Immature walnut tea substitute and method for preparing the same

Abstract

This application relates to an immature walnut substitute tea and its preparation method, belonging to the field of agricultural food processing technology. The method includes: selecting immature green-skinned walnuts 60-120 days after flowering, washing, high-pressure steaming to remove the skin, initial drying for 2-6 hours until the moisture content is 60%-70%, steaming for 10-60 minutes, and re-drying for 2-6 hours until the moisture content is 8%-13%, and optionally repeating the steaming and drying process 1-9 times. This application, through a combined steaming and drying process, significantly improves the drying rate, shape integrity, and oiliness of the walnut substitute tea, effectively reducing the sourness and astringency of the taste, and enhancing the sweetness and aroma purity, resulting in a stable quality characterized by "yellowish-brown or dark brown and oily appearance, bright orange-yellow or orange-red liquor, pure medicinal or woody aroma, and a sweet and mellow taste with a slight sourness," suitable for commercial and standardized production.

Description

Technical Field

[0001] This application relates to the field of agricultural food processing technology, specifically to a processing technology for immature walnuts as a substitute for tea. Background Technology

[0002] Walnut (Juglans regia L.), also known as walnut or Qiang walnut, is a perennial deciduous tree belonging to the genus Juglans in the family Juglandaceae. It is one of the world's four major dried fruits, along with almonds, cashews, and hazelnuts. Before walnuts are fully ripe, they contain higher levels of polyphenols and organic acids, exhibiting various biological activities such as antioxidant and neuroprotective effects, and possessing high potential application value. (Zheng Xiaoning, Li Jun, Mou Jianlou, et al. Research progress on polyphenol activity and its separation and purification in walnut fruits [J]. Food Industry Technology, 2020, 41(21):351-358.). Currently, walnut cultivation in mountainous areas is severely affected by pests and diseases. Harvesting and utilizing immature walnuts can mitigate the impact of pests and diseases, reduce the use of chemical fertilizers and pesticides, and improve the overall economic benefits of walnut cultivation.

[0003] Previous studies have found that mature walnut shells and septa, when boiled or steeped, have low water-soluble substances and low extraction rates, resulting in a bland taste. The levels of polyphenols and organic acids also decrease with increasing maturity, making them unsuitable for consumption. Developing unripe walnut tea substitutes could enrich the drinking experience and fully utilize the functional substances of natural plants. However, because unripe walnuts have high levels of polyphenols and organic acids, simply drying them before use as a substitute results in a cloudy tea liquor with a high concentration of bitter, astringent, and sour flavors, also failing to provide good drinking conditions. Furthermore, the dense structure of the walnut shell limits the drying rate of whole fruits, and cutting or piercing them results in poor appearance. Therefore, this application aims to solve the technical problems of cloudy tea liquor, poor taste, and long processing time in walnut tea substitutes, and to utilize unripe walnuts to create a standardized, commercially viable walnut tea substitute product with unique and excellent drinking value. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a substitute tea made from immature walnuts and its preparation method. This method is simple and easy to implement, and the resulting immature walnut substitute tea achieves the following qualities: "the dried fruit is of regular shape, yellowish-brown or dark brown and oily, the tea liquor is bright orange-yellow or orange-red, with a rich medicinal and woody aroma, a sweet and mellow taste, and a slightly sour flavor." The product has distinct characteristics and enhances the economic value of walnuts.

[0005] To solve the above problems, the technical solution adopted in this application is as follows:

[0006] A substitute tea for immature walnuts and its preparation method include the steps of raw material picking, washing, peeling, initial drying, steaming, re-drying, and multiple steaming and drying processes. The specific steps include:

[0007] (1) Raw material pretreatment: Immature green-skinned walnuts harvested 30 to 150 days after flowering are cleaned and then steamed under high pressure to remove the skin;

[0008] (2) Dry the peeled walnuts at 60-120℃ for 2-6 hours;

[0009] (3) Steam the walnuts after initial baking for 10 to 480 minutes;

[0010] (4) After steaming, bake the walnuts again at 60-100℃ for 2-6 hours until the moisture content is 8%-13%;

[0011] (5) Repeat steps (3) and (4) 1 to 9 times to obtain immature walnut substitute tea.

[0012] After further optimization, immature green-skinned walnuts aged 60-120 days are selected as raw materials, resulting in even better quality.

[0013] The initial drying and subsequent drying can be any one of hot air drying, heat transfer drying (drum drying), microwave drying, freeze drying, or vacuum drying. After further optimization, hot air drying produces better quality.

[0014] After further optimization, the moisture content of the finished product after initial drying is between 50% and 70%.

