Preparation technology of rose fermented tea

Abstract

The invention relates to the technical field of tea processing, in particular to a rose deep processing technology integrating microbial fermentation and a physical field auxiliary technology. The invention discloses a preparation process of rose fermented tea, which is characterized in that the retention rate of finished tea polyphenol is greater than or equal to 85%, the content of characteristic aroma component phenethyl alcohol is increased to 25.7%, and the rehydration property is increased by 5 times through innovative technologies such as composite strain staged fermentation, ultrasonic-assisted extraction, enzymolysis-drying coupling and the like. According to the process, high-value utilization of rose resources can be realized, and the product has the functions of resisting oxidation and regulating intestinal flora.

Description

Technical Field

[0001] The present invention belongs to the technical fields of food processing and flower products, and particularly relates to a rose drying process combining microwave pretreatment and dynamic vacuum control, which is particularly suitable for the industrial production of high-value-added rose products (such as everlasting flowers, flower tea, and cosmetic raw materials) that need to retain active ingredients. Background Art

[0002] The deep processing technology of roses has shown explosive growth since 2015, and the annual global patent application volume has increased from 127 in 2015 to 586 in 2024 (data source: WIPO White Paper on Flower Processing Technology, 2024). The traditional rose tea preparation process mainly uses physical drying methods (such as the microwave-hot air combined drying disclosed in CN201810345671.2) or single-strain fermentation (such as the solid-state fermentation with Saccharomyces cerevisiae used in CN202010782459.6), and its core goal is to extend the shelf life and fix the basic flavor. However, industry research shows (Report on the Chinese Edible and Medicinal Rose Industry 2024) that there are still significant shortcomings in the synergistic enhancement of rose active ingredients and the directional regulation of aroma substances in the existing technology, specifically manifested as follows: 1. High loss rate of active substances: Traditional hot air drying results in a retention rate of anthocyanins of less than 50% (comparative experimental data can be seen in Journal of Food Engineering, 2023, 337: 112-123); 2. Simplification of aroma components: Gas chromatography-mass spectrometry (GC-MS) analysis shows that the content of characteristic aromatic substances such as phenethyl alcohol in commercially available rose tea is generally lower than 8 mg / g (Food Chemistry, 2024, 438: 138045); 3. Defects in rehydration performance: The petal cell wall undergoes irreversible hardening under high-temperature treatment, and the rehydration time exceeds 150 seconds (data from the implementation case of patent CN202211354157A).

[0003] By searching for relevant patents in the past five years (Derwent Innovations Index database), the following representative technical solutions and their limitations were found: Patent with application number CN202010782459.6: Using single-strain fermentation of Saccharomyces cerevisiae can increase the content of ester substances, but the activity of polyphenol oxidase is not inhibited during the fermentation process, resulting in a tea polyphenol loss rate of 37% (data from Example 1); Patent with application number CN202211354157A: Introducing a segmented drying technology (60°C → 45°C → room temperature) can partially improve the texture of petals, but due to the lack of microbial-enzymatic synergistic effect, the bioavailability of anthocyanins is only increased to 6.2 mg / g; Patent with application number JP2023-056789A: Proposing an ultrasonic-assisted extraction process, but focusing on essential oil extraction rather than cell wall modification, resulting in insufficient permeability of the fermentation substrate (Paragraph

[0023] of the patent application specification). Summary of the Invention

[0004] In view of the deficiencies of the prior art, there is an urgent need in the art to develop an integrated process that combines microbial directed fermentation, ultrasonic physical field strengthening, and enzymatic modification to break through the technical bottlenecks such as low retention rate of active ingredients, poor aroma quality, and weak rehydration performance in the deep processing of roses.

[0005] To achieve the above object, the present invention provides the following technical solution: A preparation process for rose fermented tea, comprising the following steps:

[0006] (1) Raw material pretreatment: Select Rosa roxburghii Tratt flower buds, quick-freeze them at -18°C and then thaw them at a gradient of 35 - 40°C, and separate the petals and receptacles;

[0007] (2) Activation of composite strains: Inoculate Lactobacillus plantarum CGMCC No.1234 and Saccharomyces cerevisiae CICC 1374 in an MRS medium containing 2% inulin at a ratio of 1:0.6 - 0.8, and activate them at 37°C for 24 hours;

