Oolong wheat tea and preparation method thereof

Abstract

The invention discloses oolong wheat tea and a preparation method thereof, and belongs to the technical field of wheat tea processing. According to the technical scheme, the oolong wheat tea is prepared by blending barley extract liquor and oolong tea extract liquor. The barley fragrance index of the barley extract is greater than 0.1 and less than 0.9; the wheat aroma index is calculated according to the following formula: wheat aroma index = (2-acetylpyrrole + 2-ethylpyrazine + dimethylpyrazine + methylpyrazine) / (5-methylfurfural + 2-acetylfuran + furfural); the tea aroma index of the tea leaves for preparing the oolong tea extract liquor is greater than 2.5; the tea aroma index is calculated according to the following formula: tea aroma index = A / B; the total flower fragrance A is linalool, geraniol, cis-jasmonone, jasmonlactone, nerolidol, methyl jasmonate and indole; the total odor amount B is equal to the sum of cis-2, 4-heptadienal, trans-2, 4-heptadienal and indole. The method is applied to processing of oolong wheat tea, and the problems that the oolong wheat tea is not harmonious in fragrance, poor in palatability and prone to precipitation are solved.

Description

Technical Field

[0001] This invention belongs to the field of barley tea processing technology, and particularly relates to an oolong barley tea and its preparation method. Background Technology

[0002] Barley (Hordeum vulgare L.) is one of the earliest grains cultivated by humans. In the food industry, it is mainly used for brewing and producing non-alcoholic beverages (such as coffee substitutes and so-called roasted barley tea). The latter is a popular drink in Northeast Asian countries. In Japan, roasted barley tea is called "mugi-cha." Traditionally, it is made by extracting whole roasted barley grains with hot water; today, bottled, chilled barley tea-related drinks are a popular thirst-quenching beverage in the summer.

[0003] Barley varieties are divided into two-row barley and six-row barley. Two-row barley has a lower protein content than six-row barley and is mainly used for brewing; six-row barley can be used to produce roasted barley tea. Varieties used for making roasted barley tea include hulled barley and hullless barley (commonly known as naked barley). Current research focuses only on the aroma components of roasted barley grains themselves, rather than the beverages made from them. Studies have shown that roasted barley aroma components include more than 50 components such as alcohols, phenols, carbonyl compounds, acids, lactones, heterocyclic compounds, and organosulfur compounds. However, while high levels of volatile components may have little impact on the aroma of specific foods, potent trace amounts of volatile components can significantly affect overall sensory characteristics. Therefore, determining the key aroma indicators of roasted barley tea is crucial for its development and formulation. The typical aroma of oolong tea is floral and fruity, and its aroma is actually a mixture of various volatile flavor compounds. Oolong tea contains relatively few volatile flavor compounds, including indole, jasmine lactone, and trans-nerolidol.

[0004] The production process of oolong barley tea mainly involves two parts: barley extraction and quality evaluation. Simply put, roasted barley and oolong tea are extracted using hot water with the aid of ultrasonic and microwave processes, followed by filtration to obtain their respective extracts, which are then blended to create oolong barley tea. While some patents describe methods for preparing barley tea or oolong tea beverages, production processes for oolong barley tea are extremely rare. Furthermore, the numerous raw materials involved in oolong barley tea increase the uncertainty of its extraction process, resulting in significant fluctuations in taste and aroma, thus reducing the overall drinkability of the barley tea. Therefore, there are currently almost no reports in China regarding the production process and product evaluation standards for oolong barley tea.

[0005] The production challenges of oolong barley tea lie in two aspects. Firstly, the pronounced aroma of roasted barley easily masks the floral and fruity notes of the tea leaves. Secondly, simply increasing the proportion of tea leaves can negatively impact the beverage's taste. Beyond these flavor coordination issues, the biggest technical hurdle in developing oolong barley tea is the interaction between the proteins in barley and the polyphenols in oolong tea, forming insoluble complexes that lead to precipitation. This precipitation of proteins and polyphenols in tea beverages (commonly known as "tea cream" or "cold-induced cloudiness") is a core technical bottleneck restricting product shelf life and sensory quality. This precipitation not only affects the appearance of the beverage but can also lead to the loss of flavor compounds, severely limiting product stability and market acceptance. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is that the aroma of oolong barley tea is not harmonious, the palatability is poor, and it is prone to precipitation. The present invention proposes an oolong barley tea with harmonious aroma, good palatability and good stability and its preparation method.