[0015] After further optimization, the steaming time is 10-60 minutes, resulting in even better quality.

[0016] After further optimization, multiple steaming and drying processes, 1 to 4 times, result in even better quality.

[0017] Compared with the traditional method of simply drying (40℃~160℃) to process substitute tea products, the immature walnut substitute tea and its preparation method provided in this application have the following significant beneficial effects:

[0018] (1) The process of this application accelerates the drying rate of immature walnut substitute tea. The steaming process removes some moisture through steam, and the high humidity and strong heat penetration promote rapid heating inside the walnut, increase water activity, and help open some moisture channels on the surface of the walnut shell, thus significantly improving the drying rate.

[0019] (2) The process described in this application reduces the leakage rate during processing. Using a pre-drying temperature of 60~120℃ can significantly reduce the leakage rate in subsequent walnut processing, retain more nutrients, and lay the foundation for the development of aroma and flavor.

[0020] (3) The process of this application improves the aroma and taste quality of immature walnut substitute tea. The steaming process brings high temperature and high humidity inside the walnut shell. Combined with the baking process after steaming, it promotes the transformation of the septum and seed coat components of the walnut, develops aroma substances, and promotes the transformation of the aroma of immature walnut substitute tea from woody aroma to medicinal aroma. In terms of taste, it is conducive to the transformation of bitter and astringent substances and the generation of sweet substances, effectively reducing the bitterness and sourness of the substitute tea and enhancing the sweetness.

[0021] (4) The process parameters of this application are controllable and simple to operate. The quality of the immature walnut substitute tea prepared is stable. Compared with the walnut substitute tea prepared by simple drying, the quality is significantly improved, the aroma is richer and more abundant, the acidity is lower, and the sweetness is higher. Detailed Implementation

[0022] The present application will be further described below with reference to specific embodiments and comparative examples. Unless otherwise specified, the technical solutions described in this application are conventional solutions in the art, and the reagents or materials described are all from commercial sources unless otherwise specified.

[0023] Example 1

[0024] An immature walnut substitute tea and its preparation method, comprising the following steps:

[0025] (1) Raw material pretreatment: Immature green-skinned walnuts harvested 30 to 150 days after flowering are cleaned and then steamed under high pressure to remove the skin;

[0026] (2) Dry the peeled walnuts at 60-120℃ for 2-6 hours;

[0027] (3) Steam the walnuts after initial baking for 10 to 480 minutes;

[0028] (4) After steaming, bake the walnuts again at 60-100℃ for 2-6 hours until the moisture content is 8%-13%;

[0029] (5) Repeat steps (3) and (4) 1 to 9 times to obtain immature walnut substitute tea.

[0030] Examples 2-5 and Comparative Example 1

[0031] An immature walnut substitute tea and its preparation method are described below. The specific steps are based on Example 1, except for step (5). The effects of raw material maturity on the quality of the immature walnut substitute tea are compared. The parameters of the examples and comparative examples are shown in Table 1 below.

[0032] Table 1. Sample Raw Material Harvesting Period Parameter Setting Table

[0033] sample Harvesting season Example 2 Raw materials 30-60 days after flowering Example 3 Raw materials 60-90 days after flowering Example 4 Raw materials 90-120 days after flowering Example 5 Raw materials 120-150 days after flowering Comparative Example 1 Raw materials 150-180 days after flowering

[0034] Characterization:

[0035] 1. Sensory Evaluation: Referring to the national standard GB / T23776-2018 "Sensory Evaluation Method for Tea", the walnut substitute tea was evaluated in terms of appearance, liquor color, aroma, and taste. The total score was 100 points, which was a weighted score of appearance, liquor color, aroma, and taste, with appearance accounting for 20%, liquor color for 10%, aroma for 30%, and taste for 40%. The sensory evaluation panel consisted of 5 experts who were qualified tea tasters or had intermediate or higher professional titles in the industry.

[0036] 2. Processing Leakage Description Table: This table scores the amount of product leaching during processing.

[0037] Fraction grade Judgment criteria 5 points No exudate During the drying process, the container, such as a tray, should not have any discolored patches formed by any seepage after drying, and the walnuts should not stick to the container. 4 points Lighter During the drying process, the container such as the tray may have a small amount of oozing liquid forming colored patches on its surface after drying. The walnuts do not stick to the container or only slightly stick. 3 points medium During the drying process, containers such as trays may have discolored patches formed by the seepage of liquid on their surfaces after drying. Walnuts may stick to the containers, but they can be easily removed by shaking the tray. 2 points serious During the drying process, containers such as trays often have discolored patches on their surfaces due to the seepage of liquid. The walnuts stick to the containers and can only be removed by gently prying them off. 1 point Extremely serious During the drying process, containers such as trays often develop discolored patches on their surfaces after drying due to the large amount of exudate. The walnuts stick to the containers and can only be removed by force.