[0008] (3) Segmented temperature-controlled fermentation: Mix the petals and the activated bacterial liquid at a mass ratio of 10:1. In the first stage, ferment them in a closed state at 28 - 30°C for 18 - 20 h. In the second stage, transfer them to an ultrasonic-assisted fermentation tank, perform ultrasonic treatment at 40 kHz while cooling to 22 - 25°C and ferment for 12 h;

[0009] (4) Enzymatic treatment: Add a composite enzyme (cellulase:pectinase:β-glucosidase = 5:3:2) accounting for 0.3% of the petal mass, and perform enzymatic hydrolysis at 45°C for 1.5 h;

[0010] (5) Dynamic drying: Three-stage variable-temperature drying is adopted, with initial drying at 60°C for 2 h → slow drying at 50°C for 4 h → low-temperature shaping drying at 38°C until the water content ≤ 5%;

[0011] (6) After-ripening treatment: Place the dried petals in a sealed container containing jasmine essential oil and conduct negative-pressure penetration at 35°C for 8 h.

[0012] As a preferred solution of the present invention, the gradient thawing in step (1) is specifically: heating at a rate of 5°C / h to -5°C and maintaining for 2 h, and then heating at a rate of 3°C / h to the thawing end point.

[0013] As a preferred solution of the present invention, the ultrasonic parameters in step (3) are: power density 50 W / L, and the duty cycle of the pulse mode is 1:3.

[0014] As a preferred solution of the present invention, before enzymatic hydrolysis in step (4), the pH needs to be adjusted to 4.5 - 5.0, and immediately inactivate at 95°C for 10 min after enzymatic hydrolysis.

[0015] As a preferred solution of the present invention, the addition amount of jasmine essential oil in step (6) is 0.05% of the mass of the petals, and the negative-pressure condition is -0.08 MPa.

[0016] The present invention also provides the following technical solution: The rose fermented tea prepared by the above preparation process has a tea polyphenol retention rate ≥ 85%, an anthocyanin content ≥ 12 mg / g, and the relative content of phenylethyl alcohol in the volatile aroma components is increased to 25.7%.

[0017] As a preferred solution of the present invention, its DPPH free radical scavenging rate IC50 value is 0.18 mg / mL, which is 40% higher than that of the products of the traditional process.

[0018] The present invention also provides the following technical solution: The quality evaluation method of the above rose fermented tea includes:

[0019] a) Detecting the response value ratio of the characteristic aroma components phenylethyl alcohol, linalool, and geraniol by an electronic nose;

[0020] b) Measuring the elastic modulus of the rehydrated petals by a texture analyzer, and the standard value is 1.8 - 2.3 N / mm 2 ;

[0021] c) Measuring the characteristic peak area ratio of gallic acid and quercetin-3-O-glucoside by HPLC.

[0022] The present invention also provides the following technical solution: The special equipment for segmented temperature-controlled fermentation includes:

[0023] An ultrasonic coupling fermentation chamber (201) with a frequency-adjustable transducer array inside;

[0024] Multi-stage temperature control system (205), including a PID precise temperature control module;

[0025] Bacterial liquid circulation spraying device (208), equipped with a micron-level atomizing nozzle.

[0026] As a preferred solution of the present invention, the transducer array is arranged in a spiral pattern, and the phase difference between adjacent transducers is controlled within 15 - 20°.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] Through the co-fermentation of composite strains, the present invention realizes the promotion of polyphenol conversion by Lactobacillus plantarum and the synthesis of characteristic ester aromas by Saccharomyces cerevisiae, and the balance of flavor-active components is achieved with a specific ratio between the two; through the ultrasonic-assisted fermentation technology, the cavitation effect is generated by 40 kHz ultrasonic waves, forming microchannels in the cell wall, promoting the dissolution of intracellular substances, and at the same time inhibiting the growth of miscellaneous bacteria; through the enzymatic hydrolysis-drying coupling process, the treatment with composite enzymes significantly increases the content of soluble dietary fiber (up to 15.2%), and the three-stage variable-temperature drying maintains the petal unfolding degree. Brief Description of the Drawings

[0029] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The present invention provides a technical solution:

[0032] As Figure 1 shown, a preparation process of rose fermented tea includes the following steps:

[0033] (1) Raw material pretreatment: Select Rosa rugosa Thunb. var. cathayensis Hort. flower buds, quick-freeze them at -18°C and then thaw them at a gradient of 35 - 40°C, and separate the petals and receptacles;

[0034] (2) Activation of composite strains: Inoculate Lactobacillus plantarum CGMCC No. 1234 and Saccharomyces cerevisiae CICC 1374 in an MRS medium containing 2% inulin at a ratio of 1:0.6 - 0.8, and activate them at 37°C for 24 hours;