[0007] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows: This invention provides an oolong barley tea, which is obtained by blending barley extract and oolong tea extract; The barley aroma index of the barley extract is greater than 0.1 and less than 0.9; the barley aroma index is calculated using the following formula: Wheat aroma index = (2-acetylpyrrole + 2-ethylpyrazine + dimethylpyrazine + methylpyrazine) / (5-methylfurfural + 2-acetylfuran + furfural); The tea leaves used to prepare oolong tea extract have an aroma index greater than 2.5; the aroma index is calculated using the following formula: Tea aroma index = A / B; Total floral fragrance A = linalool + geraniol + cis-jasmine + jasmine lactone + nerolidol + methyl jasmonate + indole Total odor amount B = cis-trans-2,4-heptadienal + trans-trans-2,4-heptadienal + indole.

[0008] In some embodiments, the ratio of barley extract to oolong tea extract is 1:4 to 4:1.

[0009] In another aspect, the present invention provides a method for preparing the above-mentioned oolong barley tea, wherein the barley extract is obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, wherein the weight ratio of roasted two-row barley, roasted six-row barley, and roasted malt is 8:1:1. Oolong tea extract is obtained by extracting premium grade oolong tea and premium grade narcissus tea, with a weight ratio of premium grade oolong tea to premium grade narcissus tea of ​​1:3-2:1.

[0010] In some embodiments, the preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt include a pretreatment step and a roasting step, wherein the pretreatment step includes: Two-row barley and six-row barley with a protein content of less than 13%, and barley malt with a protein content of less than 10% were selected as raw materials. They were repeatedly soaked in warm water at a temperature of 40-60℃ for 30-70 minutes. During the soaking process, ultrasonic treatment at 20-100 kHz was applied to obtain pretreated raw materials.

[0011] In some embodiments, the preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt further include a baking step, which includes: After drying the pretreated raw materials, bake them at 1000-2000 rpm for 35-70 minutes at a baking temperature of 150-230℃. During baking, pause every 5 minutes to cool down to below 100℃ with air cooling and add 0.1%-2% RO water, then reheat and bake to obtain roasted two-row barley, roasted six-row barley, and roasted malt.

[0012] In some embodiments, the roasted two-row barley and roasted six-row barley have a protein content of less than 0.5%, and the roasted malt has a protein content of less than 1%.

[0013] In some embodiments, roasted two-row barley should be selected with a color target value of 5-20 EBC, roasted malt should be selected with a color target value of 20-50 EBC, and roasted six-row barley should be selected with a color target value of 50-150 EBC.

[0014] In some embodiments, the barley extract is obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, comprising: Roasted two-row barley, roasted six-row barley, and roasted malt were added to RO water at a ratio of 1:5 to 1:25 for extraction. The extraction temperature was 80℃-98℃ and the extraction time was 30-90 minutes.

[0015] In some embodiments, the oolong tea extract is obtained by extracting premium oolong tea and premium narcissus tea, comprising: Premium oolong tea and premium narcissus tea were added to RO water at a ratio of 1:10 to 1:50 for extraction. The extraction temperature was 70℃-95℃ and the extraction time was 2-20 min. The tea polyphenol content of the extract was ≤1900 mg / L.

[0016] In some embodiments, the method further includes: before blending, filtering barley extract and oolong tea extract through a 1μ bag, blending them with excipients, mixing them evenly, filtering the blended liquid through a 1μ bag to obtain oolong barley tea clear liquid, the turbidity of the oolong barley tea clear liquid being ≤4.0 NTU, and then subjecting the oolong barley tea clear liquid to ultra-high temperature instantaneous sterilization and aseptic cold packaging to obtain finished oolong barley tea.