[0038] 3. Total Phenolic Content: The total polyphenol content was determined according to the Folin-Ciocalteu reagent colorimetric method in GB / T44349-2024. Extraction Preparation: Weigh 1.000g ± 0.005g of the ground sample powder into a 50ml capped centrifuge tube using an electronic balance. Add 20mL of 75% ethanol solution, mix thoroughly, and sonicate in an ultrasonic cleaner for 40 minutes at 180W power and a water bath temperature of 50℃. Cool to room temperature and centrifuge at 4000 rpm for 10 minutes. Transfer all supernatant to a 50mL volumetric flask, dilute to the mark with 75% ethanol solution, and mix well. A standard curve was plotted using gallic acid standard solution at concentrations of 0.01 ~ 0.1 mg / mL. Take 0.2 mL of standard solution into a 10 mL volumetric flask, add 0.5 mL of 1M Folin-Ciocalteu reagent and 1.5 mL of 10% Na₂CO₃ solution, and bring the volume to 10 mL with distilled water. Mix well and react in the dark for 20 minutes. Measure the absorbance at 765 nm. Use an appropriate amount of extract solution instead of the standard solution for the determination (the total phenol content per gram of sample is equivalent to milligrams of gallic acid, mg gallic acid / g).

[0039] 4. Total flavonoid content was determined using the aluminum chloride colorimetric method. A 0.5 mg / mL rutin standard solution was prepared using 70% ethanol. 0–1.0 mL of the standard solution was taken and diluted to 4 mL with distilled water. Then, 0.3 mL of 5% sodium nitrite solution was added sequentially (allowed to stand for 5 minutes), 0.3 mL of 10% aluminum chloride solution was allowed to stand for 6 minutes, and 2 mL of 1 mol / L sodium hydroxide solution was added. The final volume was diluted to 10 mL, and after 10 minutes of color development, the A510 value was measured to obtain the standard curve. An appropriate amount of extract was used instead of the standard solution for determination (the total flavonoid content per gram of sample is equivalent to the number of milligrams of rutin, mg rutin / g).

[0040] 5. DPPH Free Radical Scavenging Assay: Prepare a 0.1 mM DPPH solution: Place 0.002 g of DPPH in a brown volumetric flask, dilute to the mark with 10 mL of ethanol, and dissolve by sonication as needed. Dilute 2 mL of the DPPH ethanol solution to a 10 mL brown volumetric flask, dilute to the mark, and store in the dark. Prepare a 0.1 mg / mL vitamin C solution as a positive control. Sample Solution Processing: Weigh 1 g of dried sample and extract with 75% ethanol. Extract at 50℃ and 100W with sonication for 40 minutes. Centrifuge the filtrate at 8000 rpm for 10 minutes, collect the supernatant, and repeat the extraction once more with a small amount of 75% ethanol. Combine the supernatants, dilute to 50 mL, and mix well. Add 3 mL of sample solution to 3 mL of 0.1 mM DPPH ethanol solution, mix well, and react in the dark at room temperature for 30 minutes. Measure the absorbance (A1) at 517 nm. The assay was performed in triplicate, with Vc serving as a positive control. A0 and A2 were the absorbance values ​​of equal volumes of distilled water replacing the sample solution and DPPH ethanol solution, respectively. The DPPH free radical scavenging rate was calculated using the formula.

[0041] Table 2. Sensory evaluation and exudate analysis of immature walnut substitute tea prepared from raw materials of different maturity levels.

[0042] sample Appearance (20%) Soup color (10%) Aroma (30%) Flavor (40%) Total Score Exudate situation Example 2 Relatively intact, relatively uniform, reddish-brown and oily sheen 88.5 Bright orange-yellow 92.5 Medicinal Fragrance 90.3 Sour and bitter 79.0 85.6 2 Example 3 Complete, relatively uniform, dark brown and oily. 90.0 Bright orange-yellow 92.3 Medicinal Fragrance 90.5 Sour, slightly bitter. 82.0 87.2 4 Example 4 Intact, relatively uniform, with slight cracks, dark brown and somewhat oily. 87.5 Bright orange-yellow 92.3 Medicinal Fragrance 90.5 Slightly sour, slightly bitter. 83.0 87.1 4 Example 5 Complete, uniform, yellowish-brown, and somewhat oily. 85.5 Bright orange-yellow 92.4 Medicinal and woody aromas: 89.5 Slightly acidic, slightly bland. 82.5 86.2 3 Comparative Example 1 Whole, uniform, yellowish-brown, slightly dried, with kernel 83.0 Yellowish, slightly dark, 89.0 The woody scent is weak (85.0). Bland 80.0 83.0 3