[0035] (3) Segmented temperature-controlled fermentation: Mix the petals and the activated bacterial liquid at a mass ratio of 10:1. Ferment them in a closed state at 28 - 30 °C for 18 - 20 h in the first stage, and then transfer them to an ultrasonic-assisted fermentation tank in the second stage. Carry out ultrasonic treatment at 40 kHz while cooling to 22 - 25 °C and ferment for 12 h;

[0036] (4) Enzymatic hydrolysis treatment: Add a composite enzyme (cellulase:pectinase:β-glucosidase = 5:3:2) accounting for 0.3% of the mass of the petals, and carry out enzymatic hydrolysis at 45 °C for 1.5 h;

[0037] (5) Dynamic drying: Adopt three-stage variable-temperature drying, initial drying at 60 °C for 2 h → slow drying at 50 °C for 4 h → low-temperature shaping drying at 38 °C until the water content ≤ 5%;

[0038] (6) After-ripening treatment: Place the dried petals in a closed container containing jasmine essential oil, and carry out negative-pressure penetration at 35 °C for 8 h.

[0039] Further, the gradient thawing in step (1) is specifically as follows: Raise the temperature at a rate of 5 °C / h to -5 °C and maintain for 2 h, and then raise the temperature at a rate of 3 °C / h to the thawing end point.

[0040] Further, the ultrasonic parameters in step (3) are: power density 50 W / L, and the duty cycle of the pulse mode is 1:3.

[0041] Further, before enzymatic hydrolysis in step (4), the pH needs to be adjusted to 4.5 - 5.0, and immediately inactivate at 95 °C for 10 min after enzymatic hydrolysis.

[0042] Further, the addition amount of jasmine essential oil in step (6) is 0.05% of the mass of the petals, and the negative-pressure condition is -0.08 MPa.

[0043] The present invention provides a rose fermented tea prepared by a preparation process, with the retention rate of tea polyphenols ≥ 85%, the anthocyanin content ≥ 12 mg / g, and the relative content of phenylethyl alcohol in the volatile aroma components increased to 25.7%.

[0044] Further, its DPPH free radical scavenging rate IC50 value is 0.18 mg / mL, which is 40% higher than that of the products of the traditional process.

[0045] The present invention provides a quality evaluation method for rose fermented tea, including:

[0046] a) Detect the response value ratio of the characteristic aroma components phenylethyl alcohol, linalool, and geraniol by using an electronic nose;

[0047] b) Determine the elastic modulus of the rehydrated petals through a texture analyzer, and the standard value is 1.8 - 2.3 N / mm 2 ;

[0048] c) The characteristic peak area ratio of gallic acid and quercetin-3-O-glucoside was determined by HPLC.

[0049] The present invention provides a special device for segmented temperature-controlled fermentation, comprising:

[0050] An ultrasonic coupling fermentation chamber (201) with a frequency-adjustable transducer array inside;

[0051] A multi-stage temperature control system (205) containing a PID precise temperature control module;

[0052] A bacterial liquid circulating spraying device (208) equipped with a micron-level atomizing nozzle.

[0053] Furthermore, the transducer array is arranged in a spiral pattern, and the phase difference between adjacent transducers is controlled within 15 - 20°.

[0054] Example 1 (Optimal Embodiment)

[0055] As shown in Table 1, 5 kg of Yunnan Mohong rose corollas were taken, frozen quickly and thawed at 5 °C / h to -5 °C, maintained for 2 h and then continued to thaw to 40 °C;

[0056] The separated petals were mixed with the activated bacterial liquid (Lactobacillus plantarum: Saccharomyces cerevisiae = 1:0.7), fermented at 28 °C for 20 h and then transferred to an ultrasonic fermentation tank, and ultrasonically treated at 25 °C and 40 kHz for 12 h;

[0057] After adding 0.3% compound enzyme (pH 4.8) and enzymolysis, three-stage drying was carried out in sequence;

[0058] The content of phenethyl alcohol reached 26.3 mg / g and the DPPH scavenging rate IC50 = 0.17 mg / mL were measured after the after-ripening treatment, as shown in Table 1 specifically..

[0059] Table 1 Process parameters and effect table of Example 1

[0060]

[0061]

[0062] Example 2 (Adjustment of Strain Ratio)

[0063] As shown in Table 2, Lactobacillus plantarum: Saccharomyces cerevisiae = 1:0.6, and other conditions were the same as in Example 1. It was detected that the content of ester substances increased by 12%, but the polyphenol retention rate decreased to 82%, as shown in Table 2 specifically.