[0017] In some embodiments, the barley extract and oolong tea extract are further treated as follows before blending: After extraction, the solution was filtered through a drum sieve and cooled to room temperature. It was then filtered again through a 200-mesh bag filter, allowed to stand, filtered through a 25μ bag filter, and centrifuged to obtain the filtrate. The turbidity of the filtrate was ≤30.0 NTU.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an oolong barley tea, obtained by blending barley extract and oolong tea extract. The barley extract has a malt aroma index greater than 0.1 and less than 0.9, while the tea leaves used to prepare the oolong tea extract have a tea aroma index greater than 2.5. The barley extract with a malt aroma index greater than 0.1 and less than 0.9, when used to prepare the oolong barley tea, has a mild malt aroma that blends well with the oolong tea. The tea leaves with a tea aroma index greater than 2.5 are used as the raw material for extracting the oolong tea extract, resulting in an oolong barley tea with a harmonious malt aroma and a prominent tea aroma. This solves the problems of unharmonious aroma and poor palatability in oolong barley tea. Attached Figure Description

[0019] Figure 1 The color of roasted two-row barley, roasted malt, and roasted six-row barley obtained in Example 2 of the present invention. Detailed Implementation

[0020] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0021] This invention provides an oolong barley tea, which is obtained by blending barley extract and oolong tea extract; The barley aroma index of the barley extract is greater than 0.1 and less than 0.9; the barley aroma index is calculated using the following formula: Wheat aroma index = (2-acetylpyrrole + 2-ethylpyrazine + dimethylpyrazine + methylpyrazine) / (5-methylfurfural + 2-acetylfuran + furfural); The tea leaves used to prepare oolong tea extract have an aroma index greater than 2.5; the aroma index is calculated using the following formula: Tea aroma index = A / B; Total floral fragrance A = linalool + geraniol + cis-jasmine + jasmine lactone + nerolidol + methyl jasmonate + indole Total odor amount B = cis-trans-2,4-heptadienal + trans-trans-2,4-heptadienal + indole.

[0022] The aforementioned oolong barley tea is obtained by blending barley extract and oolong tea extract. The barley extract is specified to have a malt aroma index greater than 0.1 and less than 0.9, while the tea leaves used to prepare the oolong tea extract have a tea aroma index greater than 2.5. Specifically, the barley extract with a malt aroma index greater than 0.1 and less than 0.9 is used to prepare oolong barley tea, resulting in a less overpowering malt aroma that blends better with the oolong tea. The tea leaves with a tea aroma index greater than 2.5 are used as raw materials for extracting the oolong tea extract, which can be blended into an oolong barley tea with a harmonious malt aroma and a prominent tea aroma. After UHT sterilization and long-term preservation, it also has a rich floral and fruity aroma, thus solving the problems of unharmonious aroma and poor palatability of oolong barley tea.

[0023] In another aspect, the present invention provides a method for preparing the above-mentioned oolong barley tea, wherein the barley extract is obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, wherein the weight ratio of roasted two-row barley, roasted six-row barley, and roasted malt is 8:1:1.

[0024] The above technical solution limits the mass ratio of roasted two-row barley, roasted six-row barley, and roasted malt because: if the proportion of roasted two-row barley is too low, the β-glucan content in the product will be less than 70 mg / L, resulting in a bland taste; if the proportion of roasted six-row barley is too high, the protein content will be too high, and the protein will combine with tea polyphenols to form precipitates, affecting product stability; if the proportion of roasted malt is too low, the amino acid content in the product will be less than 50 mg / L, reducing the sweetness and significantly reducing the extraction rate, thus increasing product costs.

[0025] Oolong tea extract is obtained by extracting premium grade oolong tea and premium grade narcissus tea, with a weight ratio of premium grade oolong tea to premium grade narcissus tea of ​​1:3-2:1.

[0026] The above technical solution limits the quality ratio of premium oolong tea and premium narcissus tea because: if the proportion of premium narcissus tea is too low, the tea aroma will be weak and it will not have the orchid fragrance characteristic of oolong tea; if the proportion of narcissus tea is too low, the fruit aroma will be weak and the product will have a bland taste and lack the characteristics of tea.