[0043] Table 3. Evaluation of Functional Components of Immature Walnut Substitute Tea Prepared from Raw Materials of Different Maturity Levels

[0044] sample Total phenolic content (mg gallic acid / g) Total flavonoid content (mg rutin / g) DPPH free radical scavenging rate (%) Water extract content (%) Example 2 78 63 95 39 Example 3 73 57 93 38 Example 4 62 49 91 31 Example 5 53 37 92 23 Comparative Example 1 45 27 84 14

[0045] Analysis of the data in Tables 1, 2, and 3 above shows that this application used immature walnuts (30-180 days after flowering) as raw materials for comparison, and further optimized them to use raw materials aged 60-120 days. After processing, these raw materials exhibited good sensory evaluation scores (all greater than 85 points), intact appearance, good aroma and taste, less exudate during processing, and greater retention of functional components. Furthermore, the tea substitute product possesses good antioxidant properties, making it suitable for commercialization.

[0046] Example 2 uses raw materials with a maturity of 30-60 days, which are too brittle and tender, with small whole fruits, relatively high cost, poor appearance integrity, and more exudate during processing. The content and leaching rate of substances such as polyphenols and flavonoids are the highest, resulting in a high degree of bitterness in the tea soup. This is difficult to significantly improve in the process of Example 1, so it is not suitable for processing substitute tea.

[0047] Example 5 uses raw materials with a maturity of 120-150 days. Although the tea has a uniform appearance, the tea soup tastes slightly bland, and the content of polyphenols, flavonoids, etc. is low, as is the content of water extract. The finished product lacks flavor complexity.

[0048] Comparative Example 1 uses raw materials with a maturity of 150-180 days. If the maturity is too high, the walnut kernels inside are fully formed, the appearance lacks luster, is slightly dry, the soup color is poor, the aroma is weak, and the taste is bland, making it unsuitable for commercialization.

[0049] Example 6 and Comparative Examples 2-15

[0050] An immature walnut substitute tea and its preparation method are described, with no step (5) in the specific steps of Example 1. The drying method, initial drying temperature, and moisture content of the finished product after initial drying were adjusted to compare the effects of the initial drying process on the quality of the immature walnut substitute tea. The specific parameter settings for the examples and comparative examples are shown in Table 4.

[0051] Table 4 Initial Drying Process Parameter Setting Table

[0052] sample Initial drying temperature (°C) Moisture content (%) after initial drying Steaming time (minutes) Re-drying temperature (°C) Comparative Example 2 40 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 3 60 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 4 80 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 5 100 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 6 120 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 7 140 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 8 160 (Hot air drying) 8~13 No steaming No re-baking Comparative Example 9 -35~60 (freeze-dried) 8~13 No steaming No re-baking Comparative Example 10 80 (drum-cooked) 8~13 No steaming No re-baking Comparative Example 11 80 (microwave drying) 8~13 No steaming No re-baking Comparative Example 12 80 (vacuum + hot air drying) 8~13 No steaming No re-baking Comparative Example 13 80 (Hot air drying) 80 60 80 Example 6 80 (Hot air drying) 60 60 80 Comparative Example 14 80 (Hot air drying) 40 60 80 Comparative Example 15 80 (Hot air drying) 20 60 80

[0053] Table 5. Drying time and exudate levels during processing of immature walnut substitute tea prepared using different initial drying processes.

[0054] sample Example 6 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 Comparative Example 15 Exudate situation 4 4 3 3 2 2 1 1 5 3 3 2 3 5 5 Drying time (hours) 6.5 168 120 18 9 7 6 5.5 96 16 9.5 6 7 6.5 6.5

[0055] Table 6. Sensory evaluation of immature walnut substitute tea prepared by different initial drying processes.