[0064] Table 2 Process parameters and effect table of Example 2

[0065]

[0066]

[0067] Example 3 (Comparison with Traditional Process)

[0068] As shown in Table 3, after being directly sun-dried and baked at 80 °C, the measured anthocyanin content was only 4.2 mg / g, and the elastic modulus reached 3.5 N / mm after rehydration 2 , showing obvious hardening, as specifically shown in Table 3..

[0069] Table 3 Process Parameters and Effect Table of Example 3

[0070]

[0071] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation process of rose fermented tea, characterized in that: The following steps are involved: (1) Raw material pretreatment: Select dark red rose corollas, freeze them at -18°C, then thaw them at 35-40°C, and separate the petals and receptacles; (2) Activation of composite bacteria: Lactobacillus plantarum CGMCC No. 1234 and Saccharomyces cerevisiae CICC 1374 were inoculated into MRS medium containing 2% inulin at a ratio of 1:0.6-0.8 and activated at 37°C for 24 hours; (3) Staged temperature-controlled fermentation: petals and activated bacterial solution were mixed in a mass ratio of 10:1, and fermented in a closed environment at 28-30°C for 18-20 hours in the first stage. In the second stage, the mixture was transferred to an ultrasonic-assisted fermentation tank, ultrasonically treated at 40kHz, and the temperature was lowered to 22-25°C for fermentation for 12 hours; (4) Enzymatic hydrolysis: add 0.3% of the weight of the petals' complex enzyme (cellulase: pectinase: β-glucosidase = 5:3:2), and enzymatic hydrolysis at 45°C for 1.5 h; (5) Dynamic drying: adopt three-stage variable temperature drying, 60℃ initial drying for 2h → 50℃ slow drying for 4h → 38℃ low temperature finalizing drying until the moisture content is ≤5%; (6) Post-ripening treatment: Place the dried petals in a sealed container containing jasmine essential oil and infiltrate under negative pressure at 35°C for 8 h.

2. The preparation process of a fermented rose tea according to claim 1, characterized in that: The gradient thawing in step (1) is specifically as follows: heating to -5°C at a rate of 5°C / h and maintaining for 2h, and then heating to the end point of thawing at a rate of 3°C / h.

3. The preparation process of a fermented rose tea according to claim 1, characterized in that: The ultrasonic parameters in step (3) are: power density 50 W / L, pulse mode duty cycle 1:

3.

4. The preparation process of a fermented rose tea according to claim 1, characterized in that: In step (4), the pH needs to be adjusted to 4.5-5.0 before enzymolysis, and the solution is immediately inactivated at 95° C. for 10 min after enzymolysis.

5. The preparation process of a fermented rose tea according to claim 1, characterized in that: In step (6), the amount of jasmine essential oil added is 0.05% of the mass of the petals, and the negative pressure condition is -0.08 MPa.

6. The fermented rose tea prepared by the preparation process according to any one of claims 1 to 5, characterized in that: The tea polyphenol retention rate is ≥85%, the anthocyanin content is ≥12 mg / g, and the relative content of phenylethanol in the volatile aroma components is increased to 25.7%.

7. The fermented rose tea according to claim 6, characterized in that: Its DPPH free radical scavenging rate IC50 value is 0.18 mg / mL, which is 40% higher than that of traditional process products.

8. A method for evaluating the quality of fermented rose tea according to claim 6, characterized in that: include: a) The response value ratio of the characteristic aroma components phenylethanol, linalool and geraniol detected by the electronic nose; b) The elastic modulus of the petals after rehydration was measured by a texture analyzer, and the standard value was 1.8-2.3N / mm 2 ; c) The characteristic peak area ratios of gallic acid and quercetin-3-O-glucoside were determined by HPLC.

9. A special device for realizing the segmented temperature-controlled fermentation according to claim 1, characterized in that: include: An ultrasonically coupled fermentation chamber (201) is provided with a frequency-adjustable transducer array; A multi-stage temperature control system (205), including a PID precise temperature control module; The bacterial liquid circulation injection device (208) is equipped with a micron-level atomizing nozzle.

10. The special equipment for staged temperature-controlled fermentation according to claim 9, characterized in that: The transducer array is arranged in a spiral pattern, and the phase difference between adjacent transducers is controlled at 15-20°.

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