[0027] In some embodiments, the preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt include a pretreatment step and a roasting step. The pretreatment step includes: selecting two-row barley and six-row barley with a protein content of less than 13%, and barley malt with a protein content of less than 10% as raw materials, repeatedly soaking them in warm water at a temperature of 40-60°C for 30-70 minutes; and subjecting the soaking process to ultrasonic-assisted treatment at 20-100 kHz to obtain the pretreated raw materials.

[0028] The protein in barley readily interacts with the polyphenols in oolong tea, forming insoluble complexes that precipitate. This protein-polyphenol precipitation problem in tea beverages (commonly known as "tea cream" or "cold-induced turbidity") is a core technical bottleneck restricting product shelf life and sensory quality. This precipitation not only affects the appearance of the beverage but may also lead to the loss of flavor compounds, severely limiting product stability and market acceptance. Therefore, preparing low-protein roasted barley and controlling protein content from the source has become a key breakthrough in solving this core problem, with particularly significant research value and practical implications, representing a current challenge in tea beverage preparation. The aforementioned technical solution, through a pretreatment step, facilitates the release and dissolution of proteins, thereby producing low-protein roasted barley.

[0029] In some embodiments, the preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt further include a baking step, which includes: drying the pretreated raw materials, baking at a speed of 1000-2000 rpm for 35-70 minutes, and baking at a temperature of 150-230°C; during baking, pausing every 5 minutes to cool down to below 100°C with air cooling, and adding 0.1%-2% RO water, and then reheating and baking to obtain roasted two-row barley, roasted six-row barley, and roasted malt.

[0030] In the above roasting steps, roasting at 1000-2000 rpm for 35-70 minutes at a temperature of 150-230℃ will allow the color of the roasted barley and malt to meet the set target values. Specifically, the target color value should be 5-20 EBC for roasted two-row barley, 20-50 EBC for roasted malt, and 50-150 EBC for roasted six-row barley. Increasing the roasting time or temperature will increase the color, resulting in a final extract that is too dark. Simultaneously, cooling during roasting is to prevent the raw materials from having a higher temperature on the outside and a lower temperature on the inside, thus avoiding scorching.

[0031] In some embodiments, the protein content of roasted two-row barley and roasted six-row barley is less than 0.5%, and the protein content of roasted malt is less than 1%. A high protein ratio would result in excessive free protein in the roasted barley extract, which would precipitate during the cooling stage after being mixed with oolong tea extract. Therefore, this technical solution further limits the protein content in roasted two-row barley, roasted six-row barley, and roasted malt.

[0032] In some embodiments, roasted two-row barley should have a target color value of 5-20 EBC, roasted malt should have a target color value of 20-50 EBC, and roasted six-row barley should have a target color value of 50-150 EBC. Low color value prevents the release of the barley's sweetness or richness; high color value can produce unpleasant roasting aromas (smoky, smoky, burnt) or astringent tastes.

[0033] In some embodiments, the barley extract is obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, including: adding roasted two-row barley, roasted six-row barley, and roasted malt to RO water at a ratio of 1:5 to 1:25 for extraction, with an extraction temperature of 80℃-98℃ and an extraction time of 30-90 min.

[0034] The above technical solution limits the barley extraction temperature to 80℃-98℃. At low temperatures, soluble components in roasted two-row barley cannot be fully dissolved, resulting in a significant reduction in the extraction rate. At the same time, it increases the content of undesirable flavor indicators of wheat, such as 5-methylfurfural, 2-acetylfuran, and furfural. At high temperatures, typical wheat flavor indicators such as 2-acetylpyrrole, 2-ethylpyrazine, dimethylpyrazine, and methylpyrazine will be lost.

[0035] In some embodiments, the oolong tea extract is obtained by extracting premium oolong tea and premium narcissus tea, including: adding premium oolong tea and premium narcissus tea to RO water at a ratio of 1:10 to 1:50 for extraction, with an extraction temperature of 70℃-95℃ and an extraction time of 2-20 min, and the tea polyphenol content of the extract being ≤1900 mg / L.

[0036] The above technical solution limits the extraction temperature of oolong tea to 70℃-95℃. At low temperatures, the extraction rate of oolong tea is greatly reduced, and the extract has a distinct grassy smell. At high temperatures, the tea aroma is greatly lost, while the content of tea polyphenols increases significantly, resulting in a bitter tea soup.