[0056] sample Appearance (20%) Soup color (10%) Aroma (30%) Flavor (40%) Total Score Exudate situation Example 6 Complete, relatively uniform, dark brown and somewhat oily. 89.0 Bright orange-yellow 92.0 Medicinal Fragrance 92.0 Slightly acidic, with a pleasantly sweet and mellow flavor (91.5%). 91.2 4 Comparative Example 2 Complete, uniform, yellowish-brown and somewhat withered. 83.0 Huang Mingliang 90.3 Woody fragrance, weak (83.0) Slightly sour, bland 81.5 83.1 4 Comparative Example 3 Intact, relatively uniform, slightly withered yellowish-brown. 85.0 The orange-yellow color is brighter (89). Woody scent 85.0 Slightly acidic and bitter. 83.0 84.6 3 Comparative Example 4 Complete, relatively uniform, yellowish-brown and somewhat oily. 89.0 Bright orange-yellow 91.0 Woody scent with a slight medicinal aroma. 88.5 Slightly sour, slightly bitter. 83.5 86.9 3 Comparative Example 5 Complete, relatively uniform, dark brown and somewhat oily. 88.0 Bright orange-yellow 91.5 Woody scent with a slight medicinal aroma. 88.0 Slightly sour, somewhat bitter, slightly overcooked (81.0g) 85.5 2 Comparative Example 6 Complete, relatively uniform, dark brown and somewhat oily. 88.5 Bright orange-red (90.0) Slightly higher fire 83.0 Slightly sour and bitter, cooked on high heat (80°F). 83.6 2 Comparative Example 7 Complete, relatively uniform, grayish-black with a slightly oily sheen. 80.0 Slightly turbid orange-red: 85.0 Slightly burnt on high heat (80.0) Burnt, acid concentration 79.0 80.1 1 Comparative Example 8 Complete, relatively uniform, grayish-black, slightly withered. 79.0 Reddish-brown and cloudy, 80.0 Burnt 79.0 Burnt, sour and astringent. 75.0 77.5 1 Comparative Example 9 Complete, uniform, grayish-white and somewhat withered. 82.0 Huang, Shangming 87.0 Woody fragrance, weak (82.0) Slightly sour, bitter, and slightly astringent. 82.5 82.7 5 Comparative Example 10 Complete, uniform, dark brown and oily. 89.5 Bright orange-yellow 90.0 Woody scent, with a medicinal aroma 89.5 Slightly sour, somewhat bitter. 82.0 86.6 3 Comparative Example 11 Complete, uniform, slightly withered yellowish-brown. 87.0 Bright orange-yellow 91.0 The woody scent is weak (84.0). Slightly sour and bitter. 80.5 83.9 3 Comparative Example 12 Intact but somewhat shriveled, uniform, yellowish-brown and somewhat oily. 88.5 Bright orange-yellow 91.5 Woody scent with a slight medicinal aroma. 88.0 Slightly sour, slightly bitter. 83.5 86.7 2 Comparative Example 13 Complete, relatively uniform, dark brown and somewhat oily. 89.3 Bright orange-yellow 92.3 Medicinal Fragrance 91.0 Slightly sour, still sweet 90.0 90.4 3 Comparative Example 14 Complete, relatively uniform, dark brown with a slightly oily sheen. 87.0 Bright orange-yellow 92.1 Medicinal Fragrance 91.3 Slightly sour, moderately sweet, slightly bitter. 89.0 89.6 5 Comparative Example 15 Complete, relatively uniform, dark brown with slight dryness. 83.0 Bright orange-red 91.0 Medicinal Fragrance 91.5 Slightly sour, moderately sweet, slightly bitter. 88.5 88.6 5

[0057] Analysis of Tables 5 and 6 above shows that,

[0058] The immature walnut substitute tea prepared in Example 6 has a high oiliness, a brighter liquor color, a purer aroma, and a more prominent and harmonious sweetness. At the same time, it significantly reduces the drying rate and increases the yield.

[0059] Comparative Example 2 used a one-step drying process at 40℃, which took too long. The resulting immature walnut substitute tea had a weak aroma and bland taste, making it unsuitable for commercialization.

[0060] Comparative Examples 3-6 were dried in one step at 60℃~120℃, with the processing time gradually shortened. The resulting immature walnut substitute tea had an impure medicinal aroma and a distinctly bitter taste, making it unsuitable for commercialization.

[0061] Comparative Examples 7 and 8 were dried in one step at 140℃ to 160℃. The resulting immature walnut substitute tea had poor color and a noticeable burnt taste, making it unsuitable for commercialization.

[0062] Comparative Example 9 used freeze drying, which had a long drying time and high cost. The resulting immature walnut substitute tea had a high bitterness and was not suitable for commercialization.

[0063] Comparative Example 10, which uses drum drying, produced immature walnut substitute tea with a better aroma but higher bitterness, which was weaker than that produced by hot air drying.

[0064] Comparative Example 11 used microwave drying, but the process resulted in severe exudation, and the prepared immature walnut substitute tea had a high degree of bitterness and was not suitable for commercialization.

