0075] 3) The harvested new shoots were subjected to the withering, drying and grinding methods described in Example 1 to prepare tea powder samples of various tea germplasm.

[0076] 4) According to the method described in Example 1, each tea powder sample D 50 Carry out determination.

[0077] 5) The test results are shown in Table 7. Particle size D of 1 bud and 1 leaf new shoot tea powder of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2', 'Longjing 43' 50 The average values ​​are 44.32μm, 46.21μm, 47.52μm, 45.35μm, 43.56μm, 44.63μm; the particle size of 1 bud 2 leaves new shoot tea powder D 50 The average values ​​are 38.32μm, 42.63μm, 38.42μm, 37.52μm, 36.24μm, and 36.74μm; the particle size D of the tea powder of 1 bud and 3 leaves new shoots 50 The average values ​​are 34.49μm, 36.34μm, 35.16μm, 34.62μm, 33.29μm, and 31.53μm.

[0078] Table 7

[0079]

[0080] 6) According to the determination method of Example 1, in the autumn of 2023, the tenderness of new shoots of 'Fuding Dabaicha', 'Golden Bud', 'Yingshuang', 'Zhe Nong 301', 'Chunyu No. 2', and 'Longjing 43' with 1 bud and 1 leaf were respectively first grade, special grade, special grade, special grade, first grade, and first grade; the tenderness of 1 bud and 2 leaves were respectively second grade, first grade, second grade, second grade, second grade, and second grade; the tenderness of 1 bud and 3 leaves were respectively third grade, second grade, third grade, third grade, third grade, and third grade (Table 8). It can be seen that the results obtained by this method are consistent with those obtained by the conventional shear force method.

[0081] Table 8

[0082]

[0083] Comparative Example 1-1: The shading rate in Example 1 was changed from "(12±1)%" to "(5±1)%", and the rest was the same as Example 1. Taking the germplasm 'Golden Bud' as an example, three biological replicates of 1 bud 1 leaf, 1 bud 2 leaves and 1 bud 3 leaves were obtained. 50 The values, average values ​​and coefficients of variation are shown in Table 9. The coefficient of variation among the three replicates was too high to reflect the true value of the sample and to effectively distinguish the tenderness of the samples.

[0084] Table 9

[0085]

[0086] Comparative Example 1-2: The shading rate in Example 1 was changed from "(12±1)%" to "(30±1)%", and the rest was the same as Example 1. The test result data was generally small, which was difficult to reflect the true value of the sample and could not effectively distinguish the tenderness of the sample. The details are shown in Table 10.

[0087] Table 10

[0088]

[0089] Comparative Example 2: The grinding times of 30 times in Example 1 was changed to 50 times, that is, grinding 50s*50=2500s, and the rest was the same as Example 1. The results are shown in Table 11. 50 The value difference is too small to effectively distinguish the tenderness of the samples.

[0090] Table 11

[0091]

[0092] Comparative Example 3: Change "weigh 1.000 g" in Example 1 to "1.500 g", and the rest is the same as Example 1. The results are shown in Table 12. The particle size of the sample particles is too large, and the tenderness of the samples cannot be effectively distinguished.

[0093] Table 12

[0094]

[0095] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for evaluating the tenderness of new shoots of tea trees, characterized in that The following steps are involved: 1) Sampling: Take the new shoots of the tea tree to be tested; 2) Preparation of dry tea powder: Place the new shoots in a microwave oven at 800±50W for 1.5 min~2 min, and then dry at 80±10℃ until the moisture content is less than 5%; After removing the stems of the new shoots, 1 g was weighed and added to a 10 mL grinding tube. Then, three 304 steel grinding beads with a diameter of 50 mm were added. The grinding tube was placed on a ball mill for grinding: grinding time 50 s, interval time 10 s, grinding times 30 times, grinding frequency 60 Hz; after grinding, the grinding beads were taken out and the tea powder in the grinding tube was fully mixed; 3) Tea powder D 50 analyze: The particle size distribution of the ground tea powder was measured using a laser particle size analyzer. Water was used as the medium for the measurement, and ultrasound was applied for 1 min. The shading rate was 11%-13%. The D 50 data; 4) Determination of tenderness of new shoots: Using the judgment criteria, according to the D 50 Data was collected to obtain the tenderness grade of the new shoots of the tea tree germplasm to be tested.

2. The method for evaluating the tenderness of new shoots of tea trees according to claim 1, characterized in that: The judgment criteria in step 4) are: Grinded tea powder D 50 The tenderness of new shoots >45 μm is "special grade", 40 μm <D 50 The tenderness of new shoots ≤45 μm is "first grade", 35 μm <D 50 The tenderness of new shoots ≤40 μm is "secondary", 30 μm <D 50 The tenderness of new shoots ≤35 μm is "level 3", D 50 The tenderness of new shoots ≤30μm is "Level 4".

3. A method for evaluating the tenderness of new shoots of tea trees according to claim 2, characterized in that: In the step 1), when the seedlings grow to 1 bud and 1 leaf, 1 bud and 2 leaves, or 1 bud and 3 leaves, healthy new shoots with the same growth potential are harvested. Each germplasm is subjected to 3 biological replicates, and each replicate has no less than 30 new shoots: In the step 2), tea powder samples with three replicates of new shoots 1 bud 1 leaf, 1 bud 2 leaves and 1 bud 3 leaves were obtained for each tea tree germplasm.

Images