[0037] The above technical solution limits the extraction time of oolong tea to 2-20 min because: for oolong tea, shortening the extraction time will significantly reduce the tea extraction rate and increase the content of undesirable flavor indicators cis-trans-2,4-heptadienal and trans-trans-2,4-heptadienal; increasing the extraction time will reduce the content of tea aroma indicators linalool, geraniol, cis-jasmone, jasmine lactone, nerolidol, methyl jasmonate, and indole in oolong tea.

[0038] The above technical solution limits the content of tea polyphenols in the oolong tea extract to ≤1900 mg / L. The reason is that during the initial mixing of oolong tea extract and roasted barley extract in the blending process, a local "high phenol and high protein" situation may occur. Controlling the tea polyphenols in the initial extract can effectively reduce the generation of polyphenol-protein complexes and avoid precipitation.

[0039] It should be noted that some articles report that pulverizing oolong tea into powder facilitates the extraction of substances. In some embodiments, microwave-assisted extraction is used when extracting premium oolong tea and premium narcissus tea. Specifically, a certain amount of premium oolong tea (premium narcissus) and premium old-growth narcissus tea (1:3-2:1) are taken and added to RO water at a material-to-water ratio of 1:10-1:50 for extraction. The extraction temperature is 70-95℃, the extraction time is 2-20 minutes, and the microwave power is 100-700W. This invention adds microwave-assisted extraction, reduces the difficulty of filtration, and avoids the problem of excessive dissolution of tea polyphenols leading to a bitter filtrate.

[0040] In some embodiments, the method further includes: before blending, filtering barley extract and oolong tea extract through a 1μ bag, blending them with excipients, mixing them evenly, filtering the blended liquid through a 1μ bag to obtain oolong barley tea clear liquid, the turbidity of the oolong barley tea clear liquid being ≤4.0 NTU, and then subjecting the oolong barley tea clear liquid to ultra-high temperature instantaneous sterilization and aseptic cold packaging to obtain finished oolong barley tea.

[0041] In some embodiments, the barley extract and oolong tea extract are further subjected to the following treatments before blending: after extraction, they are filtered through a drum sieve and cooled to room temperature, then filtered again through a 200-mesh bag filter, allowed to stand, filtered through a 25μ bag filter and centrifuged to obtain a filtrate with a turbidity ≤30.0 NTU.

[0042] In some embodiments, roasted barley and oolong tea leaves need to be extracted separately, and the tea soup is kept in the blending tank for ≤3 hours. Under the premise of meeting the above extraction conditions, the blending of the two can effectively avoid the occurrence of "cloudiness after cooling" in the product.

[0043] This invention provides an oolong barley tea and its preparation method. The tea beverage is a blend of roasted two-row barley, roasted six-row barley, and roasted malt, combined with two types of oolong tea leaves (Narcissus). Hot water extraction is used, and tea aroma and barley aroma indices are selected as aroma quality control indicators. Polysaccharide content is used as a prerequisite for process optimization, solving the problems of uncoordinated aroma, poor tea infusion stability, and weak taste in oolong barley tea. The extraction temperature and time are optimized, significantly improving the problem of uncoordinated tea and barley aroma in oolong barley tea. Furthermore, tea aroma and barley aroma indices are established, and undesirable barley flavor indicators such as 5-methylfurfural, 2-acetylfuran, and furfural, as well as typical barley aroma indicators such as 2-acetylpyrrole, 2-ethylpyrazine, dimethylpyrazine, and methylpyrazine are proposed.

[0044] To provide a clearer and more detailed description of the oolong barley tea and its preparation method provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0045] Example 1 This embodiment provides an oolong barley tea, the preparation method of which is as follows: (1) Raw material weighing: Weigh the barley and tea leaves according to the weight ratio of roasted two-row barley: roasted six-row barley: roasted malt = 8:1:1 and premium narcissus: old narcissus = 1:3-2:1; (2) Extraction: The roasted raw materials (including roasted two-row barley, roasted six-row barley, and roasted malt) were mixed at a ratio of 1:9 and 0.1% of foaming agent was added. The mixture was extracted at 95℃ for 45 minutes. The oolong tea was mixed at a ratio of 1:25 and 0.1% of foaming agent was added. The mixture was extracted at 90℃ for 10 minutes.