[0065] Comparative Example 12 used vacuum + hot air drying. The quality of the immature walnut substitute tea prepared was similar to that of hot air drying, but the cost was high and the exudate during the processing was severe.

[0066] Comparative Examples 13-15 and Example 3 were modified by adding a steaming process, resulting in immature walnut substitute tea with a pure medicinal aroma and a prominent sweetness.

[0067] Comparative Example 13 showed significant effusion during processing, and the walnuts were prone to sticking to the drying equipment, making it unsuitable for production.

[0068] The immature walnut substitute tea prepared in Comparative Example 14 lacked sufficient oiliness and still had a bitter taste, making it unsuitable for commercialization.

[0069] The immature walnut substitute tea prepared in Comparative Example 15 had a lower oiliness and also had a bitter taste, making it unsuitable for commercialization.

[0070] Examples 7-13 and Comparative Example 16

[0071] A substitute tea for immature walnuts and its preparation method are described. The specific steps are based on Example 1, except for step (5). The effect of steaming time on the quality of walnut tea is compared. The specific parameter settings for the examples and comparative examples are shown in Table 7.

[0072] Table 7 Steaming Time Parameter Setting Table

[0073] sample Initial drying temperature (°C) Moisture content (%) after initial drying Steaming time (minutes) Re-drying temperature (°C) Comparative Example 16 80 60 No steaming 80 Example 7 80 60 10 80 Example 8 80 60 20 80 Example 9 80 60 30 80 Example 10 80 60 60 80 Example 11 80 60 120 80 Example 12 80 60 240 80 Example 13 80 60 480 80

[0074] Table 8. Sensory evaluation table of walnut substitute tea prepared by different steaming times.

[0075] sample Appearance (20%) Soup color (10%) Aroma (30%) Flavor (40%) Total Score Exudate situation Comparative Example 16 Complete, relatively uniform, dark brown and somewhat oily. 88.5 Bright orange-yellow 90.0 Woody scent with a slight medicinal aroma. 88.0 Slightly sour, slightly bitter. 83.0 86.3 4 Example 7 Complete, relatively uniform, dark brown and somewhat oily. 88.0 Bright orange-yellow 92.0 Medicinal Fragrance 90.5 Slightly acidic, fairly sweet and mellow. 90.0 90.0 4 Example 8 Complete, relatively uniform, dark brown and somewhat oily. 89.3 Bright orange-yellow 92.5 Medicinal Fragrance 90.3 Slightly acidic, with a pleasantly sweet and mellow flavor (92.0%). 91.0 4 Example 9 Complete, relatively uniform, dark brown and somewhat oily. 89.5 Bright orange-yellow 91.5 Medicinal Fragrance 90.0 Slightly acidic, with a pleasantly sweet and mellow flavor (92.0%). 90.8 4 Example 10 Complete, relatively uniform, dark brown and somewhat oily. 89.0 Bright orange-yellow 92.0 Medicinal Fragrance 92.0 Slightly acidic, with a pleasantly sweet and mellow flavor (91.5%). 91.2 4 Example 11 Complete, relatively uniform, dark brown and somewhat oily. 89.0 Bright orange-yellow 90.3 It has a medicinal fragrance. (88.0) Sweet and mellow, slightly bland. 88 88.4 4 Example 12 Complete, relatively uniform, dark brown and somewhat oily. 89.0 Bright orange-yellow 90.5 It has a medicinal fragrance. (88.0) Sweet and mellow, but rather bland (87.5) 88.3 4 Example 13 Complete, relatively uniform, dark brown and somewhat oily. 88.5 Huang Mingliang 89.5 Slight medicinal fragrance 85.5 Sweet and mellow, bland 87.0 87.1 4

[0076] Analysis of Table 8 above shows that,

[0077] Examples 7-10, which involve steaming for 10-60 minutes, produce immature walnut substitute tea with excellent sensory evaluation scores. The acidity is reduced and sweetness is added, the aroma intensity is moderate, and the overall taste is more harmonious.

[0078] Examples 11-13 involve steaming for 120-480 minutes. The long steaming time results in a light-colored tea soup with a low aroma intensity and a relatively bland taste, making it unsuitable for commercialization.

[0079] Comparative Example 16, which was not steamed, produced an immature walnut substitute tea with a weak medicinal aroma and a bitter taste, making it unsuitable for commercialization.

[0080] Examples 14-16 and Comparative Examples 17-18

[0081] A substitute tea for immature walnuts and its preparation method are described. The specific steps are based on Example 1, except for step (5). The effect of re-drying temperature on the quality of walnut tea is compared. The specific parameter settings of the examples and comparative examples are shown in Table 9.

[0082] Table 9. Parameter settings for different drying temperatures

[0083] sample Initial drying (°C) Moisture content (%) after initial drying Steaming time (minutes) Re-drying temperature (°C) Comparative Example 17 80 60 60 40 Example 14 80 60 60 60 Example 15 80 60 60 80 Example 16 80 60 60 100 Comparative Example 18 80 60 60 120

[0084] Table 10 Sensory Evaluation Table of Walnut Substitute Tea Prepared at Different Re-drying Temperatures

[0085] sample Appearance (20%) Soup color (10%) Aroma (30%) Flavor (40%) Total Score Leachate condition Comparative Example 17 Complete, relatively uniform, dark brown and somewhat oily. 88.3 Bright orange-yellow 92.0 It has a medicinal fragrance. (89.0) Slightly sour, slightly sweet. 89.0 89.2 4 Example 14 Complete, relatively uniform, dark brown and somewhat oily. 88.7 Bright orange-yellow 92.3 Medicinal Fragrance 90.0 Slightly acidic, with a pleasantly sweet and mellow flavor. 93.0 91.2 4 Example 15 Complete, relatively uniform, dark brown and somewhat oily. 89.3 Bright orange-yellow 92.5 Medicinal Fragrance 90.3 Slightly acidic, with a pleasantly sweet and mellow flavor. 93.0 91.4 4 Example 16 Complete, relatively uniform, dark brown and somewhat oily. 88.0 Bright orange-yellow 91.0 The medicinal aroma is quite strong (92). Slightly sour, slightly sweet, slightly bitter, with a slightly spicy flavor. 89.7 90.2 4 Comparative Example 18 Complete, relatively uniform, dark brown with slight dryness. 87.0 Bright orange-yellow 90.0 Herbal aroma, slightly high heat 87.0 Slightly sour, slightly sweet, rather bitter, with a slightly spicy flavor. 85.0 86.5 4

[0086] Analysis of Table 10 above shows that,

[0087] Examples 14-16, prepared by re-drying at 60-100℃, yielded immature walnut substitute tea with generally high sensory evaluation and good quality, making them suitable for commercialization.

[0088] Comparative Example 17: The re-drying temperature was low and the processing time was long, resulting in a weaker sweetness and slightly inferior taste and quality of the immature walnut substitute tea.

[0089] Comparative Example 18: The re-drying temperature was too high, resulting in a stronger bitter taste and a more significant reduction in appearance and quality of the unripe walnut substitute tea.

[0090] Examples 17-22

[0091] An immature walnut substitute tea and its preparation method are described. Referring to the steps in Example 1, the tea is steamed and dried 1-9 times, and the steaming time is adjusted for each of the 9 steaming and drying processes. The effects of multiple steaming and drying processes on the quality of the walnut tea are compared. The parameter settings for the examples and comparative examples are shown in Table 11.

[0092] Table 11 Parameter Setting Table for Multiple Steaming and Drying Process

[0093] sample Initial drying (°C) Moisture content (%) after initial drying Steaming time (minutes) Re-drying temperature (°C) Number of steaming and drying cycles Example 17 80 60 20 80 1 Example 18 80 60 20 80 4 Example 19 80 60 20 80 9 Example 20 80 60 60 80 9 Example 21 80 60 240 80 9 Example 22 80 60 480 80 9

[0094] Table 12 Sensory Evaluation Table of Walnut Substitute Tea Prepared Through Multiple Steaming and Drying Processes

[0095] sample Appearance (20%) Soup color (10%) Aroma (30%) Flavor (40%) Total Score Leachate condition Example 17 Complete, relatively uniform, dark brown and somewhat oily. 89.3 Bright orange-yellow 92.5 Medicinal Fragrance 90.3 Slightly acidic, with a pleasantly sweet and mellow flavor. 92.0 91.0 4 Example 18 Complete, relatively uniform, dark brown and somewhat oily. 89.5 Bright orange-yellow 92.0 Medicinal Fragrance 91.5 Sweet and mellow, slightly concentrated (93.5%) 92.0 4 Example 19 Complete, relatively uniform, dark brown and oily. 90.0 The orange-red color is slightly dark, 85.0. It has a slight medicinal aroma and is cooked at a slightly higher temperature (86.5). Sweet and mellow, but with an off-flavor, 85.0 86.5 5 Example 20 Complete, relatively uniform, dark brown and somewhat oily. 89.0 Bright orange-red 91.0 Medicinal Fragrance 90.0 Shangtianchun 91.5 90.5 5 Example 21 Complete, relatively uniform, dark brown and oily. 89.5 Bright orange-yellow 91.5 It has a medicinal fragrance. (88.5) Sweet and mellow, bland 89.0 89.2 5 Example 22 Complete, relatively uniform, dark brown and oily. 89.0 Huang Mingliang 91.5 It has a medicinal fragrance. (88.5) Sweet and mellow, bland 89.0 89.1 5

[0096] The analysis in Table 12 above shows that:

[0097] Example 17: Steaming and drying once for 20 minutes resulted in an immature walnut substitute tea with a harmonious aroma and taste, slightly lower oiliness in appearance, and higher overall quality.