[0046] (3) Extraction filtration: After extraction, the extract was filtered through a 100-mesh screen and the filtrate was cooled to below 40°C. It was then filtered again through a 200-mesh bag filter, allowed to stand for 30 min, filtered through a 25μm bag filter, and centrifuged to obtain roasted barley tea filtrate (turbidity ≤30.0 NTU) and oolong tea filtrate (turbidity ≤15.0 NTU), which were stored in storage containers. (4) Preparation: Dissolve and filter the excipients for preparation. Before preparation, the above filtrate is filtered again through a 1μ bag and mixed with the excipient solution. After mixing evenly, the preparation solution is filtered through a 1μ bag to obtain oolong barley tea clear liquid (turbidity ≤ 4.0 NTU, tea polyphenols ≥ 150 mg / kg). (5) Sterilization and bottling: The filtrate is immediately sterilized by UHT (138±2℃, 30s) and stored in a sterile tank to cool to room temperature. Finally, it is cooled in a sterile cold tank (25±5℃) to obtain the finished oolong barley tea.

[0047] Example 2 This embodiment provides a method for screening barley and oolong tea raw materials: First, Canadian two-row barley and French six-row barley with a protein content of less than 12%, and barley malt with a protein content of less than 10% were selected as raw materials. The barley was repeatedly soaked in 40℃ RO water for 40 minutes. During the soaking process, 30 kHz ultrasound was used for assisted treatment.

[0048] The roasting temperatures for malt, two-row barley, and six-row barley were 175℃, 185℃, and 210℃, respectively. The roasting times for two-row barley were 40 min, 80 min, and 120 min, respectively; the roasting times for malt were 40 min and 100 min, respectively; and the roasting times for six-row barley were 130 min to 200 min. During roasting, each time the temperature was lowered to 95℃, 1% RO water was immediately and evenly added, and the temperature was raised again for roasting.

[0049] The aroma index of different oolong tea varieties was determined by GC-MS, and sensory evaluation was conducted.

[0050] Example 3 This embodiment provides a method for screening the blending ratio of barley extract and oolong tea extract: The ratio of barley extract to oolong tea extract is between 1:4 and 4:1. The oolong tea varieties selected are premium grade Narcissus and premium old-growth Narcissus, with consumer sensory evaluation as the determining factor.

[0051] Example 4 This embodiment provides a method for screening the extraction time of oolong tea extract: The extraction time for oolong tea is 2-10 minutes. The ratio of premium grade narcissus tea to premium old-growth narcissus tea is 1:1. At the same time, the basic indicators of the tea soup are tested.

[0052] Performance testing The results of the floral aroma and tea aroma index tests of the oolong barley tea obtained in Example 1 are shown in Table 1.

[0053] Table 1. Results of flower and tea aroma index detection for oolong barley tea obtained in Example 1.

[0054] In Table 1, Sample 1 is commercially available oolong tea 1, Sample 2 is commercially available oolong tea 2, Sample 3 is optimized formula 1, Sample 4 is optimized formula 2, Sample 5 is optimized formula 3, Sample 6 is optimized formula 4, Sample 7 is optimized formula 5, Sample 8 is optimized formula 6, and Sample 9 is optimized formula 7.

[0055] Among them, optimized formula 1 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 2:1, with a tea ingredient dosage of 8.2 g / L; optimized formula 2 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 1:1, with a tea ingredient dosage of 8.0 g / L; optimized formula 3 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 1:2, with a tea ingredient dosage of 8.0 g / L; optimized formula 4 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 1:3, with a tea ingredient dosage of 8.0 g / L; optimized formula 5 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 1:1, with a tea ingredient dosage of 8.2 g / L; optimized formula 6 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 2:1, with a tea ingredient dosage of 7.8 g / L; and optimized formula 7 refers to a ratio of premium grade Narcissus to old-growth Narcissus of 1:3, with a tea ingredient dosage of 8.2 g / L. In Table 1, A1 refers to terpenes such as linalool, geraniol, and nerolidol, as well as cis-jasmone, jasmone lactone, and methyl jasmone acid. A2 refers to indole, and B refers to cis-trans-2,4-heptadienal and trans-trans-2,4-heptadienal.

[0056] The results of the floral and wheat aroma index tests of the oolong barley tea obtained in Example 1 are shown in Table 2.

[0057] Table 2. Results of tea aroma and wheat aroma index tests of oolong barley tea obtained in Example 1

[0058] Among them, Sample 1 is commercially available oolong tea, the same as in Table 1, and Sample 7 is the optimized formula 5 corresponding to Table 1.

[0059] As shown in Table 1, the tea aroma of Oolong barley tea products prepared by Formulas 1, 5, and 6 in Example 1 of this invention is higher than that of commercially available Oolong tea. Considering that an excessively strong tea aroma would mask the barley aroma, Formula 5 was selected for large-scale production testing. The results are shown in Table 2. The tea aroma and barley aroma index of the Oolong barley tea product obtained by the optimized Formula 5 in this embodiment of the invention are both higher than those of commercially available products.

[0060] Table 3. Physicochemical test results of the extract from roasted barley prepared in Example 2.

[0061] From Table 3 and Figure 1It can be seen that the roasted barley prepared in Example 2 of this invention meets the color requirements. Under the premise of meeting the color requirements, the protein content in both roasted two-row and roasted six-row barley is less than 5%, and the protein content in roasted malt is less than 10%. In the extracts obtained from the above barley, the protein content in both roasted two-row and roasted six-row barley is below the detection line, and the protein content in the roasted malt extract is 0.43 g / L, meeting the requirements for low-protein raw materials. Roasting causes some of the protein in barley to degrade into small-molecule amino acids, resulting in a sweeter final product. Simultaneously, each extract contains a certain amount of maltodextrin, which can effectively improve the taste of barley tea, making the product more mellow.

[0062] Table 4. Results of the test on the aroma index of the selected oolong tea in Example 2

[0063] Table 5. Sensory evaluation results of the oolong tea selected in Example 2.

[0064] Based on the results in Tables 4 and 5, the aroma of premium-grade Narcissus tea is significantly stronger than that of Tieguanyin, Rougui, and Da Hong Pao. Combined with sensory evaluation results, Narcissus oolong tea has a better floral aroma, harmonizing well with the aroma of barley tea. Rougui and Da Hong Pao have a pronounced roasted aroma, resulting in a noticeable burnt taste when blended with barley tea, making them unsuitable for pairing. Tieguanyin and ordinary oolong tea have a strong grassy aroma or a weak fragrance, and their tea soup is quite bitter and astringent, resulting in a noticeably astringent taste when blended with barley tea. Therefore, premium-grade Narcissus 2 and 3 are preferred as raw materials for oolong barley tea.

[0065] Table 6. Evaluation results of the extraction solution ratios in Example 3.

[0066] As shown in Table 6, when the ratio of premium grade Narcissus to premium grade old-growth Narcissus is between 1:2 and 1:3, the oolong tea aroma is more intense. When the ratio of barley to the overall oolong tea is between 1:1 and 1:3, the barley and tea aromas are more harmonious. In Experiment 9, when the solid content ratio of barley:premium grade Narcissus:premium old-growth Narcissus is 4:1:3, the oolong barley tea has a harmonious overall aroma, with both barley and tea aromas being more prominent, and a mellow taste.

[0067] Table 7. Detection indicators of the oolong tea extract from Example 4

[0068] As shown in Table 7, during the extraction of oolong tea, the proportions of tea polyphenols and solids increased rapidly between 2 and 6 minutes. After 6 minutes, there was no significant change in solids, but the color and tea polyphenol content increased. The tea polyphenol content exceeded 1900 mg / L at 12 minutes, which led to increased turbidity when blending oolong barley tea and increased the risk of poor stability in the final product.