[0098] Example 18 involved steaming and drying the tea four times for 20 minutes each time. This extended processing time resulted in improved aroma and taste scores for the prepared immature walnut substitute tea, indicating higher quality.

[0099] Example 19: Steaming and drying 9 times for 20 minutes each time resulted in an improved oiliness in the appearance of the immature walnut substitute tea, but the soup color and aroma were poor, and the taste had an off-flavor, making it unsuitable for commercialization.

[0100] Examples 20-22 involved steaming and drying nine times for 60-480 minutes, resulting in immature walnut substitute tea with a high degree of oiliness in appearance. While the appearance quality improved significantly with prolonged steaming time, the aroma and flavor noticeably decreased, and the overall flavor remained inconsistent, making it unsuitable for commercial production.

[0101] In summary, the advantages of the immature walnut substitute tea and its preparation method provided in this application are summarized as follows:

[0102] (1) This application further optimizes the raw material of green walnuts that are 30 to 180 days after flowering to a raw material that is 60 to 120 days old. The immature walnut substitute tea prepared has a good sensory evaluation score, complete appearance, good aroma and taste, less exudate during processing, more functional components are retained, and it has good antioxidant function, making it suitable for product commercialization.

[0103] (2) The optimized primary and secondary drying processes make the immature walnut substitute tea more oily, brighter in color, purer in aroma, stronger in medicinal aroma, sweeter and more mellow in taste, and more harmonious in flavor. At the same time, the drying rate is significantly reduced and the yield is increased.

[0104] (3) The optimized steaming process makes the aroma and medicinal fragrance of the immature walnut substitute tea more pure and rich, reduces the acidity and adds sweetness, and makes the overall taste more harmonious.

[0105] (4) Through multiple steaming and drying processes, the aroma of immature walnut substitute tea is enhanced, the flavor concentration is increased, and the acidity is reduced.

[0106] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0107] Finally, it should be noted that the above embodiments do not limit this application in any way. Those skilled in the art can make modifications and improvements based on this application. Therefore, any modifications or improvements made without departing from the spirit of this application are within the scope of protection claimed in this application.

Claims

1. A method for preparing an immature walnut substitute tea, characterized in that, Includes the following steps: (1) Raw material pretreatment: Immature green-skinned walnuts harvested 30 to 150 days after flowering are cleaned and then steamed under high pressure to remove the skin; (2) Dry the peeled walnuts at 60-120℃ for 2-6 hours; (3) Steam the walnuts after initial baking for 10 to 480 minutes; (4) After steaming, bake the walnuts again at 60-100℃ for 2-6 hours until the moisture content is 8%-13%; (5) Repeat steps (3) and (4) 1 to 9 times to obtain immature walnut substitute tea.

2. The method for preparing immature walnut substitute tea according to claim 1, characterized in that, After further optimization of the raw material pretreatment, immature green-skinned walnuts aged 60-120 days are selected, resulting in better quality.

3. The method for preparing immature walnut substitute tea according to claim 1, characterized in that, The initial drying and subsequent drying can be any one of hot air drying, heat transfer drying (drum drying), microwave drying, freeze drying, or vacuum drying. After further optimization, hot air drying produces even better quality.

4. The method for preparing immature walnut substitute tea according to claim 1, characterized in that, The initial drying time is 2 to 6 hours. After further optimization, the moisture content of the finished product is 50% to 70%.

5. The method for preparing immature walnut substitute tea according to claim 1, characterized in that, The steaming process involves steaming for 10 to 480 minutes, and after further optimization, steaming for 10 to 60 minutes yields even better quality.

6. The method for preparing immature walnut substitute tea according to claim 1, characterized in that, The multiple steaming and drying processes can be performed 1 to 9 times. After further optimization, performing 1 to 4 times will result in better quality.

7. An immature walnut substitute tea prepared according to any one of claims 1 to 6, characterized in that: Its dried fruit has a regular shape, is yellowish-brown or dark brown and oily, and has a bright orange-yellow soup with a medicinal and woody aroma. It tastes sweet and mellow with a slight sourness and a harmonious flavor.