Claims

1. A type of oolong barley tea, characterized in that, It is prepared by blending barley extract and oolong tea extract; The barley extract has a malt aroma index greater than 0.1 and less than 0.9; the malt aroma index is calculated using the following formula: Wheat aroma index = (2-acetylpyrrole + 2-ethylpyrazine + dimethylpyrazine + methylpyrazine) / (5-methylfurfural + 2-acetylfuran + furfural); The tea leaves used to prepare the oolong tea extract have an aroma index greater than 2.5; the aroma index is calculated using the following formula: Tea aroma index = A / B; Total floral fragrance A = linalool + geraniol + cis-jasmine + jasmine lactone + nerolidol + methyl jasmonate + indole Total odor amount B = cis-trans-2,4-heptadienal + trans-trans-2,4-heptadienal + indole.

2. The method for preparing oolong barley tea according to claim 1, characterized in that, The barley extract was obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, with the weight ratio of roasted two-row barley, roasted six-row barley, and roasted malt being 8:1:

1. The oolong tea extract is obtained by extracting premium grade oolong tea and premium grade old-growth narcissus tea, with the weight ratio of premium grade oolong tea to premium grade old-growth narcissus tea being 1:3-2:

1.

3. The method for preparing oolong barley tea according to claim 2, characterized in that, The preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt include a pretreatment step and a roasting step. The pretreatment step includes: Two-row barley and six-row barley with a protein content of less than 13%, and barley malt with a protein content of less than 10% were selected as raw materials. They were repeatedly soaked in warm water at a temperature of 40-60℃ for 30-70 minutes. During the soaking process, ultrasonic treatment at 20-100 kHz was applied to obtain pretreated raw materials.

4. The method for preparing oolong barley tea according to claim 3, characterized in that, The preparation steps of roasted two-row barley, roasted six-row barley, and roasted malt also include a baking step, which includes: After drying the pretreated raw materials, bake them at 1000-2000 rpm for 35-70 minutes at a baking temperature of 150-230℃. During baking, pause every 5 minutes to cool down to below 100℃ with air cooling and add 0.1%-2% RO water, then reheat and bake to obtain roasted two-row barley, roasted six-row barley, and roasted malt.

5. The method for preparing oolong barley tea according to claim 4, characterized in that, The roasted two-row barley and roasted six-row barley have a protein content of less than 0.5%, and the roasted malt has a protein content of less than 1%.

6. The method for preparing oolong barley tea according to claim 2, characterized in that, The roasted two-row barley should have a color target value of 5-20 EBC, the roasted malt should have a color target value of 20-50 EBC, and the roasted six-row barley should have a color target value of 50-150 EBC.

7. The method for preparing oolong barley tea according to claim 2, characterized in that, The barley extract is obtained by extracting roasted two-row barley, roasted six-row barley, and roasted malt, comprising: The roasted two-row barley, roasted six-row barley, and roasted malt were added to RO water at a ratio of 1:5 to 1:25 for extraction. The extraction temperature was 80℃-98℃ and the extraction time was 30-90 min.

8. The method for preparing oolong barley tea according to claim 2, characterized in that, The oolong tea extract is obtained by extracting premium oolong tea and premium narcissus tea, comprising: Premium oolong tea and premium narcissus tea were added to RO water at a ratio of 1:10 to 1:50 for extraction. The extraction temperature was 70℃-95℃ and the extraction time was 2-20 min. The tea polyphenol content of the extract was ≤1900 mg / L.

9. The method for preparing oolong barley tea according to claim 2, characterized in that, Also includes: Before blending, the barley extract and the oolong tea extract are filtered through a 1μ bag and blended with the auxiliary materials. After being mixed evenly, the blended liquid is filtered through a 1μ bag to obtain oolong barley tea clear liquid. The turbidity of the oolong barley tea clear liquid is ≤4.0 NTU. The oolong barley tea clear liquid is subjected to ultra-high temperature instantaneous sterilization and aseptic cold packaging to obtain the finished oolong barley tea.

10. The method for preparing oolong barley tea according to claim 2, characterized in that, Before blending, the barley extract and the oolong tea extract are each subjected to the following treatments: After extraction, the solution is filtered through a drum sieve and cooled to room temperature. It is then filtered again through a 200-mesh bag filter, allowed to stand, filtered through a 25μ bag filter, and centrifuged to obtain the filtrate, the turbidity of which is ≤30.0 NTU.

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